Science and Technology of Lighting · Dominic O’Brien (University of Oxford) Philip Shadbolt (Zeta Group) Philip Shields (University of Bath) Manuel Spitschan (University of Oxford)

16th International Symposium on the

Science and Technology of Lighting

June 17-22, 2018

University of Sheffield, United Kingdom

1

CONFERENCE CHAIRS

WELCOME TO LS16! It is our great pleasure to invite you to participate in the

16th International Symposium on the Science

and Technology for Lighting (LS16)

CONFERENCE HIGHLIGHTS

LS Symposia: The International Symposium on the

Science and Technology of Lighting (LS) aims to provide

an excellent forum for scientists and engineers worldwide,

in both academia and industry, to share and exchange the

latest progress on the Science and Technology of Lighting.

LS used to be held every three years, such as LS7 in Kyoto

(1995), LS8 in Greifswald (1998), LS9 in Ithaca (2001),

LS10 in Toulouse (2004), LS11 in Shanghai (2007), LS12

in Eindhoven (2010). Since LS13 in Troy (2012), LS has

become a series of biennial symposiums, followed by LS14

in Lake Como (2014) and LS15 in Kyoto (2016).

Invited Speakers: A number of leading scientists

in lighting science and technology fields have been invited

and will give invited talks this year.

Special Sessions: Special sessions about colour

science and technology will be held on Wednesday

morning.

Conference Banquet: Don’t miss this year

banquet on Wednesday night in INOX within the campus of

University of Sheffield.

Refreshment and Welcome: An evening

refreshment and a welcome reception will be held on

Sunday and Monday night, respectively, at the Diamond

conference venue.

Robin Devonshire

FAST-LS, UK

Tao Wang

University of Sheffield

TABLE OF CONTENTS CONFERENCE SCHEUDLE OVERVIEW 2

TRANSPORTATION RESOURCES 3

CAMPUS MAP 4

FLOOR PLANS 5

SPONSORS& SUPPORTING ORGANIZATIONS 6

COMMITTEES 7

SYMPOSIUM TOPICS 8

PLENARY SPEAKERS 9

INVITED SPEAKERS 10

EVENTS AT-A-GLANCE 11

SPECIAL EVENTS 12

PROGRAMME 13

ORAL PRESENTATIONS 18

POSTER PRESENTATIONS 34

2

Plenary Talks

Invited Talks

Contributed Talks

Day/Time Sunday

3.1.3 C1.3

3.2.3

Opening remarks

Refreshments

C1.4

Poster session Th4.4

Coffee Break

08:00 - 09:00

10:30 - 11:00

15:30 - 17:00

17:00 - 18:00

15:00 - 15:30

2.1.1

2.1.4

09:00 - 10:30

12:30 -13:30

13:30 - 15:00

11:00 - 12:30

1.2.3

1.2.4

1.2.1

1.2.2

Coffee Break

2.1.2

2.1.3

C1.1 Plenary 4.1.1

Plenary 1.1.2

Plenary 1.1.3

4.3.3

1.4.1

1.4.2

1.4.3

1.4.4

1.3.1

1.3.2

1.3.3

1.3.4

Coffee Break

4.2.3

Lunch

Plenary 4.1.2

4.1.3

4.3.5

C1.2

C2.1

C2.2

Registration

Registration

Plenary 0.1.1

Plenary 0.1.2

Banquet (19:00-21:00)

2.2.5 3.2.4

2.3.4

2.3.5

Plenary 2.3.1

Free Afternoon

Coffee Break

Welcome Reception

Lunch

3.1.1

3.1.2

3.1.4

Opening 1.1.1

1.4.5

Friday

Registration Registration Registration

5.1.1

Coffee Break

Monday Tuesday Wednesday Thursday

Coffee BreakCoffee Break

5.1.2

5.1.3

5.1.4

Coffee Break

5.2.1

2.2.1

2.2.4

3.2.2

3.2.15.2.2

Closing remarks4.2.4

4.2.5

5.2.32.2.3

2.2.2

2.4.1

2.4.2

2.4.3

2.4.4

2.4.5

4.3.1

4.3.4

4.2.1

Lunch Lunch

4.3.2 2.3.2

2.3.3

4.2.2

C2.3

CONFERENCE SCHEDULE OVERVIEW

TRANSPORTATION RESOURCESCONFERENCE

SCHEUDLE OVERVIEW

TRANSPORTATION RESOURCES


SCHEUDLE OVERVIEW


SCHEUDLE OVERVIEW





SCHEUDLE OVERVIEW


SCHEUDLE OVERVIEW



SCHEUDLE OVERVIEW


SCHEUDLE OVERVIEW


3


















TRANSPORTATION

The nearest international airport

to Sheffield is Manchester

Airport.

The airport also has its own

railway station and visitors can

easily catch the 1-hour train

directly into Sheffield.

Once in the Sheffield railway

station, you can get the Blue Line

tram (destination Malin Bridge)

from the station to The University

of Sheffield stop, which is just a

few minutes’ walk to The

Diamond.

TRANSPORTATION



Airport.






station, you can get the Line

tram (destination Malin Bridge)

from the station to The University

of Sheffield stop, which is just a

few minutes’ walk to The

Diamond.

TRANSPORTATION



Airport.






station, you can get the Line

PARKING

Parking close to the Diamond on

Brook Hill and Broad Lane or you

can pre-book your parking at Q-

Park at Rockingham St.

Parking





PARKING





Parking





PARKING

ACCOMMODATION

Hotel booking:

https://book.passkey.com/event/4

9241700/owner/9279439/home


accommodation:

https://www.sheffield.ac.uk/accom

modation/visitors/index

CAMPUS MAPAccommodation

Hotel booking:

https://book.passkey.com/event/4

9241700/owner/9279439/home


accommodation:

https://www.sheffield.ac.uk/accom

modation/visitors/index

CAMPUS MAP

REGISTRATION

Visit the University of Sheffield

online store and select ‘Book

event’

Create an account to register

your details (or login if you’ve

used the online store before)

and select the delegate rate

you wish to purchase.

The conference banquet and

accompanying person

registration are shown as

optional extras during the

registration process.

Once you’ve paid online you

will be sent an order

confirmation email with an

order number. Please retain

this information as it also

serves as your ticket for the

event.

Name badges can be collected

at the reception desk of the

Diamond and should be worn

for the duration of the

conference.

REGISTRATION

Visit the University of Sheffield

online store and select ‘Book

event’

Create an account to register

your details (or login if you’ve

used the online store before)

and select the delegate rate

you wish to purchase.

The conference banquet and

accompanying person

registration are shown as

optional extras during the

registration process.

Once you’ve paid online you

will be sent an order

confirmation email with an

order number. Please retain

this information as it also

https://www.q-park.co.uk/en-gb/cities/sheffield/rockingham-street/








https://book.passkey.com/event/49241700/owner/9279439/home


https://www.sheffield.ac.uk/accommodation/visitors/index






https://onlineshop.shef.ac.uk/conferences-and-events/faculty-of-engineering/electronic-electrical-engineering/ls16




4

The Diamond, Conference Venue:

Address: The University of Sheffield, 32 Leavygreave Rd, Sheffield S3 7RD

Phone: 0114 222 9134

INOX, Banquet Venue:

Address: Inox, Level 5, Student's Union Building, Durham Rd, Sheffield, S10 2TG

Phone: 0114 222 6043

CAMPUS MAP

FLOOR PLANSCAMPUS MAP

FLOOR PLANS



FLOOR PLANS

FLOOR PLANS

FLOOR PLANS



FLOOR PLANS



FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

5

Ground Floor, the Diamond, University of Sheffield:

Basement, the Diamond, University of Sheffield

LT1, Lecture Theatre 1: Sunday Evening Lecture and Monday Plenary Session

LT3, Lecture Theatre 3: Daily Session, Tuesday and Thursday Plenary Session

LT4, Lecture Theatre 4: Colour Workshop Session

Atrium: Lunch, Refreshment and Poster Session

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

FLOOR PLANS

Atrium

SPNOSOR

S&

SUPPORT

ING

ORGANIZ

ATIONSL

OBBY

SPO

NSO

RS &

SUPP

ORTI

NG

ORG

ANIZ

6

Platinum sponsor

Sponsors

Technical co-sponsorship

Supporting organizations:

The LS16 is organized and supported by the University of Sheffield, Centre for

GaN Materials and Devices.

SPONSORS & SUPPORTING ORGANIZATIONS

COMMITTEESSPNOSORS& SUPPORTING

ORGANIZATIONS

COMMITTEES

SYMPOSIUM TOPICSCOMMITTEESSPONSORS &

SUPPORTING ORGANIZATIONS


ORGANIZATIONS

COMMITTEES

SYMPOSIUM TOPICSCOMMITTEES

SYMPOSIUM TOPICS

TOPICS AT-A-GLANCESYMPOSIUM

TOPICSCOMMITTEES




ORGANIZATIONS

COMMITTEES




ORGANIZATIONS

7

International scientific committee

Chair: Robin Devonshire (University of Sheffield, UK, FAST-LS)

Secretary: Georges Zissis (Toulouse University, France, FAST-

LS) Treasurer: John Stocks (Consultant, UK, FAST-LS)

Members:

Helmar Adler (OSRAM Sylvania, USA)

Yukio Akashi (University Fukuoka, Japan)

Erich Arnold (Heraeus Noblelight, Germany)

Istvan Bakk (Tridonic, Austria)

Laszlo Balazs (Óbuda University, Hungary)

Kanji Bando (Nichia Co, Japan)

Howard Cooper (Institut Cellule Souche et Cerveau,

France)

Alessio Corazza (SAES Getters S.p.A, Italy)

Rudy Geens (Havells-Sylvania Lighting, Belgium)

Peter Hanselaer (University of Leuven, Belgium)

Masafumi Jinno (Ehime University, Japan)

Gerrit M. W. Kroesen (Technical University of

Eindhoven, Netherlands)

Mu-Qing Liu (Fudan University, China)

Ruiqing Ma (UDC, USA)

Jakob Maya (Next Light LLC, USA)

Matteo Meneghini (University of Padova, Italy)

Tessa Pocock (Rensselaer Polytechnic Institute,

USA)

Mark S. Rea (LRC – Rensselaer Polytechnic

Institute, USA)

Manuel Spitschan (University of Oxford)

John Stocks (Ceravision, UK, FAST-LS,Treasurer)

Ching-Chang Sun (National Central University,

Taiwan)

Nikolai Timofeev (University of St Petersburg,

Russia)

Takeo Yasuda (Toshiba Lighting and Technology

Corp, Japan)

Local organising committee:

Chair: Tao Wang (University of Sheffield)

Vice Chair: Stuart Mucklejohn (CIE-UK)

Secretary: Rick Smith (University of Sheffield)

Deputy secretary: Katherine Greenacre (University of Sheffield)

Treasurers:

Peter Raynham (UCL)

John Stocks (Consultant) Members:

Gilberto Brambilla (University of Southampton)

Martin Cryan (University of Bristol)

Phillip Davis (Stockbridge Technology Centre Ltd)

Robin Devonshire (University of Sheffield)

Steve Fotios (University of Sheffield)

Jess Gallacher (Institution of Lighting Professionals)

Allan Howard (Technical Director Lighting & Energy

Solutions at WSP)

Sir Colin Humphreys (University of Cambridge)

Poopathy Kathirgamanathan (Brunel University)

Brendan Keely (Society of Light and Lighting)

Huiyun Liu (University College London)

Rob Martin (University of Strathclyde)

Janet Milne (Genmhor Ltd.)

Martin Morgan-Taylor (De Montfort University)

Dominic O’Brien (University of Oxford)

Philip Shadbolt (Zeta Group)

Philip Shields (University of Bath)

Manuel Spitschan (University of Oxford)

Jack Silver (Brunel University)

Peter Smowton (Cardiff University)

Stephen Sweeney (University of Surrey)

Kevin Theobald (International Association of Lighting

Designers)

COMMITTEES


SYMPOSIUM TOPICS


TOPICSCOMMITTEES


SYMPOSIUM TOPICS

TOPICS AT-A-GLANCESYMPOSIUM TOPICS

SYMPOSIUM TOPICS


TOPICSCOMMITTEES


SYMPOSIUM TOPICS


TOPICSCOMMITTEES


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS

8

A full program of invited speakers, each well known in their respective research fields, has

been planned to provide coverage of important recent advances in lighting.

Contributed Papers in the following areas of lighting science and technology have been

considered for presentation at the conference:

Light sources and systems

Solid State Lighting systems (LED; OLED; Lasers)

III-nitride semiconductors for visible lighting

Novel & legacy light sources

Light source materials

Lighting controls and electronic control gear

Smart lighting systems

Human-factors in lighting

Physical and psychological effects of light

Lighting and visual environment

Lighting design

Applications and technologies

Biological effects of optical radiation

Lighting for transport

Lighting for Smart Cities

Lighting for horticulture & animal husbandry

Lighting metrics & metrology

Environmental impacts

Light pollution

Impacts on eco-systems

Lifecycle Assessment & Lifecycle Costs

Regulations, guidelines & public policies

Authors of Contributed Papers regarded by referees as representing particularly notable and

interesting work will be offered the opportunity to present their papers orally to the conference

as Landmark Papers; otherwise authors of Contributed Papers are expected to prepare a

Poster Presentation of their work. All accepted Contributed Papers will appear in the

published LS16 Proceedings Volume.

SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS


SYMPOSIUM TOPICS

9

Sunday June 17th, 2018, LT-1 (The Diamond)

________________________________________________________________________________

Special Evening Lectures, LS16 Arrival / Registration Day,

Robert Karlicek, RPI, USA

“Cognitive Lighting Systems: A Model for the Future of Illumination”

Ian Tutt, Maritime Signals Consultant, UK

“A History of Lighthouse Lighting”

Monday June 18th, 2018, LT-1 (The Diamond)

_____________________________________________________________________________

Keynote Lectures, LS16 Opening Session,

Ling Wu, Secretary General, CSA, China

“Recent Development of SSL in China”

Yoichi Kawakami, Kyoto University, Japan

“Nitride-based 3D-structures for polychromatic LEDs”

Thursday June 21st, 2018, LT-1 (The Diamond)

_________________________________________________________________________________

Keynote Lectures, LS16 Human Factors Session,

Mariana Figuiero, LRC, USA

“Circadian Light and Circadian Stimulus: Science to Applications”

Arnold Wilkins, University of Essex, UK

“Disruptive aspects of colour science and illumination”

Allan Howard, WSP,

“What future for public lighting in an autonomous world?”

PLENARY SPEAKERS

INVITED SPEAKERSINVITED SPEAKERS

INVITED SPEAKERS

EVENTS AT-A-GLANCEINVITED

SPEAKERSPLENARY SPEAKERS


INVITED SPEAKERS

EVENTS AT-A-GLANCEINVITED SPEAKERS

EVENTS AT-A-GLANCE

SPECIAL EVENTSEVENTS AT-A-GLANCEINVITED

SPEAKERS




INVITED SPEAKERS




INVITED SPEAKERS

10

Yukio Akashi, University of Fukui, Japan

Annette Allen, University of Manchester,

UK

Jan Audenaert, KU Leuven, Belgium

Sebastian Babilon, TU Darmstadt,

Germany

John Barbur, City, University of London

Martin Charlton, University of

Southampton, UK

Siming Chen, UCL, UK

Yong-Hoon Cho, KAIST, South Korea

Martin Dawson, University of Strathclyde,

UK

Xavier Denis, Nichia, Japan

Jiajie Fan, Hohai University, China

Martin Foster, University of Sheffield

Danny Garside, University College

London, UK

Harald Haas, University of Edinburgh, UK

Naoya Hara, Kansai University, Japan

Kale Harbick, Cornell University, USA

Hideki Hirayama, Riken, Japan

Sir Colin Humphreys, University

of Cambridge, UK

Matthieu Iodice, ENTPE, France

Gareth John, the LIA, UK

Takako Kimura-Minoda, Stanley Electric,

Japan

Katsumi Kishino, Sophia University,

Japan

Michael Kneissl, TU Berlin, Germany

Mitsuhiro Koden, Yamagata University,

Japan

Douglas McKenzie, Xanthella, UK

Youri Meuret, KU Leuven, Belgium

Celine Nicole, Philips Lighting Research,

The Netherlands

Peter Parbrook, University College Cork,

Ireland

Simon Pearson, University of Lincoln, UK

Andras Poppe, BME, Hungary

Jose Pozo, European Photonics Industry

Consortium, EU

Luke Price, Public Health England, UK

Sujan Rajbhandari, Coventry University,

UK

Mark Sheinin, Technion Israel Institute of

Technology, Israel

Bo Shen, Peking University, China

Jack Silver, Brunel University, UK

Peter Skabara, University of Glasgow, UK

Kelly Smith, WSP, UK

Andrew Stockman, UCL, UK

Hutomo Suryo Wasisto, TU

Braunschweig, Germany

Nicola Trivellin, LightCube

Rong Zhang, Xiamen University, China

Shanduan Zhang, Fudan University,

China

INVITED SPEAKERS


EVENTS AT-A-GLANCE


SPEAKERS


EVENTS AT-A-GLANCE

SPECIAL EVENTSEVENTS AT-A-GLANCE

SPECIAL EVENTS

PROGRAM AT-A-GLANCESPECIAL

EVENTSEVENTS AT-A-GLANCE


SPEAKERS


EVENTS AT-A-GLANCE


SPEAKERS


EVENTS AT-A-GLANCE

11

Pre-LS16 Satellite Meeting, Friday June 15th and Saturday June 16th

“China-UK Workshop on GaN Materials & Devices”

N.B. Details and registration at: http://gancentre.group.shef.ac.uk/workshop/

Special Evening Lectures, LS16 Arrival / Registration Day, Sunday June 17th

Location: LT-1, The Diamond

Robert Karlicek, RPI, USA “Cognitive Lighting Systems: A Model for the Future of Illumination”

Ian Tutt, Maritime Signals Consultant, UK “A History of Lighthouse Lighting”

Keynote Lectures, LS16 Opening Session, Monday June 18th, 2018


Ling Wu, Secretary General, CSA, China “Recent Development of SSL in China”

Yoichi Kawakami, Kyoto University, Japan “Nitride-based 3D-structures for polychromatic LEDs”

OSA Color Technical Group & The Colour Group (GB) Joint Session,

Wednesday June 20th, 2018


“Colour Science & Technology” Invited Lectures and Panel Discussion

N.B. Day-registration available for non-LS16 delegates

Keynote Lectures, LS16 Human Factors & Environmental Sessions, Tuesday &

Thursday June 19th & 21st, 2018


Mariana Figuiero, LRC, USA “Circadian Light and Circadian Stimulus: Science to Applications”

Arnold Wilkins, University of Essex, UK “Disruptive aspects of colour science and illumination”

Allan Howard, WSP, “What future for public lighting in an autonomous world?”

EVENTS AT-A-GLANCE


SPECIAL EVENTS

PROGRAM AT-A-GLANCESPECIAL EVENTSEVENTS

AT-A-GLANCE


SPECIAL EVENTS

PROGRAM AT-A-GLANCESPECIAL EVENTS

PROGRAMME

ABSTRACTS OF PRESENTATIONSPROGRAM AT-A-

GLANCESPECIAL EVENTS


AT-A-GLANCE


SPECIAL EVENTS


AT-A-GLANCE


SPECIAL EVENTS

http://gancentre.group.shef.ac.uk/workshop/

12

Pre-LS16 Satellite Meeting: “China-UK Workshop on GaN Materials & Devices”

Friday June 15th and Saturday June 16th

This workshop aims to bring together scholars from China and UK to carry out extensive

discussion on Growth Technique, Structures and Properties of Materials, Optoelectronic

devices in wide bandgap semiconductor materials and other fields. And then, to promote the

application for cooperation projects between China Natural Science Foundation (NSFC) and

the UK Engineering and Physical Sciences Research Council (EPSRC), the Royal Society

Project and other British Exchange Projects. http://gancentre.group.shef.ac.uk/workshop/

OSA Color Technical Group & The Colour Group (GB) Joint Sessions “Colour

Science & Technology”

Wednesday June 20th, 2018, LT-4, The Diamond.

The goal of these sessions sponsored jointly by the OSA Color Technical Group and the

Colour Group (GB) is to bring together researchers in colour science working on key

advancements in understanding colour vision and designing colour, and facilitate interactions

at the interface of research and industry.

Session chair: Dr Manuel Spitschan, University of Oxford; Co-Chair OSA Color Technical

Group

Social events

An evening welcome reception will be held in the Diamond conference venue on the opening

day, Sunday, June 17th, immediately following two Keynote Lectures that are a special feature

of the conference. On Wednesday afternoon delegates either have free time or can take the

opportunity to visit local places of interest of which there are many, including for example,

Chatsworth House and many historic industrial sites. The all-ticket conference Banquet for

delegates and accompanying persons (with tickets!) will be held Wednesday evening in INOX

within the University of Sheffield campus.

SPECIAL EVENTS


PROGRAMME




PROGRAMME


GLANCE

PROGRAMME




PROGRAMME




PROGRAMME


GLANCE

http://gancentre.group.shef.ac.uk/workshop/

13

Sunday, June 17

15:00 - 16:45 Registration Venue: Reception Desk of the Diamond

16:45 - 17:00 Welcome Remarks Venue: LT-1

Session 0.1 Chair: Robin Devonshire & Tao Wang Venue: LT-1

17:00 - 17:30 0.1.1 Robert Karlicek (Plenary) Cognitive Lighting Systems: a Model for the Future of Illumination

17:30 - 18:00 0.1.2 Ian Tutt (Plenary) A History of Lighthouse Lighting

Refreshments Venue: Diamond

Monday, June 18


Session 1.1 Chair: Tao Wang & Robin Devonshire Venue: LT-1

09:00 - 09:30 1.1.1 Various Opening

09:30 - 10:00 1.1.2 Ling Wu (Plenary) Recent Development of SSL in China

10:00 - 10:30 1.1.3 Yoichi Kawakami (Plenary) Nitride-based 3D-structures for polychromatic LEDs

10:30 - 11:00 Coffee Break Venue: Atrium

Session 1.2 Chair: Yoichi Kawakami Venue: LT-3

11:00 - 11:25 1.2.1 Colin Humphreys (Invited)

11:25 - 11:50 1.2.2 Harald Haas (Invited) LiFi within a Taxonomy for Optical Wireless Communications

11:50 - 12:05 1.2.3 Anton Alexeev Optical Wireless Communication Model for LED Bandwidth Based on Electrical Small-Signal Response Analysis

12:05 - 12:30 1.2.4 Martin Dawson (Invited) The transition of solid state lighting from smart to digital

12:30 - 13:30 Lunch Venue: Atrium

Session 1.3 Chair: Colin Humphreys Venue: LT-3

13:30 - 13:55 1.3.1 Katsumi Kishino (Invited) Emission-color control of InGaN-based nanocolumns and monolithically integrated multi-color nanocolumn LEDs

13:55 - 14:20 1.3.2 Mark Sheinin (Invited) Bulb Flicker as an Information Source

14:20 - 14:35 1.3.3 Hoi Wai Choi Monolithic Integration of GaN Light-emitting Diodes and Photodetectors and their Applications

14:35 - 15:00 1.3.4 Jose Pozo (Invited) Novel visible, IR and UV LEDs and VCSELs changing day to day lives


Session 1.4 Chair: Hoi Wai Choi Venue: LT-3

15:30 - 15:55 1.4.1 Simon Pearson (Invited) To what extent can LED lighting systems help feed the world?

15:55 - 16:20 1.4.2 Kale Harbick (Invited) GLASE - Greenhouse Lighting and Systems Engineering

16:20 - 16:35 1.4.3 Dan Gao A supplemental lighting system in saffron outdoor cultivation

PROGRAMME


GLANCE

PROGRAMME


GLANCE

PROGRAMME


GLANCE

PROGRAMME


GLANCE

PROGRAMME


GLANCE

PROGRAMME


GLANCE

PROGRAMME


GLANCE

14

16:35 - 17:00 1.4.4 Celine Nicole (Invited) Control of plant nutrients, taste and shelf life with LEDs

17:00 - 17:25 1.4.5 Douglas McKenzie

(Invited) Artificial lighting (LED)-based biomass (algal) production

17:25 - 18:30 Welcome Reception Venue: Diamond

Tuesday, June 19


Session 2.1 Chair: Georges Zissis Venue: LT-3

09:00 - 09:25 2.1.1 Mitsuhiro Koden

(Invited) Roll-to-roll and printing technologies for electrodes of flexible OLED

09:25 - 09:40 2.1.2 Suneal S Ghataora

Hybrid III-nitrides/organic LEDs with non-radiative energy transfer

09:40 - 10:05 2.1.3 Peter Skabara (Invited) Tunable organic 'phosphors' for white light devices and visible light communications

10:05 - 10:30 2.1.4 Martin Charlton (Invited) Color tunable hybrid Photonic Crystal quantum dot Light Emitting Diodes

10:30 - 11:00 Coffee Break Venue: Atrium Session 2.2 Chair: Katsumi Kishino Venue: LT-3

11:00 - 11:25 2.2.1 Rong Zhang (Invited) Recent progress of III-nitride semiconductor based micro/nano-LEDs and UV photodetectors

11:25 - 11:40 2.2.2 Lai Wang Theoretical Study on Internal Quantum Efficiency of Modulated Light Emitting Diodes for Visible Light Communication

11:40 - 11:55 2.2.3 Wei Lin Abnormal emission induced by polarized orbitals in Al-rich AlGaN quantum wells

11:55 - 12:10 2.2.4 Ada Czesnakowska

Phosphor-converted white light using near-ultraviolet laser diode

12:10 - 12:35 2.2.5 Peter Parbrook (Invited) Growth and Fabrication of Semi-Polar LEDs, for application in communications

12:35 - 13:30 Lunch Venue: Atrium Session 2.3 Chair: Rong Zhang Venue: LT-3

13:30 - 14:00 2.3.1 Mariana Figuiero

(Plenary) Circadian Light and Circadian Stimulus: Science to Applications

14:00 - 14:15 2.3.2 Steve Fotios Precise experimental design: does it matter in lighting research?

14:15 - 14:30 2.3.3 Muqing Liu Simulating Solar Spectra Using Monochromatic LEDs and a Spectral Mismatch Index for Evaluation

14:30 - 14:45 2.3.4 Aleksandra Liachenko Monteiro

Pedestrian reassurance and road lighting: minimum illuminance is a better predictor than mean illuminance

14:45 - 15:10 2.3.5 Hutomo Suryo Wasisto

(Invited) GaN nano-/microLED arrays for compact lensless microscopes

15:10 - 15:30 Coffee Break Venue: Atrium Session 2.4 Chair: Peter Skabara Venue: LT-3

15:30 - 15:55 2.4.1 Xavier Denis (Invited) Spectral Optimization with Phosphor for Enhancing Performance of LED Device

15

15:55 - 16:20 2.4.2 Nicola Trivellin (Invited) Phosphors for laser baser lighting systems: quantitative investigation of performance and degradation processes

16:20 - 16:35 2.4.3 Yudai Shibata Inorganic Crystal Encapsulation for High Thermal Conductivity and Stability of Phosphor Devices

16:35 - 17:00 2.4.4 Jack Silver (Invited) The need for new red Phosphors for LEDs: Replacing Eu3+ Activators in LiEu(WO4)2 with Al3+ and Y3+ Cations.

17:00 - 17:25 2.4.5 Youri Meuret (Invited) Opto-thermal modelling of novel solid-state light sources

Wednesday, June 20


Session 3.1 Chair: Peter Parbrook Venue: LT-3

09:00 - 09:25 3.1.1 Siming Chen (Invited) III-V Quantum Dot Light Sources Grown on Si

09:25 - 09:50 3.1.2 Matthieu Iodice (Invited) Methodology for discomfort glare investigations: limits for experimental procedures

09:50 - 10:05 3.1.3 Qiuyi Han The algorithms for full spectrum white-LEDs mixed with eight and nine colours

10:05 - 10:30 3.1.4 Yong-Hoon Cho (Invited) Classical and quantum light generation based on group III-nitride semiconductor micro/nanostructures

Session C1 Chair: Manuel Spitschan Venue: LT-4

09:00 - 09:25 C1.1 Annette Allen (Invited) Using metameric displays to interrogate melanopsin vision

09:25 - 09:50 C1.2 Sophie Wuerger (Invited) Effect of illumination on the perception of natural and additively manufactured skin

09:50 - 10:15 C1.3 Sebastian Babilon

(Invited) Improvements on memory-based approaches to evaluate the colour rendition of white light sources

10:15 - 10:40 C1.4 Danny Garside (Invited) Is there a role for melanopsin in chromatic adaptation?


Session 3.2 Chair: Muqing Liu Venue: LT-3

11:00 - 11:25 3.2.1 Martin Foster (Invited) Emerging trends in lighting driver electronics

11:25 - 11:50 3.2.2 Bo Shen (Invited) Epitaxial growth of AlN and AlGaN-based MQWs on nano-patterned sapphire substrates

11:50 - 12:05 3.2.3 Jianjun Liu Failure mechanism and behaviour of electrode on high current discharge

12:05 - 12:30 3.2.4 Jiajie Fan (Invited) Prognostics and Health Management for Light-emitting Diodes

Session C2 Chair: Manuel Spitschan Venue: LT-4

11:00 - 11:25 C2.1 Luke Price (Invited) Towards a CIE System for Metrology of Optical Radiation for Responses to Light

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Influenced by Intrinsically-Photosensitive Retinal Ganglion Cells

11:25 - 11:50 C2.2 Andrew Stockman

(Invited) Human colour vision, photopic and scotopic luminous efficiency and lighting

11:50 - 12:15 C2.3 John Barbur (Invited) Limits of chromatic sensitivity in normal trichromats and in congenital deficiency

12:15 - 13:30 Lunch Venue: Atrium

13:30 - 19:00 Free Time

19:00 - 21:00 Banquet Venue: INOX

Thursday, June 21


Session 4.1 Chair: Robin Devonshire Venue: LT-3

09:00 - 09:30 4.1.1 Arnold Wilkins (Plenary) Illumination from Darwin and Discomfort from Illumination

09:30 - 10:00 4.1.2 Allan Howard (Plenary) What future for public lighting in an autonomous world?

10:00 - 10:25 4.1.3 Takako Kimura-Minoda

(Invited) Future automotive lighting based on fatal and injury accident analyses


Session 4.2 Chair: Bo Shen Venue: LT-3

11:00 - 11:25 4.2.1 Michael Kneissl (Invited) AlGaN-based deep UV-LED: Applications and Challenges

11:25 - 11:40 4.2.2 Norihiko Kamata Nonradiative recombination centers in AlGaN MQW for deep UV-LED revealed by below-gap excitation light and its energy dependence

11:40 - 11:55 4.2.3 Li Chen Orbital engineering of quantum confinement in high-Al-content AlGaN

11:55 - 12:10 4.2.4 Songrui Zhao AlGaN Nanowires by Molecular Beam Epitaxy: Towards Deep Ultraviolet Lasers by Direct Current Injection

12:10 - 12:35 4.2.5 Shanduan Zhang

(Invited) High power-density UV-LED curing system

12:35 - 13:30 Lunch Venue: Atrium l

Session 4.3 Chair: Stuart Mucklejohn Venue: LT-3

13:30 - 14:00 4.3.1 Jan Audenaert (Invited) Near-field goniophotometry: from the theoretical principles to the practical implementation

14:00 - 14:15 4.3.2 Jim Uttley Lighting increases cycling rates after-dark

14:15 - 14:40 4.3.3 Kelly Smith (Invited) Human factors in lighting

14:40 - 15:05 4.3.4 Sujan Rajbhandari

(Invited) Gallium Nitride LEDs for Li-Fi applications

15:05 - 15:30 4.3.5 Hideki Hirayama (Invited) Recent progress of AlGaN-based high-efficiency deep-UV LEDs

15:30 - 17:30 Poster Session Th4.4 Venue: Atrium

Friday, June 22

Session 5.1 Chair: John Stocks Venue: LT-3

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09:00 - 09:25 5.1.1 Andras Poppe (Invited) LED based application design in an “Industry 4.0” approach: implementation as proposed by the Delphi4LED project

09:25 - 09:40 5.1.2 Qiuyi Han The thermal simulation of high power-density UV-LED modules with water cooling

09:40 - 09:55 5.1.3 Haibing Li A new type of xenon metal halide lamp and driving power supply

09:55 - 10:20 5.1.4 Gareth John (Invited) Measurement challenges facing the solid-state lighting industry


Session 5.2 Chair: Steve Fotios Venue: LT-3

10:50 - 11:15 5.2.1 Naoya Hara (Invited) The influence of the distance between the light source and the gazing point on the discomfort glare in the central vision

11:15 - 11:30 5.2.2 Yichong Mao Lighting for trip hazard detection: raised objects versus potholes

11:30 - 11:55 5.2.3 Yukio Akashi (Invited) Age-related changes in readability of printed letters

11:55 - 12:10 Closing Remarks Venue: LT-3

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Sunday, 17:00 Session 0.1.1

(Plenary) Cognitive Lighting Systems: a Model for the Future of Illumination

Robert Karlicek

Sunday, 17:30 Session 0.1.2

(Plenary) A History of Lighthouse Lighting

Ian Tutt

Lighthouses can be seen the world over and are frequently associated with notions of protection and benevolence. Phrases such as ‘a guiding light’ have entered common parlance. But the history of the technology of lighting such structures has often been overshadowed by the immense effort it took to build them and the more romantic notions portrayed by writers. Work on lighthouse lighting and light projection by scientists and engineers through the ages has often been at the forefront of technology at the time. Huge amounts of effort and money have been expended on providing and upgrading lighting apparatus over the centuries in order to improve safety at sea. This paper seeks to show some of the important milestones in the provision of marine aid to navigation lights—to give them their correct title—up to the present day.

Monday, 09:30 Session 1.1.2

(Plenary) Recent Development of SSL in China

Ling Wu

Driving by the urgent needs of energy saving and environmental protection, Chinese R&D communities, industries and public authorities have been paying great attention to the development of SSL technology and applications in China.


(Plenary) Nitride-based 3D-structures for polychromatic LEDs

Yoichi Kawakami and Mitsuru Funato

Nitride semiconductor based on InGaN and AlGaN active layers attain a new functionality of polychromatic light-emitting diodes (LEDs) by the use of three-dimensionally faceted microstructures, which may lead to an advanced lighting technology in which the light source spectra are synthesized in a tailor-made way so as to meet requirements of the application.


(Invited)

Colin Humphreys


(Invited) LiFi within a Taxonomy for Optical Wireless Communications

Harald Haas

This paper introduces a taxonomy for optical wireless communications (OWC). Based on this taxonomy the paper discusses the unique features and challenges of light fidelity (LiFi) attocellular networks and how these extend existing radio frequency (RF) cellular systems.


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Optical Wireless Communication Model for LED Bandwidth Based on Electrical Small-Signal Response Analysis

Anton Alexeev and Jean-Paul Linnartz

This paper presents an extraction procedure for an optical response model of a GaN light-emitting diode (LED) with a quantum-well (QW). The modelling relies on the characterization of carrier transport and recombination processes. The characterization is based on an electrical small-signal frequency response analysis over a wide range of the forward bias currents. The analysis enables quantification of carrier recombination rate, QW escape and capture time constants, and also the optical response and its 3dB bandwidth which is relevant for wireless optical communication.


(Invited) The transition of solid state lighting from smart to digital

Martin Dawson

The emergence of solid state lighting, based in particular on gallium nitride LED technology, has facilitated early stage ‘smart lighting’ capability. What has been little appreciated so far, however, is that this semiconductor based lighting offers the prospect of interfacing to very sophisticated electronics. In prospect is a truly digital lighting technology which embeds imaging, navigation, tracking, communications, sensing and other functions as part of systems that may be integration into communications networks and/or powered off-grid. We will overview our work to explore these concepts based on gallium nitride micro-LED technology interfaced to CMOS.


(Invited) Emission-color control of InGaN-based nanocolumns and monolithically integrated multi-color nanocolumn LEDs

Katsumi Kishino

The emission–color control mechanism of InGaN-based nanocolumn (NC) arrays is discussed, demonstrating the monolithic integration of multi-color micro NC LEDs.


(Invited) Bulb Flicker as an Information Source

Mark Sheinin, Yoav Schechner and Kyros Kutulakos

Most artificial lights are powered by alternating current (AC) and, as such, flicker periodically, faster than our eyes can perceive. Bulbs have distinct ‘flicker signatures,’ namely, the periodic light intensity they emit has a unique temporal shape that depends on the bulb type and brand. Sensing the flicker in the scene enables to digitally render the scene as if illuminated by only a subset of bulbs; retrieving scene bulb types and electric grid phases; and separating semi-reflections from windows. To capture scene flicker, we develop novel imaging techniques specifically designed to sense AC lighting.


Monolithic Integration of GaN Light-emitting Diodes and Photodetectors and their Applications

Kwai Hei Li, Wai Yuen Fu and Hoi Wai Choi

The monolithic integration of GaN light-emitting diodes and photodetectors is reported. Both devices make use of the same set of InGaN-GaN quantum wells for light emission and absorption respectively. The availability of an on-chip photodetector enables accurate monitoring of light output intensity from the adjacent emitter, or, with the aid of a control circuit, light output intensity stabilization. Additionally, high-speed data transmission via waveguides between the emitter and photodetector is demonstrated.


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(Invited) Novel visible, IR and UV LEDs and VCSELs changing day to day lives

Jose Pozo

Solid state lighting sources, both LEDs and lasers are revolutionising the lighting industry. Current advances in UV LEDs, IR Infrared LEDs, lasers, and most importantly VCSELs are enabling further miniaturization and lower cost of high-end lighting systems.


(Invited) To what extent can LED lighting systems help feed the world?

Simon Pearson

There is considerable interest in the application of LED lighting systems to produce foods with completely artificial or supplementary lighting systems. These include massive indoor farms that are completely enclosed from solar radiation, or modern greenhouses where solar radiation is supplemented by electrically generated lighting systems. The capital investments in the US, Japan, China and EU behind some of these systems has been enormous. Here I consider the rationale for these “vertical/LED” farm and provide views on how this technology might evolve in the coming years. I also consider views on the biological and engineering constraints impacting vertical farm applications and consider how the technology may evolve going forward.


(Invited) GLASE - Greenhouse Lighting and Systems Engineering

Kale Harbick

GLASE (Greenhouse Lighting and Systems Engineering) is a consortium of industry and research stakeholders, led by Cornell University and Rensselaer Polytechnic Institute. The research goals of the consortium include plant science and engineering objectives. CO2 and spectral response of leafy greens and fruiting crops (tomato and strawberry) will be quantitatively measured. Improvements to previous work on lighting and CO2 control will be made. Natural light modelling with raytracing will inform improvements in greenhouse construction and orientation. Additional research results will be presented, including energy modelling of controlled environment agriculture facilities, lighting optimization, and weather data analysis.


A supplemental lighting system in saffron outdoor cultivation

Dan Gao, Xinyu Ji, Weizhong Pei, Xue Zhang, Fusheng Li, Qiuyi Han and Shanduan Zhang

Light plays a crucial role in saffron outdoor cultivations, hence the aim of this study was to improve daughter corm numbers and yields through outdoor supplemental lighting with blue- and red-LED luminaires. The results indicated that the mean leaf area growth rate was 9.5% for small-size, 11.7% for medium-size, and 12.7% for big-size mother corms. The average dry weight of leaves per mother corm for small-size mother corms grew 9.7%, while that also has a slight increase for medium-size and big-size. More significantly, the daughter corm yields grew 13.2% and the reproduction coefficient had a slight improvement of 2.3% for small-size mother corms under supplemental lighting.


(Invited) Control of plant nutrients, taste and shelf life with LEDs

Celine Nicole and Jarno Mooren

We have grown leafy green vegetables under LED lighting in a closed environment (indoor farm) under various spectra, light intensities and photoperiods. The effects of these parameters on the growth efficiency, nutrient content, taste and shelf life of the harvest has been investigated for several plants cultivars. We show that especially the daylight integral and spectral composition of the light (blue % or far red %) have a significant impact on the nutritional content, colour, taste and shelf life. In conclusion, each plant variety may have its quality attributes tuned with a tailored lighting recipe.

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(Invited) Artificial lighting (LED)-based biomass (algal) production

Douglas McKenzie

Tuesday, 09:00 Session 2.1.1

(Invited) Roll-to-roll and printing technologies for electrodes of flexible OLED

Mitsuhiro Koden, Tadahiro Furukawa, Toshinao Yuki and Hitoshi Nakada

Roll-to-roll (R2R) and printing technologies for electrodes of flexible OLED (Organic light Emitting Diode) lighting have been developed by the academia-industry collaboration. The developed technologies consist of R2R vacuum depositions, R2R screen printing, R2R wet cleaning, etc., inducing innovations in fabricating technologies of flexible OLED lighting. Flexible OLED lighting prototypes were fabricated by applying the developed technologies to ultra-thin glass, stainless steel foil or barrier film.


Hybrid III-nitrides/organic LEDs with non-radiative energy transfer

Suneal S Ghataora, Rick Smith, Modestos Athansiou, Tao Wang


(Invited) Tunable organic 'phosphors' for white light devices and visible light communications

Peter Skabara

Materials suitable as active components in organic light-emitting diodes (OLEDs) have attracted widespread interest in recent years, as this technology develops towards replacing existing less efficient technologies, e.g., incandescent and fluorescent bulbs, in consumer applications such as solid-state lighting. To this end, both polymers and molecular structures have been exploited. Whilst polymers offer high luminescence and solubility, they can suffer from problems associated with high polydispersity and batch-to-batch reproducibility. Molecular systems offer advantages such as monodispersity, synthetic reproducibility and, depending on structure, they can be processed via vacuum deposition or solution processing techniques. They can be tuned by chemical structure to emit light at any desired wavelength in the visible spectrum. At the same time, they can be tailored to absorb at various wavelengths and the absorption/emission characters can be independent of each other. This makes organic materials highly suitable as frequency downconverters for device applications.


(Invited) Color tunable hybrid Photonic Crystal quantum dot Light Emitting Diodes

Martin Charlton

In current commercial quantum dots (QDs) based LEDs; QDs are dispersed into polymer matrix and optically pumped by blue LED. In this far-field architecture, the majority of the light emitted by LED is trapped within epitaxy due to total internal reflection and reducing the out-coupling efficiency. We demonstrate photonic quasi crystal hybrid LED geometry that allows QD emitters to be placed in close proximity to multiple quantum wells (MQWs). This architecture greatly improves the coupling between MQWs and QDs, simultaneously allowing for non-radiative energy transfer between MQWs and the QDs. In this configuration we have demonstrated efficient color conversion reaching 123% effective quantum yield for single-color conversion LED. Using this hybrid approach, modular array LED with individually addressable LEDs gives the flexibility of tuning wide range of CIE co-ordinates.


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(Invited) Recent progress of III-nitride semiconductor based micro/nano-LEDs and UV photodetectors

Rong Zhang , Bin Liu, Dunjun Chen, Hai Lu and Youdou Zheng

Despite of great success of III-nitride based optoelectronic devices, the efficiency of light emitting diodes(LEDs) and photodetectors(PDs) are not as high as expected or suffering from severe efficiency droop. One of the most promising approaches is to fabricate well-ordered nitride mirco/nano-structures, further achieve efficient and functional devices. At first, we have developed ultra-violet(UV) soft nano-imprint lithograph(UV-NIL) patterning and top-down etching techniques to fabricate nanorod array LEDs, surface plasmon enhanced LEDs and hybrid white III-nitride/II-VI quantum dot LEDs. Secondly, we have fabricated successfully high-gain solar-blind AlGaN APDs based on a separate absorption and multiplication (SAM) structure by developing a series of effective methods.


Theoretical Study on Internal Quantum Efficiency of Modulated Light Emitting Diodes for Visible Light Communication

Kamran Rajabi, Yuchen Xing, Lai Wang, Zibao Hao, Yi Luo, Changzheng Sun, Yanjun Han, Bing Xiong, Jian Wang and Hongtao Li

The modulation of light emitting diodes (LEDs) for communication purposes has become a hot topic in recent years and the modulation bandwidth for the visible spectrum increased significantly, but the relation between internal properties and modulation bandwidth has not been investigated yet. Here, we calculate the internal quantum efficiency (IQE) in terms of radiative and non-radiative recombination rate at an applied pulsed carrier number. A general equation is obtained that shows the effects of different parameters on IQE and modulation bandwidth.


Abnormal emission induced by polarized orbitals in Al-rich AlGaN quantum wells

Wei Lin, Li Chen, Junyong Kang and Rong Zhang

AlGaN has attracted a great deal of attention as a fundamental material motivated by the possibility of developing more efficient, portable, and safer light sources in the deep ultraviolet region at high power and under harsh environmental conditions. Despite their recognized prospective applications, a major obstacle has been the low external quantum efficiency for Al-rich AlGaN optical devices. To gain insight of the underlying mechanism, CL cross-sectional analysis exhibit an abnormal emission of the quantum wells at the band edge which is insensitive to the applied bias. Identified by first-principles simulations, the primary radiative interband transition originated from the crystal field split-off hole-band dispersive in the confined dimension. By comparing the orbital configuration, the abnormal emission is attributed to the CH band composed of delocalized pz orbitals. The abnormal radiative interband transitions presented in this work provide a basis for further improvement in Al-rich AlGaN optoelectronic devices.


Phosphor-converted white light using near-ultraviolet laser diode

Ada Czesnakowska, Gerald Ledru, Benoit Glorieux and Geroges Zissis

Two types of phosphors, blue and yellow, were prepared for phosphor-converted white light by n-UV laser diode generation. Results showed that coupling diode with these materials let us obtain the good white light parameters. Using filter cutting the n-UV light not converted by phosphor shows that with optimisation of blue phosphor we could obtain the light close to “light of the day”.


(Invited) Growth and Fabrication of Semi-Polar LEDs, for application in communications

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Peter Parbrook, Duc Dinh, Vitaly Zubialevich, Zhiheng Quan, Pleun Maaskant, Mahbub Akhter and Brian Corbett

GaN based light emitting diodes (LEDs) are well established for efficient illumination. However, current technology is based on a blue+phosphor arrangement, due to poor efficiency in the green-yellow region. III-Nitrides orientations with reduced polarisation have been proposed as a potential solution to this issue. A further benefit of such orientations is that the recombination speeds are much higher, allowing application for Li-Fi systems to be built into a smart lighting system, with higher bandwidths. Here we report on semipolar LEDs allowing communication bandwidths in the Gbit/s regime.


(Plenary) Circadian Light and Circadian Stimulus: Science to Applications

Mariana Figuiero

The daily pattern of light and dark incident on the human retinae sets the timing of the circadian systems’ master clock, which controls the timing of circadian rhythms and whose disruption can lead to serious health problems. Our research shows that it is both important and possible to tailor lighting applications that meet the circadian system requirements of those who occupy any given space and thereby promote circadian entrainment, alertness, positive mood outcomes, healthy sleep, and health and well-being.


Precise experimental design: does it matter in lighting research?

Steve Fotios

The applications side of lighting research requires an understanding of how changes in lighting affect people. Experimental research of human factors is relatively easy to set up, frequently requiring little more than a test space and a variable source of lighting. It is, however, even easier to reach a misleading outcome in such research. Often, the manner in which the question is asked influences the results to a greater extent than do the visual conditions, leading the unwary researcher to misplaced confidence in their conclusions. This presentation will discuss examples of the precautions required to improve the robustness of experimental research.


Simulating Solar Spectra Using Monochromatic LEDs and a Spectral Mismatch Index for Evaluation

Luyao Tang, Muqing Liu, Shaofan Chen and Chengyue Su

In this paper, twelve different types of light-emitting diodes (LEDs) with different peak wavelengths were utilized to simulate solar spectrums of different colour temperatures. A spectral mismatch evaluation index E was proposed to indicate the level of similarity between two different spectrums, and was further used to estimate their likeness to real sunlight.


Pedestrian reassurance and road lighting: minimum illuminance is a better predictor than mean illuminance

Aleksandra Liachenko Monteiro, Steve Fotios and James Uttley

A field study was carried out to investigate pedestrian’s reassurance under road lighting of different illuminances – reassurance is the confidence to walk alone, after dark. This was done using a repeated measures day-dark approach, with evaluations captured in daytime and after dark, and this was done to better isolate the effect of lighting in these evaluations. While guidance specifies average

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illuminance, these results suggested minimum illuminance or illuminance uniformity to be a better fit for a day-dark difference.


(Invited) GaN nano-/microLED arrays for compact lensless microscopes

Hutomo Suryo Wasisto, Jan Gülink, Steffen Bornemann, Gregor Scholz, Shinta Mariana, Klaas Strempel, Matthias Auf der Maur, Aldo di Carlo, Joan Daniel Prades and Andreas Waag

GaN nano-/microLED arrays have been developed as a novel illumination source for being integrated in compact lensless microscopes. Different fabrication techniques have been applied to realize the LED chips with individual pixel control capability, which mainly consist of nanolithography, hybrid etching, planarization, and bonding processes. 3D fabrication and processing techniques of nano-/microLED arrays have been created and optimized in accordance to finite element modelling (FEM) results as device design guidance. Meanwhile, for investigating the viability of the illumination sources depending on the designed dimensions, performance investigations of nano-/microLEDs in cathodo- and electroluminescence measurements have been conducted. As a proof-of-concept for device application in life science, a compact field-portable lensless microscope comprising an LED point source and a CMOS imaging sensor has been built for live-cell culture imaging inside a cell incubator environment. The system has been tested with various biological samples including immortalized mouse astrocyte cells.


(Invited) Spectral Optimization with Phosphor for Enhancing Performance of LED Device

Xavier Denis and Kei Haraguchi

The general lighting market is transitioning to LED segment with a focus on LED devices’ energy efficiency and longer lifetime. Emerging from this trend, is a demand for white and color LEDs with spectral enhancement for indoor and outdoor LED lighting applications. In this paper, we present optimization of peak and range of wavelengths with phosphor to achieve higher luminous flux performance for low correlated color temperature (CCT) LED. We also describe an approach for spectral improvements with phosphor mix to reach color rendering index (CRI) up to 100. Additionally, we cover similar technical solutions to design full-spectrum light sources for horticulture lighting, with red and far-red supplements. Finally, we explain phosphor conversion advantages for color LEDs.


(Invited) Phosphors for laser baser lighting systems: quantitative investigation of performance and degradation processes

Nicola Trivellin, Matteo Buffolo, Loris Bogo, Carlo De Santi, Alessandro Longato, Alessandro Martucci, Gaudenzio Meneghesso, Enrico Zanoni and Matteo Meneghini

In the present work we report on the development of GaN (Gallium Nitride) laser based white lighting systems. Different phosphor configurations were studied: i) drop casted phosphors deposited on sapphire substrates and ii) phosphors dispersed in sintered glass support. Phosphors are critical to achieve a high quality white light also at high excitation intensities. Here we report on the main limits in operating temperature and saturation. The obtained results show that, while saturation cannot be reached up to 40 W/cm2, thermal quenching is still imposing a limit on system output performances.


Inorganic Crystal Encapsulation for High Thermal Conductivity and Stability of Phosphor Devices

Yudai Shibata

In this paper, we describe a novel phosphor encapsulation technology. This technology can encapsulate phosphors inside the inorganic crystal which has high thermal conductivity. In our

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experiment, the phosphor devices using the encapsulation technology showed outstanding thermal diffusivity and thermal stability compared with the silicone resin encapsulation devices.


(Invited) The need for new red Phosphors for LEDs: Replacing Eu3+ Activators in LiEu(WO4)2 with Al3+ and Y3+ Cations.

Jack Silver

Europium is used as an activator in phosphors to generate the red component of white light, but there is concern about its’ cost in the current market as discussed herein. The replacement of Eu3+ cations with alternative M3+ cations is described in this work. To lower the cost of the phosphor Al3+ and Y3+ were used to minimise the amount of Eu3+ activators needed in LiEu(1-x)Mx(WO4)2 (where M = Al or Y and x = 0.0, 0.15, 0.30, 0.45, 0.60, 0.75 and 0.95). Surprisingly though both the cations incorporate into the phosphor easily they were found to behave very differently.


(Invited) Opto-thermal modelling of novel solid-state light sources

Youri Meuret, Antonio Correia and Peter Hanselaer

White laser-based light sources and on-chip quantum dot LEDs are two novel types of solid-state light sources which offer specific advantages. In both cases, thermal quenching can have a significant impact on the light source performance. The feedback mechanism between optical loss and temperature increase, in the case of thermal quenching, can only be modelled correctly with an accurate multi-physics approach. The opto-thermal framework that we have developed to address this issue is illustrated for both source types.

Wednesday, 09:00 Session 3.1.1

(Invited) III-V Quantum Dot Light Sources Grown on Si

Siming Chen, Alwyn Seeds and Huiyun Liu

We discuss our recent progress made in the epitaxial growth of various InAs/GaAs quantum dot (QD) light-emitting sources on Si substrates for Si photonics, including Fabry-Perot (FP) lasers, distributed-feedback (DFB) laser array, micro-disk (MD) lasers and superluminescent light emitting diodes (SLDs).

Wednesday, 09:00 Session C1.1 (Parallel colour session)

(Invited) Using metameric displays to interrogate melanopsin vision

Annette Allen, Esther Hazelhoff, Franck Martial, Christian Cajochen and Robert Lucas

Intrinsically photosensitive retinal ganglion cells (ipRGCs) respond to light thanks to their expression of melanopsin, and are specialised to encode long-term light intensity. To understand melanopsin’s contribution to reflex light responses and pattern vision, we have developed a visual display comprised of 5 spectral channels that can regulate the activity of melanopsin independently of rods and cones in space and time. We have used this technology to examine distinct ways in which melanopsin influences form vision in mice and subconscious visual reflexes in humans.


(Invited) Methodology for discomfort glare investigations: limits for experimental procedures

Matthieu Iodice

Discomfort glare has been widely studied using various experimental procedures to investigate this phenomenon. Hence a good question is to find out if a certain procedure can be more relevant than

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another one and to observe if the choice of procedure could impact the results. In this study, several physiological and psychophysical procedures are applied to the same experimental set-up. An analysis of the obtained data highlights the limits and the potential experimental biases of these procedures.


(Invited) Effect of illumination on the perception of natural and additively manufactured skin

Sophie Wuerger

For prosthetic reconstruction, it is important to understand how the appearance of natural and manufactured skin depends on the prevailing illumination. In Experiment I, we investigated how sensitive the visual system is to subtle colour changes of skin images and its dependence on the illuminant. Our results show that discrimination thresholds are higher when skin images are viewed under fluorescent light (TL84) compared to simulated daylight (D65). In Experiment II, we calculated the perceptual differences (CIEDE2000) between natural and additively manufactured skin when viewed under a range of widely used illuminations (D65, and also: F1, F3, F7, F10, and F11/TL84). To a first approximation the perceptual differences (as predicted by CIEDE2000) are in an acceptable range (3.5-9.2) and the perceptual errors are fairly constant across the simulated illuminations. We conclude that a skin-colour specific difference metric would be important for automated assessment of the colour quality of synthetic skin.


The algorithms for full spectrum white-LEDs mixed with eight and nine colours

Siwan Liu, Fusheng Li, Qiuyi Han and Shanduan Zhang

Two algorithms of full spectrum white LED are proposed to use eight and nine initial spectra respectively. According to the chromaticity coordinates of initial spectra and the target color temperatures, the best color mixing ratio can be deduced. The results show that these two synthetic white lights can realize correlative color temperature (CCT) adjustable range of 2700–6500 K, with Ra, R9 and R12 higher than 95 as well as |Duv| less than 0.001, which is obviously advantageous over the other solutions.


(Invited) Improvements on memory-based approaches to evaluate the colour rendition of white light sources

Sebastian Babilon and Tran Quoc Khanh

With their inherent ability of serving as an internal reference, memory colours provide a very powerful concept in the evaluation of colour rendering properties of white light sources with respect to visual appreciation. In this context, a new experiment on the colour appearance rating of familiar real objects was devised with the intention of eventually developing an improved memory-based colour quality metric. A meta-correlation analysis including data of several different visual studies on colour preference was performed in order to prove that this newly proposed metric outperforms all alternative approaches.


(Invited) Classical and quantum light generation based on group III-nitride semiconductor micro/nanostructures

Yong-Hoon Cho

We present classical and quantum light generation using various types of group III-nitride micro- and nano-structures. We demonstrate phosphor-free broad-band and white light emission with three-dimensional GaN structures, unidirectional light propagation in energy-gradient, tapered core-shell rod structures, ultrafast single photon generation from a quantum dot formed at the apex of pyramid

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structures, and exciton-polariton formation at room-temperature in bulk GaN and GaN/InGaN core-shell rod structures.


(Invited) Is there a role for melanopsin in chromatic adaptation?

Danny Garside

We consider the applied problem of producing museum lighting which is visually pleasing yet causes minimal damage to objects. Within this context we consider whether melanopsin (the photo-pigment expressed by intrinsically photosensitive retinal ganglion cells) may have the right attributes to play a role in chromatic adaptation (the process by which human vision adapts to ambient lighting of different chromaticities). I shall give an overview of the context and motivation, and multiple experiments which are ongoing, and which attempt to answer this question from different perspectives.


(Invited) Emerging trends in lighting driver electronics

Martin Foster

The migration towards energy efficient LEDs and the commercial availability of wide-bandgap power devices opens up many new opportunities in the lighting sector. Recent advances include high frequency driver electronics operating in excess of 10MHz and the use of piezoelectric transformers to achieve greater miniaturisation. This paper will describe some of these recent technological achievements and discuss the new challenges that are facing engineers at the leading edge of research and development in this field.


(Invited) Towards a CIE System for Metrology of Optical Radiation for Responses to Light Influenced by Intrinsically-Photosensitive Retinal Ganglion Cells

Luke Price

The latest developments concerning CIE’s international standard for light measurements relating to ipRGC-influenced light responses (IILs) will be presented, where ipRGC stands for intrinsically-photosensitive Retinal Ganglion Cell. The role of this third mammalian photoreceptor type in human and rodent “non-visual” photoreception, in addition to rods and cones, quickly became established following the discovery of melanopsin in 1998. The international standard will build on the consensus in human action spectra published in 2013, and update the definition of equivalent illuminance.


(Invited) Epitaxial growth of AlN and AlGaN-based MQWs on nano-patterned sapphire substrates

B. Shen, F.J.Xu, L.S.Zhang, M.X.Wang, N.Xie, Y.H.Sun, B.Y.Liu, and Z.X.Qin

The crystalline quality and surface morphology of AlN epilayers on sapphire substrate have a crucial influence on the crystalline quality of AlGaN epilayers and AlGaN-based MQWs. Therefore, it is essential to obtain AlN/sapphire template of high quality for developing the deep ultraviolet light emitting diodes (DUV-LEDs). In this study, AlN epitaxial growth on nano-patterned sapphire substrates (NPSS) has been investigated. The crystalline quality of AlN was greatly improved by using the optimized NPSS. The X- -scan full width at half maximum (FWHM) values for (002) and (102) reflections of AlN are 134 arcsec and 159 arcsec, respectively. The characterizaton results indicate that the optimized NPSS contributes to eliminate almost entirely the threading dislocations (TDs) originating from the AlN/sapphire interface via bending the dislocations by image force from the void sidewalls before coalescence. Meanwhile, reducing the misorientations of the adjacent regions during coalescence adopting the low lateral growth rate is a key step for decreasing TDs in AlN epilayers. On the basis of AlN/NPSS templates of high quality, AlGaN-based MQWs with the

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luminescence wavelength of 281nm have been fabricated. A high IQE value of 73.9% for the MQWs was obtained by means of the temperature-dependence photoluminescence measurements.


(Invited) Human colour vision, photopic and scotopic luminous efficiency and lighting

Andrew Stockman

The standards for colorimetry and photometry should be traceable to the spectral sensitivities of the three light-sensitive cone photoreceptors in the human eye. In 2006 and 2015, the Commission Internationale de l'Éclairage have adopted “physiologically-relevant” international standards for colorimetry and photometry based on the cone spectral sensitivity estimates of Stockman & Sharpe (2000). However, the primary standard for photometry (which defines lux, lumens, and cd/m2) continues to be based on flawed CIE standards from 1924 and 1931, which are significantly in error at short wavelengths.


Failure mechanism and behaviour of electrode on high current discharge

Jianjun Liu, Haibing Li, Ruihua Wu, Ruoyan Shao and Hairong Liang

Enriched zones of Ce atoms on the surface area of electrode after thermal activation process is good for improve the electron emission property. The high speed photography and scanning electron microscopy demonstrate that there are many spots on the emission surface during discharge. And the erosion and micro-explosion phenomena have happened in course of discharge, which will result in sputtering and decrease the optical output of flashlamp.


(Invited) Limits of chromatic sensitivity in normal trichromats and in congenital deficiency

John Barbur

In addition to luminance contrast signals, our perceptual experience also relies heavily on the relative strengths of red / green (RG) and yellow / blue (YB) colour signals. In the case of colored objects, each of these signals is affected by the wavelength of peak responsivity of cone photopigments, the spectral separation between them and the corresponding pigment optical densities, the spectral absorption of pre-receptoral filters in the eye and the relative numbers of long- and middle-wavelength cones. Changes in any of these parameters can affect colour vision, both in terms of chromatic detection and discrimination sensitivity as well as the perception of suprathreshold colours and the type of metamerism one can achieve. Normal aging also affects colour vision. Data obtained in a series of studies involving over 1400 subjects will be presented to illustrate the variability in RG and YB chromatic sensitivity as a function of age.


(Invited) Prognostics and Health Management for Light-emitting Diodes

Jiajie Fan

High-power white light-emitting diodes (LEDs) have attracted much attention due to their versatility in a variety of applications and growing demand in markets such as general lighting, automotive lamps, communications devices, and medical devices. The need for high reliability and long lifetime poses new challenges for the research and development, production, and application of LED lighting. Accurate and effective prediction of the lifetime or reliability of LED lighting has emerged as one of the key issues in the solid-state lighting field. Prognostics is an engineering technology that predicts the future reliability or determines the remaining useful lifetime (RUL) of a product by assessing the extent of deviation or degradation of a product from its expected normal operating conditions.This talk

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will provide an overview of the prognostic methods and models that have been applied to both LED devices and LED systems, especially for use in long-term operational conditions.

Thursday, 09:00 Session 4.1.1

(Plenary) Illumination from Darwin and Discomfort from Illumination

Arnold Wilkins

The human visual system evolved in the natural world and processes natural scenes efficiently. The natural world has little flicker, few repetitive contours and modest colour contrast. When lighting is un-natural it results in inefficient neural processing and this in turn leads to discomfort.


(Plenary) What future for public lighting in an autonomous world?

Allan Howard

As we move into a world of electric and autonomous vehicles (AV)with energy potentially becomes more expensive due to higher demand what will be the future for public lighting? The paper will look at these demands and consider the future user needs for artificial exterior lighting discussing the key questions:

What tasks need lighting?

What are the challenges?

How will the lighting infrastructure support AV technologies? and

How may good lighting practice be developed and provided to meet them?

The paper will draw on the application of adaptive lighting within the UK and consider approaches that WSP are developing in Finland for projects such as the Crown Bridges project. It will also draw on development work within Norway.


(Invited) Future automotive lighting based on fatal and injury accident analyses

Takako Kimura-Minoda, Yasushi Kita, Takeshi Waragaya, Wataru Nakashima and Kouki Kudoh

The analysis of fatal and injury traffic accident gives us many hints of lighting solution that might either reduce or eliminate the accidents. We analysed traffic accident datasets occurred in Japan and the United States, which are available through Institute for Traffic Accident Research and Data Analysis (ITARDA) and Fatality Analysis Reporting System (FARS) created by National Highway Traffic Safety Administration (NHTSA) respectively, and introduce some Japanese accident analyses which were reported by ITARDA. Finally, we determined safety benefit of lighting.


(Invited) AlGaN-based deep UV LEDs: Applications and Challenges

Michael Kneissl

This presentation will provide an overview of state-of-the art in deep UV-LED device technologies and present recent advances in the development of AlGaN materials, including the growth of high quality AlGaN heterostructures by metalorganic vapour phase epitaxy (MOVPE). We will demonstrate (In)AlGaN multiple quantum well LEDs in the wavelength range between 320 nm and 218 nm and illustrate how today’s UV-LEDs are being already successfully applied in various applications, e.g., plant growth lighting and sensing.


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Nonradiative recombination centers in AlGaN MQW for deep UV-LED revealed by below-gap excitation light and its energy dependence

Norihiko Kamata, Md Ismail Hossain, Yuri Itokazu, Noritoshi Maeda and Hideki Hirayama

We fabricated a deep UV-LED by MOCVD growth of AlGaN MQW on a sapphire substrate and measured the MQW photoluminescence (PL) under an above-gap excitation (AGE) light of 4.66 eV (266 nm). Nonradiative recombination (NRR) centers were detected by observing a decrease in the MQW-PL intensity due to the addition of below-gap excitation (BGE) light as a function of photon energies between 0.93 eV (1,340 nm) and 1.46 eV (852 nm). The BGE energy of 1.27 eV (980 nm) showed maximum PL quenching, which corresponds to a mean energy separation of two NRR centers.


Orbital engineering of quantum confinement in high-Al-content AlGaN

Li Chen, Wei Lin, Junyong Kang and Rong Zhang

AlGaN is an important semiconductor for solid-state lighting applications operating in the deep ultraviolet region. High-Al-content AlGaN materials exhibit a very different valence band order, the optical polarization properties differ from other III-nitrides, and the dispersive lowest hole quantum level shows an abnormal phenomenon in optical properties due to the characteristics of constituent orbitals. It turns out that the orbital manipulation plays an essential role in understanding and controlling the observed abnormal behaviors because the orbitals at the top of the valence band underpin a strong coupling between quantum confinement and structural degrees of freedom. In this work, an orbital engineering is developed by modulating the orientation of the quantum well in the crystal. Confining the valence electrons to the appropriate orbital or energy band enhances quantum confinement by varying available degrees of freedom in different orientation, which opens up the opportunity to apply the design principles to high-Al-content AlGaN.


AlGaN Nanowires by Molecular Beam Epitaxy: Towards Deep Ultraviolet Lasers by Direct Current Injection

S. Zhao, X. Liu and Z. Mi

In this talk, we discuss the path towards electrically pumped deep ultraviolet (UV) lasers with bottom- up AlGaN nanowire heterostructures grown by molecular beam epitaxy. We first show that with the use of Anderson localization of photons in disordered AlGaN nanowires, lasing as short as 239 nm, under direct current injection, can be measured. The threshold current densities are less than 3.5 kA/cm2. We further show the controllability on the AlGaN nanowire formation site, size, and spacing by selective area epitaxy, which promises more practical deep UV lasers under direct current injection.


(Invited) High power-density UV-LED curing system

Qiuyi Han, Siqi Li, Zhong Jing and Shanduan Zhang

The high power-density UV-LED modules with various cooling methods were tested for junction temperature and radiant characteristics, including water cooling, heat pipe cooling and GaIn liquid metal cooling. The maximum electrical power density can reach 631.5, 829.8, 1232.2 W/cm2, respectively. The UV-LED curing systems based on these high power-density modules have had very successful applications. The successful examples of the UV-LED curing systems are introduced in optical-fibre manufacture and BTC synthesis. The great features of these systems promise a bright future of UV-LED in industrial curing.


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(Invited) Near-field goniophotometry: from the theoretical principles to the practical implementation

Jan Audenaert, Peter Hanselaer, Knut Bredemeier, Udo Krüger and Frédéric Leloup

Near-field goniophotometry has been introduced in the 1990s as an alternative to far-field goniophotometry for measuring the luminous intensity distribution of a light source. In this manuscript and presentation, the theoretical principles of the measurement technique are discussed and practical advantages and potential issues are considered. Ways to deal with possible errors are discussed. Finally, avenues for future research within the field of near-field goniophotometry are suggested.


Lighting increases cycling rates after-dark

Jim Uttley and Steve Fotios

Previous research has shown that the number of people walking and cycling significantly reduces after-dark, when other seasonal and time-of-day factors are controlled for. We assessed whether lighting can help limit this reduction in active travellers. We compared the reduction in cyclists after-dark against lamp density – the number of road lights per 100 m of road. Results suggested the presence of lighting encourages people to cycle after-dark.


(Invited) Human factors in lighting

Kelly Smith


(Invited) Gallium Nitride LEDs for Li-Fi applications

Sujan Rajbhandari

The Light Fidelity (Li-Fi) takes advantage of recent enhancement in the solid-state lighting technology especially Gallium Nitride (GaN) based light emitting diodes (LEDs) and utilises the illumination infrastructure for realisation wireless communication. Thus, the Li-Fi can be realised with limited additional cost. In this tutorial, the current trend in Li-Fi technology and advanced techniques that have enabled high-speed communication will be highlighted with emerging application areas such as internet of things (IoT), connected autonomous vehicles (CAV) and smart cities.


(Invited) Recent progress of AlGaN-based high-efficiency deep-UV LEDs

H. Hirayama, Y. Kashima,N. Maeda, M. Jo, E. Matsuura, and N. Kamata

Deep ultraviolet light-emitting diodes (DUV-LEDs) are attracting a great deal of attention for applications to sterilization, water purification, UV curing, and in the medical and biochemistry fields. The increase of light-extraction efficiency (LEE) is currently an important issue to increase an efficiency of AlGaN DUV LEDs [1]. In this work, we demonstrated an wall plug efficiency (WPE) ofover 10% in an AlGaN DUV-LED by increasing LEE. We also demonstrated the LEE enhancement by using highly-reflective photonic crystal (PhC) fabricating on the surface of p-AlGaN contact layer.

Friday, 09:00 Session 5.1.1

(Invited) LED based application design in an “Industry 4.0” approach: implementation as proposed by the Delphi4LED project

András Poppe, Márta Rencz, Robin Bornoff, Christophe Marty, Joan Yu and Genevieve Martin

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In the Industry 4.0 era digitalization of design and manufacturing processes takes place. The aim of the Delphi4LED H2020 ECSEL R&D project of the EU (www.delphi4LED.org) is to trigger such a transition in the solid-state lighting industry by developing testing and modelling methodologies aimed at multi-domain characterization of LED based products at different levels of integration along the SSL supply chain. In this paper we describe our approaches to creating the appropriate “digital twins” of LED packages, modules and luminaires to be used in virtual prototypes used in different system level design tasks.


The thermal simulation of high power-density UV-LED modules with water cooling

Kun Qian, Qiuyi Han, Zhong Jing and Shanduan Zhang

The numerical study is made on high power single-chip UV-LED modules which are mounted on water cooler. The size of the chip is 3 × 3 = 9 mm2. The electrical input power is changed to the maximum of 142.94 W. Besides, the simulations of the fins are conducted including shape, height and number of fins, in order to seek the most suitable structures. It is shown that the long fins placed in the middle have the best heat dissipation ability.


A new type of xenon metal halide lamp and driving power supply

Haibing Li, Jianjun Liu and Wenzheng Lin

On the basis of the working principle and the production techniques of metal halide lamps and xenon arc lights, we developed a novel xenon metal halide lamp using xenon as the filling gas and corresponding power supply. In addition to characterization of instant-starting and hot-starting, the new light source achieve combination of high color rendering index, luminous efficacy and excellent luminous flux maintenance rate.


(Invited) Measurement challenges facing the solid-state lighting industry

Gareth John

A discussion of the problems of optical metrology with respect to thed measurement of visible light when considering the response of the human eye is outlined. Possible solutions are outlined, included a comparison of the respective merits of spectroscopy and filter based photometers. An experimental method for the assessment of light meter accuracy is proposed. The results show stronger than expected performance for filter based light meters compared to polychromator spectrometers, with a possible explanation being the poor wavelength increments of polychromators.


(Invited) The influence of the distance between the light source and the gazing point on the discomfort glare in the central vision

Naoya Hara

This study aims at constructing a new evaluation method of discomfort glare for a central vision, which can reflect the influence of gaze distance and light source distance. In this paper, we report the analysis results of the subjective evaluation experiment by the paired comparison method, which relatively evaluate the discomfort glare of the condition pair with various gaze distance and light source distance set. As a result, it was shown that the closer the gaze distance is to the light source distance, the more discomfort glare is felt.


http://www.delphi4led.org/

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Lighting for trip hazard detection: raised objects versus potholes

Yichong Mao, Steve Fotios, James Uttley and Chris Cheal

Obstacle detection is an important task contributing to walking safety for pedestrians after dark. We describe here an experiment to investigate obstacle detection under road lighting. Past experiments have tended to use only raised targets – here we also consider the detection of lowered surfaces such as potholes. The results suggest that raised targets and potholes are detected with similar probability.


(Invited) Age-related changes in readability of printed letters

Yukio Akashi, Yuta Kuno and Kaori Murakami

This study developed readability models for older people with various visual capabilities based on readability evaluations in which young and older subjects assessed the degrees of readability of Japanese letters with different sizes, luminance contrasts and adaptation luminances. Because there were large individual differences in readability, we divided the subjects into three groups based on the subjects’ contrast sensitivities. The results of the readability evaluations allowed us to develop visual performance models representing equal readability contour lines for each of the readability levels for each of the three subject groups.

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Th4.4.1 High-Performance AlGaN-Based flip-chip Ultraviolet Light-Emitting Diodes with epitaxial ITO/Al reflective mirror and Symmetry Electrode arrangement

Bingfeng Fan, Yuqin Lao, Linchao Yan, Xuejin Ma, Zimin Chen, Yi Zhuo, Yanli Pei and Gang Wang AlGaN-Based flip-chip Ultraviolet Light-Emitting Diodes at 365 nm with epitaxial ITO transparent ohmic contact layers and Al reflective were fabricated. The epitaxial ITO thin film exhibits higher transmittance than that of sputter ITO at 365nm, which is 93.6% and 85%, respectively. The epitaxial ITO thin film is more suitable for 365nm UV-LED. And the reflectance of the ITO/Al layers is 81.2% at 365nm, much higher than that of the ITO/Ag layers, which is only 53.2% at 365nm. When the current injection is 350mA, the forward voltages are 3.43V and 4.05V for flip-chip UV-LED and conventional UV-LED, respectively. The forward voltages of flip-chip UV-LED is much lower than that of conventional UV-LED, because the series resistance (Rs) of the flip-chip UV-LED is 0.73 Ω, much lower than 2.98 Ω of conventional UV-LED. The flip-chip UV-LED with epitaxial ITO/Al reflective mirror and Symmetry Electrode arrangement is more suitable for high power application. Th4.4.2 Emission Performances on Remote Phosphor LED Lighting with Phosphors Applied to Lens

Takayuki Misu, Narufumi Kawanobe and Yujiro Suyama

In this study, we anticipate that higher light-dispersing effects can be obtained by applying phosphors to a lens which has a high level of optic effect. As the phosphors, RGB phosphors which are excited by near ultraviolet radiation with a dominant wavelength of 375 nm are used. We have constructed a lighting device which generates white light by illuminating the phosphor-applied acrylic lens with light of a bullet-type Near-UV LED. The remote phosphor LED lighting we created has achieved a luminous efficiency of ηm=61.3lm/W, an illuminance uniformity 24.7%, a color-rendering index of Ra=96.2. Th4.4.3 Effect of color temperature change programs on work efficiency

Hiroshi Takahashi, Ryotaro Yuyama and Masashi Tozuka

The aim of this study is to clarify the effects of correlated color temperature (CCT) changes during rest on subsequent work efficiency. In this experiment, the CCT was initially set at 4000 K and decreased to 3000 K, after which it was increased to either 4000 K or 5000 K. Searching for differences in pairs of paintings was chosen to evaluate work efficiency. The results showed that if the CCT was gradually lowered before working and then increased from 3000 to 4000 K within one minute prior to the start of work, higher work efficiency was achieved. Th4.4.4 Lighting for pedestrians: The basis of design guidance

Steve Fotios

Road lighting in minor roads is designed to meet primarily the needs of pedestrians. The basis of current guidance (whether for the UK or international) is, however, extremely well hidden. There is no known basis for the recommended light levels nor the process by which a lighting class is chosen. This paper discusses the current status of design guidance and a proposed approach to better-informed guidance. Th4.4.5 Development of LED-based dental light for improving illumination uniformity

Sie-Wook Jeon, Sunghyun Kim, Jina Choi and Jae-Pil Kim The projection-type dental lighting based on the remote phosphor LED package is designed to enhance uniformity of illuminance and correlated color temperature (CCT) on target plane and to remove glare in the eyes of patient. This dental lighting enables dentists to illuminate effectively patient’s mouth by increasing the inner area (50 mm x 25 mm) described in ISO 9680. The optical module comprised of the LED package and optical lens is modelled to satisfying the inner area wider than 100 mm x 50 mm and illuminance over 5,000 lx per the designed optical module. The fabricated prototype dental lighting contains four optical modules, and the maximum illuminance is 22,786 lx. The measured inner area is 105 mm x 74 mm, and the ratio of inner area in outer area is about 76%. Also, the CCT variation is below 450 K in total illuminance pattern. Th4.4.6 Determination of the thermal time constant of a LED system from luminous intensity

Pascal Dupuis, Mégane Dufaur, David Gleizes and Georges Zissis Temperature is the factor that negatively affects the most the lifespan and performances of LEDs. Various methods permit to evaluate the junction temperature, based on electrical or spectral properties. This paper presents a method to determine heat dissipation using the thermal time constant from luminous intensity combined with the equations of the photo-electro-thermal model of the LED. This new approach can be easily used to characterize the LED in their operating environment.

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Th4.4.7 Color and Therapeutic Lighting: an alternative treatment for the Sundowning Syndrome

Estelle Guerry, Georges Zissis, Céline Caumon, Laurent Canale and Elodie Bécheras Sundowning syndrome is a clinical phenomenon that affects institutionalized elderly with cognitive impairment. It’s a physiological response to a decreasing light that leads to disruptive behavior. To limit his impact, we must intervene on the trigger, the light. We were interested to the project "Bon séjour", in the geriatric day hospital of Robertsau, Strasbourg, France. The study of this project demonstrates the value of a strong chromatic program and adapted lighting. The symptoms related to the syndrome are diminished, the project thus providing an alternative solution to drug treatments. Th4.4.8 A Hyperspectral Imaging System for Monitoring of the Plant Leaves

Xiaolin Zhang, Qianbing Gong, Xiaojian Hu and Muqing Liu To monitor the growth of the plant, a new hyperspectral imaging system was built, including rows of monochromatic LEDs, one RPi, one camera and one standard reflecting plate. The system had a very small size and low price. The plant leaves could be evaluated by the spectral reflectance which was much more accurate than RGB evaluation. This system can be adopted in the automatic agriculture. Th4.4.9 Molecular constants and thermochemical parameters for SbX<g> and BiX<g> (X = F, Cl, Br, I), 298.15 to 6000 K

Stuart Mucklejohn Molecular constants for the series SbX<g> and BiX<g>, where X = F, Cl, Br, I, have been collated from published papers and supplemented by estimated values as necessary in order to derive Cp(T) and S(T) from 298.15 to 6000 K. The enthalpies of formation at 298.15 K for the series have been estimated based on published values for reactions: MX<g> = M<g> + X<g>. Values for the thermochemical parameters are listed in the SGTE database format. Th4.4.10 Comparative study of temperature measurement in a blue-LED package by using pulsed-laser Raman scattering and thermocouple method

Makoto Horiuchi, Keisuke Miura, Takao Shimada, Yoshio Manabe and Yukihiko Yamagata A thermal characteristic of a phosphor-less blue-LED package was studied comparatively by a pulsed-laser Raman scattering technique and thermocouple method. A junction temperature and a substrate temperature of the blue-LED package was measured by the Raman shift of E2 mode of the GaN layer and by a thermocouple attached to the reference point of the package, respectively. It is concluded that pulsed-laser Raman scattering technique would be a powerful tool for thermal design and management of solid state light sources. Th4.4.11 Curing effect of LED spectra on collotype photoresist

Minghao Li, Zhiping Sun, Jianhua Fu, Feng Li, Wei Feng, Zhong Jing, Qiuyi Han and Shanduan Zhang

A calculation method for the Collotype radiation absorption efficiency is proposed to analyses the performance of the sunlight and the artificial light sources, which reveals the shortcomings of white light. A curing experiment is performed to evaluate the curing effect and ability of the light sources including four monochrome LEDs with peak wavelength 385, 410, 450 and 480 nm as well as two white-LEDs with correlative color temperature 2700 and 6500 K. The results show that 385 nm and 410 nm LEDs have a better curing effect on Collotype photoresist when the irradiance reaches at 200 W/cm2. Th4.4.12 Manipulation of optical properties in nitride-based semiconductor materials

Jing Li, Jun Yin, Li Chen, Junyong Kang and Rong Zhang Recently, employing surface plasmon resonance (SPR) effect has become a well-recognized strategy for light manipulation in Nitride-based semiconductor materials or corresponding optoelectronic devices with enhanced properties either in light emission or absorption/detection. [1-5] In this report, ordered metal (Ag, Au or Al) nanostructures were proposed and well produced, using template-based nanosphere lithography and thin film deposition techniques, on several Nitride-based wide-band-gap semiconductor materials, including GaN,TiN and BN. The optical modes of local surface plasmon (LSP) induced within the metal/semiconductor hybrid structures were systematically investigated experimentally and theoretically by controlling the size, separation, contact mode of those metal nanostructures. Therefore, the coupling effect between metal and semiconductors can be manipulated to enhance the emission or absorption/detection efficiencies in either AlGaN quantum wells (QWs) or TiN/BN thin films. Additionally, some potential applications in light emission devices, or photovoltaic devices will be demonstrated. Th4.4.13 Simulation Analysis on the Light Pipe of Optical Detector in GIS

Zijie Wang, Xiaoli Zhou and Muqing Liu

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Partial discharge (PD), which occurs in the gas insulated switchgear (GIS), brings hidden danger to electrical safety, even causes serious problems in power grid. Optical detection is employed to monitor PDs. In this manuscript, a simulation model of I-shaped GIS tank was built and the effect of various light pipes of optical detectors on the PD optical signal was studied. By and large, the Cone B pipe was founded to perform the best. The result may contribute to the design of light pipe of optical detectors, improving the accuracy and effectiveness of PD optical detecting system. Th4.4.14 Adaptive street lighting for curved roadway

Xuan-Hao Lee, Ivan Moreno, Chen-Hao Lee, Yeh-Wei Yu, Tsung-Hsun Yang and Ching-Cherng Sun In this paper, a simple and efficient adaptive LED luminaire is proposed to meet the challenge of efficient lighting of roadways with curved shapes. The proposed LED luminaire can maximize illumination performance to deliver a roadway-shape light pattern for reducing the appearance of glare and energy loss problems and improving both the eyes comfort and the visual discrimination ability of car drivers and pedestrians. The design concept and its related simulation analyses are demonstrated. Th4.4.15 Study of the Target Recognition in Simulated Fog Environment

Fanghui Xu, Antian Xu, Hongming Zhou, Xiaoli Zhou and Muqing Liu Visibility can be seriously affected in foggy weather. The OCR simulates the visual acuity of human. In this paper, a simulated fog environment is established to study the impact of OCR target recognition accuracy under different conditions. The visual acuity of human has strong connection with the level of fog density. The result may provide a basis for the design requirements of the related traffic sign characters and the precision requirements of the image acquisition equipment in the fog environment. Th4.4.16 Effect of Pulsed Overcurrent on the Current-Voltage Time Response of High-Brightness LED

James Edward Hernandez, Shigeo Gotoh and Motoi Wada Pulsed overcurrent degradation of LEDs is being evaluated by applying current pulses of the amplitude exceeding the rated current. Leakage current significantly increased with LED voltage for degraded samples. A sign of LED degradation associated with high localized temperature was observed at the wire bond semiconductor interconnect. Another observation was longer discharge time constants for degraded samples. One LED chip failed at about 140,000 pulses at 8.6 times the rated current of 10% duty cycle for 100 ms duration. Th4.4.17 Yellow light-emitting diodes for skin phototheraphy

Wei Dai, Fusheng Li, Qiuyi Han and Shanduan Zhang Phototherapy is a popular method for treating skin disorders. It’s commonly considered that light mainly acts on chromophore in skin cells like cytochrome C oxidase (CCO) which leads to a chain reaction in mitochondria to affect cell proliferation and activity. The yellow light is often used in skin rejuvenation and wound healing treatment dominated by fibroblast in dermis of human skin. The electrical and luminescent parameters of a 590 nm single-chip LED (SC-LED) packages are measured under different water temperatures and input power to reveal the proper working condition. Th4.4.18 High Power Blue Superluminescent LEDs

Rory Cahill and Brian Corbett A high power superluminescent LED (SLED) emitting in the blue is demonstrated. The GaN based device uses a novel surface emitting structure to provide optical peak powers >2W under pulsed operation. The devices exhibit an external quantum efficiency >40%. A smooth, broad spectrum with a peak emission wavelength of 419nm is measured. The FWHM of the spectrum is 8nm. The device is capable of very short pulse generation with pulse widths <300ps having been demonstrated. Th4.4.19 Influence of electrical and thermal stress on luminance decay of large area white organic light emitting diodes

Laurent Canale, Alaa Alchaddoud and Georges Zissis The aim of this paper is to identify the influence of electrical and thermal stress on luminance decay of large area white organic light emitting diodes (41cm² active area). Nine devices have been stressed at a constant current density of 11.25mA/cm², 13mA/cm² and 15mA/cm² at 23°C (room temperature), 40°C and 60°C. We have also stocked three devices under purely thermal stress at the same temperatures. Thus, we can make comparison between electrical-thermal stress and purely thermal stress. Over aging time, the luminance decay increases with the increase of electrical stress (current density) at the same temperature and vice versa. Th4.4.20 Improvement of road-obstacle visibility by temporal control of the contrast between road-obstacle and background

Yoshihisa Ikeda, Koji Okusa, Daiki Shigematsu, Kenji Miyake and Masafumi Jinno

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In the tunnel, the visibility of an object has strong relation with the luminance contrast between the object and its background road surface. In this research we focused on the luminance contrast by temporal control. The Pro-beam LEDs were pulsed operated and the contrast of the road-obstacle and background i.e. the luminance of road-surface were temporally changed. As the results, visibility improvement was confirmed at a frequency of 50 Hz. And when the frequency was increased more than 50 Hz, the visibility became the same as when the LED was operated by direct current. Th4.4.21 Improving the visibility of fallen objects in expressway tunnel by optimum luminance contrast between objects and road surface tunnel

Koji Okusa, Daiki Shigematsu, Kenji Miyake, Yoshihisa Ikeda and Masafumi Jinno To improve visibility of fallen objects in expressway tunnel, we optimized the illuminance ratio of the horizontal one to the vertical one based on subject experiments using a miniature model tunnel. In case that luminance contrast between objects and background road surface was higher than 1.40, subjects recognized the objects as reverse silhouette. In contrast luminance contrast was lower than 0.73, subjects recognized the objects as silhouette. The same results as the model tunnel were obtained in actual tunnel. Th4.4.22 Feasibility study of thermal losses conversion into Light for High Power LEDs using thermoelectric modules

Rabeb Ben Hassen, Laurent Canale, Zouhour Araoud and Georges Zissis Light Emitting Diodes emits no IR and no UV and their spectrum is fully in the visible part. But LEDs are not cold and all energy losses are thermal losses. The aim of this paper is to prove the feasibility to reuse the thermal losses to produce light through a thermoelectric module. Papers where Peltier modules are included in LEDs systems are all the time used for cooling [1-6]. At the knowledge of the authors, this the first time that thermal losses are used to increase the global efficiency of a high power LED lighting system by using Peltier modules to produce light.

Documents

Science and Technology of Lighting · Dominic O’Brien (University of Oxford) Philip Shadbolt (Zeta Group) Philip Shields (University of Bath) Manuel Spitschan (University of Oxford)