Design and Correction of Optical Systemsand...Optical System Classification Overview, photographic...

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Design and Correction of Optical

Systems

Lecture 12: Optical system classification

2017-06-30

Herbert Gross

Summer term 2017

2

Preliminary Schedule - DCS 2017

1 07.04. Basics Law of refraction, Fresnel formulas, optical system model, raytrace, calculation

approaches

2 21.04. Materials and Components Dispersion, anormal dispersion, glass map, liquids and plastics, lenses, mirrors,

aspheres, diffractive elements

3 28.04. Paraxial Optics Paraxial approximation, basic notations, imaging equation, multi-component

systems, matrix calculation, Lagrange invariant, phase space visualization

4 05.05. Optical Systems Pupil, ray sets and sampling, aperture and vignetting, telecentricity, symmetry,

photometry

5 12.05. Geometrical Aberrations Longitudinal and transverse aberrations, spot diagram, polynomial expansion,

primary aberrations, chromatical aberrations, Seidels surface contributions

6 19.05. Wave Aberrations Fermat principle and Eikonal, wave aberrations, expansion and higher orders,

Zernike polynomials, measurement of system quality

7 26.05. PSF and Transfer function Diffraction, point spread function, PSF with aberrations, optical transfer function,

Fourier imaging model

8 02.06. Further Performance Criteria Rayleigh and Marechal criteria, Strehl definition, 2-point resolution, MTF-based

criteria, further options

9 09.06. Optimization and Correction Principles of optimization, initial setups, constraints, sensitivity, optimization of

optical systems, global approaches

10 16.06. Correction Principles I Symmetry, lens bending, lens splitting, special options for spherical aberration,

astigmatism, coma and distortion, aspheres

11 23.06. Correction Principles II Field flattening and Petzval theorem, chromatical correction, achromate,

apochromate, sensitivity analysis, diffractive elements

12 30.06. Optical System Classification Overview, photographic lenses, microscopic objectives, lithographic systems,

eyepieces, scan systems, telescopes, endoscopes

13 07.07. Special System Examples Zoom systems, confocal systems

1. Overview

2. Achromates and apochromates

3. Collimators

4. Relay systems

5. Miscellaneous

6. Photographic lenses

7. Scan lenses

8. Lithographic lenses

9. Telescopes

10. Microscopic lenses

3

Contents

Field-Aperture-Diagram

0.20 0.4 0.6 0.80°

4°

8°

12°

16°

20°

24°

28°

32°

36°

NA

w

40°

micro

100x0.9

double

Gauss

achromat

Triplet

micro

40x0.6micro

10x0.4

Sonnar

Biogon

split

triplet

Distagon

disc

projection

Gauss

diode

collimator

projection

Petzval

micros-

copy

collimator

focussing

photographic

projection constant

etendue

lithography

Braat 1987

lithography

2003

Classification of systems with

field and aperture size

Scheme is related to size,

correction goals and etendue

of the systems

Aperture dominated:

Disk lenses, microscopy,

Collimator

Field dominated:

Projection lenses,

camera lenses,

Photographic lenses

Spectral widthz as a correction

requirement is missed in this chart

4

Throughput as field-

aperture product

Additional dimension:

spectral bandwidth

Classification: l-Lw-Diagram

Lw

l

Photography

Microscopy

Astronomy

LithographyInterferometer

lensmetrology lens

5

Achromate:

- Axial colour correction by cementing two

different glasses

- Bending: correction of spherical aberration at the

full aperture

- Aplanatic coma correction possible be clever

choice of materials

Four possible solutions:

- Crown in front, two different bendings

- Flint in front, two different bendings

Typical:

- Correction for object in infinity

- spherical correction at center wavelength

with zone

- diffraction limited for NA < 0.1

- only very small field corrected

Achromate

solution 1 solution 2

Crown in

front

Flint in

front

6

Achromate

Achromate

Longitudinal aberration

Transverse aberration

Spot diagram

rp

0

486 nm

587 nm

656 nm

0.1 0.2

s'

[mm]

1

axis

1.4°

2°

486 nm 587 nm 656 nm

l = 486 nm

l = 587 nm

l = 656 nm

sinu'

y'

7

Choice of at least one special glass

Correction of secondary spectrum:

anomalous partial dispersion

At least one glass should deviate

significantly form the normal glass line

Axial Colour : Apochromate

656nm

588nm

486nm

436nm1mm

z0-0.2mm

z-0.2mm

2030405060708090

N-FK51

N-KZFS11

N-FS6

(1)

(2)

(3)

(1)+(2) T

PgF

0,54

0,56

0,58

0,60

0,62

8

Conventional achromate: strong bending of image shell, typical

Special selection of glasses:

1. achromatization

2. Petzval flattening

Residual field curvature:

Combined condition

But usually no spherical correction possible

'

111

2

2

1

1

12 fnnRptz

'3.1 fRptz

New Achromate

perfect

image

plane

Petzval

shell

y'

f

RP

mean

image shell

2

1

2

1

n

n

02

2

1

1

FF

02

2

1

1 n

F

n

Fn

selected crown glass

line of solutionfor flint glass

9

Collimation

D

source

G/2divergence

f

u

Collimating source radiation:

Finite divergence angle is reality

Geometrical part due to finite size :

Diffraction part:

Defocussing contribution to divergence

f

DG

DD

l

uf

zsin

2

10

Collimator Optics

spherical

coma

astigmatism

curvature

distortion

1 2 3 sum

-0.1

0

0.1

-5

0

5

-2

0

2

-2

0

2

-4

-2

0

2

4

4

Monochromatic doublet

Correction only spherical and coma:

Seidel surface contributions

Limiting : astigmatism and curvature

Enlarged aperture : meniscus added

11

Relay Systems: Achromate

Large residual aberrations:

1. Astigmatism

2. Field curvature

-1.5 0 1.5

0.5

1.0

a) spherical aberration

z

[mm]

yp

/ ypmax

-2.0 0 2.0

0.5

1.0

b) astigmatic field curves

z

[mm]

y' / y'

maxsagtan

-1.0 0 1.0

0.5

1.0

c) distortion

[%]

y' / y'

max

656 nm

546 nm

486 nm

435 nm

12

Relay Systems: Achromate with Field Lens

Correction comparable

Better fit of pupil

-1.5 0 1.5

0.5

1.0

a) spherical aberration

z

[mm]

yp

/ ypmax

-2.0 0 2.0

0.5

1.0

b) astigmatic field curves

z

[mm]

y' / y'

maxsagtan

-1.0 0 1.0

0.5

1.0

c) distortion

[%]

y' / y'

max

656 nm

546 nm

486 nm

435 nm

-1.5 0 1.5

0.5

1.0

a) spherical aberration

z

[mm]

yp

/ ypmax

-2.0 0 2.0

0.5

1.0

b) astigmatic field curves

z

[mm]

y' / y'

maxsag

tan

-1.0 0 1.0

0.5

1.0

c) distortion

[%]

y' / y'

max

656 nm

546 nm

486 nm

435 nm

13

Relay Systems: More Complicated Systems

Improved performance with more lenses

In particular better color correction

Magnification m = 0.2 -0.5 0 0.5

1.0

a) spherical aberration

z

[mm]

yp

/ ypmax

-0.1 0 0.1

0.5

1.0

b) astigmatic field curves

z

[mm]

y' / y'

max

656 nm

546 nm

486 nm

solid: tan

dashed: sag

0.5

486 nm

587 nm

656 nm

y/ymax

b) field curvature

T S

0.1-0.05 0 0.05

s'

[mm] -0.05 0

T S T S y/ymax

c) distortion

[%]

a) spherical aberration

-0.2 0 0.2

0.5

1.0

z

[mm]

yp

/ ypmax

14

Double telecentric: magnification

Wave transport: phase is invariant

use in phase imaging

Use in Fourier-optical setups or pupil transfer systems

final

plane

starting

plane

f1

f1

f2

f2

d'd

1

2

f

f

yxEyxE ,

1),('

Relay Systems: 4f-Systems

15

Relay Systems: 4f-Systems

Basic system with achromates

Split achromates

-1.5 0 1.5

0.5

1.0

a) spherical aberration

z

[mm]

yp

/ ypmax

-2.0 0 2.0

0.5

1.0

b) astigmatic field curves

z

[mm]

y' / y'

max

sag

tan

-1.0 0 1.0

0.5

1.0

c) distortion

[%]

y' / y'

max

656 nm

546 nm

486 nm

435 nm

-1.5 0 1.5

0.5

1.0

a) spherical aberration

z

[mm]

yp

/ ypmax

-2.0 0 2.0

0.5

1.0

b) astigmatic field curves

z

[mm]

y' / y'

max

sagtan

-1.0 0 1.0

0.5

1.0

c) distortion

[%]

y' / y'

max

656 nm

546 nm

486 nm

435 nm

16

Relay Systems: Endoscopes

Different subsystems:

Differences in performance, complexity, distance, weight

17

Relay Systems: Endoscopes

Transport over large distances

Combination of several relay subsystems

Large field-angle objective lens

Applications: Technical or medical

Different subsystems:

objective 1. relay 2. relay 3. relay

0.5

486 nm

587 nm

656 nm

0.4

00 0.4

Wrms

[l]

0.8 1.2 21.6

y'

[mm]

0.3

0.2

0.1

diffraction limit

18

Relay Systems: Periscope

Major parts:

1. Eyepiece

2. Relay system, several stages

3. Objective

4. Turnable prism

eyepiece

objective

field lens

1. image

1. relay system

2. relay system

2. image

3. relay system

19

Beam Guiding Systems

= 5

= 5

= 4

= 50

= 4

a)

b)

c)

d)

e)

adjustment

Transport of laser light over large

distances

Adaptation of beam diameter

Solutions :

Telescopes of Kepler or Galilei type

20

Interferometer Collimator Lens

Example lens

Aperture NA = 0.5

Spherical correction with

one surface

possible surfaces

under test

Wrms

[l]

0.1

0.08

0.06

0.04

0.02

00 0.03 0.06 0.09 0.150.12

w [°]

diffraction limit

-0.02

0

0.02

sph

-4

-2

0

2

4

coma

surfaces

sumL1 L2 L3 L4lenses

1 2 3 4 5 6 7 8

21

Families of photographic lenses

Long history

Not unique

Classification

Singlets

Landscape

Achromatic

Landscape

Petzval, Portrait

Petzval,Portrait flat R-Biotar

Petzval

Petzval

Projection

Quasi-Symmetrical Angle

Pleon

Panoramic

Lens

Extrem Wide Angle

Fish Eye

VivitarRetrofocus II

Wide Angle Retrofocus

Distagon

SLR

Flektogon

Retrofocus

PlasmatKino-Plasmat

Ultran

Noctilux

Quadruplets

Double Gauss

Biotar / Planar

Double Gauss II

Celor

Compact

Special

Plastic Aspheric

II

IR Camera Lens

Catadioptric

UV Lens

Plastic

Aspheric I

Telephoto

Telecentric II

Telecentric I

Super-Angulon

Hologon

MetrogonTopogon

Hypergon

Pleogon

Biogon

Triplet

Triplets

Inverse Triplet

Heliar Hektor

Pentac

Sonnar

Ernostar II

Less Symmetrical

Ernostar

Orthostigmatic

Symmetrical Doublets

Periskop

Rapid

Rectilinear

Aplanat

Dagor

Dagor

reversed

Angulon

Protar

AntiplanetUnar

Quasi-Symmetrical Doublets

Tessar

22

Tessar

Double Gauss

Super Angulon

Photographic Lenses

Distagon

Tele system

Wide angle

Fish-eye

23

Example lens 2

Distagon

Retrofocus Lenses

24

Nikon 210°

Pleon

(air reconnaissance)

Fish-Eye-Lens

25

Zoom lens

Three moving groups

Zoom Lens

e)

f' = 203 mm

w = 5.64°

F# = 16.6

d)

f' = 160 mm

w = 7.13°

F# = 13.7

c)

f' = 120 mm

w = 9.46°

F# = 10.9

b)

f' = 85 mm

w = 13.24°

F# = 8.5

a)

f' = 72 mm

w = 15.52°

F# = 7.7

group 1 group 2 group 3

26

Handy Phone Objective lenses

Examples

Ref: T. Steinich

US 7643225L = 4.2 mm , F'=2.8 , f = 3.67 mm , 2w=2x34°

US 6844989L = 6.0 mm , F'=2.8 , f = 4.0 mm , 2w=2x31°

EP 1357414L = 5.37 mm , F'=2.88 , f = 3.32 mm , 2w=2x33.9°

Olympus 2L = 7.5 mm , F'=2.8 , f = 4.57 mm , 2w=2x33°

27

Scan Systems: Introduction

Basic setup

Scan-magnification m = 1...2

Virtual source point on curved line: special flattening formula

Requirements: - Duty cycle - Point resolution

- Speed - Accuracy

- Linearity - Cost

d

dm

point

source

lens 1 lens 2

scan

mirror

marginal ray

chief ray due

to scan angle

D

L

s't

s

field

sizescan

anglevirtual source

point for scan

angle

28

Scan Systems: Introduction

Scan resolution:

Number of resolvable points in the field of view

corresponds to angle resolution

Information capacity:

1. Resolvable points

2. Speed of scanning

l

max2 ExP

Airy

D

D

LN

log

log v

angle

resolution

scan speed

growing scan

capacity

acoustic optical modulator

polygon

mirror

galvo

scanner

holographic

scanner

electro

optical

modulator

resonant

galvo

scanner

29

Scan System

Non-telecentric

Scan angle 2x30°

Monochromatic

F--corrected

a) standard distortion

-10%

1

0.5

y/ymax

b) f--distortion

0 10% -0.2% 0 0.2%

1

0.5

y/ymax

0

0.1

0.08

0.06

0.04

0.02

0

Wrms

[l]

15° 30°

c) wave aberration

0° 5° 10°

20°

15°

24° 28° 30.4°

30

Scan Systems: Introduction

Deflecting components

allows a field scan

Mostly rotating mirrors

Pre-objective scanning

Post-objective scanning

y

scan

objective

lens

rotating scan

mirror

scan

angle image

plane

y

scan

mirror

scan lens

image

surface

31

Deflecting Components: Polygon Mirrors

Rotating mirror with plane facets

Pyramidal

Prismatic

scan

line

objective

lens

prismatic

polygon

scan line

pyramidal

polygon objective

lens

32

Fundamental System Groups

Principal layout of a lithographic system

beam steering

mirror

pupil

shaping

integrator rod

reticle

wafer

laser

projection

lens

rema relay lenshomogenizer

diffuser

beam guiding

diameter

adaptation

axicon

zoom

33

Moores Law

Historical development of shrinking feature size

Moores law: factor 2 every two years

EUV

ArF 193 immersion

ArF 193

resolution

[mm]

1.0

0.7

0.5

0.35

0.25

0.18

0.13

0.1

0.07

0.05

0.035

1985 1990 1995 2000 2005 2010year

g-line 436

i-line 365

KrF 248

Intel 48633 Mhz

Pentium

Pentium II

Pentium III

Pentium IV

FutureProcessors

Processors:

66- 100 Mhz-

300 Mhz

600 Mhz

1-2 Ghz-

3 Ghz

4-10 Ghz-

34

Ref: W. Kaiser

Development of Stepper Lenses

35

Ref: Carl Zeiss AG

Lithographic Lens in Reality

36

Development of Lithographic Lenses

b) Refractive spherical systems

a) Early systemsg) EUV

mirror

systems

M1

M3

M2

M4

M4

M3

M1

M2

M5

M6

M1

M2

M3

M4

M5

M6

M8

M6

c) Refractive with aspheres and immersion

d) Catadioptric cube systems

e) Multi-axis catadioptric systems

f) Uni-axis catadioptric systems

37

Lithographic Optics

H-Design

38

Lithographic Optics

I-Design

39

Lithographic Optics

X-Design

40

Field Flatness

Principle of multi-bulges to

reduce Petzval sum

Seidel contributions show principle

-0.2

0

0.2

10 20 30 40 6050

1. bulge 2. bulge 3. bulge1. waist 2. waist

one waist two waists

Petz Petz

1 1

rn

n fp k kk

'

41

Resolution

Lateral resolution (CD)

k1 = 0.25 ... 0.5

Axial resolution

High NA :

Influence:

Wavelength and NA

Diagram : k1 = 0.36, k2 = 0.28

0.85

0.75

0.65

0.55

0.45

0.35

0.95 = NA

z [mm]

10-1

10-1

100

x

[mm]

405

l = 157

193

248

365

NAkx 0

1

l

2

02

NA

nkz

l

2

)/(11 2

2

02

nNA

NA

nkz

l

42

Evolution of Projection lenses

Growing NA and field of view:

Increasing size of objective lenses

Problems with correction, homogeneity, material cost, thermal effects

Technological steps: aspherical surfaces, immersion, catadioptric designs

0.5 0.7 0.9 1.1 1.3 1.5 1.7

Volume

[a.u.]

NA

pure

spherical

immersion

high index

hypothetical

n = 1 n H20

(193nm)

0

0.2

0.4

0.6

0.8

1

aspherical

strong

aspherescatadioptric

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70

Volume [a.u.]

refractive

folded catadioptric

HI

inline catadioptric

-

NA

HI

expectation

hyper-NA

n = 1 nH2O

(193 nm)

design

progress

43

Size Reduction by Aspheres

Considerable reduction

of length and diameter

by aspherical surfaces

a) NA = 0.7

spherical

b) NA = 0.8

spherical

c) NA = 0.8

aspherical

d) NA = 0.9

aspherical

-13%

-9%

44

Projection Processing Modes

Different process modes:

1. Full field

2. Scanning

3. Step and repeat

a) Full wafer projection

Reticle

Lens

Wafer

b) Full wafer scanning

Reticle

Lens

Wafer

c) Step and repeat

Reticle

Lens

Wafer

d) Step and scan

Reticle

Lens

Wafer

45

Lithographic Optics

EUV a-Tool 2008

46

Basic Refractive Telescopes

Kepler typ:

- internal focus

- longer total track

- > 0

Galilei typ:

- no internal focus

- shorter total track

- < 0

Telescopepupil

intermediatefocus

Eyepiece

Eye pupil

telescope focal length fT

eyepiece focal length f

ETelescopepupil

Eye pupil

telescope focal length fT

eyepiece focal length f

E

a) Kepler/Fraunhofer

b) Galilei

47

Catadioptric Telescopes

Maksutov compact

Klevtsov

M1

M2

L1

L2L3 L4, L5

M1

L1, L2

M2

48

Astronomical Telescope

Primary and

secondary mirror

49

Four-Mirror Schiefspiegler Telescopes

Solution Variants A

B

D

E

F

GH

50

Catadioptric Telescopes

Schmidt Telescope

- Aspherical corrector plate

- Residual chromatical aberrations

- Achromatic corrector plate possible

Image

Primary mirror

r = 2f

f

Stop

M1

Correctorplate

Stop

M1

focal plane(curved)

N-BK7N-F2

primary mirror

focus

corrector plate

y

r

a

marginal rays

field

51

Evolution of Eyepiece Designs

Monocentric

Plössl

Erfle

Von-Hofe

Erfle diffractive

Wild

Erfle type(Zeiss)

BerteleScidmore

Loupe

Erfletype

Bertele

Kellner

Ramsden

Huygens

Kerber

König

Nagler 1

Nagler 2

Bertele

Aspheric

Dilworth

52

instrument

pupil

x'

z'

e x

s'

F'

f1

f2

field

lens

intermediate

image

stopeye

lens

eye

pupil

Eyepiece: Notations

Field lens reduces chief ray

height

Eye lens adapts pupil diameter

Matching of

1. Field of view

2. Pupil diameter

3. Pupil location

Eye relief :

- distance between last lens surface and eye cornea

- required : 15 mm

- with eyeglasses : 20 mm

Pupil size: 2-8 mm

53

Kellner Eyepiece

Corresponds to Ramsden type

Field lens moved

Eye lens achromatized

-1.000 0.000 1.000

0.250

0.500

0.750

1.000

LONGITUDINALSPHERICAl ABER.

DIOPTER

-3.000 0.000 3.000

2.625

5.250

7.875

10.500

tan sag

ASTIGMATICFIELD CURVES

DIOPTER

-20.00 0.00 20.00

2.625

5.250

7.875

10.500

DISTORTION

Distortion (%)

0°

10°

20°

24°

20

arc

min

54

Abbe Orthoscopic Eyepiece

Distortion corrected

General problems with eyepieces:

- remote eye pupil

- typical eye relief 22 mm

-1.000 0.000 1.000

0.250

0.500

0.750

1.000

LONGITUDINALSPHERICAl ABER.

DIOPTER

-3.000 0.000 3.000

2.000

4.000

6.000

8.000

tan sag

ASTIGMATICFIELD CURVES

DIOPTER

-20.00 0.00 20.00

2.000

4.000

6.000

8.000

DISTORTION

Distortion (%)

0°

10°

18°

20 a

rcm

in

55

Application Fields of Microscopy

Ref: M. Kempe

Cell biology

biological development

toxicology,...

Biomedical basic

research

Material

research

Research

Medical

routine

Pharmacy

semiconductor inspection

semiconductor manufacturing

Industrial

routine

Routine

applications

Microscopy

Micro system technology

geology

polymer chemistry

Pathology

clinical routine

forensic,...

Microscopic surgery

ophthalmology

56

Image Planes and Pupils

Principal setup of a classical optical microscope

Upper row : image planes

Lower row : pupil planes

Köhler setup

source

collector condenser objective eyepiece eyetube lens

eye

pupil

exit pupil

objective

aperture

stopfield

stop

object intermediate image image

57

Microscope with Infinite Image Setup

Basic microscopic system with infinite image location and tube lens

Magnification of the first stage:

Magnification of the complete setup

Exit pupil size

eyeobj

tubemicro

f

mm

f

fm

250

obj

tubeobj

f

fm

obj

obj

objExPm

NAfNAfD

2'2

marginal

ray

eyepiece

chief ray

w'

intermediate

imageobjective

lens

object

eye

tube length t

h'

h

fobj

w

pupil tube lens

s1

feye

eye

pupil

58

Upright-Microscope

Sub-systems:

1. Detection / Imaging path

1.1 objective lens

1.2 tube with tube lens and

binocular beam splitter

1.3 eyepieces

1.4 optional equipment

for photo-detection

2. Illumination

2.1 lamps with collector and filters

2.2 field aperture

2.3 condenser with aperture stop

eyepiece

photo

camera

tube lens

objective

lens

lamp

lamp

collector

collector

condensor

intermediate

image

binocular

beamsplitter

object

film plane

59

Stereo microscopes Upright microscopes Inverse microscopes

Routine microscopes

From M. Kempe

Microscope Stands

60

Microscope Objective Lens: Performance Classes

Classification:

1. performance in colour correction

2. correction in field flattening

Division is rough

Notation of quality classes depends on vendors

(Neofluar, achro-plane, semi-apochromate,...)

improved

field

flatness

improved colour correction

Achromate

Plan-

Apochromat

Fluorite Apochromatno

PlanPlan-

achromat

Plan-

Fluorite

61

Microscope Objective Lens: Structure

Typical parts of lens structure for high NA-objective lenses

Separation of the lens setup in 3 major sections

afront part :

1. spherical aberration : only small

2. coma : only small

3. astigmatism : only small

4. curvature : only small

b

middle part :

1. spherical aberration : correction

2. color : correction

3. coma : correction

rear part :

1. curvature : correction

2. astigmatism : correction

3. color : correction

c

62

Microscope Objective Lens Types

Medium magnification system

40x0.65

High NA system 100x0.9

without field flattening

High NA system 100x0.9

with flat field

Large-working distance

objective lens 40x0.65

63

Microscope Objective Lens: Correcting lens

Floating element to

adjust and correct

spherical aberration

Applications:

1. different thickness values

of cover glass

2. index mismatch at

the sample

floating

element

+1.80 mm

+1.63 mm

0.7 mm

cover

slide

air distance

1.2 mm

1.7 mm

0 mm

4.46

mm

3.99

mm

3.66

mm

3.32

mm

+2.04 mm

64

Microscope Objective Lens: Pupil

Object space telecentric

Real rear stop is not

defining the pupil

Collimated outgoing

beam

Exit pupil usually

not accessible

object

plane

objective

lens

rear stop

exit pupil

marginal ray

chief ray

telecentric,

entrance pupil infinity

y'p

u

f'f'

chief

ray

exit

pupil

rear

stopobject

plane

pupil

65

Illumination Optics: Overview

Instrumental realizations

a) incident illumination

bright fieldb) incident illumination

dark fieldc) transmitted illumination

bright field

d) transmitted illumination

dark field

ring

mirrorobservation

illumination

object

plane

ring

mirror

objective

lens

object

plane

observation

illumination

observation

ring

condenser

object

plane

illumination

condenser

object

plane

observation

illumination

66

Stereo Microscope

Telescopic setup : common main objective lens

View along the axis

eyepiece

tube

system zoom

system object

plane

eye

common

axis

stereo

angle

common

objective

lens

left

imaging

channel

right

imaging

channel

possible

illumination

channels

67