CLARREO FTS Design: Achieving Robust On-Orbit SI Traceability for IR - Principles Distilled from NIST John A. Dykema, Joe Demusz, Chris Tuozzolo, Norton

CLARREO FTS Design: Achieving Robust On-Orbit SI Traceability for IR -

Principles Distilled from NIST

John A. Dykema, Joe Demusz, Chris Tuozzolo, Norton Allen, James G. Anderson, Harvard

Hank Revercomb, Fred Best, P. Jonathan Gero, Joe Taylor, Bob Knuteson, Dave Tobin, Bob Holz, UW

Jerry Fraser, Eric ShirleySergey Mekhontsev, Leonard Hanssen, Vladimir Khromchenko

NIST

NRC DS and CLARREO

• “a long-term global benchmark record of critical climate variables that are accurate over very long time periods, can be tested for systematic errors by future generations, are unaffected by interruption, and are pinned to international standards”

• CLARREO science team:- High information content- High accuracy, proven on-orbit- Sampling errors in time, angle, space lower than

climate noise

What is SI Traceability?

• SI traceability is conferred by a chain of comparisons, each of stated uncertainty, back to a recognized SI standard

• CLARREO needs to:– have uncertainty low enough for decadal

science and – needs to prove that biases (systematic error)

that specify this uncertainty are within tolerances

SI Traceability and CLARREO• Jerry Fraser (NIST) has introduced the idea of strength of SI

traceability claim• NIST would recognize that CLARREO requires robust

traceability to achieve its ambitious science goals

The National Measurement Institute (NMI) Model for Traceability

• Measurements are Based on Well-Defined Physical Quantities

• Measurements are Compared among NMIs• Measurements are Compare to Independent

Approaches• Uncertainty Claims are Rigorous and Validated• Methods are Documented in Quality Systems

and Peer-Reviewed Publications• Research is Undertaken to Lower Uncertainties• Fundamental Scales are Realized Periodically

From Jerry Fraser, NIST

Immerse the Cavity into the Phase Transition Cell

SI - Kelvin Traceable

Measure with Contact Thermometer

SI - Kelvin Traceable

APPROACH:APPROACH:

Measure with Absolute Radiation

Thermometers SI Traceable via

Cryogenic Radiometer(Future development)

EffectiveEmissivity

Reference(Effective)

Temperature

Cavity AbsorptanceMeasurements

Comparison of Independent

Scale Realizations

Planck Equation

Monte-Carlo Simulation

Material Emissivity Measurements

+

SI (Kelvin) - based IR Radiance Scale Realization Principles

Plan for suggested CLARREO IR Evaluation at NIST

Metrology activity NIST facility Bias source

Measurement of surface BRDF FTIS Blackbody emissivity

Computation of blackbody emissivity from measured BRDF STEEP-3 Blackbody emissivity

Modeling of blackbody cavity emissivity monitor STEEP-3 Blackbody emissivity

Measurement of blackbody emissivity (1) CHILR Blackbody emissivity

Measurement of blackbody emissivity (2) AIRI scene plate Blackbody emissivity

Evaluation of on-orbit emissivity monitor AIRI, CHILR Blackbody emissivity

Measurement of blackbody radiance AIRI Blackbody emissivity, temperature

Measurement of blackbody radiance over wide temperature range (~190 to ~320 K) OARS (UW): tested as above Nonlinearity

Measurement of uniform, monochromatic source OSRM (Harvard) Spectral calibration (ILS)

Viewing tested blackbodies with controlled, varied background CBS Stray light

Viewing tested blackbodies with controlled, varied background at different positions CBS Polarization

Viewing primary BB sources NIST primary BB sources System-level

Envisioned NIST Infrared Metrology Support The case study involved elements in red

Case Study: Goals

1 Characterize Blackbody Spectral Emissivity using AIRI Facility- Infrared spectral radiance measurements compared to Reference Blackbodies

- Use controlled background “scene plate”; also characterize spectral radiance uniformity

2 Characterize Blackbody Cavity Emissivity using Sphere Reflectometer (CHILR)- Lasers used for low divergence, small spot, high power, 1.32 µm & 10.6 µm

- Custom sphere for complete measurement of cavity reflected light

3 Model Blackbody Cavity Emissivity using characterized cavity coating properties:A. Spectral directional hemispherical reflectance (FTIS Facility)

- Near-normal - Reference Integrating Sphere with Fourier Transform IR Spectrometer

- Variable angle - Center Mount Sphere with FTIR

B. Cavity Coating BRDF, Bi-directional reflectance distribution function (IR SIRCUS / BRDF)

- Laser-based system, 1.55 µm & 10.6 µm

C. Monte Carlo Raytrace Modeling of Blackbody Cavity

- Custom Cavity Modeling Software Suite, “STEEP3” and upgraded / modified versions

- Requires cavity coating properties data

- ArtifactsCase Study - Involved Facilities

Complete Hemispherical Laser-based Reflectometer (CHILR)

-20

-10

0

10

20

Y (mm)

-20

-10

0

10

20

X (mm)

0.000000.000050.000100.00015

-5.0e-05 0.0e+00 5.0e-05 1.0e-04 1.5e-04Apr22_HVBB_10_6_XY_txt_30

CavityIntegrating sphere

Detector

Sphere rotation& X-Y stage

1.32 µm 10.6 µm

Internal (FTIS / AIRI) Comparisons

0.99

0.991

0.992

0.993

0.994

0.995

0.996

2 4 6 8 10 12 14

Reflectometry, DIGILABARM

Em

issi

vity

Wavelength (um)

Pyramid (Structured) Target Emittance

Diffuse Black Target Emittance

Radiometric Characterization of Target Emittance: Experimental Implementation

Target Side View Radiometer Side View

Target Plate Emissivity Measurements

Scene Plate with Alternating Temperature(e.g. 20 C and 75 C)

Through Hole Larger Than Radiometer Nominal Spot Size

20 C Emitting Plate

Layer of Insulating Foam

IR Radiometer (spectrometer)

Target PlateUnder Test

Calibration Artifacts

Pyramid Target and Coupon(Diffuse Black Paint)

Flat Target and Coupons (Diffuse Black and Diffuse Silver Paints)

Spectrophotometric Charactrization of Target Emittance: Integrating Sphere Reflectometer

0.96

0.965

0.97

0.975

4 6 8 10 12

ARM, 13 C background2TM, 13C / 20 C backgrounds2TM, 20 C and 27 C backgroundsARM, 27 C BackgroundReflectometry, Digilab FTIR

Em

issi

vity

Wavelength (um)

Radiance Temperature Measurement Validation

Observed Radiance Temperatureof the diffuse black target measured by the Absolute Radiance Method (ARM) at background 13 C well agrees with predictions based on the data from ARM at BG 27 C and DIGILAB FTIR-based Reference Reflectometer

This indicates a good agreement between thermistor-based and actual surface temperature values

Specifications• l range: 1.0 - 18 µm• 6 inch diameter• gold-electroplated plasma -sprayed metal

coating • MCT detector w/ concentrator optics• baffling in sphere• 8° incidence angle

Capabilities• Reflectance, Transmittance & Emittance• Temperatures 15 - 200 °C• absolute & relative, specular & diffuse

• uncertainties (2s):Ø specular: = 0.3%Ø diffuse: 1.5 - 3.5%Ø larger for angle dependent structure

19.8

19.82

19.84

19.86

19.88

19.9

3 5 7 9 11 13

Wavelength (um)

Rad

ian

ceT

emp

erat

ure

,C

AR M , BG 13 C (observed)

AR M , BG 27 C (converted)

FT IR D ata (predicted)

Folding mirror

Spatialfilter

Polarizer-analyzerattenuator

FilterWheel

Half-Wave Plate

DetectorUnit II

DetectorUnit I Sample

Mirror/Beamsplitter

TiltGoniometer

DetectorRotation

SampleRotation

(10.6 µm)

Black Enclosure

Folding mirror

Spatialfilter

Polarizer-analyzerattenuator

FilterWheel

Half-Wave Plate

DetectorUnit II

DetectorUnit I Sample

Mirror/Beamsplitter

TiltGoniometer

DetectorRotation

SampleRotation

(10.6 µm)

Black Enclosure

Fourier Transform Spectrophotometry (FTS) and IR BRDF Facilities

SSEC-UW AERI Blackbody

Harvard University Sectional Blackbody

Cone Sec 1 Sec 2 Sec 3


0.99

0.991

0.992

0.993

0.994

0.995

0.996

2 4 6 8 10 12 14


Em

issi

vity

Wavelength (um)








20 C Emitting Plate








0.96

0.965

0.97

0.975

4 6 8 10 12


Em

issi

vity

Wavelength (um)




Specifications• l range: 1.0 - 18 µm• 6 inch diameter• gold-electroplated plasma -sprayed metal

coating • MCT detector w/ concentrator optics• baffling in sphere• 8° incidence angle

Capabilities• Reflectance, Transmittance & Emittance• Temperatures 15 - 200 °C• absolute & relative, specular & diffuse

• uncertainties (2s):Ø specular: = 0.3%Ø diffuse: 1.5 - 3.5%Ø larger for angle dependent structure

19.8

19.82

19.84

19.86

19.88

19.9

3 5 7 9 11 13

Wavelength (um)

Rad

ianc

eT

empe

ratu

re,C





0.99

0.991

0.992

0.993

0.994

0.995

0.996

2 4 6 8 10 12 14


Em

issi

vity

Wavelength (um)








20 C Emitting Plate








0.96

0.965

0.97

0.975

4 6 8 10 12


Em

issi

vity

Wavelength (um)




Specifications• l range: 1.0 - 18 µm• 6 inch diameter

• gold-electroplated plasma -sprayed metal

coating

• MCT detector w/ concentrator optics

• baffling in sphere

• 8° incidence angle

Capabilities• Reflectance, Transmittance & Emittance

• Temperatures 15 - 200 °C

• absolute & relative, specular & diffuse

• uncertainties (2s):

Ø specular: = 0.3%Ø diffuse: 1.5 - 3.5%Ø larger for angle dependent structure

19.8

19.82

19.84

19.86

19.88

19.9

3 5 7 9 11 13

Wavelength (um)

Rad

ianc

eT

empe

ratu

re,C




0.997

0.9975

0.998

0.9985

0.999

0.9995

1

3 5 7 9 11 13

Wavelength, microns

Em

issi

vity

Advanced Infrared Radiometry and Imaging Facility (AIRI)

Case Study: Results of Cavity Emissivity from Reflectance, Radiance, and Modeling

Blackbody Cavity

Laser Reflecto-

metry(CHILR)

Thermal Reflecto-

metry(AIRI)

Absolute Radiance

(AIRI)

Modeling(STEEP-3)

SSEC-AERI 0.9994 0.9990 0.9996 0.9993

HU Cone 0.9982 0.9983 n/a 0.9964

HU 1 Section 0.99960 >0.9996 n/a 0.99942

HU 2 Section 0.99985 n/a n/a 0.99978

HU 3 Section 0.99991 >0.9998 n/a 0.99989

On-orbit Traceability for Blackbody1

NIST:

CBS-3: reflectometry,

scene plate

T: contact, fixed point

On-orbit diagnostics:

: Reflectometer (QCL2, halo)

T: phase change cells3,4

1. Dykema and Anderson, Metrologia 43 287-293 (2006).

2. Gero, et al., in press, J.TECH. (2009).

3. Gero, et al., J.TECH. 25 (2008).

4. Best et al., GC23A-0753.

Emissivity / QC Power Evaluation

(1)

(2) (1 )

:

CavityQC

Cavity QC

v

QC

dTC P

dt

d dA I d B T P

dTStrategy Measure I and

dt

Evaluate P and On Orbit

dT/dt = 5 x 10-5 K/sec

Lab result: C(dT/dt)=35 mW

PQC(measured)=33mW

Primary Demonstration of SI Traceability

(used in combination with space view for instrument calibration)

(used for blackbody reflectivity and Spectral Response Module)

(Includes Multiple Phase Change Cells for absolute temperature calibration and Heated Halo for spectral reflectance measurement )

Heated Halo

(Measures instrument line shape)

QCL Laser

How to prove uncertainty is consistent with what is claimed? (NIST perspective)

From Joe Rice, NIST

1st Sensor

2nd Sensor

1st Sensor1st Sensor

2nd Sensor 2nd Sensor

CLARREO solution: two complete, independent test sensors with

independent Test/Validation modules

Advantages to Dual Interferometers

• Testing uncertainty on cold scenes that can’t reliably produced in laboratory

• High duty cycle available for systematic error testing without disturbing benchmark

• Testing systematic error by perturbing thermal or stray light environment

• Optimization of radiometric performance for far- and mid-IR

• Testing blackbody knowledge through thermal gradient perturbation

• Agreement between two instruments invaluable in proving uncertainty is consistent with claims

Lessons Learned

• QCL reflectometer paper to peer review: improve laser power normalization

• NIST demonstration study: demands different blackbody control design

• Iteration/communication between science and engineering: getting dual interferometers into trade space, looking for realistic path

The National Measurement Institute (NMI) Model for Traceability

• Measurements are Based on Well-Defined Physical Quantities

• Measurements are Compared among NMIs• Measurements are Compare to Independent

Approaches• Uncertainty Claims are Rigorous and Validated• Methods are Documented in Quality Systems

and Peer-Reviewed Publications• Research is Undertaken to Lower Uncertainties• Fundamental Scales are Realized Periodically

CLARREO flight designs must be evaluated against the logic of these principles

Documents

CLARREO FTS Design: Achieving Robust On-Orbit SI Traceability for IR - Principles Distilled from NIST John A. Dykema, Joe Demusz, Chris Tuozzolo, Norton