Recent results towards verification of measurement uncertainty for clarreo ir measurements
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Recent results towards verification of measurement uncertainty for CLARREO IR measurements. John Dykema CLARREO SDT, 2012 Hampton, VA. On-orbit Test/Validation (OT/V) Modules. (Measures instrument line shape). Heated Halo. (used in combination with space view for instrument calibration).

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Recent results towards verification of measurement uncertainty for CLARREO IR measurements

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Recent results towards verification of measurement uncertainty for CLARREO IR measurements

John Dykema

CLARREO SDT, 2012

Hampton, VA


On-orbit Test/Validation (OT/V) Modules

(Measures instrument line shape)

Heated Halo

(used in combination with space view for instrument calibration)

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

QCL Laser

(used for blackbody reflectivity and Spectral Response Module)

  • Viewing configuration providing immunity to polarization effects.

Wisconsin & Harvard Technology Developments Under NASA IIP


DARI Testbed (1)


QCL Housing: Optics, Thermal Management, Electronics

New kinematic lens mount


Quantum Cascade Laser Housing – Exploded View

Purge valve

Relief valve (for use during purge)

House-keeping sensor unit (T,p,RH)

Emission window (AR coated ZnSe)

QCL device mounting clamp

Collimating optic/mount

Thermal cold plate

TEC and electrical connection

Mounting structure


QCL Electronics and Built-In Housekeeping


Collimation of 60°-40° output QCL device

QCL

Asphere

Collimated

Beam


QCL Electronics Chassis


Vacuum and Thermal Management


OSRM: TRL 5

Flip mirror

Blackbodies for thermal testing

Laser power meter

QCL w/

integrated

housekeeping

Chilled

ethanol

QCL thermal management

Electronics

bus


Vacuum Test Results


Vacuum Test Results (2)

Results of vacuum test runs

Thermal requirements for different QCL packaging options


DARI Testbed (2)


OSRM: TRL 6

System level test with CO2 laser, integrating sphere: an absolute IR lineshape standard


OSRM : CO2 to QCL ILS Comparison (1)

QCL, when T and I specifications are met, matches CO2 laser lineshape

MCT Detector


OSRM : CO2 to QCL ILS Comparison (2)

Pyroelectric Detector


DARI Testbed ILS


OCEM-QCL TRL 6

Inferring emissivity from laser reflection


Calibrated, Illuminated Blackbodies

Pyroelectric Detector

MCT Detector


Calculation of Power on Detector


Optical Modeling for OCEM-QCL

f: div angle

Reflected Laser Light to FTS and Detector

d

q


Compute Cavity Emissivity

Cf=39 (Knuteson et al.

J.TECH 2004)


QCL Subsystem: Pathway to TRL 7


Current

Sensing

Power

Conditioning

Filter

+

+

Output

Power In

Switching

RegulatorController

-

-

FB

β

Setpoint

Temperature

Offset

TEC Controller


TEC Controller

  • Single Supply Operation

  • High Efficiency

  • No Heat Sink Necessary

  • Buffered Temperature Readout

  • Remote/Local Setpoint


V/I Board

Modified

Howland

Current

Source

+

Input

Waveform

LASER

Protection

-

Voltage Monitoring

V

Power

Monitoring

Current Monitoring

I

Temperature Monitoring

T

IOUT

+

VIN

-

To LASER


V/I Board

  • Single Supply Operation

  • No Heat Sink Required

    • (depending on LASER current)

  • Multiple Monitoring Options:

    • LASER Voltage, Current (Power)

    • LASER Temperature

  • ESD Protection


In Situ Temperature


Temporal Drift in Measurement

= Satellite overpass


Spatial Drift in Measurement


First Assessment of Uncertainty Practices

From Immler et al., AMT 2010


Atmospheric Satellite Measurement

Satellites make wavelength-dependent measurements of radianceR: retrieve x (temperature, humidity, clouds, trace gases, surface properies)


Infrared Profiling Process


Site Atmospheric State Best Estimate

Radiosondes drift in time and space

Radiosondes ascent time much greater than satellite measurement length

Solution: use ancillary measurements to interpolate in space and time

One approach: Tobin et al., “Atmospheric Radiation Measurement site atmospheric state best estimates for Atmospheric Infrared Sounder temperature and water vapor retrieval validation,” JGR 2006

See also Calbet et al., AMT, 2011


Tobin 2006 Approach to SASBE

Two sondes were launched within 2 hours of overpass time

Interpolate sonde profiles in time with IR-based atmospheric profiling

Interpolate sonde profiles in space with geostationary measurements

Perform weighted average of interpolated profiles to get best estimate of atmospheric column


Blackbody Calibration and Uncertainty

  • Practical Blackbody:

  • Finite Aperture •Temperature Gradients


Uncertainty Assessment for Vector Quantities

Uncertainty Assessment: In Situ Temperature Profile TSASBE

Uncertainty Assessment: Infrared Temperature Profile x


Acknowledgements

Thanks to NASA for:

IIP funding (ESTO)

IPT funding (LaRC)

SDT funding


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