clarreo science meeting july 2010 mgm: 5a- 1 presenter: marty mlynczak infrared instrument overview...
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CLARREO Science Meeting July 2010 MGM: 5a- 1
Presenter: Marty Mlynczak
Infrared Instrument Overview- CLARREO Infrared Team
CLARREO IR Science Lead
CLARREO Science Meeting July 2010 MGM: 5a- 2
• IR Requirements, Concept, Calibration Drivers, etc.
• Review Instrument Re-Scope Study
• Current Radiometric Modeling– Measured Pyroelectric Detector Performance– Updated Noise Performance – Updated Systematic Uncertainty Assessment
• NIST Activities– Investments in FY2011
• Overview of Phase-A Planning
• Status, Concerns, Summary
Outline
CLARREO Science Meeting July 2010 MGM: 5a- 3
• Infrared Baseline Science Measurement: CLARREO shall obtain infrared radiance spectra of the Earth and its atmosphere using nadir views from orbiting satellites. The benchmark and reference intercalibration measurements require:
• a Broad spectral coverage of the earth emitted spectrum, including the Far-Infrared, that captures climate trend information about atmospheric structure, composition, clouds, and surface properties;
• b Spectral resolution chosen for greenhouse gas species separation and for vertical structure information;
• c Radiance measurement systematic error that corresponds to < 0.1 K brightness temperature radiometric calibration uncertainty (3-s confidence, excluding random noise) for the range of expected earth scene temperatures and wavelengths relevant to climate;
• d Spatial and temporal sampling sufficient to provide global coverage and reduce sampling errors to levels that degrade the measured climate trend accuracy by less than 15%, and that degrade the time to detect climate trends less than 10%. The degradation of trend accuracy is relative to the limits of accuracy caused by climate natural variability.
Level 1 IR Requirements
CLARREO Science Meeting July 2010 MGM: 5a- 4
• Spectral Range: 200 to 2000 cm-1 (2760 cm-1 goal)– Rationale:
Spectral Range for Climate Benchmark and Fingerprinting Spectral Range for Reference Intercalibration of Longwave Broadband
Sensors (CERES; GERB; Megha-Tropiques)
• Spectral Resolution: 0.5 cm-1 unapodized– Rationale:
Ability to resolve effects of temperature and water vapor as functions of altitude
• Systematic Uncertainty: 0.100 Kelvin (3s, i.e. coverage factor, k=3)– Rationale:
0.1 K is half of the expected trend in global temperature change per decade
• IFOV: No less than 25 km– Rationale: Enables climate record, reference intercalibration
• Ground sampling: One calibrated spectrum every 200 km or less– Rationale: Nyquist samples the autocorrelation length of the radiation field
• Nadir Viewing within +/- 0.2 deg– Rationale: Keeps temporal bias between satellites < few milli-Kelvin
Level 2 requirements defined
Level 2 IR Instrument Requirements
CL.SYS.1.REQ.1001
CLARREO Science Meeting July 2010 MGM: 5a- 5
Space View (Off-Zenith)
Heated Baffles
Int. SphereVerification
Phase-Change
Blackbody
QCLScene Select
Space View (Zenith)
Earth View (Nadir)
Calibr
ation
Phase
-
Chang
e
Blackb
ody
Mid-IR Detector
Electronics
Far-IR Detector
Electronics
Mid-IR Cryocooler
Mid-IR Aft Optics
Mid-IR Detector
Far-IR Aft Optics
Far-IR Detector
Fore Optics
Reference Blackbody
Scan Mechanism
FTS
Calibration/CollectionElectro-Optical
Verification
IR Concept Consists of Electro-Optical and Calibration-Verification Modules
Unique verification system quantifies calibration uncertainties
CLARREO Science Meeting July 2010 MGM: 5a- 6
Driving error terms defined
Major Terms Driving Calibration
Hot Calibration Blackbody Radiance
Cold Calibration Blackbody Radiance
FTS Error TermsSignal Gain Term
•Measurement equation converts sensor output signals into calibrated scene radiance
ThermometrySpace View UsedOn-Orbit – Not a Significant Contributor
Uncertainty inLinearity Correction
FTS Instrument Temperature Changes
Between Calibrations
Error Drivers
TargetRadiance
CLARREO Science Meeting July 2010 MGM: 5a- 7
Methodology for Measuring Spectral Radiance
Measure spectral radiance with quantified uncertainties
Emissivity
Temperature
SI Traceable Fixed Points Provide Known Temperature with Known Uncertainty
Compare to NIST BBs
Enabling SI Traceable measurements of absolute spectral radiance, spectral emissivity and temperature of Blackbody sources
NIST Approaches for Emissivity Determination
Paint and Cavity Reflectivity Measurements
Monte Carlo Modeling
NIST Approach for Temp Sensor Calibration
Planck Equation
NIST’s Advanced Infrared Radiometry and Imaging (AIRI) Facility -IR Spectral Radiance and Radiance Temperature at Ambient Conditions
CLARREO Science Meeting July 2010 MGM: 5a- 8
Maintaining Accuracy On-Orbit
On-orbit, SI traceable measurements of temperature and emissivity
• High accuracy determination of the time-dependent bias is critical to creating trusted, enduring climate records.
• Traditional Approach:
Space-based measurements of emitted thermal radiances are determined using blackbodies that have been well-characterized on the ground. The dominant sources of uncertainties include those in the BB cavity temperature and emissivity.
• Challenge: On-orbit sensors generally change/degrade over time.
-- Temperature sensors and electronics drift
-- BB surface coatings are known to change after extended exposure to LEO environment (e.g., atomic oxygen, outgassing)
• Solution: SI traceable measurements that quantify the BB T and e on-orbit
CLARREO Science Meeting July 2010 MGM: 5a- 9
On-Orbit Verification
SI Traceability: Unbroken chain of comparisons with stated uncertainties
Emissivity Temperature3 Phase Change CellsProvide SI Traceable Fixed Points (-40oC, 0oC, 30oC)
Cavity Emissivity Measurement
SI (Kelvin)-Based IR Radiance Scale Realization
Quantum Cascade
Laser (QCL)
Heated Baffle
Phase Change Cells
Melt Material
Planck Equation
CLARREO Science Meeting July 2010 MGM: 5a- 10
Verification System Overview
CLARREO Science Meeting July 2010 MGM: 5a- 11
• Three initial and independent studies of FTS instruments show that the CLARREO accuracy requirements can be met
– University of Wisconsin/Harvard University analysis indicates CLARREO accuracy requirement (total combined uncertainty) will be met over full spectrum
– Analysis by Space Dynamics Lab (SDL) indicates requirement will be met at wavelengths > ~ 5.5 mm (280K scene)
Calibration Equation used to quantify > 40 contributors to total uncertainty
» Major contributors identified and tolerances assigned» Risk factors identified and mitigation plan prepared
– Current analysis at Langley for CLARREO design also indicates requirement can be met
Can L1 Accuracy Requirement be Met?
CLARREO Science Meeting July 2010 MGM: 5a- 12
IR Instrument Meets Level 1 Requirements
Meet level 1 & level 2 requirements
Combined Type BUncertainty
54 mK
Calibration Blackbody Radiance
31 mK
Space ViewRadiance
< 1 mK
Gain Nonlinearity
29 mK
FTS Uncertainty
Terms33 mK
Estimated k=3 uncertainties at 1000 cm-1 for scene temperature of 250K, with calibration BB
at 270K
IR Level 1 Requirement
100 mK, 3 s (k=3)
Annual Type A
Uncertainty< 1 mK
Total Combined
Uncertainty 54 mK
SI Traceability: Unbroken chain of comparisons with stated uncertainties
CLARREO Science Meeting July 2010 MGM: 5a- 13
• CLARREO, with its climate focus, looks to generate accurate radiances on annual to semi-annual time scales, on global average– Random uncertainty is present as noise on the measured radiance– Random uncertainty is reduced by averaging
More than 2 x 106 spectra per year reduce random uncertainty by ~ 1440
• IR FTS noise is dependent on detector type (Pyroelectric vs. Solid State)
• Prior analyses indicated single spectrum noise: 0.05 K < NeDT < 10 K
– Annual average uncertainty due to random noise: 0.034 mK to 7 mK
• Random noise substantially impacts time to calibrate on ground and in-orbit
• Examined current off-the-shelf pyroelectric devices to verify performance
Random Measurement Uncertainty
Random uncertainty is not a science concern
14
Acquired 15 pyroelectric detectors from SELEX and their Specifications:
• IR waveband range: 15 to 50-micrometer for CLARREO Far-IR• Material: DLATGS (Deuterated L-alanine doped Triglycine Sulfate)• Operating temperature: ~300K• Element active area: 3 mm• Window: CsI• Frequency range of operation: 10 Hz to 1 KHz
Type Number: P5504 (5)• Detectivity: 4.5x108 cm-Hz1/2/W @ 100 Hz, 2.5x108 cm-Hz1/2/W @ 1KHz
Type Number: P5546 (5)• Detectivity: 6x108 cm-Hz1/2/W @ 100 Hz, 3.2x108 cm-Hz1/2/W @1KHz
Type Number: P5550 (5) • Detectivity: 1.8x109 cm-Hz1/2/W @10 Hz
SELEX Pyroelectric Detector Characterization
15
Detector Temperature: 20oC
Detector/Monochromator with N2 Purge
Vendor Specifications (Spec.):
Frequency: 10 Hz
D*: 25.0×108 Jones
Note: This is beginning of life performance. We are looking into flight performance of similar pyroelectrics to estimate end of life performance
SELEX P5550-03 DLATGS Pyroelectric Detector
100
101
102
103
104
107
108
109
1010
Frequency [Hz]
D*
[Jon
es]
1.94471X108
16.1996X108
4.64423X108
Calculated
Spec.
Detectivity variation with Chopper Frequency
SELEX Pyroelectric D* Calculations
16
Selected Four SELEX Pyroelectric Detectors
SELEX Pyroelectric D* Summary
17
NEdT Comparison of SELEX DLATGS and Old Pyroelectric
(200 cm-1 to 700 cm-1 with 25 cm-1 interval, Scene Temperature: 250K)
200 250 300 350 400 450 500 550 600 650 7000
2
4
6
8
10
12
Wavenumber (cm-1)
NE
dT (K
)
NEdT comparison results of SELEX DLATGS and Old Pyroelectric Detector
P5546-04
P5550-03Old Pyroelectric detectorSELEX Detectors:
D* (P5546-04):
1.296×109 Jones @100Hz
5.82×108 Jones @1000Hz
D* (P5550-03):
1.62×109 Jones @100Hz
4.64×108 Jones @1000Hz
Old Pyroelectric Detector:D*:
2.5×108 Jones @100Hz
1.5×108 Jones @1000Hz
NeDT Comparison, SELEX and Prior Pyro
18
Detector NER Summary
19
Detector NeDT Summary
20
Total Radiance Uncertainty by Detector and Scene
21
Total Error (TB) by Detector and Scene
Third Independent Study Supports CLARREO IR can meet Accuracy Reqm’t.
CLARREO Science Meeting July 2010 MGM: 5a- 22
Radiometric Modeling Status
• Testing at Langley and GSFC of SELEX pyroelectrics will continue
• Devices tested at Langley show much improved far-IR noise performance than previously calculated with data from SELEX catalog
– Maximum NeDT is ~ 2 K vs. ~ 15 K at 200 cm-1 previous
• Three separate modeling efforts (UW; SDL; LaRC) all indicate CLARREO systematic error requirement (0.1 K, k = 3) can be achieved
• Integrated Product Team (selection coming soon) will continue to refine and update radiometric model to further guide instrument development
CLARREO Science Meeting July 2010 MGM: 5a- 23
Instrument Mass, Power, Thermal
CLARREO Science Meeting July 2010 MGM: 5a- 24
IR Instrument Suite
Instrument suite is of moderate size and complexity
QCL Radiator
Metrology Laser Radiator
IR Bench Radiator
Cryo-Cooler Radiator
Blackbody Radiator
IR Scene Select Assembly
IR FTS Scan Mechanism
Cryo-Cooler
Mid IR Detector Optical Assembly
IR Instrument Mount
Far IR DetectorOptical Assembly
IR Instrument Mount
Verification Assembly
CLARREO Science Meeting July 2010 MGM: 5a- 25
IR suite is moderate class
Infrared Instrument Comparison
Class Instrument Mass (kg)
Pwr (W)
Vol (m3)
SpectralBand
Spectral Rsltn (cm-1)
Absolute Accuracy
(K)
IFOV (km);
Swath Width (km)
Detector Format
Explorer
IRIS 22 5-25 mm 4.3 0.4-1.7 ~110 km Single element
CIRS 39 33 0.35 7-1000 mm 0.5 - 20 1.9-6.2 N/A Detector
array
ACE 41 37 0.172.3-13.3 mm 0.02-1.0 Solar occult Single
element
CLARREO IR Suite* 76 124 0.277
5 – 50 mm 0.5 0.1 K (k=3) 25
nadir onlyThree single-
element
Sounders
CrIS 165 123 0.60 4 – 15 mm 0.62-2.5 0.3 K 14 +/- 1000
9 element array
AIRS (Grating) 177 220 1.754 – 15 mm 0.5-2.5 0.3 K 13.5
+/- 9002378 element
array
IASI 236 210 1.714 – 15 mm 0.25 0.5 K 12
+/- 1000Single
element
* Values reflect results of “DAC-5” activity to become compatible with Falcon 1-e
26
• Vital Stats as of 5/2010– Mass: 85 kg– Power: 152 W
• Falcon 1-e accommodation requires – Mass target: 80 kg– Power target: 140 W
• Held IDC session to evaluate alternate instrument configuration– Identify driving requirements and evaluate impact (e.g., risk,
science) and benefit (e.g., mass, power, cost reduction) of relaxing the requirement
Task: Develop IR Compatible with Falcon 1-e
27
• Modified or no fore-optics• Smaller blackbodies (emissivity vs. size)• No dedicated instrument controller (i.e., use s/c processor)• Reduce spectral range• Reduce mid-IR detectors from 2 to 1• Reduce measurement requirements (e.g., resolution, accuracy, etc.)• Methods for reducing and handling non-linearity• Reduce temperature stability/control requirements• Operation of verification system when excess power is available• Use of composite materials• Data rate reduction with compression
IDC Potential Trades
28
• Use more “evolved” instrument design• Breadboard-like design, with smaller volume and surface area• Reduced cooling requirements and power• Update mass in cooling system hardware
• Mass change: - 3.7 kg
• Heater Power change: - 1.1 W
• Volume: 0.277 m3 (Prior 0.49 m3)
Instrument Geometry Trade
29
CLARREO IR Instrument Assembly, 05/01/2010
0.560 m 0.76 m
0.65 m
Nadir
Zenith
Volume0.277 m³
LaRC Optic Design, Four Port FTS, Pupil Image and Winston Cone Combined SystemBreadboard Version IR Instrument Configuration
30
• Knowledge of system response non-linearity in observed scene temperatures on orbit required
• More than 98% of earth scenes are between -70C and +50C
• Have cold calibration via space view below -70C
• Reduce cooling requirement (DAC4: -80C) to -70C
• Little impact (-1W) in reducing high (+50C) temperature; retain this for complete non-linearity verification
• Heater Power change: - 8W
Verification Blackbody Temperature
31
• Analysis: Mid-IR MCT detectors with similar spectral ranges and sensitivities– BAE (AIRS-LITE) operates at 60K– Teledyne (CrIS) operates at 80K
• Change to higher temperature (80K) Teledyne HgCdTe over prior baselined BAE AIRS-LITE 60K cryocooler temperature
• No change in science performance
• Cryocooler power change: - 11.1W
Mid-IR Cryocooler Temperature
32
• Details now available concerning components sketched out in prior design cycles
• Determined specific component and board masses and powers
• Assumed cabling is 7% of final instrument mass
• Separate survival board electronics removed – Function to be provided by s/c
• Mass Change: - 4.1 kg• Power Change: - 7.7W
Refined Electronics Hardware Definitions
33
• Reviewed MEL in detail to identify areas in need of additional refinement
– FTS Assembly and Scanner: - 2.95 kg
– Scene Select Components: + 0.6 kg
– Thermal Control (Heat Pipes): + 1.5 kg
MEL Scrub
34
• Implemented the following changes– Instrument form factor changed– Raised minimum verification blackbody temperature to -70C– Changed mid-IR detector (increased operating temperature)– Refined MEL definition
• Results– Mass Change: - 8.6 kg (- 5 kg target)– Power Change: - 27.9 W
DC-DC converter power reductions with this change: - 6.4 W– Total Power Change: - 34.3 W (- 18 W target)
• Current IR Instrument: 76 kg, 124 W
Current IR Instrument fits well within envelope for Falcon 1-e
“Falcon 1-e” Summary
35
• NASA has funded, via Instrument Incubator, Advanced Component Technology, and Advanced Technology Initiatives several projects since 2001
• These have addressed fundamental needs for CLARREO IR instrument– FTS Technology– Verification system– Calibration– Component hardware– Detector technology
Technology Development Status
36
NASA Technology Investments in CLARREO IR
• IIP 2001: FIRST– FTS; Focal planes; Beamsplitters; Far-IR science
• IIP 2004: INFLAME– FTS; Calibration;
• IIP 2007: CORSAIR – Beamsplitters, Blackbodies, Detectors
• IIP 2007: AASI– Blackbodies; Phase Change Cells; QCL; Verification system
• ACT 2008: FIREBIB – Far-IR detectors and Calibration
• ATI 2008: Melt Cell– Testing of Wisconsin and Utah State/SDL melt cells on the ISS– First launch in January 2011
CLARREO Science Meeting July 2010 MGM: 5a- 37
• LaRC has developed technology for CLARREO for nearly one decade– FIRST and INFLAME FTS instruments developed and flown– CORSAIR, FIREBIB, Melt Cell projects in progress
Detectors, beamsplitters, blackbodies in development
• UW/Harvard developing CLARREO Technology– Verification system elements in development
Key CLARREO technologies in development to TRL 6
Technology Development Heritage
Melt Material
BlackbodiesEmissivity Monitoring
Phase ChangeCells
QCL
CLARREO Science Meeting July 2010 MGM: 5a- 38
September 5 2009 – PWV = 0.75 mm
18
CLARREO Science Meeting July 2010 MGM: 5a- 39
September 5 2009 – PWV = 0.75 mm
19
CLARREO Science Meeting July 2010 MGM: 5a- 40
September 19 2009 – PWV = 0.4 mm
20
CLARREO Science Meeting July 2010 MGM: 5a- 41
IIPs and Breadboard Provide Early Risk Reduction
Technology Development Plan Leverages Hardware Matured Through Breadboard and IIP Programs
AASI
Phase-ChangeBlackbodies Emissivity
Measurement
FlightQualification
LaRC Breadboard
DetectorPackaging
4-port FTS
FIRST INFLAME
Far-IR Measurements
4-port FTS
Cryocooler Electronics
Vendor
Mid-IR Detector
Electronics
Far-IR Detector
Electronics
Mid-IR Cryocooler
Phase-Change
Blackbody Assembly #1
Phase-Change
Blackbody #2
Scene Select
Assembly
Mid-IR Aft Optics
Assembly
Mid-IR Detector
Assembly
Far-IR Aft Optics
Assembly
Far-IR Detector
Assembly
Fore Optics Assembly
Reference Blackbody
Scan Mechanism Assembly
FTS
Space View (Zenith)
Space View (Off-Zenith)
Earth View (Nadir)
QCLIntegrating
Sphere
Heated Baffle
TRL 4/5
TRL 6
CORSAIR
BeamsplitterCoatings
CORSAIR(NIST Support)
SI Traceable Far-IR BB
CLARREO Science Meeting July 2010 MGM: 5a- 42
Technology Assessment
Item TRL Status
Calibration and Verification Module4
Developed as part of the University of Wisconsin (UW) & Harvard (HU) and Space Dynamics Laboratory IIPs.
Verification and Calibration Blackbody4
Developed as part of the UW & HU IIP. Phase change cells, thermometry, and emissivity monitor are the pacing items.
Scene Select Assembly6
Standard technology; design will be configured and tested for CLARREO.
Integrating Sphere6
Standard technology; design will be configured and tested for CLARREO.
Structure6
Standard technology; design will be configured and tested for CLARREO.
Reflects Current TRL AssessmentExpect TRL-6 at Completion of IIP
CLARREO Science Meeting July 2010 MGM: 5a- 43
Technology Assessment
Item TRL StatusElectro-Optical Module
4Pacing items are the Quantum Cascade Laser and beam-splitter.
FTS Assembly4
Coating spots on beam-splitter for reference laser -unknown TRL
Mid-IR Assembly5
The detector assembly is comprised of two single-element detectors, MCT and InSb, sharing a pupil image.
Far-IR Assembly6
Far-IR: baseline of a pyroelectric detector system is a configuration of high TRL parts not yet selected and tested for CLARREO. Selex pyros have flown on TES and Mini-TES
Optical Bench6
Standard Al honeycomb technology.
Quantum Cascade Laser4
Laboratory QCLs are available from several vendors and low power QCLs have been flight qualified on SAM.
Fore-Optics6
Standard optical components.
Structure6
Not a new technology, have flown before. Design will be tailored for CLARREO; standard practice.
Radiator6
Not a new technology, have flown before. Design will be tailored for CLARREO; standard practice.
Electronics Module6
Electronics 6
Mostly standard electronics design with high TRL components
Reflects Current TRL AssessmentExpect TRL-6 at Completion of IIP
NIST-CLARREO (IR-Instrument) Partnership- Activities Funded in Next Few Months -
1. QCL Laser (23 mm) will be purchased this summer. The laser will be used to measure the BRDF of various candidate surface treatments. It will also be used for Reflectometry measurements in CHILR to measure reflections (emissivity) of actual assembled blackbodies
2. STEEP-3 Emissivity Modeling Software will be upgraded to incorporate BRDF for better blackbody modeling and design prior to construction.
BRDF Integrating Sphere
CLARREO Calibration Facility Requirements- Activities Under Consideration for Phase A -
CHILR Investments: Complete Hemispherical IR Laser Reflectometer will provide necessary data to the blackbody designers in order to develop high-fidelity models of emitting surfaces at wavelengths beyond ~15 mm. Currently, there are no facilities that can acquire this data. These data will be fed back into the STEEP-3 upgrade as actual working parameters.
CBS3 Investments: The Controlled Background Spectroradiometry and Spectrophotometer System will serve as NIST’s premier calibration facility for high accuracy (15 mK at 10 mm / 300 K k = 2) investigations of blackbodies and detectors in the near to far IR (Range of operation: 1 mm to 100 mm, 190K to 350 K) This will provide absolute radiometric calibrations of the CLARREO flight blackbodies with high accuracy and confidence
CHILR CBS 3
CavityIntegrating sphere
Detector
Sphere
rotation
& X -Y stage
23 µ m 10.6 µ m
46
Climate Absolute Radiance and Refractivity Observatory(CLARREO)
IR Instrument Phase A Trades
47
• T1: Operating Temperature and Control
• T2: Optical Alignment Sensitivity
• T3: Detector Frequency Response
• T4: Temperature Measurement Electronics
• T5: Linearity
• Potential Trades discussed on following charts
List of Potential Phase-A Trades
48
• Operating temperature, thermal control, and thermal knowledge
– Examines the trade between accurately measuring changes in temperature, reducing sensitivity to temperature changes by reducing the operating temperature, and the difficulty in controlling temperature at different operating temperatures.
– Includes scene select mirror and baffles, fore optics and baffles, temperature difference between beamsplitter and compensator, and internal reference blackbody source.
T1: Operating Temperature and Control
49
• Optical alignment Sensitivity
– Examine the ability of the optical path (including input and output optical axes, the beamsplitter and corner cube mounts, and FTS scan mechanism) to maintain shear alignment over the 15s calibration cycle.
– Derive tolerance for changes in temperature gradients in the optical bench over the calibration period.
T2: Optical Alignment
50
– Examine the trade between leveling the frequency response of the pyroelectric detector (by boosting gain for high frequency?), maintaining well-behaved group delay in the signal chain, and maintaining velocity reproducibility in the FTS scan mechanism.
– Right now the fact that the pyroelectric response decreases so rapidly with frequency means that slight changes in FTS scan velocity give significant changes in responsivity and decrease calibration accuracy.
T3: Detector Frequency Response
51
• Electronics trade to evaluate best sensors for measuring absolute temperature (used primarily for calibration and verification sources) vs. best sensors for measuring small relative changes in temperature where you don't really care so much about the absolute temperature.
• Suspect that this means using a very linear temperature sensor; otherwise you need to know the temperature to get the temperature difference. There are places like the reference source where we need to measure changes in temperature over 15s to significantly better than 10 mK, but don't really need to know the absolute temperature.
T4: Temperature Measurement Electronics
52
• Electronics linearity knowledge and stability.
– Sensitivity analysis to see if detector signal processing chain, detector through preamp and ADC to bits, can be linearized to better than 3e-5 (1> sigma) and if the electronics gain can be kept stable over 15s to better than 0.01%.
T5: Linearity
CLARREO Science Meeting July 2010 MGM: 5a- 53
• Thermometry – – Challenging radiometric accuracy requirements (0.1 K, k = 3) result in
stringent accuracy of temperature measurements in the entire IR system– Addressing requirements through instrument modeling,– Temperature metrology labs (e.g., Langley, UW, SDL) are characterizing
thermistor and PRT performance
• Radiometry – sources for calibration across the spectrum– Verifying accuracy of radiometric sources continue to be an issue– Continuing to work with NIST – Mlynczak to visit PTB/Berlin (NIST for Germany) July 19– Will view their far-IR and Thz synchrotron sources for possible
applicability to CLARREO
Issues and Concerns
CLARREO Science Meeting July 2010 MGM: 5a- 54
• IR Instrument Suite Concept meets the science objectives and is feasible– Instrument– Calibration (preflight and on orbit)
• Instrument design concept is viable– Uncertainty budget is defined and continually being updated– Key trade studies have been completed; Others defined for Phase A
• Plans to mature technologies are in place– IIPs– Breadboard under development
• Engaged fully with NIST
• Fully experienced team is (pending IPT and SDT selection) in place and ready to begin Phase A
Ready to proceed into Phase A
IR Summary & Status
CLARREO Science Meeting July 2010 MGM: 5a- 55
• Backup Material
CLARREO Science Meeting July 2010 MGM: 5a- 56
Verification System Overview
Check systematic errors on-orbit
Calibrated Earth spectra L(ν) and total systematic uncertainty are derived from observed spectra S
E using
calibration equation, Ambient BB (L
HBB; S
H) and Deep Space (L
CBB; S
C)
Total Systematic Uncertainty estimate validated with Verification System:
Verification Blackbody Integrating sphere with
monochromatic (QCL) source Verification blackbody checked with:
Phase change cells to recalibrate temperature sensors
Emissivity monitor and QCL to check cavity emissivity
Off-zenith view to check for polarization effects
Vary temperature of verification BB to check nonlinearity
57
Grating Monochromater from Optronics Lab
• Spectral Range: 250 nm to 30-m• Calibrated Detectors: InGaAs (1- to 2.6-m), PbS (1- to 3.2-m), and Pyroelectric Detector (1- to 30-m)
Fourier Transform Spectrometer
Nicolet 6700 FT-IR Spectrometer from Thermo Fisher Scientific
• Spectral Range: UV – Far IR (0.25- to 200-m, or 40,000 to 50 cm-1)• Beam Splitters: CaF2, KBr, and Polyethylene (Solid Substrate) • Detectors: DTGS (CaF2 and KBr) and DTGS (Polyethylene-Solid Substrate)• Sample Compartment: Internal Beam-splitter and Filter Characterization• TOM (Tabletop Optical Module) Box: External Detector Charaterization
Detector Characterization at Langley
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