NASTER System Definition Proposal

Remote Sensing Team NASTER System Definition Proposal All rights reserved. - 7/14/03 Page 1

Overview Review and comment the mid-ir requirements Presentation of ABB s current platform technology Proposed approach for mid-ir NASTER Proposed approach for initial NASTER Discussion Page 2

Review of Requirements Page 3 The first NASTER Strawman requires wide coverage and high spectral resolution A modular concept has been developed to address as much as possible the entire specification Mid-IR NASTER Strawman requirements are less constraining on the spectral coverage and resolution Modules of the initial concept have been used to address this new specification We review the Mid-IR requirement first

Mid-IR Requirement Review Spectral Limits (SL): 665-2860 cm 1 (3.5-15 microns) We suggest to split the range in 2 bands at 1750 cm 1 (5.7 microns) 1.4 x 1 1.2 Page 4

Spectral Coverage 1.4 x 10-5 1.2 Radiance [W/(sr cm 2 cm -1 )] 1 0.8 0.6 0.4 0.2 GIFTS EHS FDS AIRS IASI CrIS NASTER Page 5 0 0 500 1000 1500 2000 2500 3000 Wavenumbers [cm -1 ] NASTER seems to be an Application test-bed for HES NASTER does not seem to be a Hardware test-bed for HES

Mid-IR Requirement Review Spectral Resolution (SR): Selectable from 0.25-1.25 cm 1 Resolution limits maximum divergence inside interferometer Off-axis pixels result in more constraining limitations We suggest 0.25 cm 1 for the mid-wave and 0.5 cm 1 for the short - wave and use off-axis IFOV s with an inverse telescope (0.5) Page 6 Circular, on-axis

Mid-IR Requirement Review Ground Resolution (GR): Contiguous at 500 meters from 20 km flight altitude within single FOR Defines IFOV of 25 mrad We suggest 250 meters ground resolution (12.5 mrad IFOV) Field of Regard (FOR): 2 km from 20 km flight altitude Requirement suggests a 4x4 detector array We suggest an 8x8 detector array to cover the 100 mrad square FOR Page 7

Mid-IR Requirement Review Page 8 Along-track Scan Coverage (ATSC): 2 km FOR contiguity at 20 km for an aircraft speed of 400 kts Speed and IFOV defines observation time of 10 seconds Motion compensation and 10 seconds observation time provide contiguous along-track coverage Cross-track Scan Coverage (CTSC): Selectable from 2 to 20 km, depending on spectral resolution, from 20 km flight altitude for an aircraft speed of 400 kts Defines a minimum observation time of 1 second

Mid-IR Requirement Review Noise Equivalent delta Temperature (NEdT): Spectrally random brightness temperature 0.25 K @ 0.25 cm 1 spectral resolution within the spectral range of 4.5 to 14 microns scene temperature of 260 K 10-4 Page 9 NESR [W/(cm 2 sr cm -1 )] 10-6 10-8 10-10 Blackbody @ 260K 0.25K NEdT CrIS Design Goals scaled for 2.5 sec observation time and required resolution 500 1000 1500 2000 2500 3000 Wavenumber [cm -1 ] Required performances are similar to Design Goals for CrIS

Mid-IR Requirement Review Absolute Error (AE): Absolute brightness temperature error 0.5 K within the spectral range of 4.5 to 14 microns scene temperature within the 200-300 K range Main contributors are radiance uncertainty of calibration targets and non-linearity of detector response Calibration Sources (AE): Warm Blackbody, Ambient Blackbody, Zenith Sky view Page 10

Mid-IR Requirement Review Scan Angle Coverage (SAC): Selectable over a range from zenith (180 ) to Horizontal (at either + or - 90 ) to any combination of a set of viewing angle steps which together provide contiguous coverage over a range from ±50 degrees about Nadir (0 ) Defines the scene selection continuous pointing range of ±50 degrees plus 5 discrete pointing position Requires scanning without FOV rotation Page 11 50 degrees 2km

Mid-IR Requirement Review Page 12 Lifetime: 10 years through parts replacement over time Build the system with standard parts used in commercial standard products Requires a single contractor responsible for the system Contractor must have access to standard spare parts Design type: Modular to allow for detector, spatial and spectral resolution, and data system upgrades as technology matures throughout the lifetime of the NASTER Use flexible electronics (digitally controlled interferometer) Provide good transmission over a broad spectral range for the interferometer Provide sufficient resolution capability

Mid-IR Requirement Review Operational Requirements: Command Uplink/Data Downlink via over-the-horizon communications Aircraft Compatibility: ER-2 (20 km), Proteus (17 km), Global Hawk (20 km), and, if feasible, the new SCI space plane Spaceship 1 (55 km) Low pressure not seen as a problem with components used Page 13

Overview Review and comment the mid-ir requirements Presentation of ABB s current platform technology Proposed approach for mid-ir NASTER Proposed approach for initial NASTER Discussion Page 14

ABB s Current Platform Technology Page 15 Current platform technology consists of cube-corner based interferometers Provides low-cost, reliable, products 24/7 unattended operation 4-port, 2-port, and double-pass Based on wishbone scan arm Permanently aligned Flat mirror DA interferometers not used in commercial products Porchswing scanning mechanism only supported for space qualified projects Flat mirror interferometers are optically efficient for large imaging

ABB s Current Platform Technology Page 16 New BMXS electronics Digital scan servo control Programmable scan profile Flexible IR sampling based on high density fringe sampling Constant clock sampling with phase detection Variable OPD sampling Ethernet, LVDS, 10/100 base Embedded Linux May support dynamic alignment

Page 17 ABB s Current Platform Software FTSW100 software suite includes Run time module Continuous spectrometer operation Continuous housekeeping logging and diagnostics using multiple I/O CAN Bus and CAN Open Control of measurement cycles Configuration tools Spectroscopy module Radiometric functions Chemometric functions Database management Propriatary SPC type files Data can be exported to industry standard XML type

Overview Review and comment the mid-ir requirements Presentation of ABB s current platform technology Proposed approach for mid-ir NASTER Proposed approach for initial NASTER Discussion Page 18

Page 19 Proposed Approach for Mid IR NASTER 2 Spectral Bands with band separation optics at 1750 cm 1 2 imaging, fiber coupled, detector modules New COTS control electronics with Ethernet link Digitally controlled spectrometer Double pendulum, cube-corner, interferometer with good efficiency from 300 to 2860 cm 1 Selectable resolution with 0.075 cm 1 as minimum spectral sampling ILS compatible with spectral sampling of 0.25 cm 1 from 665 to 1750 cm 1, and 0.5 cm 1 from 1750 to 2860 cm 1 250 meters IFOV at 20 km altitude 10 seconds per interferometer sweep for 2 km swath 34 mm entrance pupil. f/1 optics at detector 8x8 FOR with contiguous coverage along-track Motion compensation pointing mirror 2 on-board calibration targets (Ambient and Hot)

Proposed Approach for Mid IR NASTER Instrument Control Electronics Calibration Targets Spectrometer Page 20 Scene Selection Module

Modules Description Instrument Integration & Support Scene Selection Module Telescope Pointing mirror with motion compensation Control electronics Spectrometer Interferometer with control electronics Output optics Detectors and readout electronics Page 21 Calibration Targets 1 ambient (passive) cavity 1 hot (active) cavity Temperature controller Instrument Control Electronics Data management Dashboard (user interface)

Mid IR NASTER - Resolution Inverse telescope to reduce beam divergence inside interferometer IFOV of 12.5 mrad FOR made of 8x8 IFOV s 2 ILS @ 2860 cm -1. MPD = 1 cm. 1.5 Lower limit FWHM = 0.603 cm -1 FWHM = 0.65367 cm -1 3.5 3 ILS @ 1750 cm -1. MPD = 2 cm. Lower limit FWHM = 0.3015 cm -1 Instrument Line Shape 1 0.5 Asymmetry = 0.24918 % Shift of peak = 1.3775 cm -1 2.5 FWHM = 0.34127 cm -1 0 Page 22 Instrument Line Shape 2 1.5 1 0.5 0-0.5 1746 1747 1748 1749 1750 1751 1752 1753 Wavenumber [cm -1 ] Asymmetry = 0.46937 % Shift of peak = 0.84241 cm -1-0.5 2852 2854 2856 2858 2860 2862 2864 2866 Wavenumber [cm -1 ]

Mid IR NASTER - NEdT Page 23 Gold coated mirrors for pointing, telescope, and cube corners CsI beamsplitter PIR fiber to couple the interferometer to a PC-MCT linear array of 64 elements D* of 4x10 10 jones for the LW and 8x10 10 jones for the SW LW cut-off at 14.3 microns, SW cut-off at 5.7 microns 375 microns pixels (f/1 optics at the detector) 10 seconds observation time 2x2 pixel aggregation for 500 meters ground resolution Instrument temperature at 25 C SW is the middle portion of the full interferogram

Mid IR NASTER - NEdT 10 2 Noise Equivalent delta Temperature. 0.25, 0.5 cm -1 Resolution. 10 0 Page 24 NEdT [K] 10-2 10-4 10-6 500 1000 1500 2000 2500 3000 Detector noise limited Wavenumber [cm -1 ] Total NEdT Scene Shot noise Background Shot noise Detector & electronic noise Quantization noise Speed fluctuations & filter slope Speed fluctuations & delay mismatch Sampling jitters Requirement Second contributor is shot noise from self-emission

Mid IR NASTER - NEdT LW cut-off at 18.2 microns to get the entire CO 2 absorption bands D* of 2x10 10 jones for the LW Loss of performances in the water vapour bands from 1450 to 1750 cm 1 10 2 Noise Equivalent delta Temperature. 0.25, 0.5 cm -1 Resolution. 10 0 Page 25 NEdT [K] 10-2 10-4 500 1000 1500 2000 2500 3000 Wavenumber [cm -1 ] Total NEdT Scene Shot noise Background Shot noise Detector & electronic noise Quantization noise Speed fluctuations & filter slope Speed fluctuations & delay mismatch Sampling jitters Requirement

Mid IR NASTER - NEdT Decrease the resolution to 2.5 cm 1 in the SW to meet requirement at 4.5 microns 10 2 Noise Equivalent delta Temperature. 0.25, 2.5 cm -1 Resolution. 10 0 Page 26 NEdT [K] 10-2 10-4 10-6 500 1000 1500 2000 2500 3000 Wavenumber [cm -1 ] Total NEdT Scene Shot noise Background Shot noise Detector & electronic noise Quantization noise Speed fluctuations & filter slope Speed fluctuations & delay mismatch Sampling jitters Requirement

Overview Review and comment the mid-ir requirements Presentation of ABB s current platform technology Proposed approach for mid-ir NASTER Proposed approach for initial NASTER Discussion Page 27

Page 28 Proposed Approach for Initial NASTER 3 Spectral Bands (300 to 500 cm 1, 500 to 1650 cm 1, and 1650 to 2550 cm 1 ) 3 detectors in 1 Stirling cooler (no band separation optics) New COTS control electronics with Ethernet link Digitally controlled spectrometer Selectable resolution with 0.075 cm 1 as minimum spectral sampling ILS compatible with spectral sampling of 0.075 cm 1 in the LW, 0.25 cm 1 in the MW, and 2.5 cm 1 in the SW 250 meters IFOV 1.25 second per interferometer sweep 34 mm entrance pupil. f/1 optics at detector 1x8 FOR with contiguous coverage along-track +/- 34 degrees cross track scans with motion compensation 2 on-board calibration targets (Ambient and Hot)

Proposed Approach for Initial NASTER Aircraft Motion Ground Instantaneous Footprint LW 34 degrees MW 250m 2km Page 29 SW 2km

Resolution LW 12 ILS @ 500 cm -1. MPD = 6.6667 cm. MW SW 2km 250m Instrument Line Shape 10 8 6 4 2 Lower limit FWHM = 0.09045 cm -1 FWHM = 0.096437 cm -1 Shift of peak = 0.26322 cm -1 0 Page 30 Instrument Line Shape 4 3.5 3 2.5 2 1.5 1 0.5 0-0.5 ILS @ 1650 cm -1. MPD = 2 cm. Lower limit FWHM = 0.3015 cm -1 FWHM = 0.32103 cm -1 Shift of peak = 0.86883 cm -1-1 1646 1647 1648 1649 1650 1651 1652 1653 Wavenumber [cm -1 ] Instrument Line Shape 0.35 0.25 0.15 0.05-0.05-2 498.5 499 499.5 500 500.5 501 0.4 0.3 0.2 0.1 0 Wavenumber [cm -1 ] ILS @ 2500 cm -1. MPD = 0.2 cm. -0.1 2460 2470 2480 2490 2500 2510 2520 2530 Wavenumber [cm -1 ] Lower limit FWHM = 3.015 cm -1 FWHM = 3.0281 cm -1 Shift of peak = 2.0107 cm -1

Proposed Approach for Initial NASTER 10 1Noise Equivalent delta Temperature. 0.075, 0.25, 2.5 cm-1 Resolution. 10 0 NEdT [K] 10-1 10-2 Page 31 10-3 10-4 Total NEdT Scene Shot noise Background Shot noise Detector & electronic noise Quantization noise Speed fluctuations & filter slope Speed fluctuations & delay mismatch Sampling jitters Requirement 0 500 1000 1500 2000 2500 Wavenumber [cm -1 ] D* = 4 10 9 (LW), 4 10 10 (MW), and 1 10 11 (SW) jones MW and SW are middle portions of full resolution interferogram 1 sweep, IFOV s aggregation to 500 meters square

Proposed Approach for Initial NASTER 10 1 Noise Equivalent delta Temperature. 0.25, 0.25, 2.5 cm-1 Resolution. 10 0 10-1 NEdT [K] 10-2 10-3 10-4 Total NEdT Scene Shot noise Background Shot noise Detector & electronic noise Quantization noise Speed fluctuations & filter slope Speed fluctuations & delay mismatch Sampling jitters Requirement Page 32 10-5 0 500 1000 1500 2000 2500 Wavenumber [cm -1 ] 3 sweeps, IFOV s aggregation to 500 meters square

Proposed Approach for Initial NASTER 10 1 Noise Equivalent delta Temperature. 2.5, 2.5, 2.5 cm -1 Resolution. 10 0 10-1 NEdT [K] 10-2 10-3 Page 33 10-4 10-5 Total NEdT Scene Shot noise Background Shot noise Detector & electronic noise Quantization noise Speed fluctuations & filter slope Speed fluctuations & delay mismatch Sampling jitters Requirement 0 500 1000 1500 2000 2500 Wavenumber [cm -1 ] 33 sweeps, IFOV s aggregation to 500 meters square

Summary for Initial NASTER Desired Proposed Range 100 2500 cm 1 300 2500 cm 1 Resolution 0.025 cm 1 0.075 cm 1 < 500 cm 1 Ground resolution FOR 0.25 cm 1 < 1650 cm 1 2.5 cm 1 < 2500 cm 1 500 m x 500 m 250 m x 250 m Page 34 2km 2 km aggregate to 4x1 Observation time 10 sec 1.25 sec Cross-track 2 20 km 2 20 km (0.825 cm 1 ) NedT (260 K) 0.2 1 K 1.2 K < 500 cm 1 0.05 1 K < 1650 cm 1 0.7 2.5 K < 2500 cm 1

Proposed Approach for Initial NASTER MR type (AERI) interferometers with higher resolution and larger aperture considered in other airborne and space programs Page 35

Page 36 SOFIS FTS On-board GCOM-A1

Overview Review and comment the mid-ir requirements Presentation of ABB s current platform technology Proposed approach for mid-ir NASTER Proposed approach for initial NASTER Discussion Page 37