Detectors and focal plane modules for weather satellites

A. I. D'Souza; E. Robinson; S. Masterjohn; P. Ely; V. Khalap; S. Babu; D. S. Smith

doi:10.1117/12.2228898

2 May 2016 Detectors and focal plane modules for weather satellites

A. I. D'Souza, E. Robinson, S. Masterjohn, P. Ely, V. Khalap, S. Babu, D. S. Smith

Proceedings Volume 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV; 988115 (2016) https://doi.org/10.1117/12.2228898
Event: SPIE Asia-Pacific Remote Sensing, 2016, New Delhi, India

Abstract

Weather satellite instruments require detectors with a variety of wavelengths ranging from the visible to VLWIR. One of the remote sensing applications is the geostationary GOES-ABI imager covering wavelengths from the 450 to 490 nm band through the 13.0 to 13.6 μm band. There are a total of 16 spectral bands covered. The Cross-track infrared Sounder (CrIS) is a Polar Orbiting interferometric sensor that measures earth radiances at high spectral resolution, using the data to provide pressure, temperature and moisture profiles of the atmosphere. The pressure, temperature and moisture sounding data are used in weather prediction models that track storms, predict levels of precipitation etc. The CrIS instrument contains SWIR (λ_c ∼ 5 μm at 98K), MWIR (λ_c ∼ 9 μm at 98K) and LWIRs (λ_c ∼ 15.5 μm at 81K) bands in three Focal Plane Array Assemblies (FPAAs).

GOES-ABI contains three focal plane modules (FPMs), (i) a visible-near infrared module consisting of three visible and three near infrared channels, (ii) a MWIR module comprised of five channels from 3.9 μm to 8.6 μm and (iii) a 9.6 μm to 13.3 μm, five-channel LWIR module. The VNIR FPM operates at 205 K, and the MWIR and LWIR FPMs operate at 60 K. Each spectral channel has a redundant array built into a single detector chip. Switching is thus permitted from the primary selected array in each channel to the redundant array, given any degradation in performance of the primary array during the course of the mission. Silicon p-i-n detectors are used for the 0.47 μm to 0.86 μm channels. The thirteen channels above 1 μm are fabricated in various compositions of Hg_1-xCd_xTe, and in this particular case using two different detector architectures. The 1.38 μm to 9.61 μm channels are all fabricated in Hg_1-xCd_xTe grown by Liquid Phase Epitaxy (LPE) using the HDVIP detector architecture. Molecular beam epitaxy (MBE)-grown Hg_1-xCd_xTe material are used for the LWIR 10.35 μm to 13.3 μm channels fabricated in Double layer planar heterostructure (DLPH) detectors. This is the same architecture used for the CrIS detectors.

CrIS detectors are 850 μm diameter detectors with each FPAA consisting of nine photovoltaic detectors arranged in a 3 x 3 pattern. Each detector has an accompanying cold preamplifier. SWIR and MWIR FPAAs operate at 98 K and the LWIR FPAA at 81 K, permitting the use of passive radiators to cool the detectors. D* requirements at peak wavelength are ≥ 5.0E+10 Jones for LWIR, ≥ 9.3E+10 Jones for MWIR and ≥ 3.0E+11 Jones for SWIR. All FPAAs exceeded the D* requirements. Measured mean values for the nine photodiodes in each of the LWIR, MWIR and SWIR FPAAs are D* = 5.3 x 10¹⁰ cm-Hz^1/2/W at 14.0 μm, 1.0 x 10¹¹ cm-Hz^1/2/W at 8.0 μm and 3.1 x 10¹¹ cm-Hz^1/2/W at 4.64 μm.

Citation Download Citation

A. I. D'Souza, E. Robinson, S. Masterjohn, P. Ely, V. Khalap, S. Babu, and D. S. Smith "Detectors and focal plane modules for weather satellites", Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 988115 (2 May 2016); https://doi.org/10.1117/12.2228898

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