Cooled focal-plane assembly for ocean color and temperature scanner

ABSTRACT The Ocean Color and Temperature Scanner (OCTS) is a piece of observation equipment that measures ocean color andtemperature from a scientific satellite. The OCTS is equipped with two focal plane assemblies: one observes ocean color inthe range of visible to near infrared, and the other measures ocean temperature in the infrared region. We report here on theresults of the so called bread boad model of the latter focal plane assembly. This focal plane assembly contains four infrared detectors that are cooled to lOOK by radiational cooling. We have evaluated this cooled focal plane assembly, and have confirmed that it has satisfied such NEP (noise equivalent power) values, registration accuracy and power consumption as arerequired in view of the OCTS performance characteristics. 1. INTRODUCTION The OCTS is one of eight pieces of observation equipment to be carried in a scientific satellite named "The AdvancedObserving Satellite (ADEOS)" which is scheduled for launch in 1995 by the National Space Development Agency of Japan.The OCTS will be equipped with two focal plane assemblies. We report here on one of these, the cooled focal plane assemblyintended for the measurementofocean temperature. This cooledfocalplaneassemblycomprises fourbands (9th to 12th bands)ofinfrared detectors as indicated in Table 1. The 9th band is composed ofa 10-element InSb linear array sensor with a sensitivearea of 250pm x 230im per element, a JFET array for impedance conversion, and a bandpass filter. Three other bands (10th,1 ith and 12th bands) consistof 10-elementHgCdTelineararray sensors having a sensitive areaof250im x 230j.tm per elementand suitable bandpass filters, which are optimized for high detectivity in the respective wavelength ranges. In addition, siliconphotodiodes are mounted to detect the temperature of the cooled focal plane assembly. The configuration of this cooled focalplane assembly is an octagon inscribed in a square area of 24.2 x 24.2 mm.Band Center Wavelength(jim)Spectral ResponseRange (jim)Detectors9th band 3.7 3.55-3.85