Test for mechanical-cooler-induced noise in a low-noise infrared 2D detector array: spaceborne application for sensing wave structure in thermal CO 2 emission

Abstract

For IR detectors that require cooling to temperatures lower than viable by passive radiative cooling, the mechanical refrigerator is an attractive alternative to expendable cryogen. It provides dramatic reduction in mass, and increased lifetime. For very low noise detectors, there may be some concern that mechanical cooler operation could provide an additional significant detector noise source. Here at LMAATC we have developed a mini-cooler for space borne application, a Stirling compressor driving a pulsetube, and have conducted test to determine if it would induce significant additional noise no cooling a low noise Mie HgCdTe 2D detector array with 3800 nm cutoff. We set up to cool the detector with our mini-cooler, and measure the noise with the cooler running, and with it turned off. We found that cooler operation increased noise barely perceptibly over the cooler off case. We will present implications for our planned space borne instrument, the Source Wave and Propagation Imager. It is an imaging spectrometer that will obtain measurements just below the limb in the 4180 to 4250 nm region of the CO 2 band. Tropospheric production of atmospheric internal gravity waves, and their subsequent propagation through stratospheric will be retrieved from these data.