Performance of an Imaging Fourier Transform Spectrometer with Photoconductive Detector Arrays: An Application for the AKARI Far-Infrared Instrument

Abstract

We have developed an imaging Fourier transform spectrometer (FTS) for space-based far-infrared astronomical observations. The FTS employs newly developed photoconductive detector arrays with acapacitive trans-impedance amplifier, which makes the FTS acompletely unique instrument. The FTS was installed as afunction of the far-infrared instrument (FIS: Far-Infrared Surveyor) aboard the Japanese astronomical satellite, AKARI, which was launched on 2006 February21 (UT) from Uchinoura Space Center. The FIS-FTS had been operated for more than one year before liquid helium ran out on 2007 August 26. The FIS-FTS was operated nearly six hundreds times, which corresponds to more than one hundred hours of astronomical observations and almost the same amount of time for calibrations. As expected from laboratory measurements, the FIS-FTS performed well and has produced alarge set of astronomical data for valuable objects. Meanwhile, it has become clear that the detector transient effect is aconsiderable factor for FTSs with photoconductive detectors. In this paper, the instrumentation of the FIS-FTS and interesting phenomena related to FTS using photoconductive detectors are described, and future applications of this kind of FTS system are discussed.