Space-borne Imaging Fourier Transform Spectrometer, which selects plane mirrors as its movable mirror and fixed
mirrors, adopts dynamic adjustment system (DAS) to keep the alignment of the two mirrors. This paper addresses a DAS
scheme in the space-borne FTS.
The laser reference path serves as the measure standard of the movable mirror displacement and
velocity in Fourier Transform Spectrometer (FTS). In the Space-borne Imaging FTS, whose
movable mirror is plane, it is also used to measure the tilt of the mirror. So, the quality of the laser
interference signal plays an importance role in the instrument. This paper discusses and analyzes
the features of the reference laser signal mainly according to the experiment results.
The vertical atmospheric sounding interferometer is based on the classical Michelson Interferometer mechanics. To keep
the uniformity of the speed and the alignment of the movable plane mirror, it introduces the referential optical path. As
the metrological standard, it is very important to get high-quality referential signals. Because of the complexity of the
interference system, the referential signals will degenerate when arriving at the laser detectors. In this paper, three factors
that impact the quality of the referential signals and countermeasures are presented. Firstly because the laser speckle is
not ideally proportioned and the laser beam is not ideally vertically reflected by the movable mirror, the laser speckle
swings with the movement of the movable mirror, resulting in the fluctuating of the power radiated on the laser detectors.
Secondly, when the initial angle between the fixed mirror and the movable mirror is too large, the modulation depth
ripples in a large scale with the small misalignment of the movable mirror. Lastly, the light reflected back to the
semiconductor laser will engender impact on the light source. By taking countermeasures, usable, accurate enough
referential laser signals are finally acquired.