Computational Sciences Division, National Aerospace Laboratory(NAL)
Control Systems Division, National Aerospace Laboratory(NAL)
Computational Sciences Division, National Aerospace Laboratory(NAL)
出版者
航空宇宙技術研究所
出版者（英）
National Aerospace Laboratory(NAL)
雑誌名
航空宇宙技術研究所報告
雑誌名(英)
Technical Report of National Aerospace Laboratory TR-1024
巻
1024
ページ
32
発行年
1989-06
抄録（英）
It is anticipated that the pushbroom scanning scheme will be used very widely in future airborne and spaceborne imaging spectrometers for remote sensing, because of its potential capability for high resolution and high reliability. At NAL we have produced, for test purposes, two pushbroom imaging spectrometers, one for aircraft and the other for spacecraft. Both utilize a CCD linear array for the opto-electronic sensor elements. This is the first attempt to apply the pushbroom scan scheme to airborne spectrometers(customary spectrometers have used a mechanical scan scheme). In our attempt, small refracting optics(lens system) were used to get a very wide viewing angle. The optics were able to collect sufficient radiative energy. The dimensions of this airborne spectrometer system are very small compared to the customary systems, which have to have very large dimensions. For the spaceborne spectrometer we applied a sort of cata-dioptic(reflect-refractive)optics, the so called Wright-Schmidt telescope, as the collecting optics. This telescope has not such a wide viewing angle, but has very high resolution and a planar focal plane (a usual Schmidt telescope has a spherical focal plane). This planar focal plane is a necessary condition for a CCD sensor arrangement. This utilization of cata-dioptic optics for imaging spectrometer is also the first attempt in a spaceborne imaging spectrometer. If we use the usual lens system for the collecting optics, the system dimension and weight will be huge because of the long focal length and large aperture. The optical performances of collecting optics for these airborne and spaceborne imaging spectrometers, the opto-electronic characteristics of the CCD linear array, and the performances of the electronics were measured and analyzed. Then the total performances of the ariborne and spaceborne spectrometers were measured. As a result, some problem areas for such future airborne and spaceborne pushbroom scanning radiometers were clarified. One of the most important points which affect system performances is the blur characteristics of the CCD linear sensor array. On the spaceborne spectrometer, degradation of the modulation transfer function of the collecting optics at the end of the viewing angle is a critical issue.
Characteristics of Pushbroom Scanning Type Radiometer Utilizing Linear Sensors
naltr01024.pdf
(2.98MB)
