TANSO-CAI-2 onboard GOSAT-2 satellite is a multi-spectral imager for the observation of cloud and aerosol. The CAI- 2 has 10 observation bands with 7 different wavelengths, which cover 340-1630 nm. The wavelength width of each band is less than 13 nm in the UV to NIR band and less than 73 nm in the SWIR band. From Feb. 2019, the evaluation of the initial calibration phase was carried out to calibrate the geometric and radiometric characteristics. Following the initial calibration phase, the evaluation of radiometric performance has been continuously conducted. The evaluation of dark level and dark noise has shown almost stable results, although there is some variation. The radiometric response evaluation using the lunar calibration data and the ROLO model showed a degradation in the UV Bands, especially in Band 1 (340 nm), which showed a degradation of about 8% in the two years relative to Band 4 (865 nm). No obvious response degradation was observed for the other bands. Those results suggest that the radiometric performance of the CAI-2 is almost maintained for two years since the initial calibration phase.
The imager that observes the ground surface with high spatial resolution from geostationary orbit has been studied. To obtain image data with high ground sampling distance (GSD) from a geostationary orbit, an extremely large-diameter and long-focal-length telescope is required. In order to realize this imager, we plan to adopt a synthetic aperture type reflection optical telescope (Korsch type) in which the primary mirror is composed of six segmented mirrors. The diameter of the synthesized aperture telescope is approximately 3.6m, and the focal length is approximately 30 m. Prior to the development of the actual imager, we have been producing a full-scale prototype of the segmented mirror that constitutes the primary mirror and its supporting structure. The aperture shape of the prototype segmented mirror is hexagonal, and its diagonal length is approximately 1.35 m. The supporting structure of the prototype segmented mirror incorporates a mechanism (6-axes adjustment mechanism) for adjusting the alignment of the segmented mirror with six degrees of freedom. A mechanism for adjusting the curvature of the segmented mirror (curvature adjustment mechanism) was also incorporated. In this paper, the design, the manufacturing, and the testing status of this prototype are described.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.