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This paper introduces the optical sensor system (OPS) and OPS checkout results in orbit. The OPS has been mounted on the Japanese Earth Resources Satellite 1 (JERS-1) and is receiving earth images in the visible to shortwave infrared bands. The OPS can obtain high-resolution ground images because it embodies newly developed technology, including a one-dimensional charge coupled device (CCD) for the detector which has as many as 4096 elements and a highly accurate optical system. Another distinctive feature of the OPS is the ability, for the first time in the world, to obtain stereoscopic images with a single optical system frequently in the same orbit.

The hyper-multi spectral mission named HISUI (Hyper-spectral Imager SUIte) is the next Japanese earth observation project that will be on board ALOS-3 satellite. This project is the follow up mission of the Advanced Spaceborne Thermal Emission and reflection Radiometer (ASTER). HISUI is composed of hyperspectral radiometer with higher spectral resolution and multi-spectral radiometer with higher spatial resolution. The functional evaluation model is under development to confirm the spectral and radiometric performance prior to the flight model manufacture phase. This model contains the VNIR and SWIR spectrograph, the VNIR and SWIR detector assemblies with a mechanical cooler for SWIR, signal processing circuit and on-board calibration source.

The Japanese hyper-spectral sensor provides data products covering continuous spectral bands in the wavelength range from 400 nm to 2500 nm. It is characterized by a SNR of > 450 in the VNIR and>300 in the SWIR range at a ground resolution of 30 m x30 m. This report is concerned with the onboard wavelength calibration methods for the Japanese hyper-spectral sensor. As a result of trade study, the combination of a transmission type glass filter containing rare earth oxides, a Mylar polyester film and a quartz tungsten-halogen-lamp was selected. This method covers the wavelength range from 400 nm to 2450 nm. For the purpose of wavelength shift estimation, the method employing the mean square deviation as merit-function was found to be stable and precise. The accuracy of the absorption peak wavelength determination will be expected less than 2% (=0.2 nm) for the VNIR spectral resolution and 5% (=0.625 nm) for the SWIR spectral resolution.

The OPS has been mounted on the Japanese Resources Satellite-1 (JERS-1). It is confirmed that the OPS was operating successfully, including image data in orbit. The authors have obtained uniform data for the sensitivity variation among 4096 pixels. This paper gives the sensitivity variations results and the high-precision optical temperature control results. >

This paper presents the preliminary design results of the visible and near-infrared radiometer (VNIR) of the ASTER instrument for the EOS-AM1 program. The VNIR is a spaceborne radiometer employing push broom scanning with 5,000 element CCD sensors. The VNIR provides image data with high spatial resolution of 15 X 15 m, and has the pointing capability of +/- 24 deg in the cross-track direction to obtain a wide swath. The VNIR also provides stereoscopic image data in band 3 (0.76 - 0.86 micrometers ) with nadir- and backward- looking telescopes for topographical studies and mapping of the earth.

Preliminary design and basic performance of the VNIR and CSP subsystems of the ASTER instrument for the EOS-A platform is discussed. The VNIR is characterized by the high spatial resolution of 15 x 15 m and stereoscopic imaging in the 0.76-0.86 micron band. It corrects the geometric aberration caused by the rotation of the earth and calibrates the radiometer with the halogen lamps on orbit. The CSP is based on a signal processor which multiplexes system telemetry for image data, packetizes image data in CCSDS format, converts parallel signals into serial, and controls output to EOS-A transfer frame generator.

Optical sensor system capable of acquiring earth image data in visible, near-infrared, and shortwave-infrared region in 7 spectral bands, with spatial resolution of 18 x 24 m is described. In the near infrared band it provides stereoscopic images on the same orbit. In the shortwave-infrared region of 1.5-2.4 um it operates in the range of 4 bands to identify minerals and rocks.

We developed a new high accuracy prelaunch radiometric calib-ration system for the Optical Sensors (OPS), mounted on Japanese Earth Resources Satellite (JERS) to be launched in early 1992. This paper presents on detailed description of an internally irradiated integrating sphere of 1 meter in diameter, which suppliesradiance necessary for prelaunch calibration of the OPS in the spectral range from 500 nm to 2400 nm. The integrating sphere has aaperture of 280 mm over which uniform radiance is expected, and hastwelve halogen lamps of 500W operated at 100V DC to give the OPS the nearly maximum spectral radiance for each spectral band from the earth surface. Non—uniformity of the spectral radiance over the aperture is very small, which depends on wavelength ; percent at 650 nm andpercent at 2200 nm. This enables to cal ibrate al 1 the elements of each band and at the same time, for Visible and Near Infrared Radiometer (VNIR) and Shortwave Infrared Radiometer (SWIR) each.The integrating sphere is calibrated against transfer standards

Current trends in the development of optical imaging systems are reviewed, along with the demands for future improvements in the areas of resolution, the range of coverage, narrowing individual wavebands, simultaneous imaging, stereoscopic color imaging, and shortening of imaging intervals. A method of high-resolution stereoscopic imaging utilizing wide-zone coverage and data compression is proposed. It is pointed out that a conceptual system would be an extension of the wide-zone imaging function provided by an aspherical optical system with multiple electronically switched CCDs mounted on the focal plane. The data compression is discussed in detail, and it is noted that with optical sensors incorporating multiple CCDs, the best results can be obtained by using the inter-line correlation as data for deriving forecast values. Future high-resolution intelligent imaging systems are discussed.