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A laser communication system has an advantage of realizing the high speed transmission under the conditions of small size and low electrical power. The laser communication system requires a high accuracy of pointing control because of the directional characteristics of laser beam. Due to the attitude control accuracy of micro-satellites, the pointing device carried in micro-satellite is required to have mitigated pointing accuracy, wide range pointing, small size, mass and low electrical power. We have developed a new pointing device characterized by two-axis pointing control mechanism. Breadboard model of pointing control mechanism consists of steering mirror, angular sensor and electrical unit. The steering mirror mechanism is accomplished using rod-end-bearings. The pointing accuracy and the performance of tracking system of the laser communication device were evaluated in simulator of between satellite and ground station. This paper describes development of the breadboard model of pointing control mechanism and the performance evaluation.

The earth observation micro-satellite “TAIKI” is 50 kg satellite which has low-cost and small bus-subsystem. TAIKI is characterized by a low-cost spaceborne small hyperspectral sensor “HSC-III”. HSC-III is targeted at the performances of 30 m ground sampling distance, visible and near infrared wavelength range, 10 nm spectral resolutions, 61 spectral bands and 10 kg weight. HSC-III consists of the telescope, the imaging spectrometer, the electrical system, the on-orbital calibration equipment. The telescope has a pupil diameter of 0.2 m, and has two mirror configuration of Ritchey-Chretien type. The spectrometer has the transmitting grating with the slit and relay lens unit, and array sensor using back-illumination type CMOS image sensor. As a SNR model of HSC-III, we did some calculations and concluded that SNR is approximately 340. Last year, we succeeded to develop the breadboard model of HSC-III optics instrument, and we obtained result of more requirement specification. Also, we have developed the on-orbit spectral calibration equipment. It achieved 0.02 nm of spectral calibration accuracy.