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In remote sensing imaging, bidirectional reflectance distribution function (BRDF) is powerful tool to describe light reflectance characteristic. Based on BRDF distribution of ground object, reflectance distribution in all directions will be calculated, and radiation difference of remote sensing imaging can be calibrated. This paper analyzes the several empirical / semi-empirical BRDF model suitable for the rough earth surface. The cement ground was selected as typical experiment topography, and the ground reflectance in all directions at different solar zenith angle was obtained. We compare measurement data to calculation results of three theoretical models, including five parameter model, Staylor & Suttles model and Walthall model, and analyze and evaluate effectiveness of various models.

With the uprating requirements of space remote sensing, the aperture of the optical remote sensor is getting larger and larger. The influences of both the support of optical elements and gravity deformation on the optical system are difficult to conquer. Therefore, it is necessary to compensate the descending optical performance which is caused by the surface error of primary mirror by means of adjusting the position parameters of the optical elements on-orbit. A large aperture coaxial three-mirror optical system is introduced in the paper. Matlab and MetroPro are used to simulate the surface error of the primary mirror. The surface error of the primary mirror is compensated by adjusting the position freedoms of the secondary mirror. The results show that the adjustment of the position freedoms of the secondary mirror can compensate both the coma and some astigmatism of the primary mirror, but not the spherical aberration.

A new style calibration mechanism is designed for the infrared camera working in space. This calibration mechanism adds a locking device, which will produce magnetic force to fix the moving parts on the stage of launch. It has not been taken into account in past calibration mechanism of space infrared camera. In order to simplify structure and control system, an alnico is adopted in locking device as the source of magnetic field, which interacts with magnetic material and produces locking force. In addition, there is also a special structural design, which makes magnetic circuit closeitself to control magnetic leakage interfering with other equipment. Besides, another important component of calibration mechanism is a permanent magnet torquer. It can provide driving force for the blackbody to complete two state conversions of calibration and Non-calibration. High magnetic induction intensity and coercivity alnico is used as the stator, which will lighten the weight of torquer. On-off control strategy is selected in order to simplify the control system. Because calibration is only a temporary state, temperature rise has little influence on torquer. This setup is favorable to increase its reliability. There are guard plates on the axial direction shielding electromagnetism, also reducing magnetic leakage. Experimental investigations have been carried out to verify the feasibility and reliability of design. Result indicates the calibration mechanism can primely complete the calibration task of the space infrared detector. It has an important application value on the field of infrared detection.

The reflector is influenced by force and temperature more and more seriously with the increasing of reflector diameter. The error analysis and adjustment of reflector is important to satisfy the optical performance. In fact, the error of the reflector include figure error, position error and curvature radius error, which are often coupled and difficult to adjust. The method of the separation of the three type errors and way of adjustment are studied in this paper. The separation of the error is following the belows: first, the deformation of the nods on the reflector surface are analyzed and transfered to sag deformation; second, the position error is obtained by the least-square method and adjusted; third, the residual error is fit with the Zernike polynomial and the curvature radius error is acquired and adjusted, at last; the remained error is the high-frequency figure error. A reflector under the load of heat is simulated and analyzed in this paper with the method above. The results indicate that the error of piston and curvature radius are the major errors, so it is possible to adjust the error of piston and curvature radius alone to improve the quality of reflector in optical system, in order to simplify the mount system of the reflector.