The Thermal Effect On Image Quality Of The Remote Sensor Optical System

In space-to-ground remote sensing field, the resolution of ground remote sensing images have become higher and higher. In space, the temperature has become the major effect on image quality of optical system. Analyzing the effect of uniform temperature level and kinds of temperature difference on image quality of optical system and proposing a reasonable temperature indicator have important guiding sense to the remote sensor's thermal control.The off-axis three mirror system has been selected to complete optical design after comparing various solutions and analyzed the image quality in theory, then the request of mirror RMS is deduced. Selected mirror materials considering many factors, matched each element materials reasonably to decide materials combination that make the image surface displacement minimum. Introduced the network node-pair method and the finite element method, and selected the fitting method applicable to non-circular mirror of the off-axis three mirror system. The Zernike coefficients have been calculated to be the interface between finite element analysis and optical design software. Temperature distribution of space remote sensor optical system has been described to calculate the mirror distortion in difference temperature by finite element model. The Zernike coefficients have been inputted to CODE V to analysis the image quality of optical system in difference temperature, then the temperature indicator has been constituted.Designed the thermal optical experiment of the sample and state camera to proof that the theoretical analysis is correct and the temperature indicator is reasonable. The MTF meets the requirement of system index in 14℃~21℃, proof that the thermal control is effective. The linear relation curve between best image surface and temperature is drown by the experiment data to predict the image surface in difference temperature.