Design and Optimization for Mounting Primary Mirror with Reduced Sensitivity to Temperature Change in an Aerial Optoelectronic Sensor

Abstract

In order to improve the image quality of the aerial optoelectronic sensor over a wide range of temperature changes, high thermal adaptability of the primary mirror as the critical components is considered. Integrated optomechanical analysis and optimization for mounting primary mirrors are carried out. The mirror surface shape error caused by uniform temperature decrease was treated as the objective function, and the fundamental frequency of the mirror assembly and the surface shape error caused by gravity parallel or vertical to the optical axis are taken as the constraints. A detailed size optimization is conducted to optimize its dimension parameters. Sensitivities of the optical system performance with respect to the size parameters are further evaluated. The configuration of the primary mirror and the flexure are obtained. The simulated optimization results show that the size parameters differently affect the optical performance and which factors are the key. The mirror surface shape error under 30 °C uniform temperature decrease effectively decreased from 26.5 nm to 11.6 nm, despite the weight of the primary mirror assembly increases by 0.3 kg. Compared to the initial design, the value of the system’s modulation transfer function (0° field angle) is improved from 0.15 to 0.21. Namely, the optical performance of the camera under thermal load has been enhanced and thermal adaptability of the primary mirror has been obviously reinforced after optimization. Based on the optimized results, a prototype of the primary mirror assembly is manufactured and assembled. A ground thermal test was conducted to verify difference in imaging quality at room and low temperature, respectively. The image quality of the camera meets the requirements of the index despite degrading.

Image restoration techniques for space-based lightweight optically sparse aperture Earth-observation telescopes in the longwave infrared domain

“…Further reduction in overall mass budget of the satellite system is also ensured by a reduction of the associated 3-point support framework behind each of the constituent sub-apertures. 47 As mentioned earlier, these suggested mirror configurations have a significant loss in collecting area but with very little blurring and inconsequential loss of contrast. This uncompromised imaging quality is achieved primarily due to pronounced sidelobe suppression in the resultant PSFs.…”

Research on thermal stability of monolithic near-infrared Doppler asymmetric spatial heterodyne interferometer

“…They include the rigid-body motion of the optical surface and higher-order surface distortion. The mathematical description of the Zernike polynomials for a distorted surface is defined as follows: 28 ΔZ(ρ,ξ)=A00+∑n=2∞An0Rn0(ρ)+∑n=1∞∑m=1nRnm(ρ)[Anm cos(mξ)+Bnm sin(mξ)],where ΔZ(ρ,ξ) denotes the deformed surface; ρ is the normalized radius of the reflection surface; ξ is the azimuth angle; Anm and Bnm are the Zernike coefficients in the X and Y…”

Opto-mechanical dynamics optimization of electro-optical stabilized sighting system based on data driving

“…Wang et al established the forward and inverse kinematics model of the series spherical mechanism of the airborne photoelectric platform and verified them through joint simulation, improving the load ratio of platform [9] . Zhang carried out topology optimization on supporting structure model of Cassegrain optical system, which improved the optical performance and environmental adaptability of the main mirror supporting structure [10] . Yang et al has identified modal parameters of the reaction flywheel, providing reference for design of micro vibration suppression in optical remote sensing satellites [11] .…”