Thermal optical property representation and optimization method of optical window under low-temperature vacuum environment

Abstract

The invention discloses a thermal optical property representation and optimization method of an optical window under a low-temperature vacuum environment, wherein a fused quartz window in a large-diameter parallel optical tube system under the low-temperature vacuum environment is simulated through a finite element method. The method is based on a customized surface type of an optical design software, wherein the surface type is combined with an even order aspheric surface type and the surface type of a gradient refractive index surface and used for representing optical window surface shape variation and material refractive index variation caused by temperature difference and pressure difference. A biasing afocal lens group is used for optimizing off-axis field of view wave aberration of the large-diameter parallel optical tube system, after surface shape variation caused by temperature variation is added, a zoom design is used for compensating system wave aberration and focal length variation caused by temperature, the wave aberration is optimized to be less than diffraction limit, thus, requirements of use are satisfied. The method has the advantages of comprehensively representing the optical window thermal optical property, using a small-diameter element for optimizing aberration of the large-diameter element, being adaptive to various temperature variations, being simple in structure, and so on.

Description

technical field [0001] The invention belongs to the field of optical thermal analysis, and in particular relates to a method for characterization and optimization of thermo-optical characteristics of an optical window in a low-temperature vacuum environment. Background technique [0002] As a common optical element, the optical window is widely used as an optical channel of the optical system in space payloads and equipment such as submarines, tanks, and missiles. It plays the role of light transmission, pressure isolation, and temperature isolation. Its optical performance directly affects The performance of the optical system. [0003] When the optical window is in use, the two sides are usually in different environments. The resulting temperature and pressure differences will change the surface shape of the optical window and the refractive index of the material, thereby changing the transmitted wavefront of the optical window and affecting the imaging quality of the subs...

AI Technical Summary

Problems solved by technology

[0004] At present, the thermo-optical simulation of the optical window mainly includes: first, use the temperature analysis function of the optical design software for analysis, its limitation is that it can only analyze the axial temperature field, and cannot accurately simulate the real environment where the window is located; It uses finite element software such as ANSYS to analyze the influence of temperature and pressure on the surface shape, and fits the node deformation into a Zernike polynomial representation, and transfers it to the optical design software for analysis, without considering the influence of refractive index changes on optical performance; the third is Use the formula of refractive index change with temperature to solve the refractive index of each point, use the gradient refractive index formula to fit, and transfer the fitted data to the optical design software for analysis. This method does not consider the influence of its surface shape change

Literature "Design of an off-axis parabolic mirror aberration correction lens group, Acta Optics Sinica, 2014, 34(6): 219-224." and patent "Large field of view off-axis main focus type collimator optical system CN 203337922 U[ In P].2013.", the author Hu Mingyong proposed a three-piece offset lens group to correct the off-axis field aberration of the off-axis paraboloid in the large-aperture collimator system. The optimization environment is normal temperature and pressure. The influence of temperature changes on the wave aberration of the system is not considered, so no thermo-optical analysis is performed on the optical window

In the reference "Method of determining effects of heat-induced irregular refractive index on an optical system" Applied Optics, 2015, 54(25): 7701-7, the author Song Xifa proposed to use gradient refractive index to fit the refraction of optical element materials caused by temperature However, it does not consider the surface shape change of optical components caused by temperature, the characterization is not comprehensive enough, and the optical system is not optimized accordingly

[0005] The traditional methods of optimizing window temperature deformation leading to system wave aberration changes include optimizing window thickness, controlling window temperature to reduce deformation, and designing double-layer window structures. These methods are costly and difficult to operate.

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