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摘要:
为了减小对卫星上的空间使用,针对定标特点,本文提出了一种用于积分球光源准直照明的自由曲面反射镜设计方法。采用该方法,能够以小口径的积分球实现大面积的方形均匀辐照度分布。首先,通过点光源模型建立自由曲面离轴反射照明数学模型,然后,通过切比雪夫点离散自由曲面,并求解出满足点光源照明的自由曲面模型,最后,分析积分球的光源特性,通过逐步优化自由曲面能量分布方法完成点光源照明模型到积分球照明模型的转变。通过分析可知,设定照明面积为140 mm×140 mm时,目标面的辐照度非均匀性的不均匀度小于0.02。满足星载定标轻量化,短光路,结构简单的需求。
Abstract:We propose a design method of a free-form reflector for collimating illumination of integrating spherical light sources to reduce the space occupation on a satellite. By using this method, a square irradiance distribution with large area can be achieved through a integrating sphere with small diameter. Firstly, the mathematical model of off-axis reflection lighting of free-form surface is established through the point light source model, then the free-form surface is discretized by Chebyshev points, and the free-form surface model that satisfies the point light source illumination is solved. Finally, the light source characteristics of the integrating sphere are analyzed. The transformation from the point light source illumination model to the integrating sphere illumination model is achieved by the optimization of the free-form surface energy distribution. The analysis results show that when the illumination area is set as 140 mm×140 mm, the irradiance non-uniformity of the target surface is less than 0.02. This method can meet the requirements of spaceborne calibration for light weight, short light path and simple structure.
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表 1 自由曲面反射镜的相关参数
Table 1. Reference parameters of the freeform reflector
Parameters value $ \theta $/(°) 15 r/mm 432 z/mm $ 900/\sqrt 2 $ F# 1.6 -
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