大视场Ritchey-Chretien光学系统的间接成像方法

Indirect Imaging Method of Ritchey-Chretien Optical System with Large Field of View

Ritchey-Chretien(R-C)光学系统广泛应用于航空和航天等远距离探测领域,因其视场较小,所以通常采用附加光学元件的方法实现大视场成像,但这会导致结构复杂,不利于系统实现小型化和轻量化。鉴于此,提出一种R-C系统间接成像方法。首先分析系统的像差特性,接着基于波前像差理论和Zernike多项式构建波前模型,然后通过傅里叶变换建立PSF模型,最后结合反卷积算法处理图像。在仅采用主、次镜的情况下,可以实现R-C系统大视场成像。对焦距为1300 mm、全视场为0.9°和F数为4的R-C光学系统进行仿真模拟。模拟结果表明,所提方法的MTF在频率为40 cycle/mm处平均提升约为0.25,成像质量显著提升。

Ritchey-Chretien(RC)optical system is widely used in long-distance detection fields such as aviation and aerospace.Due to its small field of view,additional optical elements are usually used to achieve large field of view imaging,but this will lead to a complex structure,which is not good for miniaturization and lightweight of the system.In view of this,a R-C system indirect imaging method is proposed.First,the aberration characteristics of the system are analyzed.Then,the wavefront model is constructed based on the wavefront aberration theory and Zernike polynomial.Second,the PSF model is established by Fourier transform.Finally,the image is processed by combining the deconvolution algorithm.In the case that only primary and secondary mirrors are used,the R-C system can achieve large field of view imaging.The R-C optical system with a focal length of 1300 mm,a full field of view of 0.9°and an F number of 4 is simulated.The simulation results show that the MTF of the proposed method increases by about 0.25 on average at a frequency of 40 cycle/mm,and the imaging quality is significantly improved.