扫描式微透镜阵列系统的角放大率特性研究

Characterizing the Angular Magnification of Scanning Microlens Array System

扫描式微透镜阵列系统通过微动扫描成像,能够有效解决小行程与大视场之间的矛盾。扫描式微透镜阵列一般采用开普勒式望远结构,通过镜片横向相对位移实现视场扫描。本文提出了一种基于开普勒式望远结构的四片式微透镜阵列,探究了微透镜阵列的角放大率对于3~5μm波段的扫描式微透镜阵列系统的影响。当角放大率小于1时,经过串扰产生的杂散光较多,系统的能量利用率上限受到限制,导致衍射极限受到限制。角放大率越大,能量利用率上限越高,当角放大率从0.67^(×)改变为0.83^(×),能量利用率可以从43%提升到69%。当角放大率大于1时,系统的能量利用率不再受到结构限制,在抑制串扰的条件下,优化得到角放大率为1.5^(×)的结构。对其像质进行评价,各扫描视场RMS半径达到探测器像元尺寸,MTF达到0.6@17 lp/mm。角放大率作为表征微透镜阵列结构特点的参数,与系统能量利用率相关,从而影响像质,因此对于角放大率的分析与研究可为扫描式微透镜阵列系统的设计与实现提供依据。

Scanning microlens array systems can effectively resolve the contradiction between small strokes and large fields of view using micromotion scanning imaging.They generally adopt the Keplerian telescope structure and perform field-of-view scanning through the relative lateral displacement of the lenses.In this paper,we propose a four-piece microlens array based on the Keplerian telescope structure and evaluate the effect of the angular magnification of the microlens array on the scanning microlens array system in the 3-5μm band.When the angular magnification is less than 1,more stray light is generated after crosstalk and the upper limit of the energy utilization of the system is limited,resulting in a restricted diffraction limit.Higher angular magnifications increase the upper limit of energy utilization.When the angular magnification is^(×)changed from 0.67 to 0.83^(×),the energy utilization increases from 43%to 69%.When the angular magnification is greater than 1,the energy utilization of the system is no longer limited by the structure,and^(×)the structure with an angular magnification of 1.5 is optimized under the condition of suppressing crosstalk.The results of the image quality evaluation are as follows:the RMS radius of each scanning field reaches the pixel size of the detector,and the MTF reaches 0.6@17l p/mm.As a parameter characterizing the structure of the microlens array,the angular magnification is related to the energy utilization of the system,which affects the image quality.Therefore,the analysis and study of angular magnification can provide a basis for the design and implementation of the scanning microlens array system.