航空遥感相机Ronchi光栅自准直检焦模型分析与验证

为解决航空遥感相机检焦系统故障分析、元器件选型及提高检焦精度的问题,本文深入研究了基于Ronchi光栅的光电自准直检焦法。首先,归纳总结了国内外航空相机常用的几种检焦方法,对比了每种检焦方法的优缺点。接着,重点介绍了基于Ronchi光栅的光电自准直检焦系统的构成和工作原理,建立了数学模型,模拟了检焦系统在不同像面位置处的输出波形。然后,为衡量离焦程度,提出了离焦评价因子的概念,接着分析了光学系统的衍射效应和像差大小、Ronchi光栅的周期选择及检焦光源的能量分布这三种因素对检焦精度的影响,给出了Ronchi光栅周期的选择方法。最后,通过实验的方法对本文的仿真结果加以验证。实验结果表明:合焦波形的峰峰值占比0.82,对应0.05 mm步长下的平均检焦分辨力约为10%。

Theoretical analysis and verification of Ronchi grating auto-collimated focusing for aerial remote camera

To address issues such as auto-focusing system fault analysis and component selection, and to improve the focusing accuracy of aerial remote cameras, this article offered insights into the auto-collimated focusing technology based on the Ronchi grating.First, in this paper,several common focusing methods of both domestic and foreign aerial cameras were summarized and compared. Then, the composition and operating principle of optoelectronic auto-collimated focusing systems based on the Ronchi grating were introduced, the mathematical model was established, and the simulation curves of the focusing waveform with different imaging positions were presented. To measure the focal distances, the concept of the defocusing evaluation factor was proposed.Next, the three factors that affect the focusing accuracy of the diffraction effect and the aberration of the optical system, the period selection of the Ronchi grating, and the energy distribution of the light source were analyzed. The influence of the Ronchi grating period selection method was then presented. Finally, the experimental results verify the validity of the simulation results and show that the peak-to-peak ratio of the focusing waveform is 0.82, corresponding to an average focusing detection resolution of 10% at 0.05 mm.