激光转镜扫描系统中自由曲面 f-θ物镜的设计

摘要

为了满足扫描系统高分辨率、大工作面、小型化的需要，设计了一款具有衍射受限聚焦能力的超广角f-θ物镜。在此基础上，针对五面转镜引起f-θ物镜入瞳偏移从而导致系统分辨率降低、线性畸变增大的问题进行了分析，计算得到光瞳偏移量与扫描转角存在非对称分布的非线性关系。采用在系统中引入含有奇次高阶项自由曲面校正光瞳漂移的方法，在ZEMAX软件中利用多重结构对f-θ转镜扫描系统建模优化设计，并给出了设计实例。该物镜采用远摄型结构，有效减小了扫描系统总体长度及透镜尺寸。结果表明，经优化校正后，f-θ物镜性能得到显著改善，在其扫描角度115°范围内，线性畸变小于0．5％，60％以上能量集中在半径30μm圆内。该f-θ扫描系统具有结构紧凑、分辨率高、线性畸变小等优点，有良好的适用性。%In order to satisfy the need of high resolution , large operation area and miniaturization of the scanning system, one f-θlens with super wide angle and diffraction-limited focusing performance was designed .On this basis, the resolution reduction and the linear distortion increasing caused by the pupil deviation due to the polygonal mirror were analyzed.After calculation, it was found that the pupil deviation had an aspheric nonlinear relationship with the scanning angle.Using the higher order terms of free surfaces to correct the deviation of pupil , the models of polygonal mirror f-θscanning system was optimized with ZEMAX and the multiple structures and the practical example was given .Due to the telephoto type of lens , the overall length of the scanning system and the aperture of the lens were effectively reduced .The simulation result shows that the f-θ performance is significantly improved through optimization and correction .Within the scanning angle of 115°, linear distortion is less than 0.5% and 60% of incident light energy is gathered in a circle in 30μm radius.The practical f-θ scanning system has the advantages of compact structure , high resolution and low linear distortion.