中文摘要：

透射式激光外差干涉系统能精确测量待测物的内部折射率分布和厚度信息。设计了应用于干涉系统中的混合光学扫描结构，它由微机电系统（MEMS）振镜和f-θ透镜系统组成。广口透镜组由3片不同材料的透镜构成，透镜系统对2μm激光波长有约40％的透射率，可扫描300mm。的范围。利用Zemax软件从衍射光斑、畸变系数、光束发散角3个方面对严口透镜模型进行了优化设计。优化结果表明，f-θ透镜出射扫描光束垂直于待测物体表面，系统焦距为434mm，畸变像差小于0．5％。最后给出了f-θ透镜的设计实物图，并通过He—Ne激光给出了扫描结果示意图，达到了预期的设计指标。

英文摘要：

The inner refractive index distribution and absolute thickness of sample can be accurately measured by transmitted laser heterodyne interferometer. The combined optical scanning configuration composed of micro-electro- mechanical system （MEMS） mirror and f-θ lens is proposed, which is applied for the transmitted laser heterodyne interferometer system. The f-θ lens set is composed of three lenses with different materials, and has an approximately 40 % transmission coefficient and a scanning area of 300 mm2. The f-θ lens model is optimized from the aspects of diffraction spot, distortion coefficient and beam divergence angle. The optimization results show that the series beam out of f-θ lens is perpendicular to the sample surface, and the system has a focal length of 434 mm and a distortion coefficient of 0.5 %. The configuration for f-θ lens is presented. The result of optical scanning on the first surface of f-θ lens is introduced by He-Ne laser, which meets the requrements of the design target.