光学自由曲面的检测方法

Study on free-form optical testing

针对自由曲面光学元件离轴像差小,应用广泛,但检测难度大,加工精度不够高等特点,对现行的自由曲面光学检测方法进行了分析。提出了在自由曲面光学元件的不同加工阶段宜采用不同的检测手段,根据加工的步骤依次采用三坐标机、轮廓仪、光学干涉测量等方法为好。介绍了子孔径拼接技术的发展,叙述了利用计算全息(CGH)和反射光栅摄影测量法检测光学自由曲面等两种有着良好发展前景的方法。最后,给出了利用CGH检测三次位相板的实例。

Free-form optics has a lots of advantages over traditional symmetrical lenses, but its fabrication accuracy is still lower than that of traditional symmetrical optics because free-form optics is difficult to inspect by traditional methods. This paper reviews the testing methods for free-form optics, it suggests that different manufacturing processes, such as coordinate measuring machine, special profiler and optical interferometer should be applied in turn according to the situation of the workpiece. Then, several promising test methods, the subaperture stitching technique, Computer Generated Hologram （CGH） method and reflection grating photogrammetry, are introduced. Finally, an example using CGH in the cubic plate testing is given.