基于单测头双剪切扫描的光学自由曲面在位测量方法

Freeform optics have the features of enhancing the optical system performance, simplifying system structure and realizing system integration easily. They lead to broad application prospects in various areas including national defense industry and civilian market, and also new challenges for optics manufacturing and measurement. On-machine measurement is an effective method for improving accuracy of freeform optics. As development of a variety of freeform optics, on-machine 3D measuring technologies with high precision, large aperture, large measuring range and high lateral resolution for many kinds of figures are requested urgently. This proposal brings forward firstly a novel scanning measuring method with single displacement probe and two shears. Problems of on-machine measurement for various freeform optics could be solved by this method with meeting all of these requirements. This measuring method can realize and extend the function of multi-probe method by single probe. It needs no accessional instrument for pitch angles. Many kinds of problems of existing scanning measuring methods, such as long term unstability of measuring system, errors of probe distance and difference between probe’s performance, could be solved. The novel developing exact reconstruction arithmetic can separate the errors of scanning motion completely in theory with high efficiency. Any 3D surface can be reconstructed exactly by this arithmetic. Scanning once can measure many 2D-profiles with large size and bidirectional high lateral resolution by developed long travel decoupled 2D micro-motion flexure hinge shearing stage. The proposed method can exceed the measuring range of probe and measure surface with large sag.

光学自由曲面具有增强光学系统性能、简化结构、便于集成等优点，在国防和民用领域得到越来越广泛的应用，同时也给加工和测量带来新的挑战，在位测量是提高光学自由曲面加工精度的有效方法。随着光学自由曲面的多样性发展，能适应多种面形的高精度、大口径、大量程、高横向分辨率三维在位测量技术的需求日益迫切。项目首次提出一种位移单测头双剪切扫描测量方法，以期在同时满足这些要求的情况下解决多种光学自由曲面的在位测量问题。该方法采用单个测头实现并拓展多测头扫描功能，无需额外的偏摆误差检测装置，可以解决现有扫描测量方法中存在的系统长时不稳定性、测头间距误差、测头性能差异等多种问题。创新的精确重构算法可以高效地、在理论上完全分离扫描运动误差以重构任意三维面形；研制大行程解耦的柔性铰链二维微动剪切平台，单程扫描即可实现多个线轮廓的大范围、双向高横向分辨率测量；提出的扩大量程方法可以突破测头量程限制实现大矢高表面测量。

光学自由曲面具有增强光学系统性能、简化结构、便于集成等优点，在国防和民用领域得到越来越广泛的应用，同时也给加工和测量带来新的挑战，在位测量是提高光学自由曲面加工精度的有效方法。随着光学自由曲面的多样性发展，能适应多种面形的高精度、大口径、大量程、高横向分辨率三维在位测量技术的需求日益迫切。.主要研究内容包括：微位移剪切平台的研制，线轮廓双剪切扫描高效精确重构方法研究，基于线轮廓组合的光栅式扫描和径向扫描三维面形精确重构方法研究，扩程扫描测量方法的研究，剪切平台的重复性测试，测量系统的不确定度分析和轮廓扫描测量实验。实现了预期的研究指标：测量系统不确定度0.1µm@100mm，横向分辨率达1.8µm；立式扫描和卧式扫描测量最大行程可达300mm，测量量程理论上不受限制，一般在20mm以上。.项目提出单测头双剪切扫描测量方法采用单个测头实现并拓展了多测头扫描功能，可以解决现有扫描测量方法中存在的系统长时不稳定性、测头间距误差、测头性能差异等多种问题。研制的精确重构算法可以在理论上完全分离扫描运动误差以重构任意三维面形，提出的扩大量程方法可以突破测头量程限制实现大矢高表面测量。通过对多种导轨平台的测量实验研究，发现偏摆误差对轮廓的重构精度影响极小，可以忽略不计。