光学自由曲面的高精度原位偏折测量技术研究

In-situ measurement is the key to improving the manufacturing efficiency and reliability of optical functional surfaces. Deflectometry is advantageous in in-situ measurement of optical surfaces due to its large dynamic range and strong anti-disturbance capability. Aiming at the problems of severe measuring error and difficulty at whole-surface measurement for complex freeform surfaces, this project will conduct investigation on the following four aspects, (1)Reliable calculation of the deflected light field of the catadioptric imaging system, (2)Accurate reconstruction of complex freeform surfaces, (3)Planning of measurement route and stitching of sub-aperture data, and (4)Design of an in-situ measuring system and error analysis. Based on the thoughts of light field camera and compressive sensing, an innovative method is proposed to precisely calculate the deflected light fields by optimal coding of the screen pattern and imaging aperture. The limitation of the projection fringes and pin-hole imaging model of the phase measuring deflectometry can be broken. An accurate reconstruction algorithm is developed for freeform surfaces by reverse ray tracing aided by NURBS models. The under-constraint problem of the conventional integration method is addressed. A data fusion method based on the model-data alternate updating is proposed for sub-aperture stitching, so as to realize whole-surface measurement of complex surfaces. This project will fundamentally break the barriers which limit the measuring accuracy, and provide a universal high precision in-situ measuring method for optical functional surfaces. It is of great theoretical significance and application value for the technological progress in the intelligent manufacturing field and the performance guarantee of the opto-electronic equipment in our country.

原位测量是提高光学功能表面制造效率与可靠性的关键技术。偏折测量技术动态范围大、抗干扰能力强，在光学表面的原位测量方面具有突出优势。本项目针对自由曲面测量误差大、难以实现全表面测量的问题，拟研究以下内容：(1)折反成像系统的偏折光场计算; (2)复杂自由曲面的高精度重构; (3)测量路径规划与子孔径拼接; (4)原位测量系统设计与误差分析。突破当前投影条纹与针孔成像模型的局限性，创新性地基于光场相机与压缩感知思想，提出通过屏幕与光瞳的最优编码准确计算偏折光场；提出NURBS建模辅助逆向光线追迹法实现自由曲面的高精度重构，解决积分法的不适定性问题；提出模型-数据交互更替的子孔径拼接融合算法，实现复杂曲面的全表面测量。本项目将破除影响偏折测量精度的主要障碍，为光学功能表面提供一种通用的高精度原位测量方法，对我国智能制造领域的技术进步以及光电装备的性能保障具有重要的理论意义与应用价值。

偏折测量技术在自由曲面的高精度测量方面具有突出优势，但存在物像匹配不准确、难以实现全表面测量的问题。为此，本项目发展了高精度原位偏折测量技术与装备，研究内容如下：(1) 折反成像系统的光场建模与系统标定, 提出了空变点扩散函数的建模与计算方法，有效抑制了卷积相位偏差; 提出测量系统一体化几何标定技术，显著提高了测量效率; (2) 复杂自由曲面测量的相位解析与重构，提出基于系统结构约束的快速相位解调与透明元件双表面混叠信号分离算法;提出复杂曲面的非均匀B样条重构算法; (3) 单目测量中的工件定位与子孔径拼接，提出基于系统运动约束的工件精准定位算法，以及复杂曲面子孔径拼接算法; (4) 原位测量系统设计与实验验证，针对单点金刚石切削机床、抛光机床以及缺陷检测设计了原位偏折测量系统，并采用离线仪器进行实验对比与验证。将自由曲面的面形测量精度从微米级提升到100 nm RMS，产生了一系列具有独立知识产权的研究成果，发表高水平期刊论文23篇，授权发明专利13项，并荣获日内瓦国际发明展金奖等荣誉。研究成果应用于陀螺谐振子、汽车零部件的质量检测等关键场景，为提高光电装备的性能与可靠性，推动我国先进制造领域的技术进步具有重要意义。