基于空间光调制的光学自由曲面共光路多重波面非零位拼接干涉原理及应用

Freeform optical elements are considered to be ideal components for new optical imaging systems because they can correct several image aberrations effectively as well as simplify optical system structure. However, the fabrication and application of the freeform surfaces are not as good as traditional spheric, aspheric surfaces because it is extremely difficult to measure its surface in high accuracy. Non-null interferometric method with non-common optical path has been used for testing asphereic surface with rapid gradient change in the world recently. However, it can not be used in the testing of freeform surface because its mathematical theroy based on the tested surface with analytic formula and rotational symmetrical feature.A novel non-null common path interferometry method combined with subaperture stitching is presented for testing freeform surface in the paper. In the method, interferometric source array is produced by spatial light modulation, which can produce many spherical wavefronts with different tilt angles compensating the departure of the tested surface from a spherical one. The tested surface shape can be reconstructed precisely by subaperture stitching produced by source array planed by mathematical programming. By theoretical analysis and experimental study, how to using non-null interferometry to test freeform surface is researched, including: non-null common path interferometric mathematical theroy composed with unsymmetrical ray tracing method in three-dimensional space, the mathematical description method for freeform surface etc; spatial interferometric source array plan algorithm and design method based on spatial light modulation; phase extraction algorithm of the non-null interferogram array and surface shape reconstruction method; common path interferometric system error separation technique. The mathematical theroy and models of non-null interferometry, design method used in testing freeform surface and principle experiment platform will be the results of the project, which are theoretical foundation of making the non-null interferometer for testing freeform surface.

光学自由曲面校正各种像差同时简化系统结构，是光电系统理想元件。目前没有成熟方法能精密检测其面形，是生产和应用的瓶颈。国际上针对大梯度非球面提出非共光路非零位干涉测量法，其数理模型中用到被测件的旋转对称性及面形解析表达，故无法直接用于自由曲面检测。针对该方法不足，本项目提出一种非零位共光路梯度补偿与子孔拼接相结合的自由曲面检测新方法。该方法利用空间光调制技术对多点干涉源进行动态调制，产生多束倾斜波面来补偿被检表面梯度，再利用数学规划对同步干涉源进行空间轨迹规划完成子孔波面拼接测量。拟采用理论和实验的手段对以下关键问题展开研究：适应非旋转对称及非解析面形的非零位干涉数理模型，包括非对称三维空间的光线追迹、自由面形数学描述等；基于空间光调制的空间多点干涉源动态生成及规划方法；干涉图阵相位提取及面形拼接重构算法；共光路系统误差标定。掌握用于自由曲面的非零位共光路干涉理论体系，为研制测量仪器奠定基础

光学自由曲面是目前光学元件中最为复杂的元件，它校正各种像差的同时可以简化系统结构，是光电系统理想元件，在空间光学、精密成像系统等领域有非常重要的应用，其测量技术的研究是光学元件测量领域的前沿技术问题。目前在光学检测研究领域，还没有成熟可靠的方法能完全实现其面形的高精度测量。针对自由曲面面形高精度测量的难题，本项目研究了基于空间光调制的共光路非零位多重波面拼接干涉面形检测技术，建立了适应光学自由曲面检测的非零位共光路多重波面干涉数理模型，攻克了适应非旋转对称空间的非零位干涉图阵相位提取及面形拼接重构算法、基于空间光调制的空间多点干涉源动态生成及规划方法、共光路干涉系统的系统误差标定方法等关键技术。设计并研制了基于空间光调制的共光路非零位干涉自由曲面面形检测原理性实验系统，对项目的模型及算法进行了验证试验，建立了用于自由曲面面形检测的非零位多重波面共光路干涉理论体系。所研制的基于空间光调制的共光路非零位干涉自由曲面面形检测系统，自由曲面面的测量不确定度优于λ/30（RMS值），达到国际先进水平。本项目成果可以为各类光学自由面加工和应用，提供准确的测试手段和方法，大大降低自由曲面的加工成本和时间，解决我国在光学自由曲面加工上的难题，为光学自由曲面的国产化以及广泛应用奠定工业基础，从而为我国光电产品的革新提供优质元件，创造更多的经济效益。同时也可以应用于船舶、电子、航空、航天等国防与民用行业的企业、研究所与高校，作为光学元件的产品生产、科学研究的测量方法。项目发表学术论文6篇，SCI收录4篇，EI收录5篇，申请国家发明专利7项，已授权3项。