离轴非球面在细磨与粗抛阶段的波面再现检测方法

Surface error of off-axis aspherics in the stage of grinding and pre-polishing is too large to test by common interferometer. Comparing with infrared interferometer and profiler, Foucault test has irreplacable advantages, and is used widely. However, convetional Foucault has its disadvantages to test off-axis aspheric surface: it is not quantitative; the judgement of surface needs up-to-down and left-to-right cut the image of source, and depand on experience of the users. According to its disadvantanges, wavefront retrieval based on Foucault test is proposed to test aspherical surface in the stage of grinding and pre-polishing. The method integrates conventional Foucault test with image collecting and processing system and data processing software. Firstly, mathematical model is abstracted from shadow variation. Secondly, data of surface error would be acquired through data processing of theoretical model. Hence that shadow pattern by conventional Foucault test is convirted to surface error contour, and quantitative test by Foucault test is achieved. The mathematical model gives greater scope than Foucault quantitative test ever before to be applicable for large scale error of off-axis aspherac surface in the stage of grinding and pre-polishing, meanwhile, it is consitent with surface error by interferometer test. Comparing with other methods, it would quicken convergent speed, reduce high frequency surface error, and improve surface error.We strive to achieve the breakthrough of the test of aspheric surface in the stage of grinding and pre-polishing through the improved Foucault test.

离轴非球面在细磨及粗抛阶段的面形误差较大，超出了普通干涉仪检测的范围。和红外干涉仪及轮廓仪相比，付科法有着不可替代的优势，仍然被广泛使用。但是利用传统付科法检验离轴非球面也有局限性：不能定量；面形判断需上下与左右切割弥散斑，严重依赖使用者的经验。针对其缺陷，提出了基于付科法的离轴非球面在细磨及粗抛阶段的波面再现定量检测方法。该方法将刀口仪、图像采集处理系统及数据处理软件三者有机结合，从阴影图灰度变化中抽象出数学模型，然后利用该模型进行数据处理得到被检镜面的面形误差数据，从而将付科检测得到的阴影图转换成面形轮廓图，实现付科法定量检验离轴非球面。创建的数学模型拓展了以往付科定量的检测范围，以适用于细磨及粗抛阶段大误差值的离轴非球面检验，且能够与精抛阶段的干涉仪检测相衔接。该方法直观准确，可以大大改善离轴非球面的面形误差收敛速度、降低高频误差、提高面形精度，力求实现在细磨及粗抛阶段检测的突破。

随着天文学及空对地观测等领域的发展，对光学系统的成像质量要求越来越高。对于离轴非球面的口径越来越大，其技术要求也越来越严格。目前，在离轴非球面的细磨及粗抛阶段仍然缺乏有效的检测手段。细磨阶段的检测已经成为制约离轴非球面加工精度及表面平滑程度的主要因素。.本研究在对刀口切割弥散斑过程数学分析的基础上建立了付科法定量检测细磨和粗抛光阶段离轴非球面的数学模型，并从中找到了波面重建的原理与方案；依据数学模型描述的方法对刀口水平与竖直切割弥散斑得到的阴影图进行数据处理，实现了付科法的波面再现技术；在实验中，将付科法波面再现检测技术的检测结果和4D干涉仪的检测结果相对比，两种检测方法的面形误差轮廓图基本一致，实践证明付科法波面再现检测技术是可信的；为在检测过程中更加便捷，编写了人机界面。.基于付科方法的离轴非球面检测技术不仅具有传统付科方法的灵敏度及精度高、易于发现带差的的优点，而且重建的波面图打破了传统付科检验只能靠主观判断面形相对高低，不易于整体判断面形误差而且不能定量的缺点。该技术可以实现离轴非球面的实时在线检测，能够对细磨粗抛阶段光学镜面的加工提供指导，尤其适用于细磨改非球面阶段的检验，大大提高了镜面的磨制效率、加工精度，减少镜面检验过程中经验不足带来的误判提高镜面的平滑程度。

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