Area expansion for aspherical shape measurement with phase-detection wavelength-scanning interferometry

使用相位检测波长扫描干涉测量法进行非球面形状测量的面积扩展

基本信息

批准号：
12650259
负责人：
KATO Jun-ichi
金额：
$ 2.37万
依托单位：
RIKEN (The Institute of Physical and Chemical Reseach)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

We investigated the new possibilities of the phase-detection wavelength-scanning interferometry (PWSI) with the concept of the sub-Nyquist interferometry, in which an external-cavity tunable laser diode and a PZT-mirror were used as the light source and the phase-shifter. With the present method, the profile measurements of various engineering surfaces including steps higher than the half-wavelength and specular aspheric forms are realized. Accuracy of this method has proved to be better than 50 nm with 8 nm of wavelength-excursion by experiments because the error sources of the PWSI, especially the influence of back-reflections by optics including the cover glass of the CCD chip, was successfully suppressed. Because this technique is based on pixel by pixel detection, the height measurement can also be conducted under the sub-Nyquist condition of fringe density, in which fringes spacing is less than a pitch of CCD pixel. The measurable area for aspherical surfaces can be extended more than twice by this feature, and it was shown that the complex shapes including the steps and aspherical form, such as the Fresnel lens, can be easily measured by the simulation researches. This technique is now extended to the multiple-aperture synthetic interferometry for profile evaluations of large optics. The present technique is also applied to the profilometry using the phase-shifting digital holography in which the phase-slope due to the wavelength-change is detected on the digitally reconstructed object surfaces, which might lead to more simplified and accurate shape measurement techniques.

我们利用亚奈奎斯特干涉测量的概念研究了相位检测波长扫描干涉测量 (PWSI) 的新可能性，其中使用外腔可调谐激光二极管和 PZT 镜作为光源和相位-变速器。该方法可实现包括半波长以上台阶和镜面非球面在内的各种工程表面的轮廓测量。实验证明，该方法的精度优于50 nm，波长偏移为8 nm，因为PWSI的误差源，特别是包括CCD芯片盖玻片在内的光学器件的背反射的影响被成功抑制。。由于该技术基于逐像素检测，因此也可以在条纹密度的亚奈奎斯特条件下进行高度测量，其中条纹间距小于CCD像素的间距。通过这一特性，非球面的可测量区域可以扩大两倍以上，并且通过模拟研究表明，包括台阶和非球面形状在内的复杂形状，例如菲涅尔透镜，可以很容易地测量。该技术现已扩展到多孔径合成干涉测量，用于大型光学器件的轮廓评估。本技术还应用于使用相移数字全息术的轮廓测量，其中在数字重建的物体表面上检测由于波长变化引起的相位斜率，这可能导致更简化和更准确的形状测量技术。