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

• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650259/
• 关键词: Optical profilometry; Waveiength-Scanning Interferometry; Phase-shifting Technique; Sub-Nyquist Interferometry; Digital Holography; Aperture-Synthetic Interferometry; 干渉法; 位相測定; 自由曲面; Optical profilometry; Waveiength-Scanning Interferometry; Phase-shifting Technique; Sub-Nyquist Interferometry; Digital Holography; Aperture-Synthetic Interferometry; 干渉法; 位相測定; 自由曲面

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.

我们调查了相检测波长扫描干涉法（PWSI）的新可能性，该概念的概念是尼奎斯的干涉法的概念，其中将外部腔室可调激光二极管和PZT-MIRROR用作光源和相变。使用当前方法，可以实现各种工程表面的轮廓测量值，包括高于半波长和镜面非球形形式的步骤。事实证明，该方法的精度比通过实验的8 nm波长脱落更好，因为PWSI的误差来源，尤其是通过光学材料（包括CCD芯片的盖玻片）的后反转的影响，成功地抑制了。由于该技术基于按像素检测的像素基于像素，因此在边缘密度的子号格条件下也可以进行高度测量，其中条纹间距小于CCD像素的音调。通过此特征，可以将非球面的可测量区域扩展到两次以上，并且显示出包括步骤和非球形形式在内的复杂形状，例如壁炉透镜，可以通过仿真研究轻松测量。现在，该技术扩展到用于大型光学概况评估的多孔合成干涉仪。本技术还使用相位变化的数字全息图应用于文档学，其中在数字重建的对象表面上检测到由于波长变化而引起的相斜率，这可能会导致更简化和准确的形状测量技术。