Accuracy-enhanced diffraction image profilometry using foreign aberration for resolving image ambiguity

Guo-Wei Wu; Liang-Chia Chen

doi:10.1117/12.2621901

20 May 2022 Accuracy-enhanced diffraction image profilometry using foreign aberration for resolving image ambiguity

Guo-Wei Wu, Liang-Chia Chen

Proceedings Volume 12137, Optics and Photonics for Advanced Dimensional Metrology II; 121370M (2022) https://doi.org/10.1117/12.2621901
Event: SPIE Photonics Europe, 2022, Strasbourg, France

Abstract

A new optical surface measuring method based on correlation-based diffractive image profilometry (DIP) is developed for accuracy enhancement by introducing external optical aberration to the microscope. According to the diffraction theory, the diffractive images formed in the microscope mainly depend on the microscopic optical system and the surface features of the tested object. The most critical issue affecting the measurement accuracy of the DIP is that the uniqueness of the diffractive images corresponding to various surface geometric parameters such as different heights and orientations cannot be always guaranteed. This situation can bring undesired uncertainties in surface measurement since undesired ambiguity in image correlation or model estimation may be introduced. To resolve this, a designed foreign aberration is introduced into the microscopic optical system to develop the feature variance of diffractive images for significantly increasing the degree of the image variance, therefore the risk of ambiguity is effectively avoided. Proved by some experimental tests, with this method, the accuracy in measuring height, tilting angle, and tilting direction can be achieved to a level of sub-micrometer and less than 0.01 degrees, respectively.

Conference Presentation

Citation Download Citation

Guo-Wei Wu and Liang-Chia Chen "Accuracy-enhanced diffraction image profilometry using foreign aberration for resolving image ambiguity", Proc. SPIE 12137, Optics and Photonics for Advanced Dimensional Metrology II, 121370M (20 May 2022); https://doi.org/10.1117/12.2621901

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