Least-square fitting a wave-front distortion estimate to an array of phase-difference measurements

We propose a method for simultaneously measuring the front and back surface profiles of transparent optical components. The proposed method combines dual-wavelength transmission deflectometry with liquids to record distorted phases at different wavelengths, and then numerically reconstructs the three-dimensional phase information to image the front and back surfaces of the lens. We propose a theoretical model to determine the surface information, and a bifocal lens is experimentally investigated. Unlike conventional transmission deflectometry, our proposed method supports direct observation of the front and back surface profiles of the optical elements.

Section: 편향법unclassified

Simultaneous Determination of Both Surface Profiles of a Bifocal Lens Using Dual-Wavelength Transmission Deflectometry With Liquid

Shin¹,

Yu²

2015

“…위상 펼침 방법에는 경로추적법 (Path-following Phase unwrapping)과 시간추적법 (Temporal Phase Unwrapping) 방법이 있는데, 시간 추적법이 상대적으로 잡음에 덜 민감하 여 본 연구에서는 시간추적 위상펼침을 이용하였다 [15][16][17] . 즉 위상의 기울기를 위상이동방법과 위상 펼침을 이용하여 얻 고, 이로부터 시료의 기울기 데이터를 얻을 수 있으며, 이를 이용하여 식 (3)과 같이 최소자승법을 이용하여 시료의 3차 원 형상을 계산할 수 있다 [18][19][20] . 에 의한 위상변화는 식(4)와 같다 [21,22] .…”

Section: 투과형 편향법unclassified

Determining the Refractive Index Distribution of an Optical Component Using Transmission Deflectometry with Liquids

Shin¹,

Yu²

2014

Phase-measuring deflectometry is a full-field gradient measuring technique that lends itself very well to testing specular optical surfaces. We have measured the deformation of the surface of a lens by transmission deflectometry with liquids. In this study, a method is proposed for measuring the refractive index distribution of a transparent object component. The proposed method combines transmission deflectometry with liquids. The deformed fringe patterns of a sample immersed in different fluids are recorded, and then the three-dimensional phase information of the sample is reconstructed numerically. We have used phase-shifting and temporal phase-unwrapping methods to retrieve the phase from the measured deformed fringe pattern, and we have used a least-squares method to find the height information of the specular surface from the calculated slope. In particular, we have proposed a theoretical model for determining the refractive index of sample and planar convex lens are demonstrated experimentally.

“…[14,15] 측정 된 기울기를 가지고 시료의 3차원 형상을 구현하는 방법은 경로적분 방법과 최소자승법이 있다. [16][17][18] 본 연구에서는 최 소자승법을 이용하여 높이를 구하였다. 푸리에 변환 방식을 이용한 위상 측정은 Takeda 에 의해 제안되었다.…”

Section: 서 론unclassified

Measurement of Wafer Deformation using Deflectometry

이호동¹,

신상훈²,

유영훈

2013

Phase-measuring deflectometry is a full-field gradient measuring technique that lends itself very well to testing specular optical surfaces. We have measured deformation of a large specular surface by deflectometry. In this work, we have used a Fourier-transform method to get the phase from a measured deformed fringe pattern, and we have used least squares method to obtain the height information of the specular surface from the calculated slope. Experimentally, we have confirmed that deflectometry can be used for deformation measurement of a specular surface like that of a wafer.