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Optical Engineering

Distance measurement with extended range using lateral shearing interferometry and Fourier transform fringe analysis
Author(s): Dalip Singh Mehta; Priti Singh; Mohd Shoeb Faridi; Saba Mirza; Chandra Shakher
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Paper Abstract

We propose a distance measuring system based on lateral shearing interferometer (LSI) with extended range of measurement and improved resolution. The sensor is based on a wedge-shaped plate LSI and due to the presence of tilt, a finite number of fringes parallel to the direction of shear appear and hence significant spatial carrier frequency is generated at the focus position. On varying the distance of the object surface from the focus position, the orientation, fractional and integer order, and the width of the interference fringes change. It is shown that the orientation of the fringes is the most sensitive parameter, by means of which one can detect small changes in distance. The Fourier transform method for fringe analysis is used, and from the position of the maxima of the first-order Fourier spectrum the orientation of the fringes and hence the distance is measured. Experimental results of distance measurement by changing the focal length of the lens are presented. A large range of measurement without any fringe ambiguity problem can be achieved using the system.

Paper Details

Date Published: 1 June 2005
PDF: 10 pages
Opt. Eng. 44(6) 063602 doi: 10.1117/1.1926127
Published in: Optical Engineering Volume 44, Issue 6
Show Author Affiliations
Dalip Singh Mehta, Indian Institute of Technology Delhi (India)
Priti Singh, Indian Institute of Technology Delhi (India)
Mohd Shoeb Faridi, Indian Institute of Technology Delhi (India)
Saba Mirza, Indian Institute of Technology Delhi (India)
Chandra Shakher, Indian Institute of Technology Delhi (India)

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