Share Email Print

Proceedings Paper

Shape measurement of diffuse and transparent objects by two wavelength contouring using phase retrieval
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

Two wavelength contouring is used especially for the shape measurement and testing of steep objects. Conventional and digital holographic techniques can be utilized for this. But both these methods require the interference of the test wavefront with a known background or reference wavefront. This makes the adjustment of the two beams intensities to get high contrast fringes necessary. These methods are also prone to external noise like vibrations. Phase retrieval from intensity sampling at multiple axial planes offer an attractive alternative for whole field imaging. Diffusively reflecting objects produce volume speckle field when exposed to highly coherent radiation like laser. This volume speckle field has appreciable intensity variation both in the transverse as well as axial direction, which is the necessary condition to reconstruct the complex amplitude of the object wavefront from the intensity values. The reconstruction process uses the angular spectrum propagation approach to the scalar diffraction theory. This paper explores the use of phase retrieval in two wavelength contouring. The method can be used for the shape measurement of steep diffuse objects and the optical path length measurement of transparent objects. The method is explained using simulations. Some experimental observations are also provided to validate the simulation results.

Paper Details

Date Published: 17 June 2009
PDF: 10 pages
Proc. SPIE 7390, Modeling Aspects in Optical Metrology II, 73900D (17 June 2009); doi: 10.1117/12.827466
Show Author Affiliations
Arun Anand, The Maharaja Sayajirao Univ. of Baroda (India)
Vani K. Chhaniwal, Parul Institute of Engineering & Technology (India)
Giancarlo Pedrini, Univ. Stuttgart (Germany)
Wolfgang Osten, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 7390:
Modeling Aspects in Optical Metrology II
Harald Bosse; Bernd Bodermann; Richard M. Silver, Editor(s)

© SPIE. Terms of Use
Back to Top