Phase shift reflectometry for sub-surface defect detection
Asundi, Anand Krishna
Teoh, Eden Kang Min
May, Watt Sook
Date of Issue2012
Optical Metrology and Inspection for Industrial Applications (2nd : 2012 : Beijing, China)
School of Mechanical and Aerospace Engineering
Phase Shift Reflectometry has recently been seen as a novel alternative to interferometry since it can provide warpage measurement over large areas with no need for large optical components. To confirm its capability and to explore the use of this method for sub-surface defect detection, a Chinese magic mirror is used. This bronze mirror which dates back to the Chinese Han Dynasty appears at first sight to be an ordinary convex mirror. However, unlike a normal mirror, when illuminated by a beam of light, an image is formed onto a screen. It has been hypothesized that there are indentations inside the mirror which alter the path of reflected light rays and hence the reflected image. This paper explores various methods to measure these indentations. Of the methods test Phase Shift Reflectometry (PSR) was found suitable to be the most suitable both in terms of the sensitivity and the field of view.
DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). This paper was published in Proceedings of SPIE - Optical Metrology and Inspection for Industrial Applications II and is made available as an electronic reprint (preprint) with permission of Society of Photo-Optical Instrumentation Engineers (SPIE). The paper can be found at the following official DOI: [http://dx.doi.org/10.1117/12.1000032]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.