New Image Processing Algorithms For The Analysis Of Speckle Interference Patterns

H. A. Vrooman; A. A.M. Maas

doi:10.1117/12.962781

20 November 1989 New Image Processing Algorithms For The Analysis Of Speckle Interference Patterns

H. A. Vrooman, A. A.M. Maas

Proceedings Volume 1163, Fringe Pattern Analysis; (1989) https://doi.org/10.1117/12.962781
Event: 33rd Annual Technical Symposium, 1989, San Diego, United States

Abstract

A sequence of algorithms for processing interference patterns generated by a phase-shifting speckle interferometer is discussed. The processing yields the computation of in-plane displacement and strain components on the surface of an object, using a phase-shifting algorithm to compute the phase. Accurate phase measurement on a 512*512 grid is achieved by pixel-synchronous digitizing of four interference patterns and subsequent calculation of the phase modulo 2n radians, using a two-dimensional look-up table. A pipeline of Datacube image processing modules is configurated to perform this measurement. Digital image processing algorithms have been developed for phase unwrapping, phase restoration and smoothing. During these processing steps, invalid pixels due to low modulation or saturation are neglected. For phase unwrapping an algorithm has been developed that, starting at a chosen start pixel, propagates a "wavefront" of unwrapped phase data through the data set and that takes a set of neighbouring pixels into account to detect 2n steps. Subsequently, phase restoration is done by averaging valid neighbouring pixels. Basic binary image processing techniques are used to solve the problem of irregularly shaped objects due to holes and shadows. The measured phase change is used to compute the in-plane displacement and strain components of the deformed object. Results of a measurement of in-plane displacement and strain components on the surface of a simple aluminium object are shown.

Citation Download Citation

H. A. Vrooman and A. A.M. Maas "New Image Processing Algorithms For The Analysis Of Speckle Interference Patterns", Proc. SPIE 1163, Fringe Pattern Analysis, (20 November 1989); https://doi.org/10.1117/12.962781

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available