Decorrelation in an interferometric set-up appears due to movements of the speckle pattern. In the case of rigid body movements the effect of decorrelation severely limits the performance of speckle interferometers. If the movement is larger than the speckle size the wanted phase information of the deformation is lost. Phase modulating spatial light modulators (SLMs) provide a new method to non-mechanically deflect and shape light. By using the SLM for scanning the field-of-view and focusing at different distances it is possible to measure intensity speckle patterns in a three-dimensional volume. These intensity images can then be cross correlated to give a three-dimensional correlation coefficient of the speckle pattern. If an SLM is utilized in an interferometric set-up it is possible to compensate for unwanted movements during an experiment. The measured correlation coefficient will then provide information regarding how large movements that are allowed with maintained performance of the interferometer. It is shown that for large movements the SLM can be used to retrieve phase maps.

Date Published: 18 June 2007
PDF: 9 pages
Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 661619 (18 June 2007); doi: 10.1117/12.726054

Published in SPIE Proceedings Vol. 6616:
Optical Measurement Systems for Industrial Inspection V
Wolfgang Osten; Christophe Gorecki; Erik L. Novak, Editor(s)