SYMPOSIA PAPER Published: 01 January 1988

Video Image Processing of Laser-Illuminated Coating Defects


A video microscopy system has demonstrated the ability to detect and locate defects nondestructively in multilayer optical coatings. The system uses laser-excited scattering to illuminate defects responsible for laser-induced damage in multilayer dielectric mirrors. Scatter intensity maps and contours can be generated by digitizing the video image of scattering from individual defects. These can reveal characteristic defect scatter features that can be related to a damage probability. Due to the relatively low resolution of the stored video image, the scattering from a defect may be contained in only a few pixels. Using digital-enhancement techniques such as cross correlation, noise filtering, and Laplacian edge enhancement combined with fast-Fourier transforms, it is possible to increase the resolution of the characteristic features of a scattering defect for a more detailed analysis. Examples of these techniques for a dielectric mirror will be presented and discussed.

Author Information

Auborn, JE
Moran, MB
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Developed by Committee: F01
Pages: 388–403
DOI: 10.1520/STP24447S
ISBN-EB: 978-0-8031-5033-1
ISBN-13: 978-0-8031-4481-1