RECOGNITION OF DAMAGE IN POLARIZING TRANSMISSION-GRATING FACETS

An optical setup was built for microscopic damage inspection on transm ission-grating facets composed of a gold-wire structure. Contrast impr ovement was achieved by exploiting the polarizing properties of these gratings in the near-infrared region. Spatial filtering yields an addi tional contrast enhancement and reduces unwanted signals caused by the periodic support structure. An image-processing algorithm is develope d that evaluates the number and the size of the faults in a grating fa cet with high accuracy from only one digital image. (C) 1996 Optical S ociety of America