SHADOW MOIRE SURFACE MEASUREMENT USING TALBOT EFFECT

摘要

A method and apparatus for surface measurement using the shadow moire effect with the Talbot effect. The apparatus (10) includes a specimen mount (18) to receive a specimen (12) having a surface (14) to be measured, and a reference grating (22) mounted adjacent the specimen mount (18) so as to be substantially parallel to a mean surface plane (16) of the specimen (12). The reference grating (22) is mounted in such a manner that the distance between the reference grating (22) and the mean surface plane (16) of the specimen (16) can be adjusted to a Talbot distance delta T. The apparatus also includes a light source (24) to illuminate the specimen (12) through the grating (22), and a detector (36) positioned to detect the moire fringes produced by the grating (22) due to variation of the surface of the specimen (12).