Klaus Koerner

New grazing incidence microscope for the measurement of topography with a 2lambda-algorithm

Interferometers with grazing incidence and visible light offer a fast and practicable solution for waviness and roughness testing in mechanical engineering without the necessity of scanning. Therefore, the possibility to use the grazing incidence of light onto the specimen is considered. The experimentally proved new optical layout for the grazing incidence interference microscope with a piezo-driven mirror for phase-shifting is based on a special optical stage with a hologram as a beam deflector. The object surface is sharply imaged onto the hologram, where an interference pattern is caused by the topography of the surface under test. Then, the diffracted light of the first order is imaged by a second optical stage onto a CCD-camera chip and the fringe pattern evaluation is carried out with a phase- shifting algorithm. Additionally a 2(lambda) -algorithm was implemented in the evaluation software. The necessary variation of (lambda) is generated by a small computer- controlled variation of angle of incident of light ont he specimen surface. First measurement results of objects with continuous and discontinuous surfaces demonstrate the possibilities and the limitations of the new experimental approach.