Topography measuring apparatus.

摘要

In a contour measuring apparatus (9) a plurality of light beams is directed onto the surface (13) to be measured. The light beams are reflected through a lens (15) onto a photodetector (19) to produce measurable images. The images are analyzed to determine the local radius of curvature of the surface at each desired point of incidence of individual light beams and the three-dimensional surface contour of the surface being measured. In order to reduce instrument errors a calibration surface with a known contour is positioned in substitution of the surface being measured. A computer (24) sequentially determine and store a memory of the location of the calibration surface and compare the reflection of the light from the calibration surface as well as the surface being measured to determine the contour of the surface being measured.