Apparatus for measuring surface form

摘要

A second harmonic generating element radiates a laser beam having a wavelength of 532 nm onto a substrate surface. The laser beam corresponds to the second harmonic beam of a fundamental laser beam having a wavelength of 1064 nm. An emitting optical system emits the laser beam vertically to the substrate surface so that the laser beam is made linear. An observing means has a optical axis Lo oriented in a different direction from a optical axis Li of the emitting optical system and provides a CCD image sensor served as a two-dimensional imaging device located in conjugation with the height or thickness of the substrate surface. The observing means operates to observe a light section image formed by the linear beam fired by the emitting optical system onto the substrate surface. Then, an image processing means precisely measures the form of the surface of an object to be measured as suppressing degrade of an S/N ratio, on the basis of the image data of the light section image observed by the observing means.