Patent ID: 7916308
Filing Date: 2011-03-29
Classification: G01B,G11B

Abstract:
1. An apparatus for measuring surface topography of a surface comprising: a linearly polarized light source that generates a light beam; optics that focus the light beam on a surface to be measured such that a normally incident beam deflection is provided, the optics including polarization optics such that the incident beam has a first polarization and a reflected beam from the surface has a second polarization different from the first polarization, the optics including: a half-wave plate that receives the light beam from the linearly polarized light source; a long working distance microscope objective positioned to receive the light beam as an input from the half-wave plate and output a converging light beam; and a polarizing beam splitter positioned to receive as an input the output of the long working distance microscope objective and produce as an output a light beam with the first polarization; wherein the optics further include a quarter-wave plate positioned to receive as an input the light beam with the first polarization and output a beam in a direction normally incident to the surface, the reflected beam from the surface being reflected by the quarter-wave plate towards the position sensitive detector with the second polarization; and a position sensitive detector positioned to detect the reflected beam.