Patent ID: 9644941
Date: 2017-05-09
CPC Classifications: G01B

Claim:
1. A grazing incidence interferometer configured to measure a profile of a target surface using a measurement beam radiated on the target surface in a direction oblique to a normal line of the target surface and reflected on the target surface to cause an interference with a reference beam, the grazing incidence interferometer comprising: a light source that is configured to emit light; a beam splitter that is configured to split the light from the light source into the reference beam and the measurement beam; a λ/2 plate provided between the light source and the beam splitter and configured to change a light amount ratio between the reference beam and the measurement beam to any ratio; a light synthesizer that is configured to synthesize the reference beam and the measurement beam reflected on the target surface; a camera that is configured to capture an image of a synthesized beam of the reference beam and the measurement beam; and a controller comprising: