Patent ID: 8526008
Filing Date: 2013-09-03
Classification: G01B

Abstract:
1. A Fizeau interferometer for measuring a test surface of an object comprising: an off-axis paraboloidal reflector having a paraboloidal axis and a paraboloidal reflective surface that is offset from the paraboloidal axis; an effective light source located with respect to the off-axis paraboloidal reflector so that coherent light emanating from the light source along a main optical axis to the off-axis paraboloidal reflector is collimated by reflection from the offset paraboloidal reflective surface; a Fizeau reference surface oriented for receiving the collimated light at normal incidence, reflecting a first portion of the light, and transmitting a second portion of the light to and from the test surface; the off-axis paraboloidal reflector being arranged for forming overlapping virtual images of the of the reference and test surfaces, the overlapping virtual images being tilted through a non-normal angle to the main optical axis; and a camera detector surface together with a camera lens for converting the virtual images of the reference and test surfaces into real images on the camera detector surface having an optical orientation matching an optical orientation through which the virtual images are tilted.