Foucalt-type laser interferometer for advanced wavefront control of optical beam propagation

Proposed apparatus is a combination of well known knife-edge Foucalt optical tester and a special laser interferometer. This apparatus consists of a gas laser, two off-axis mirrors, forming two point-like sources of light, the knife of Foucalt, receiving screen or CCD for interference-fringes observation, and optics under test. The apparatus works of the following way: the beam of laser is reflected by two tiny paraboloidal mirrors, which form two point-like light sources, and therefore reference and analyzer beams. The reference beam is reflected by optics under test, and then it is crossed by knife of Foucalt and then it was recombined with analyzer beam to produce a shadow picture with a system of Twyman-Green fringes. Therefore the shadow picture can be calibrated by fringes immediately. This method can be used in a very large spectral region, from UV up to IR, as the apparatus has only mirror elements. The method can be utilized for testing communication optics in space, as well as for optical shop testing in vacuum chamber in far UV region to increase precision of the test.