Ronchi-like laser interferometer for large spectral region-from extreme UV to far infrared

Proposed interferometer is a combination of well known Ronchi optical tester and a special designed laser interferometer for large spectral region: from extreme ultraviolet to far infrared. This apparatus consists of the coherent point light source (it is possible also to use parallel coherent point light beam, for example of laser), two off-axis mirrors, forming two point sources of light, a Ronchi grating, receiving screen for CCD for fringes observation, and optics under test, for example concave mirror. This apparatus works in the following way: the coherent beam of a light is reflected by two very small hyperboloidal or paraboloidal mirrors which form two point-like light sources, i.e. reference and analyzer beams. The analyzer beam is reflected by optics under test, and then it is crossed by Ronchi grating and then it is recombined with reference beam to produce a shadow picture of Ronchi test with picture can be calibrated by Twyman-green fringes immediately. If Ronchi grating is made of wire, and the all scheme consists of mirrors, this method can be used in a very large spectral region, from UV to IR. That is why the method can be utilized for testing optics on an orbit in the space, as well as for the precision optics testing in a vacuum chamber in UV spectral region to increase the testing precision