Grating interferometers for producing large holographic gratings

Methods for producing large holographic diffraction gratings are described. In particular, the advantages of using a grating interferometer illuminated with a noncollimated beam from either an extended monochromatic source or an extended polychromatic source are described along with some of the problems that arise and methods to solve them. Experimental results illustrating the grating interferometer's ability to produce straight uniform fringes when illuminated with such noncollimated wavefronts are given.