Low-order multiple-beam interferometry

A discussion is given of the various factors affecting the intensity and sharpness of the multiple-beam Fizeau fringes and fringes of equal chromatic order used for the study of surface topography The effects of absorption in the silver film, phase condition, linear displacement of the beams, finite size of source, departure from parallelism and source line width are considered. It is shown that Fabry-Perot fringes, multiple-beam Fizeau fringes and fringes of equal chromatic order have all the same fringe shape if certain conditions are fulfilled.