A Special Interferometer for Testing Long Laser Rods

A relatively inexpensive, versatile interferometer has been developed to evaluate the combined surface and internal properties of long, highly doped laser rods. The basic interferometer configuration, which is a modified Mach-Zehnder type, can be used for Brewster-ended as well as for square-ended rods in the pumped or unpumped condition. An unusual feature of this interferometer is that both beam splitters and mirrors are located in the same arm rather than in opposite corners as found in the conventional M-Z interferometer. Some shadowgraph pictures and interferograms of laser rods obtained with the interferometer are shown.