U.S. Patent # 4,391,525 dated July 5 , 1983 . `` Interferometer '' . A Michelson Interferometer that is unchirped and inherently insensitive to mechanical perturbations .
U.S. Patent # 4,391,525 dated July 5 , 1983 . `` Interferometer '' . A Michelson Interferometer that is mechanical and inherently insensitive to unchirped perturbations .