Virginia TechWeissman, Eric M.Post, Daniel2014-04-042014-04-041982-01-01Eric M. Weissman and Daniel Post, "Moire interferometry near the theoretical limit," Appl. Opt. 21, 1621-1623 (1982). doi: 10.1364/AO.21.0016210003-6935http://hdl.handle.net/10919/46936The theoretical upper limit of moire interferometry is approached as the reference grating pitch approaches _/2 and its frequency approaches 2/_. This work demonstrates the method at 97.6% of the theoretical limit. A virtual reference grating of 4000 lines/mm (101,600 lines/in.) was used in conjunction with a phase type reflection grating of half of that frequency on the specimen. Sensitivity was 0.25 _m/fringe (9.8 _in./fringe). In-plane displacement fringes of excellent definition were obtained throughout the 76 _ 51-mm (3 _ 2-in.) field of view. They were very closely packed, exhibiting a maximum fringe density of 24 fringes/mm (610 fringes/in.). Effectiveness of moire interferometry near the theoretical limit was proved.application/pdfen-USIn CopyrightMoire Interferometry Near The Theoretical LimitArticle - Refereedhttp://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-21-9-1621Applied Opticshttps://doi.org/10.1364/AO.21.001621