Moiré deflectometry produces result that appears similar to an interferometry technique,[1][2] in which the object to be tested (either phase object or specular surface) is mounted in the course of a collimated beam followed by a pair of transmission gratings placed at a distance from each other. The resulting fringe pattern, i.e., the moiré deflectogram, is a map of ray deflections corresponding to the optical properties of the inspected object.
Moiré deflectometry can be a powerful tool for nondestructive optical testing. A major advantage of the technique is that it is less sensitive to mechanical vibration, and it is therefore widely used in the ophthalmic industry for laminar analysis. A similar implementation in wind tunnel application for quantitative measurement is moire schlieren, a variation of schlieren photography.[3]
In 2012 the first application of the method for the measurement of electron density in plasma has been published.[4] The method excels in spatial and temporal resolution comparably with a similar approach of laser schlieren deflectometry.
References
O. Kafri Optics letters 1980; 5,555
Oberthaler, M. K.; et al. (October 1996). "Inertial sensing with classical atomic beams". Physical Review A. 54 (4): 3165–3176. Bibcode:1996PhRvA..54.3165O. doi:10.1103/physreva.54.3165. PMID 9913837.
O. Kafri & I Glatt "The Physics of Moiré Metrology" J. Wiley & Sons Inc. (1990)
Valenzuela, J. C.; Wyndham, E. S.; Chuaqui, H.; Cortes, D. S.; Favre, M.; Bhuyan, H. (2012). "Implementation of moire-schlieren deflectometry on a small scale fast capillary plasma discharge". Journal of Applied Physics. 111 (10): 103301. Bibcode:2012JAP...111j3301V. doi:10.1063/1.4719982. hdl:10533/132785.
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