Moire deflectometry

Moiré Deflectometry is an interferometry technique^[1], in which the object to be tested (either phase object or secular 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 and wind tunnel measurements as a quantitative replacement to Schlieren photography and Shadowgraphy.^[2]

References

1. ^ O. Kafri Optics letters 5,555 (1980)
2. ^ O. Kafri & I Glatt "The Physics of Moiré Metrology" J. Wiley & Sons Inc.(1990)