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.
[4] The method excels in spatial and temporal resolution comparably with a similar approach of laser schlieren deflectometry.