Moire Projection Technique
Original Publication Date: 1985-May-01
Included in the Prior Art Database: 2005-Feb-18
The use of an interferometer to create the fringe pattern (cosine-type fringes) that falls on the surface of an object to be evaluated using the Moire technique has been discussed in the literature [1, 2]. A hologram of the wavefront of the interferometer consisting of the two intersecting plane waves can be made by placing the recording medium at the interferometer's output. The interferometer can be removed from the Moire system and replaced with its hologram. Illumination of the hologram with the expanded laser beam will produce fringes with the original spatial frequency on the surface of the object. An example of how the hologram is used as a primary grating is shown in the figure. A laser beam 2 is generated by the laser 1, cleaned up in a spatial filter 3, and provided to the beam expander 4.