Shape measurement by
projected fringes
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Phase-shifted projected fringes |
Unwrapped object phase |
Measured shape |
Shape measurement of an object can
be very useful in reverse engineering, medicine, arts, and different other
activities. A basic technique consists of projecting two series of
phase-shifted interference fringes on a reference surface (not necessarely
plane) and on the object to be measured.
The
modulo2p phase difference can
then be directly extracted, or the modulo2p phase
may be extracted for each series by using the relation 
, as in
the next images.
The use of the "UNWRAP"
program allows then for extracting the unwrapped phase by a
noise-robust algorithm. The unwrapped phase represents the object's shape,
measured with respect to the reference surface. 
