Changes

The Fourier Analysis method of interferograms was created in 1982 by M. Takeda, H. Ina and S. Kobayashi and originally intended as an alternative to Moire Topography and the phase-shifting technique [1,2].  However, this method was ineffective at analyzing closed fringe patterns.  A revision to the method, solved this problem by utilizing a Cartesian to polar coordinate transform [3].  The result of which could then be analyzed using the original method proposed.

The Fourier Analysis method of interferograms was created in 1982 by M. Takeda, H. Ina and S. Kobayashi and originally intended as an alternative to Moire Topography and the phase-shifting technique [1,2].  However, this method was ineffective at analyzing closed fringe patterns.  A revision to the method, solved this problem by utilizing a Cartesian to polar coordinate transform [3].  The result of which could then be analyzed using the original method proposed.

The revised Fourier Analysis method does have several limitations.  The first requirement is that the "measurement wave front be a monotonic function in the direction of the carrier frequency" [3].  This amounts to the phase of the [[Image:mexicanhat.jpg|thumb|A "Mexican Hat" function. (courtesy of [http://www.vector.org.uk/archive/v194/finn194.htm])]]  

[[Image:mexicanhat.jpg|thumb|A "Mexican Hat" function. (courtesy of [http://www.vector.org.uk/archive/v194/finn194.htm])]]

 

* requires carrier frequency, narrow frequency, low noise and open fringes

* requires carrier frequency, narrow frequency, low noise and open fringes