Fringe Projection and Interferometry are non-contact optical metrology techniques. Their use is varied, but includes optical component manufacturing, instrumentation, machine vision, reverse engineering and surface inspection for tribology. Both of them obtain measurements from the sampled area simultaneously, in contrast to stylus driven contact profilometers that obtain one measurement at a time.
Fringe Projection uses the projection of a reference pattern over an object, this is captured by means of a camera whose perspective is different to the projector's. This makes the fringe pattern distort in accordance to the objects surface. Measurements are extracted using the difference between the reference (projected) pattern and the detected distorted pattern as its basis. This technique has seen wide spread use, in great part due to the diversity of its components.
Interferometric techniques obtain measurement using the interference of two waves, optical waves being the most common. Interferometry may be used in optical surface measurement, wafer fabrication, airplane instrumentation, astronomy, etc. It offers fast measurements the order of a wavelength, but usually requires very stringent operating conditions.
I was a research assistant on “3 Dimensional Profilometry of Objects by Optical Means” for two years. This research was done under the supervision of PhD Adriana Nava Vega at the “Universidad Autónoma de Baja California” with the collaboration the “Instituto de Astronomía de la UNAM en Ensenada”. During which I received a research scholarship. I collected information and implemented several algorithms, methods and programs. I also collaborated in the establishment of the Photo-Dynamics laboratory in the Faculty of Chemical Sciences and Engineering at the UABC including the Fringe Projection system setup. And finally have developed a manual for these programs and am applying some revisions of my thesis which is based on work done during this research and whose directors are the researchers with whom I was involved during this research.
This is the first chapter of my 300 page document. It contains a brief overview of Fringe Projection, Interferometry, The Phase Detection process and experiments performed. The complete document covers many aspects of Fringe Projection, Interferometry, the Theory behind implemented algorithms and compares two implementations of this algorithm to four others in a set of numerical and physical experiments. It was presented in Spanish in October 2009, the English translation was complete a few days after presentation.
An algorithm based on Schwiders Asynchronous algorithm was developed for spatial Fringe Pattern Analysis. This algorithm is similar to Carré's Asynchronous algorithm when used for spatial carrier Analysis.
An implementation of Womack's algorithm is shown. The method itself is explained and results for this and other similar algorithms are presented.
