G. Rodríguez Zurita

Measurement of mean thickness of transparent samples using simultaneous phase shifting interferometry with four interferograms.

In this research a novel interferometric system is reported, which allows the generation of four simultaneous interferograms with phase shifts of π/2. The system consists of three coupled interferometers: a rectangular Sagnac interferometer which generates a primary pattern with crossed circular polarizations, coupled to two Michelson interferometers which operate as a multiplexing system, and generating replicas of the primary pattern. The two coupled Michelson interferometers generate four patterns retaining their polarization properties, which allow independent phase shifts by placing a linear polarizer over each pattern, thereby, four interferograms with relative phase shifts of π/2 are obtained. The optical phase is calculated using the well-known four-step algorithm. With knowledge of the optical phase, different properties of the samples can be calculated or analyzed; in this case, by knowing the mean refractive index, we can calculate the mean thickness of test objects. The results obtained for static transparent samples are presented. The capability of the system to analyze dynamic events is shown when results for the calculation of a temperature field of a heat flow are presented.

Phase Shifting Interferometry Using a Coupled Cyclic Path Interferometers

In this research we implemented a two-step phase shifting system based on two cyclic-path coupled interferometers for slope measurements of transparent samples. The optical system generates two π-shifted interferograms, and the phase shift between interferograms is obtained by rotating a linear polarizer, generating four interferograms with relative π/2-phase shifts; this simplifies the number of phase steps necessary to retrieve the optical phase, since is only necessary perform a shift operating a linear polarizer. The optical phase was processed by a four-step algorithm. In order to present the capabilities of the system, results obtained for slope for transparent structures are presented.