Measurement of the dynamic phase profile of transparent fluids

Abstract

This communication describes some details of modulation of polarization which are useful in phaseshifting interferometry applied to the study of transparent samples. As an application, the case of a two-beam phase-grating interferometer is discussed on the grounds of polarization analysis as an example. This system does not require micro-polarizer arrays or special software to isolate external vibrations; it uses a double window, and generates two beams whose separation can be varied according to the characteristics of the grid used. Experimental results are also given.

Phase profile analysis of transparent objects through the use of a two windows interferometer based on a one beam splitter configuration

“…These coefficients C n and C l will modulate the intensity pattern obtained at the image plane [2,3].…”

“…A difference with the systems presented by our groups in Ref. [2] and Ref. [5] is that we used a two-window arrangement with fixed separation, designed in accordance with the grating used and the matching condition x 0 = f/d, where x 0 is the beam separation, d the spatial period and the wavelength of the source.…”

“…mirrors M. Quarter wave plates QL (45) and QR (−45) are placed in each one of the beams respectively, to generate a right circular polarizations in A and left circular polarizations in B. This system is simpler than other arrangements previously presented such as Mach Zehnder interferometer [2] or a common path configuration [3] that have been used to generate a double window.…”

“…The optical arrangement presented is based on principles of polarization phase shifting techniques [1] and grating interferometry [2,3]. A common polarizing optical system uses linear polarizing filters and quarter-wave plates (QWP) to achieve modulation [1], one of the most relevant are the micropolarizers arrays [4] and others authors have proposed an improvements of them using harmonics rejections algorithms or the use of nine shifts [5].…”