Showing papers by "José A. Ferrari published in 2007"
TL;DR: In this article, a beam-splitter cube is used to produce two interferograms with a relative phase shift of π (rad) for spatial-carrier interferometry and flexible writing of fiber Bragg gratings.
43 citations
TL;DR: In this paper, the authors proposed a new method for phase retrieval in an interferogram with a spatial linear carrier, which does not require sophisticated data-processing and is computationally efficient.
18 citations
TL;DR: In this paper, the polarization-to-phase conversion of space-variant polarized light waves was investigated and it was shown that using an azimuthally and radially variant polarizer combined with a circular analyzer, it is possible to induce spinto-orbital angular momentum exchange and to generate optical vortices of arbitrary charge.
Abstract: We investigate the polarization-to-phase conversion of space-variant polarized light waves. Our analysis can be considered as an extension of Pancharatnam's phase to the case of space-variant polarization. In two particular cases - azimuthally and radially variant polarization - we found striking consequences. Using an azimuthally variant polarizer combined with a circular analyzer, it is possible to induce spin-to-orbital angular momentum exchange and to generate optical vortices of arbitrary charge. Radially variant polarizers with linear or quadratic radial dependence of the transmission direction generate nondiffracting beams or focus light, respectively. Our results are potentially relevant for the design of achromatic wavefront forming (and correcting) elements based strictly on space-variant polarization optics.
13 citations
TL;DR: It is demonstrated that, when the zero-order (Fourier) spatial component of the input image is not blocked by the schlieren-knife at the Fourier plane, the intensity distribution on the reconstructed image is a linear function of the phase amplitude.
Abstract: We discuss the schlieren imaging of quasi-sinusoidal phase objects. We demonstrate that, when the zero-order (Fourier) spatial component of the input image is not blocked by the schlieren-knife at the Fourier plane, the intensity distribution on the reconstructed image is a linear function of the phase amplitude. In contrast, if the zero order is completely blocked (i.e., dark Schlieren processing), the intensity distribution on the output image becomes essentially a quadratic function of the phase, and thus a direct phase retrieval is not possible. We discuss the possibility of contrast enhancement and present validation experiments.
13 citations
TL;DR: In this article, the authors demonstrate theoretically and experimentally that the contrast ratio of double-layered cells is larger than the one of a single PDLC film, but in general, it is not the product of the contrast ratios of the individual films, contrary to the result obtained neglecting multiple scattered light.
Abstract: In this article, the light transmission process in single- and double-layered polymer-dispersed liquid-crystal (PDLC) cells and its relevance for contrast ratio calculations have been discussed. Double-layered cells consist of two PDLC films with a common central wall. We demonstrate theoretically and experimentally that the contrast ratio of double-layered cells is larger than the one of a single PDLC film, but in general, it is not the product of the contrast ratios of the individual films, contrary to the result obtained neglecting multiple scattered light. The same result holds for a single film working in reflective mode. Our results may be potentially relevant for display applications.
8 citations
TL;DR: It is demonstrated that when the mask in the processor Fourier plane is an analytical function, it can be described by means of a differential operator that acts directly on the input field to give the processed output image.
Abstract: We present a differential operator approach for Fourier image processing. We demonstrate that when the mask in the processor Fourier plane is an analytical function, it can be described by means of a differential operator that acts directly on the input field to give the processed output image. In many cases (e.g., Schlieren imaging) this approach simplifies the calculations, which usually involve the evaluation of convolution integrals, and gives a new insight into the image-processing procedure.
4 citations
TL;DR: Tay et al. as discussed by the authors proposed a phase extraction method from a single fringe pattern based on a couple of assumptions on the behavior of the fringe pattern, which are closely related to the well-known Fourier transform technique.
2 citations