Francisco F. Medina-Estrada

Numerical blur-up criterion in speckle patterns

It is widely known that both the speckle pattern generated by the axial movement of a rigid diffuser surface, as well as the speckle pattern registered with low resolution, present blur-up. In the first case a blur-up criterion was proposed and applied to the study of vibrations. The statistical and optical properties of dynamic diffusers are also well modeled and well known. This paper proposes a numerical criterion to determine the blur-up of the speckle pattern resulting from superposition patterns generated by dynamic diffusers. Its application is illustrated in the analysis of the Brownian motion of colloidal particles.

Interference and diffraction effects generated by multiple apertures

The effects of interference and diffraction produced by a bidimensional structure composed of multiple and identical apertures are studied. The apertures have different shapes, sizes and spatial distribution. Such effects are competitive during the propagation, that is, in some planes the interference effects are more visible, while in others prevail the diffraction ones.

Distinguishing fine details by Fresnel domain diffraction

The capability of distinguishing fine details in simple structures by means of Fresnel domain diffraction is shown. Through numerical simulations it is shown that the bigger Fresnels number in the diffraction considered the bigger differentiability is reached. A circular clear aperture with two fine details is employed for illustrating.

Fresnel and Fraunhofer domains in diffraction of spatially partially coherent fields

We propose a criterion for distinguishing between Fresnel and Fraunhofer diffraction of optical fields in any state of spatial coherence.

Classes of source pairs and etendue renormalization in interference and diffraction

The power spectrum of a diffracted optical field is expanded as the superposition of Young interference patterns produced by all source pairs in the diffracting aperture. It shows clearly that the power spectrum can take negative values for some types of spatially partially coherent optical fields. A renormalization of the definition of the power spectrum based on the etendue is introduced to properly overcome this fact.

Phase retrieval of gratings by applying Fourier analysis

The phase distribution of regular gratings can be determined by Fourier analyzing the Fraunhofer interference pattern it produces under spatially coherent illumination.

Tubular structures of diffracted fields

The optical field diffracted through a simple circular aperture can produce optical tubular structures single-closed of twice-closed by choosing the suitable experimental conditions. An important characteristic of such structures on this way generated is that they have strong intensity gradients at their edges, making them appropriate structures for optical trapping of particles.

M2 invariance through the etendue for gaussian Schell model sources

Taking advantage of the relationship of the M2 factor for Gaussian Schell model sources on terms of the global coherence parameter, derive for Santansiero et al. in Reference 1, we have shown on this paper the invariance of the M2 factor through its connection with geometrical Etendue of the pencil. This invariance have been shown for each independent coordinate.

Spatial coherence beams in the far field

Spatial coherence of optical fields can be considered as beam structured if the size of the coherence patch varies slowly through the propagation of the optical field. As a consequence, the correlation of the optical field will be concentrated in a finite region around the direction of propagation. For properly describing it in the Fraunhofer-Fresnel domain, the marginal cross-spectral density is introduced. The superposition of spatial coherence beams in this domain is also analyzed. It produces an interference field and a spatial coherence Moire.

Partially coherent effects in Young-Michelson's interferograms

Youngs interferograms with high visibility reveals a high degree of spatial coherence. However, effects due spatially partial coherence can be observed when a Youngs interference pattern interferes itself through a compensated Michelsons interferometer, which is attached at the exit of the Youngs slit pair, as we show in this paper.