A.A. Tagliaferri

Precision small angle measurements with a digital moiré technique

A method to measure the rotation angle of structures is presented. The method is based on the projection digital moire technique, but instead of using a projection system we make use of the Talbot (self-imaging) phenomenon in order to produce the grating on the surface.

Photorefractive optical holographic correlation using a Bi12TiO20 crystal at λ=0.633 μm

Abstract This paper reports real time optical holographic correlation using the Bi 12 TiO 20 photorefractive crystal at λ=0.633 μm. The experiments were performed in the diffusion-only Bragg regime operation and are based on the anisotropic self-diffraction properties of the photorefractive material. The performance of the developed correlator is evaluated by means of the SNR concept. This system is simple and easy to control. The material employed here has high sensitivity and spatial resolution at low power HeNe laser light source illumination.

Holographic image degradation produced by mechanical stress in the photorefractive crystal

Abstract In this work we show the real time holographic image degradation produced by mechanical stress applied to a cubic photorefractive crystal of the sillenite family. The observations were performed in a diffusion only recording mechanisms in the photorefractive crystal Bi 12 TiO 20 illuminated by λ =0.633 μ m from a He–Ne laser light source. Our results can be easily extended to all BSO-type crystals where the continuous image reconstruction exploits the anisotropic diffraction.

Dynamic moiré patterns produced by sinusoidal gratings superposition in the Bi12 TiO20 crystal

Abstract In the present note a real-time holographic moire-like pattern is shown. It is produced by the superposition of two rotated sinusoidal phase gratings and the result represents a promising technique for possible metrological applications. The experiments were performed in a diffusion-only recording mechanism in a photorefractive Bi 12 TiO 20 crystal illuminated by λ = 0.633 μm from a HeNe laser light source.

Experimental evidence of the non-exponential sinusoidal phase grating decay in a BSO-type crystal

Abstract In this research note experimental evidence is reported in which the sinusoidal phase grating decay, written in the photorefractive crystal Bi 12 TiO 20 at λ = 0.633 μ m from HeNe laser light source illumination, is shown not to be exponential—as has been published and well accepted in the literature on this type of photorefractive material. Some questions relating to the experimental observations are pointed out and briefly discussed.

Real-time holographic polarization fringes for stress and strain analysis

In this work we show a real time holographic polariscope. The new system is based on the dynamic anisotropic diffraction properties that happen in cubic photorefractive crystals of the sillenite family. This result represents a promising technique for possible mechanical strain and stress analysis for scientific and technical applications. The observations about the performance and the behavior of the proposed system was made in diffusion only recording mechanism in the photorefractive crystal Bi12TiO20 illuminated by (lambda) equals 0.633 micrometers from a He-Ne laser light source.

Double matched filtering using the photorefractive Bi12TiO20 crystal at λ = 0.633 μm

In the present paper a double correlator system is proposed. This double Vander Lugt correlation system uses both dynamic photorefractive and a slow complementary holographic processing. The system shows a good discrimination capacity and employs only one bulk photorefractive sample, the Bi12TiO20 crystal at (lambda) equals 0.633 micrometers , in diffusion-only recording mechanism.

Spatial filtering and optical holographic correlation degree in a Bi12TiO20 crystal

The real time holographic correlation process was controlled and analyzed by the intentional manipulation of the intensity ratio between the writing beams in the Fourier hologram formation of an image. In this sense, and optical holographic correlation degree was defined. The experiments were performed in two wave mixing configuration based on the anisotropic self-diffraction properties of the Bi12TiO20 crystal. The correlator system was operated in the diffusion-only Bragg condition, under low power HeNe laser light illumination.

2-D color image transmission through optical fibers

Abstract A new pure optical system that makes it possible to transmit a two-dimensional image and its color is presented. This system uses only one high order diffraction grating and a set of silica multimode fibers. A good color (seven components per pixel) and image quality is achieved.

2-D Colour Image Transmission Through Optical Fibers

The transmission of a 2-0 coloured image (i.e. a 3-0 information), through an optical fiber, needs a process of codification in order to adapt the signal to be transmitted to the channel of transmission. This codification can be done in real time, by pure optical means, using the process of chromatic codification.