Oliverio D.D. Soares

Fractional Fourier transforms and optical systems

Abstract Fractional Fourier transforms of an arbitrary degree can be implemented by refractive lenses. Perfect imaging systems and correlators may be implemented by cascading fractional Fourier transformer units of the same family and fractional degree.

Evaluation of the focal distance of a lens by Talbot interferometry

A simple and precise technique, based on Talbot interferometry, of measuring the focal distance of a simple lens or a compound lens system is described. To establish the foundations of the technique, properties of selfimages in free space and of their images, when formed by a lens, are first examined and experimentally demonstrated.

Hole–electron competition with fast and slow gratings in Bi 12 SiO 20 crystals

Two samples of nominally pure Bi(12)SiO(20) show distinct behavior in experiments of diffraction efficiency kinetics, and two-beam coupling. The results can be understood by the presence of fast and slow gratings due to electrons and holes.

Cylindrical hologram of 360° field of view

The recording of a 3-D object is greatly improved when it is possible to view the object and image from many directions. A simple apparatus is described for constructing and observing cylindrical holograms of 360 degrees field of view with a minimum of effort and expense. The recording is essentially a known technique but some improvements have been introduced. To view the image a new technique was considered where all the light of the laser beam or incoherent source is directed to the cylindrical hologram by means of an easily assembled scanner, while the recording geometry is reproduced. Good holograms are made with bright, undistorted, free of shadows, and unblurred images. This hologram viewer should prove useful for many display applications.

Holographic Coupler For Fiber Optics

The analysis and demonstration of a holographic coupler for single-mode optical fibers and cables is discussed. The holographic coupler is composed of two holographic windows. The holographic window is rigidly attached to the cable end. The coupling between windows proceeds by means of plane waves. The tolerances for some of the critical coupler parameters are relaxed, namely transverse alignment. Precision work is restricted to the factory produc-tion, but of simple implementation. The result is a coupler with relatively undemanding assembly operations in the field.

Applied Laser Tooling

Laser technologies are credited as one of the essential components of present pattern of the industrial competitive transmutation. Companies to respond with flexibility and efficiency are led to the technological combination of Laser, Robots and Optical Fiber systems to increase competitiveness through high productivity, innovation and quality assurance. Industrial and economical relevant aspects of the Laser era are dealt with while emphasizing the Laser processing of metallic and non- metallic materials, microelectronics fabrication and processing of semiconductors.

Dynamics of Innovation

Dynamic aspects of the innovation process are reviewed. The culture of innovation is emphasised while the concept of a networking environment is proposed to respond to the practices of integration of technologies in the innovative procedures.

Surface inspection via projection interferometry.

Projection fringe interferometry provides a useful technique for nondestructive surface analysis. Two beam interferometric fringes were projected onto a block of aluminum whose surface had various types of grooves cut into it. The fringes were digitized and analyzed via an automatic fringe tracking algorithm. Three-dimensional topographical maps of the surfaces microstructure are presented together with a statistical analysis of surface parameters including average roughness, height distributions, and the autocorrelation function.

Spectrocolorimetric control of ancient documents postablation with excimer lasers

The application of excimer lasers in ablation, cleaning, and restoration for the recovery of paper and parchment manuscripts is a recently implemented technique. A report of the use of excimer lasers in a cleaning process by which mud was removed from Islamic papers and parchments is presented. It was found that, because of the close proximity of the binding energies of paper to paper and of paper to mud, it was difficult to maintain control of the ablation process. However, the substrate was not affected. Spectrocolorimetry was used as a technique to detect the effects of ablation on cleaned areas of the manuscripts in terms of change in color appearance and severity of aging postablation. The analysis was performed by comparison of treated and untreated areas. Mathematical modeling was developed to define a representative original color and a color-distribution parameter. Improvements in the measuring method were made to yield the required precision for evaluating differences in color produced by laser ablation and to follow the color evolution after ablation. Results show that the effects of restoration, aging, and the environmental conditions can be individually identified under certain conditions. The method has applications in other domains.

Trends in Optical Fibre Metrology and Standards

Trends on optical fibre technologies look very promising in terms of monetary market and technical advances. The maturing of the present and foreseen potential will rely on an adequate response in optical fibre measurements, metrology, standards and instrumentation. Key aspects of this evolutionary cycle, in which an important share of the investment goes in metrological activity are described stressing the exigencies brought by exploiting technical breakthroughs.