Search results for "Optical engineering"
showing 10 items of 42 documents
Dimensional control of metallic objects by artificial vision: contribution to lighting condition studies
1999
We present an original method that enables real time automatic dimensional control of defects on metallic objects. The method is based on the theoretical and experimental study of light reflection mechanisms that can be seen as a function of the surface roughness and of the light source size. We show that it is possible to reconstruct the profile of an object from a single gray level image. An industrial application enables us to validate our results. Finally, an error computation fixes the limits of our method and enables us to better understand illumination problems.
<title>Holographic recording of subwavelength structures in amorphous chalcogenide thin films</title>
2005
Holographic recording of surface-relief and refiactive-index-modulated gratings with a period ranging from 0.15 to 1 μm in thin amorphous chalcogenide films of As-S-Se and As2S3 is studied. The profile of the surface-relief gratings is measured by atomic force microscopy. By structuring the As-S-Se films with the subwavelength-period surface-relief gratings their reflectivity is decreased from 25-30% to less than 2%. In the refractive-index-modulated As2S3 films polarization effects are revealed. It is shown that the angular selectivity of the holographic recording in amorphous chalcogenide thin films can be substantially improved by decreasing the grating period.© (2005) COPYRIGHT SPIE--Th…
<title>Application of amorphous chalcogenide thin films in optical recording technologies</title>
2005
A review of the recent advances and developments in the practical application of amorphous chalcogenide materials is presented, focusing special attention to holography and lithography. The main functional principles and practical application of amorphous chalcogenide photoresists for production of the embossed rainbow holograms and holographic optical elements are discussed. The laser interference lithography can be used as a low-cost method for the exposure of large surfaces with regular patterns like subwavelength-gratings and microsieves. The surface-relief and reftactive-index modulated gratings with a period of about 50 nm and less can be fabricated by immersion holographic method. Th…
<title>Structure-relaxation-induced peculiarities of the holographic recording in amorphous As<formula><inf><roman>2</roma…
1997
The results of the experimental study of holographic recording in a-As2S3 films are reported such as exposure and intensity dependencies, spatial frequency dependence. Several peculiarities are found including recording intensity threshold, nonmonotonical intensity dependencies, nonlinear exposure curves, the change of the spatial frequency response due to films aging. These peculiarities are explained in terms of phenomenological model which is based on the simultaneous action of the photostructural changes and the relaxational structural changes.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
<title>Use of AlN ceramics in ultraviolet radiation dosimetry</title>
2003
AlN-Y2O3 ceramics is studied as a material for application in the area of ultraviolet radiation (UVR) dosimetry. The properties of optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL) revealed by AlN ceramics are characterized and considered for practical application. A special attention is devoted to studies of the spectral properties of the material, including stimulated luminescence. Spectral properties of the material make it potentially suitable for dosimetric application both in UV-C region (200-290 nm), where it has the maximum sensitivity, and in UV-B+UV-A (290-350 nm) region, where the spectral behavior of its sensitivity coincides rather well with tha…
<title>Relief holographic recording in amorphous As-S-Se</title>
2003
The relief-phase holographic gratings in amorphous As-S-Se thin films were recorded and studied. The holographic recording was performed by He-Ne laser (0.6328 μm). The influence of etching and cohernet self-enhancement processes on the formation of surface relief in amorphous As-S-Se thin films was studied.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The influence of laser beam-width and focusing angle about the precision of cutting metallic materials
2005
To realize a high precision cutting operation, we must know the position and pointing of the beam axis- which are defined in accordance with ISO, by the centers of gravity of energy density distributions at different distances from the exit lens of laser. The angle of focalization must be related at least with; material width, beam energy, cutting speed, precision requirements and workpiece destination. Authors have realized experimental set-up for simultaneous measurement of energy density distributions, correlated with the mentioned working parameters. Besides the geometrical details, the authors studied also the influence of different values of beam density, about the zone affected by he…
Micro-optical components for parallel optical networks
2002
Key components for parallel optical links are fabricated cost-effectively using LIGA technology. Multifiber ferrules and mechanical splices, 1/spl times/2 and 4/spl times/4 single-mode matrix switches and micro lens arrays with passive alignment structures are presented.
<title>Reaction-diffusion electrical network for image processing</title>
2006
We consider an experimental setup, modelling the FitzHugh-Nagumo equation without recovery term and composed of a 1D nonlinear electrical network made up of discrete bistable cells, resistively coupled. In the first place, we study the propagation of topological fronts in the continuum limit, then in more discrete case. We propose to apply these results to the domain of signal processing. We show that erosion and dilation of a binary signal, can be obtained. Finally, we extend the study to 2D lattices and show that it can be of great interest in image processing techniques.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted fo…
Safety uses of optical fiber communication systems
2005
The paper is focused on problems of optical radiation, which occurs in systems and devices of optical fiber communications, during their usual exploitation, and in breakage situations. Mainly in aspects of open (possible to disconnect) fiber optic optical system and/or accidental affection of electromagnetic radiation (in visible and infrared spectrum) on human being. Considerations about safeness of using fiber optical systems and devices were examined on the basis of directions and obligatory standards or propositions of changing them as results of newest research.