The Experts below are selected from a list of 5289 Experts worldwide ranked by ideXlab platform
Sergio Calixto - One of the best experts on this subject based on the ideXlab platform.
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Mathematical model for the surface relief formation of Photographic Emulsions
Journal of Micro Nanolithography MEMS and MOEMS, 2005Co-Authors: Enrique Navarrete-garcı́a, Sergio CalixtoAbstract:We present a mathematical model of the surface relief formation suffered by Photographic Emulsions when an intensity pattern is recorded. Traditional explanations consider that this relief is due to silver compounds, but mainly to a mass transfer process in presence of tension forces. According to this description, the model considers diffusion and smoothing processes. Main parameters of the model were obtained by fitting simulated profiles to measured profiles for different micro-optical elements. The error between simulated and measured profiles ranged from 2.6% to 7.3%. Results obtained with this model reinforce the hypothesis of the surface relief formation. This model may be useful in numerical simulations of surface relief micro optical elements.
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Continuous surface relief micro-optical elements fabricated on Photographic Emulsions by use of binary and halftone masks
Optical Materials, 2003Co-Authors: Enrique Navarrete-garcı́a, Sergio CalixtoAbstract:We investigated the fabrication of continuous surface relief micro-optical elements, using binary and halftone masks, on Photographic Emulsions. Smoothly varying relieves were obtained recording gray-scale patterns by means of two Photographic techniques. The first one involved the defocused image of a binary mask. In the second technique, a halftone mask printed at high screen frequency was used. The influence of some processing parameters on the formation of the surface relief was studied. The use of suitable values of these parameters permitted to enhance the optical performance of fabricated micro-optical elements. A description of the design, fabrication and test of microlenses, microlens arrays and sinusoidal gratings, is shown. Results are discussed.
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SURFACE RELIEF ZONE PLATES FABRICATED WITH Photographic Emulsions
Applied optics, 1998Co-Authors: Enrique Navarrete-garcı́a, Sergio CalixtoAbstract:The use of Photographic Emulsions as a photoresist medium for fabricating relief blazed zone plates is described. Lithographic methods with masks with 256 gray levels were used in the fabrication process. An example of a zone plate working in the reflection mode at 45° and having 82% diffraction efficiency is shown.
Enrique Navarrete-garcı́a - One of the best experts on this subject based on the ideXlab platform.
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Mathematical model for the surface relief formation of Photographic Emulsions
Journal of Micro Nanolithography MEMS and MOEMS, 2005Co-Authors: Enrique Navarrete-garcı́a, Sergio CalixtoAbstract:We present a mathematical model of the surface relief formation suffered by Photographic Emulsions when an intensity pattern is recorded. Traditional explanations consider that this relief is due to silver compounds, but mainly to a mass transfer process in presence of tension forces. According to this description, the model considers diffusion and smoothing processes. Main parameters of the model were obtained by fitting simulated profiles to measured profiles for different micro-optical elements. The error between simulated and measured profiles ranged from 2.6% to 7.3%. Results obtained with this model reinforce the hypothesis of the surface relief formation. This model may be useful in numerical simulations of surface relief micro optical elements.
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Continuous surface relief micro-optical elements fabricated on Photographic Emulsions by use of binary and halftone masks
Optical Materials, 2003Co-Authors: Enrique Navarrete-garcı́a, Sergio CalixtoAbstract:We investigated the fabrication of continuous surface relief micro-optical elements, using binary and halftone masks, on Photographic Emulsions. Smoothly varying relieves were obtained recording gray-scale patterns by means of two Photographic techniques. The first one involved the defocused image of a binary mask. In the second technique, a halftone mask printed at high screen frequency was used. The influence of some processing parameters on the formation of the surface relief was studied. The use of suitable values of these parameters permitted to enhance the optical performance of fabricated micro-optical elements. A description of the design, fabrication and test of microlenses, microlens arrays and sinusoidal gratings, is shown. Results are discussed.
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SURFACE RELIEF ZONE PLATES FABRICATED WITH Photographic Emulsions
Applied optics, 1998Co-Authors: Enrique Navarrete-garcı́a, Sergio CalixtoAbstract:The use of Photographic Emulsions as a photoresist medium for fabricating relief blazed zone plates is described. Lithographic methods with masks with 256 gray levels were used in the fabrication process. An example of a zone plate working in the reflection mode at 45° and having 82% diffraction efficiency is shown.
Samir Farid - One of the best experts on this subject based on the ideXlab platform.
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New Approach to Silver Halide Photography Using Radical Cation Chemistry
Pure and Applied Chemistry, 2012Co-Authors: Ian R. Gould, Jerome R. Lenhard, Annabel A. Muenter, Stephen A. Godleski, Samir FaridAbstract:A new mechanism for spectral sensitization of silver halide is described, which can potentially double the sensitivity of Photographic Emulsions. The photooxidized sensitizing dye is trapped using an organic donor molecule, which fragments to form a cation and a reducing radical, which injects an electron into the conduction band of the silver halide. In this way, two conduction-band electrons can be produced for each absorbed photon.
Nina M. Ganzherli - One of the best experts on this subject based on the ideXlab platform.
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the effect of short wave uv radiation in recording holographic structures on gelatin containing recording media overview
Optics and Spectroscopy, 2018Co-Authors: Nina M. Ganzherli, S. N. Gulyaev, I A MaurerAbstract:The review discusses the possibility of obtaining highly effective relief-phase structures on silver halide Photographic Emulsions and dichromated gelatin layers by irradiating initially recorded holographic structures with short-wave UV radiation.
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Phase recording for formation of holographic optical elements on silver-halide Photographic Emulsions
Holography: Advances and Modern Trends, 2009Co-Authors: Nina M. Ganzherli, S. N. Gulyaev, Irina A. Maurer, D. F. ChernykhAbstract:Holographic fabrication methods of regular and nonregular relief-phase structures on silver-halide Photographic Emulsions are considered. Methods of gelatin photodestruction under short-wave ultra-violet radiation and chemical hardening with the help of dichromated solutions were used as a technique for surface relief formation. The developed techniques permitted us to study specimens of holographic diffusers and microlens rasters with small absorption and high light efficiency.
Klaus G Heumann - One of the best experts on this subject based on the ideXlab platform.
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determination of ruthenium in Photographic Emulsions development and comparison of different sample treatments and mass spectrometric methods
Fresenius Journal of Analytical Chemistry, 1999Co-Authors: Petra Krystek, Klaus G HeumannAbstract:Different sample treatment procedures were combined with inductively coupled plasma mass spectrometry (ICP-MS) and negative thermal ionisation mass spectrometry (NTI-MS) for the determination of ruthenium traces in Photographic Emulsions. Dissolution of the samples in concentrated ammonia solution was used in connection with ICP-MS by external calibration, which has the advantage of a simple sample preparation technique but introduces high amounts of the silver matrix into the mass spectrometer. On the other hand, isotope dilution mass spectrometry (IDMS) with an enriched 99Ru spike solution was applied for ICP-MS and NTI-MS measurements, respectively, in connection with a significant reduction of the matrix by AgCl precipitation. In these cases loss of ruthenium by the AgCl precipitate has no effect on the analytical result. The results of the different methods agreed usually well analysing ruthenium traces in the range of 0.1–10 μg per gram emulsion. The detection limits obtained were 4 ng/g for ICP-IDMS, 20 ng/g for NTI-IDMS, and 15 ng/g for ICP-MS with external calibration. Differences in the results between the different methods could mainly be attributed to sample inhomogeneities. ICP-IDMS with silver matrix reduction by AgCl precipitation is recommended as a routine method, NTI-IDMS with the corresponding sample treatment as a calibration method.
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development of accurate mass spectrometric routine and reference methods for the determination of trace amounts of iridium and rhodium in Photographic Emulsions
Journal of Analytical Atomic Spectrometry, 1999Co-Authors: Petra Krystek, Klaus G HeumannAbstract:For the determination of trace amounts of iridium and rhodium in Photographic Emulsions different sample treatment procedures were coupled with inductively coupled plasma mass spectrometry (ICP-MS) and, for iridium, also with negative thermal ionisation isotope dilution mass spectrometry (NTI-IDMS) and ICP-IDMS. IDMS determinations of iridium were carried out using an enriched 191 Ir spike solution. Elimination of the silver matrix was established for both mass spectrometric methods, which prevents corresponding memory effects in the ICP-MS system and is essential for the formation of IrO 2 – thermal ions, respectively. For NTI-MS measurements, the gelatine matrix of the emulsion must also be eliminated by decomposition with HNO 3 -H 2 O 2 . The detection limits for ICP-IDMS and NTI-IDMS are 0.1 and 10 ng iridium per gram of emulsion, respectively, so that all relevant Photographic Emulsions, doped with iridium, could be analysed. ICP-IDMS with silver matrix elimination is recommended as a routine method, while NTI-IDMS can be applied as an accurate reference method. Determinations of the mono-isotopic element rhodium cannot be carried out by IDMS. Photographic Emulsions were therefore first dissolved in concentrated ammonia solution and rhodium was then directly measured by ICP-MS after dilution of the solution using an internal indium standard for calibration. This procedure has the advantage of a simple sample preparation technique but introduces high amounts of silver into the mass spectrometer and dilution of the sample restricts the detection limit. Because of the similar chemical and physical behaviour of Ru and Rh, ruthenium was used as an internal standard during matrix separation and subsequent ICP-MS measurements of trace amounts of rhodium. By determining the 103 Rh/ 99 Ru ratio of the separated sample, reliable results for the determination of trace amounts of rhodium were obtained, which was confirmed by the good agreement between the data obtained by the procedure with internal Ru calibration and those obtained without matrix separation and calibration by indium. The determination of trace amounts of iridium and rhodium in the range 0.5-650 ng g –1 was carried out in Photographic Emulsions with the different methods, which agreed well in their results. The relative standard deviations were usually in the range 3-10% and were substantially influenced by sample inhomogeneities.