Silver halide sensitized gelatin derived from BB-640 holographic emulsion

Silver halide sensitized gelatin (SHSG) is one of the most interesting techniques for the production of holographic optical elements, achieving relatively high sensitivity of photographic material with a low scattering of dichromated gelatin. Here we present experimental results for SHSG derived from the novel BB-640, a red-sensitive ultra-fine-grain emulsion from Holographic Recording Technologies (Steinau, Germany). The material is characterized before recording and after processing, and information about the thickness, absorption, and refractive-index modulation of the final holograms is obtained. The influence of the developer is analyzed, and diffraction efficiencies as great as 96.2% (after allowing for reflections) with a transmission of 1% and absorption and scatter losses of 2.8% are obtained with AAC developer. Our investigations reveal that high-quality SHSG transmission holograms may be obtained with the new BB-640 plates.     

Silver halide sensitized gelatin process effects in holographic lenses recorded on Slavich PFG-01 plates

In this work we study the feasibility of using silver halide sensitized gelatin based on PFG-01 (Slavich) emulsions to construct uniaxial compound lenses. This processing is able to introduce variations in the thickness and refractive index of the emulsion. We prove that these changes are not sufficient to provide the observed variations in Bragg conditions in the reconstruction and that a shear-type effect must exist to explain the performance of processed emulsions. We study the characteristics of a compound lens, obtaining acceptable image quality, good resolution, and the typical field limitation of volume holographic elements.     

Holographic optical elements recorded in silver halide sensitized gelatin emulsions. Part I. Transmission holographic optical elements

Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOE's). The drawback of DCG is its low sensitivity and limited spectral response. Silver halide materials can be processed in such a way that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-high-resolution silver halide emulsions. An optimized processing technique for transmission HOE's recorded in these materials is introduced. Diffraction efficiencies over 90% can be obtained for transmissive diffraction gratings. Understanding the importance of the selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOE's.     

Holographic optical elements recorded in silver halide sensitized gelatin emulsions. Part 2. Reflection holographic optical elements

Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOEs). The drawback of DCG is its low energetic sensitivity and limited spectral response. Silver halide materials can be processed in such away that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-fine-grain silver halide (AgHal) emulsions. In particular, high spatial-frequency fringes associated with HOEs of the reflection type are difficult to construct when SHSG processing methods are employed. Therefore an optimized processing technique for reflection HOEs recorded in the new AgHal materials is introduced. Diffraction efficiencies over 90% can be obtained repeatably for reflection diffraction gratings. Understanding the importance of a selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOEs, also including high-quality display holograms of the reflection type in both monochrome and full color.     

Hypersensitization in reflection holograms recorded in Agfa-Gevaert 8E75HD plates

Abstract

We study the effect of the hypersensitization with sodium sulphite in Agfa-Gevaert 8E75HD holographic plates in reflection holograms. An enhancement of energetic sensitivity and diffraction efficiency is observed with low solvent effects when Agfa-Gevaert 8E75HD are pre-processed. A 2–5 times increase of the sensitivity, together with temporal stability, is observed in reflection holograms.     

Non-hydroscopic vanilla doped dichromated gelatin holographic material

Dichromate gelatins are well-known holographic materials. By doping this material with synthetic vanilla a change in the spectral response from regular dichromate gelatin is observed as an increase in optical density. This mixture presents an unusual high humidity resistance. It was possible to record holographic diffraction gratings using an argon ion laser (λ=488 nm). These gratings exhibit good diffraction efficiency in transmission, on the order of 60% at Bragg angle, with more than 1700 lines/mm spatial resolution. The material development process consists simply of dipping it into using a solution of water and isopropyl alcohol. A hypothesis on the hydroscopic response of this new photosensitive material is also presented.     

Self-enhancement of holographic gratings in dichromated gelatin and polyvinyl alcohol films

New experimental results concerning real-time hologram recording in dichromated sensitized gelatin and polyvinyl alcohol are presented. Self-enhancement of the holographic gratings observed in the dark in both of these dye-polymer systems is shown.     

Holographic diffuser by use of a silver halide sensitized gelatin process

Diffusers play an important role in liquid crystal display (LCD) application as a beam-shaping device, a brightness homogenizer, a light-Scattering device, and an imaging screen. The transmittance and diffusing angle of the diffusers are the critical aspects for the applications to the LCD. The holographic diffusers by use of various processing methods have been investigated. The diffusing characteristics of different diffusing materials and processing methods have been evaluated and compared. The microstructures of holographic diffuse have been investigated by use of using scanning electron microscopy. The holographic diffusers by use of the silver halide sensitized gelatin (SHSG) method have the structural merits for the improvement of the quality of diffusers. The features of holographic diffuser were exceptional in terms of transmittance and diffusing angle. The replication method by use of the SHSG process can be directly used for the manufacturing of diffusers for the display application.     

Silver halide sensitized gelatin holograms in Slavich PFG-01 red-sensitive emulsion

Abstract

Silver halide sensitized gelatin (SHSG) is an interesting technique for the production of holographic optical elements. It combines the high sensitivity of photographic emulsions with the well-known low scattering and high diffraction efficiency corresponding to dichromated gelatin. In this paper we describe SHSG holograms recorded on Slavich PFG-01 emulsions. We will show that real high diffraction efficiencies can be obtained (as high as 93% allowing for reflections) when using this material for recording phase transmission holograms. The influence of the bleach bath temperature and a hardening bath in the processing was studied and the procedure was optimized for these two parameters. Our investigations reveal that PFG-01 emulsion is not only a substitute for Agfa material, but also offers better results, at a moment in which Agfa has stopped its production of holographic material.     

High-sensitivity measurements for formation of holographic interferograms of wedge-shaped plates

It is shown how to increase the sensitivity of wedge angle measurements by means of the formation of holographic interferograms. The sensitivity can be improved by increasing the number of interference fringes in the interference patterns formed during the optical processing of a pair of holograms of a wedgeshaped plate. The proposed method has been experimentally verified.     

Properties of microlenses produced on a layer of tot'hema and eosin sensitized gelatin

Gelatin sensitized with tot'hema and eosin (compounds used in medical therapy) appears to be an excellent material for microlens fabrication. Lenses are produced by irradiation with a 532 nm laser beam. Aspheric concave lenses are formed rapidly with low power radiation. The lens profile is analyzed, as well as imaging properties. Physics of lens formation is also proposed. All material constituents are nonpoisonous, resulting in an environmentally safe, low toxicity material.     

Methylene blue sensitized poly(methyl methacrylate) matrix: a novel holographic material

Methylene blue sensitized poly(methyl methacrylate) is shown to be an efficient medium for recording three-dimensional holographic gratings. Phase and/or amplitude holograms can be written in the methylene blue sensitized films of poly(methyl methacrylate) with a conventional source of light, a He-Ne laser operating at 632.8 nm. Diffraction efficiencies of 60% were found for thick holograms. Multiple holograms were recorded in the described system, and an optical erasing of holograms was achieved. Hologram recording speed was found to increase with temperature.     

Hybrid process of latent image formation in silver halide sensitized gelatin: differential hardening with microvoids

Renewed interest has been shown in the hybrid silver halide sensitized gelatin processes owing to the appearance of new photographic materials. In this study we show the possible compatibility between the models of latent image formation proposed prior to the existence of these new materials, bearing in mind that the refractive-index modulation and its curve of spectral response should be the figures of merit for optimization of the processes of transmission and reflection hologram formation.     

Study of the pH dependence of diffraction efficiency of phase holograms in dye sensitized dichromated gelatin

Dichromated gelatin is thought to be a good substitute for photographic emulsions in some uses. The results of a systematic study of the effect of the pH of the developer on the diffraction efficiency of volume holographic gratings recorded in dye sensitized dichromated gelatin are presented.     

Dissolution shapes ofY-rotated quartz plates andY sections derived from the polar diagram of the dissolution slowness

A study has been made of the rate at which variousY-rotated quartz plates are etched in a concentrated ammonium bifluoride solution. The changes in the surface texture of these differently oriented plates on repeated etching are systematically investigated. To obtain all the information needed for an analysis of the dissolution shapes in the framework of the tensorial representation of the dissolution slowness the profile graph of a deeply etchedY-cut plate is also reported. The polar diagramL _xz (θ) of the dissolution slowness associated with theY-rotated quartz plates is then derived using profile graph data. Numerical and graphical simulations of the dissolution shapes are used to verify the adequation of the lawL _xz (θ). The comparison of the theoretical etch profiles with the Z" etch profiles produced by repeated etching on someY-rotated quartz plates shows complete agreement. Excellent agreement is also found between the theoretical and experimental shapes of the magnified profile graph related to deeply etchedY sections. From the consistency between the observed dissolution shapes and the computed shapes deduced from the tensorial analysis of the dissolution we can conclude that the proposed polar diagramL _xz (θ) represents accurately the variations of the dissolution slowness with the angle θ in theXZ plane.     

Second-harmonic diffraction from holographic volume grating

The full polarization property of holographic volume-grating enhanced second-harmonic diffraction (SHD) is investigated theoretically. The nonlinear coefficient is derived from a simple atomic model of the material. By using a simple volume-grating model, the SHD fields and Mueller matrices are first derived. The SHD phase-mismatching effect for a thick sample is analytically investigated. This theory is justified by fitting with published experimental SHD data of thin-film samples. The SHD of an existing polymethyl methacrylate (PMMA) holographic 2-mm-thick volume-grating sample is investigated. This sample has two strong coupling linear diffraction peaks and five SHD peaks. The splitting of SHD peaks is due to the phase-mismatching effect. The detector sensitivity and laser power needed to measure these peak signals are quantitatively estimated.     

Improving the holographic sensitivity of dichromated gelatin in the blue-green part of the spectrum by sensitization with xanthene dyes

The holographic properties of dichromated gelatin (DCG) sensitized with various xanthene dyes were studied, and results are reported. The sensitivity of dyed DCG in the green part of the spectrum compared with that of pure DCG (215 mJ/cm(2)) was significantly improved by addition of Rhodamine 6G (140 mJ/cm(2)) or Erythrosin B (90 mJ/cm(2)). Diffraction gratings were recorded with a He-Ne laser at 543.5 nm. The maximum diffraction efficiency was found to be 32% at normal incidence of the readout beam; it was 80% at the Bragg angle.     

X-ray diffraction study of the effect of photohardening on the structure of self-developing dichromated gelatin sensitized with Methylene Blue

Peculiarities of the structural organization of self-developing emulsion layers based on dichromated gelatin sensitized with Methylene Blue dye and containing 76% water have been studied by X-ray diffraction. The diffraction patterns I(2θ) of the photolayers are presented. The scattering functions of the amorphous state have been calculated. Differences between the photolayer structures in the exposed and unexposed state are considered. It is shown that recording an image leads to ordering of the photolayer structure that is related to changes in the conformations of gelatin macromolecules.