Photosensitive Plates Research Articles

Death, Decay, and the Daguerreotype's Influence on “The Black Cat”

Abstract In “The Black Cat,” Poe's narrator discovers an odd pictorial representation of a crime he just committed. An “impression” of the cat he killed appears with astonishing accuracy—even the rope around the animal's neck—on his bedroom wall. This portrait resembles a daguerreotype in its placement, its durability, its verisimilitude, and its effect on viewers. The narrator's explanation for how it was produced alludes, moreover, to Louis-Jacques-Mandé Daguerre's pioneering technique for developing images on photosensitive plates that have been exposed in a camera obscura. Indeed, “The Black Cat” grotesquely parodies each step in Daguerre's procedure, as Poe himself depicted it in his initial essay on “The Daguerreotype.” The proliferating forms, figures, and facsimiles of the black cat—including how the story's second half recapitulates the first—recall other aspects of daguerreotypes, such as their print reproduction and their use in postmortem portraiture. Although the processes described in this story clearly suggest daguerreotypy, they produce different results. “The Black Cat” reflects not only Poe's familiarity with early photography but also his awareness of techniques for resisting or assisting decomposition, as explained by chemists like Humphry Davy, Justus von Liebig, and Alexander Petzholdt. Whereas early photography provided a means to preserve optical reflections—including those of family members who have died—Poe's narrator attempts to abolish such traces of the past. By modeling the macabre processes that the narrator describes on Daguerre's technique for developing latent photographic images, Poe's horror story transforms the very nature of the daguerreotype portrait to emphasize not preservation, but decay.

Fractal processing for an analysis of the quality and resistivity of large semiconductor plates

AbstractA nondestructive method is suggested for the analysis of the quality and resistivity inhomogeneity of semiconductor plates in an ionization system with a SI GaAs semiconductor plate. At the same time, a device for rapid visualization and recording the resistance inhomogeneity and photoconductivity distribution throughout the bulk material in high‐resistivity and photosensitive semiconductor plates of large diameter (50‐100 mm) is described. Semiconductor plates with the resistivity from 105 to 109 Ωcm can be analyzed in the proposed device. The possibilities of the device have been evaluated, i.e. a relative change of the resistance inhomogeneity is determined by a relative change of discharge light emission intensity when a current is passed through an ionization cell. For the quantitative analysis of quality and resistivity inhomogeneity of semiconductor plates, fractal dimension analysis was used following the records of the discharge light emission intensity. The quality of plates was analyzed using both the profile and spatial distributed light emission intensity data showing the internal inhomogeneity in the semiconductor plate. Thus, by using fractal concept, the surface quality of the high‐resistivity semiconductor plate can be assessed exactly and the size and location of the internal inhomogeneities in the semiconductor plate to be ascertained. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Characterization of Photochemical Reaction in Photosensitive Printing Plates by 13C NMR in the Bulk State and ATR FTIR Spectroscopy

Abstract Photochemical reaction in a flexographic printing plate was characterized. The distribution of photochemical reaction in the direction of thickness was successfully understood by the combination of overall reactivity obtained by 13C NMR measurement and reactivity near the surface obtained by ATR FTIR spectroscopy.

Characterization of Photochemical Reaction in Photosensitive Printing Plates.

Photochemical reaction in three different water-developable flexographic printing plates was characterized. The distribution of photochemical reaction in the direction of thickness was evaluated by utilizing 13C NMR and IR (ATR) measurements, and the results obtained showed that the distribution of reaction as well as the overall reaction in the printing plates depends on the plate compositions. 1H NMR analysis for soxhlet extracts of exposed samples showed that the reactivity of monomers depends on its structure and molecular weight in relating to a specified phase condition of the composition.

Technology Overview on Computer-to-Waterless Plates (CTWP)

Waterless printing represents a specialized printing technology, which offers many economic and environmental benefits for high quality printing. Waterless printing plates reside in the core of this unique printing technology. Recent advancement in computer-to-plate technologies spurred a series of research and development activities in the computer-to-waterless plate (CTWP) area. This paper is intended to review various technical approaches to CTWP. The reviewed CTWP approaches include thermal ablation of silicone covered composite coatings, thermally sensitive contact masks on photosensitive waterless plates, and recently developed non-ablative techniques.

Recording the resistance inhomogeneity in high-resistivity semiconductors plates

A device for recording the resistance inhomogeneity in high-resistivity and photosensitive semiconductor plates of large diameter is described. A measurement of homogeneity is realized by recording the spatial distribution of the gas discharge glow intensity between two transparent electrodes with the plate between them. Plates of GaAs with resistivity of 10 6–10 8 Ωcm, thickness from 0.3 to 1.5 mm and the diameter from 20 to 60 mm have been studied. A gas discharge gap was formed by dielectric separator with thickness from 20 to 80 μm. A discharge has been realized in air at a pressure from 60 to 600 Torr. The possibilities of the proposed device have been evaluated, i.e. a relative change of the resistance inhomogeneity is determined by a relative change of discharge glow intensity the resolution of which is determined by method of its recording. Semiconductor plates with the resistivity from 10 5 to 10 9 Ωcm can be used in the device proposed.

Waterless Lithography Using Traditional Grained or Commercial Photosensitive Plates

The author describes a process that uses silicone rubber instead of gum arabic to reject printing inks. The process eliminates the use of dampening water when printing lithographs and produces extremely stable printing plates. It works with traditional grained plates, as well as photosensitive plates, and traditional lithographic drawing materials can be used.

Computed radiography in neonatal intensive care

The Authors report their experience in the employment of a computerized digital radiographic system in Neonatal Intensive Care. The analog screen-film system is replaced by photosensitive imaging plates, scanned after X-ray exposure by a laser that releases the digital image, which can then be manipulated on computer work-stations. In a period of twelve months about 200 chest-abdomen X-ray examinations in Neonatal Intensive Care have been performed using this method with good technical and diagnostic results. The use of digital radiography in the neonatal area is of high interest: this system produces good quality images, there is a reduction in radiation dose and 'retakes', the system allows selective enhancement of different structures and their magnification.

Malachite green photosensitive plates

An experimental study of the behavior of malachite green sensitized plates was carried out. The transmittance variation of the irradiated plates was taken as a parameter. It has been observed that photoreduction in the malachite green plates is present only when ammonium dichromate is added to the plates. The introduction of external electron donors does not improve the photochemical reaction. It has been determined that malachite green molecules form a weak complex with the dichromate molecules and this complex can only be destroyed photochemically. This effect can explain the limited response of the malachite green dichromated plates.

Screenless Printing Procedures at the U.S. Geological Survey

AbstractThe U.S. Geological Survey has, for many years, been involved in printing photoimages without using conventional halftone screens. The purpose for using screenless printing in photoimage mapmaking has been to print finer detail that enables the user to make a better interpretation of the imagery. In an attempt to meet this objective, we have experimented with many photographic and screen processes and in the past several years have used the Howson-Algraphy, Inc., Alympic Gold positive plates along with their Contone developer to lithographically print photographic imagery, without the use of a screen. This screenless process uses the structure of the grain of photosensitive plates to form microscopic random dots that comprise the printed image. Changes and modifications to the manufacturer’s recommended process are included in the detailed procedures for calibration of the positive subtractive press plates, evaluation of the continuous-tone film, and quality control review during the reproduction ...

Computer-Assisted Etching

In my experiments with computer-assisted etchings over the past eight years I have tried to harness the graphic potential of available computers to the traditional art of fine printing, without sacrificing the refined beauty of gravure on rag paper. I have tried to integrate computer functions with the functions of engraving, aquatint, monotype, and other hand techniques in enhancement of a complex, figurative, lyrical style. The completed prints display little of the geometry usually associated with 'computer graphics'. Employing principles of metamorphosis, I have used the computer for codification, development, transformation, and composition of visual images. With the technology available to me-a Digital Equipment Corporation PDP10 computer with display, later a 'home computer', the Radio Shack TRS80 micro-computer and dot matrix Microline 80 printer, a Calcomp plotter, a Varian electrostatic printer, a Thermofax machine, a copy camera and darkroom, Revere photo-sensitive etching plates and chemicals, and an etching studio with press-I am able to process ideas through several steps into fine intaglio prints. I rely on graphics programs of three types: edge-finder programs, dot matrix programs for letter type, and drawing programs. In the first two kinds of programs a video camera directed by a PDP10 computer shoots artwork, objects or type fonts. The value information of the video input is digitized and processed to a linear codification suitable for etched line. The edge-finder program finds edges of real or illusional objects and sorts out levels of contrast. It establishes thresholds for value change. Demarcation of maximum value change creates a firm line. Less value change creates broken lines. Minimum value change creates dots. The thresholds for value change 'readings' can be moved easily. The drawing program is a general purpose computer graphics package. It is used to create libraries of pictures which may be called on by other programs or output on any kind of hard copy system. It permits editing by the insertion and deletion of points, by the movement of points, or by the combination of drawings or fragments of drawings. An x-y coordinate system is established. The x-y information may be entered into the computer memory from a typewriter keyboard, or from files produced by mathematical formulas, T.V. pictures, or by a light pen. The output of the programs is stored as hundreds of short line segments which may be produced as line drawings by the computer-operated plotter or electrostatic printer. Since visual data are expressed in numbers, distortions of the image can be effected by applying different factors to the numbers. To modify an image, I set it up on a vertical-horizontal axis, establishing x as a horizontal coordinate and y as a vertical coordinate. Every line is made up of hundreds of points, each having a vertical and horizontal number coordinate. Once these coordinates are given, they can be shifted by multiplication, division, addition or subtraction. The image can undergo gradual metamorphosis; it can be curved, turned inside out,

Fabrication of apodized apertures for laser beam attenuation

To obtain maximum energy output from a high-power laser system it is necessary to carefully shape the input beam's cross-sectional intensity profile. This avoids diffraction-produced hot spots which can cause damage to the amplifier components. The intensity should be at a maximum in the central part of the beam and fall of gradually at the edges to avoid hard-edge diffraction effects. This kind of beam profile can be produced using an apodized aperture — a soft-edged aperture that may be constructed in various ways. This report describes a photographic rotating-film technique for fabricating apodized apertures from photo-sensitive glass plates.

Photosensitive Ionomer. I. Preparation of Mercurous Acrylate and Photosensitive Plates

Abstract Photographic plates were prepared by coating an emulsion consisting of mercurous acrylate, polyvinyl alcohol and water on glass plates. They were found to be sensitive to light ranging from 250 nm to 340 nm. A dark brown image with density ca. 0.6 above the fog was formed by a printing-out process. The latent image could be amplified with the reducing developers such as hydroquinone or metol. Image formation was ascribed to metallic mercury which was isolated by photoreduction and/or reduction of mercurous ion.

Photosensitive Ionomer. II. Preparation of Mercurous Copoly(vinyl alcohol–acrylate) and Properties of the Plate

The disproportionating reaction of mercurous acetate was used in conjunction with polymeric carboxylic acid in order to produce a new type of photosensitive system. As for the polymeric acid, various copolymers of vinyl alcohol and acrylic acid were prepared by radical copolymerization of vinyl acetate and acrylic acid with varying monomer ratios and volumes of xylene used as a solvent. The polymeric acid was neutralized with sodium hydroxide and then converted to a mercurous salt. Photosensitive plates were prepared by coating glass plates with a dispersion of mercurous copoly(vinyl alcohol–acrylate).It was found that the plates were sensitive to ultraviolet light, and that a dark brown image was formed by a printing-out process. The latent image was proved to be developed by hydroquinone. Photographic image formation was due to metallic mercury which was isolated as a product of the disproportionating reaction. When immersed in an acetic acid solution, the photosensitive layer of the unexposed part swelled and became detached from the plate, but the layer of the exposed part was unchanged, and a relief image was fixed on the plate. The image formation was ascribed to ionic crosslinking by mercuric ions formed in the disproportionating reaction of mercurous ion.

Photography on Selenium

IT was observed many years ago that the crystallization of amorphous selenium is promoted and accelerated by illumination1,2. I rediscovered this in the summer of 1941 and succeeded in producing true photographic images by means of this effect, using the initial product of selenium manufacture, namely, aluminium or steel disks covered with a film of selenium, as photosensitive plates. To do this, the mirror-like surface of the selenium must be polished with a soft material, such as tissue paper. The disk is then placed on a metal plate, preheated at 90–95° C, and an image, preferably a diapositive, projected on the surface of the selenium. During exposure, 'self-development' takes place and in 1–2 minutes a somewhat faint but in other respects perfect image will appear. The photographic process is then complete and the disk can be removed from the hot plate.