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Glossary FAQ


14. VRP photoplates

VRP photographic plates ("Slavich" production) are used for recording of pulse transmission holograms. These plates are sensitized to green light. Although these photographic plates were originally developed for photo-lithography, they are also suitable for recording holograms. Moreover stability of properties of the emulsion layer of photographic plates VRP is much higher than in the case of purely "holographic" plates (PFG series). They can be stored several years outside refrigerators without deterioration of their photographic properties.
Thickness of the emulsion layer of the photographic plates VRP is 5 micron. From the side of the glass substrate they are covered by a transparent anti-aureole red color layer which immediately discolors in a developer.

Grains of silver bromide in the emulsion layer of the photographic plates VRP have the dimensions of about 40 nm (see figures). These dimensions are several times greater than the grain dimensions in the photographic plates PFG-03m. So, sensitivity of VRP plates is several times higher (for phase holograms) - about 75 mcJ/ (see fig.). On the other hand resolution of the VRP plates doesn't exceed 3000 lines/mm because of big sizes of the silver bromide grains. Because of this fact the process of recording reflection holograms on VRP plates is connected with certain difficulties. It's practically impossible to obtain bright Denisyuk holograms on the VRP plates, but by copying reflection holograms from transmission master holograms it's possible to get copies of satisfactory quality on the VRP plates by a fine optimization of the conditions of exposition and chemical treatment. For recording reflecting holograms it's necessary to use photographic plates without a anti-aureole layer. They are marked as VRP-M (see fig. below).

Besides VRP photographic plates, "Slavich" manufactures cheaper plates FPR (see right fig.). They are also sensitized for green color, and they have the same sensitivity and resolution as the VRP plates, but they have some worse mechanical properties - strength and temperature of deformation of the emulsion layer. These characteristics have no critical importance for hologram recording, so using of the FPR plates is preferable. -->