Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/32—Latensification; Densensitisation
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/40—Chemically transforming developed images
  • G03C5/44—Bleaching; Bleach-fixing
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/04—Processes or apparatus for producing holograms
  • G03H1/18—Particular processing of hologram record carriers, e.g. for obtaining blazed holograms

Definitions

• the invention relates to a process for the production of low noise, high light intensity phase holograms in photographic layers, using the desensitized residual silver halide for constructing the hologram.
• phase holograms have substantially higher image brightnesses than amplitude holograms. Since the photographic silver halide emulsion layers used in holography are much more sensitive than other systems such as polymer layers which can be crosslinked by light or chromate-gelatin layers, attempts have been made to produce phase holograms in such silver halide gelatin layers by reconverting the silver obtained after development into a silver salt by a bleaching process. As a rule, such bleaching processes substantially reduce the contrasts in holographic reconstructions so that the quality ofthe imageobtained is unsatisfactory.
• each silver halide grain into an elongated, usually curved thread of metallic silver the longitudinal dimension of which is greater than the diameter of the original silver halide grain.
• the bleaching process causes this silver thread to become coarser so that centres of scattering which are effective over a larger cross-section are produced, with the result that the noise due to the material is increased.
• the noise due to the material is less important than the intermodulation noise which is produced by interference of the individual object partial waves and which in the process of reconstruction preferentially scatters a portion of the signal wave at small angles.
• the granulation recorded in this way must therefore be kept as small as possible in order to obtain high quality, low noise phase holograms.
• the known photographic bleaching processes have been modified for producing phase holograms. These special bleaching processes, however, are extremely complicated and not usable in practice. In some of the known processes, for example, the developed layer must be treated in more than stages. Other of these known processes result in phase holograms which are not sufficiently stable to light, with the result that the image brightness of the holograms produced diminishes in the course of storage.
• the photographic material is fixed after development, and the silver salt produced in the bleaching process is used for constructing the phase hologram.
• the residual silver halide remaining after development of the silver halide emulsion layer may be used for producing a phase holo- LII gram.
• thephotographic material is not fixed after exposure and development.
• the image silver is converted by a conventional bleaching process into a silver salt which is more readily soluble than silver halides and therefore can be dissolved out of the layer more easily.
• the resulting reversal of the image does not adversely affect the holographic process since it only causes a phase shift by half a grid period which is insignificant for the purposes of reconstruction.
• a strongly tanning developer of the pyrocatechol type is used for development of the exposed silver halide emulsion layer.
• Gelatin reliefs are obtained which are distinct only for the low localized frequencies which cause the intermodulation noise.
• the reversal process effects partial compensation of these gelatin reliefs by phase opposition so that the scattering light is reduced. But even this process is only of limited practical use because the tanning developers are very corrosive substances and therefore physiologically harmful. Moreover, the contrast of phase holograms obtained in this way is relatively low.
• a photographic process for producing phase holograms in silver halide emulsion layers by exposing the light sensitive silver halide emulsion layer to light reflected from the hologram structure, developing the exposed layer, treating it with a short stop bath and washing it, bleaching the silver image by treatment with an oxidizing bleaching bath, dissolving out the silver compound produced by the bleaching process in the exposed areas of the layer and drying the layer has now been found in which a nomtanning developer is used for developing the exposed silver halide emulsion layer.
• the process according to the invention results in phase holograms of high light intensity and low noise .which are stable-to light.
• the process according to the invention also has procedural advantages in that in the known processes a special bath was always required at the end of the process in order to remove patches which were due to the tanning development. This is unnecessary in the process according to the invention, and the number of process steps required is therefore reduced.
• the process according to the invention is carried out as follows:
• the hologram is first' produced in the usual manner by interference of the information carrying beam with a reference beam in the photographic layer.
• the layer is then developed in a conventional alkaline development bath in which the developers used are nontanning developer substances, in particular hydroquinone, l-phenyl-pyrazolidone-3, p-aminophenol or derivatives thereof.
• the photographic material is then not fixed but is treated in a short stop bath of known composition, generally a slightly acid aqueous bath such as dilute acetic acid solution, and is then washed. Thereafter, the silver image is bleached in an oxidizing bleaching bath, preferably an acid bath containing potassium dichromate as oxidizing agent.
• an oxidizing bleaching bath preferably an acid bath containing potassium dichromate as oxidizing agent. The bleaching process oxidizes the silver image and converts it into silver compounds, e.g.
• the clarifying baths used may be slightly alkaline aqueous solutions of sodium sulphite which do not wash-out the residual silver halide from the unexposed areas of the layer.
• the layer is then again washed. It is then dried by bathing in alcohol, preferably in ethyl alcohol.
• the alcoholic bath also contains a desensitizer to eliminate the sensitivity to light of the residual silver halide still present.
• Suitable densitizers are e.g. Wursters blue perchlorate, phenosafranin, Pinakryptol yellow, Pinakryptol green or Pinawhite.
• the preferred desensitizer is phenosafranine. After the treatment in this bath, it is advisable to rinse the layer briefly with ethyl alcohol.
• the last mentioned bath desensitizes the residual silver halide and effects uniform and rapid drying of the layer, which is particularly important for producing low noise holograms.
• the desensitization and drying with alcohol may, of course, be carried out in separate baths but the combination of the two stages of the treatment in one bath is preferable for the purpose, of simplifying the process.
• the process according to the invention may be carried out with silver halide gelatin layers known per se. It is preferred to use fine grained silver halide gelatin emulsions with a particle size of between 20 and 100 nm. The thickness of the layers should preferably be to 30 um.
• the quality of the phase hologram is assessed by determining the diffraction efficiency, i.e. the ratio of an intensity diffracted in the first order to the reconstructing intensity, the material noise and the signal noise members for a given test object.
• the diffraction efficiency of phase holograms obtained by the process according to the invention is about 40 percent. This is of about the same order as that of phase holograms obtained by known processes using tanning development.
• the figures for the noise power due to the material are on an average less by a factor of 2 to 3 than those obtained with the 'corresponding process using tanning development.
• the signal/noise ratios for a diffuse object are about 30:].
• the corresponding value is about :1, which means that the signal noises are reduced by a factor of 1.5 in the process according to the invention. Due to the reduced material noise and greatly reduced signal noise numbers, phase holograms are obtained for a reference-object beam ratio of 4:1 with previously unattainable high contrast.
• the development time is 5 minutes, the development temperature 20C.
• the treatment time is l0 minutes.
• the layer is rinsed with ethyl alcohol.
• mm is about 45 percent.
• the noise due to the material is less by a factor of about 3 than that obtained when in an otherwise similar process a tanning developer with pyrocatechol as developer substance is used.
• the signal/noise ratios for the diffuse object described above are in the region of 35: 1. When development is carried out with a tanning developer, this ratio is in the region of 20:1. The average localized frequency for this measurement was 1,600 mm. The reference beam/object beam ratio was 4: l.
• phase hologram obtained has exceptionally high contrast with excellent stability to light.
• the formation of print out silver could not be observed even after prolonged exposure to daylight.
• a desensitizer selected from the group consisting of Pinakryptol yellow, Pinakryptol green, Wursters blue perchlorate and phenosafranine.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Holo Graphy (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5806231

Family Applications (1)

Country Status (5)

Cited By (2)

Citations (1)

• 1971
  • 1971-04-28 DE DE19712120864 patent/DE2120864B2/de active Granted
• 1972
  • 1972-04-25 GB GB1913372A patent/GB1350876A/en not_active Expired
  • 1972-04-26 US US00247812A patent/US3816130A/en not_active Expired - Lifetime
  • 1972-04-27 BE BE782707A patent/BE782707A/nl unknown
  • 1972-04-28 FR FR7215225A patent/FR2134644B1/fr not_active Expired

Patent Citations (1)

Non-Patent Citations (2)

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