Viktor Nikolaevic Mikhailov

Hologram recording in DuPont photopolymer films by use of pulse exposure

Reflection hologram recording in DuPont HRF-800X071-20 photopolymer films has been demonstrated by use of pulsed laser exposure with pulse lengths of 25 ns. An expected weak reflectance of the recorded mirror holograms could be significantly increased by preillumination. Although pulsed preillumination enhanced only the reflectance, continuous incoherent preillumination significantly increased both the diffraction efficiency (which reached ~80%) and the sensitivity (which reached an increase of ~100 times, thus approaching the sensitivity of cw recording). The results are compared with those for hologram recordings obtained with cw exposure under the same processing conditions. Spectral absorbance curves of recorded holograms are presented, and possible mechanisms of hologram formation are discussed.

Optical phase conjugation in difference-frequency generation

We present a theoretical treatment of difference-frequency generation in conditions of phase mismatch for seed and generated fields that propagate at different angles to the pump. The analytical solution in the case of nondepleted plane-wave pump and experiments performed with seed fields strongly phase and amplitude modulated show that the pump-field wave fronts behave as efficient phase-conjugating mirrors.

Pulse recording of slanted fringe holograms in DuPont photopolymer

We report an experimental investigation of recording of slanted fringe holograms in DuPont HRF-800X071-20 photopolymer film under pulse exposure. An initially weak polymerization ability was improved significantly by using incoherent preillumination. The line shape and position of spectral absorbance curves are discussed for a wide range of slant angles.

Solid state lasers for color holography

The problems in recording, copying and reconstruction of color transmission and reflection holograms are discussed with respect to the following source laser parameters: (a) a set of RGB (red, green, blue) wavelengths, (b) spectral bandwidth (temporal coherence), (c) spatial coherence, and (d) output power. The analysis of different optical schemes for color holography with referring to the parameters mentioned above suggests the necessity of having various lasers with different spatial, temporal and power characteristics. Based on the analysis, solid-state lasers with intracavity as well as extracavity frequency conversion examined as an efficient source of RGB (red, green, blue)--wavelengths under various operating regimes: CW, quasi-CW (with high repetition rate--up to 1,000 kHz), pulse, Q-switch, mode-locking etc. The possible optical schemes of such lasers are proposed and their parameters are discussed.

Study of electronic stage of the Herschel effect in holographic emulsions with different types of chemical sensitization

In the paper there are presented results of study of the Hercshel effect (HE) for a number of s I lver hal ide ho 1 ographic photomateri al s such as BPI1 J1014-2Y. 11014-3 14A3 under exposure by act iri c and nonact I ni c 1 aser radi at Ion (NAR) of various durations (10 10 10 s). The observed in experiment reciprocity law failure according to the HE is specified by different contributions of electron and hole components of the HE. In accordance with such a not ion the centers of 1 atent I mage C LI ) can be damaged by two ways : 1) absorption of NAR by LI center accompanied by transition of electron into conduction band with the following recombination and 2) release under the action of NAR of holes from surface traps into valence band and their recombination with electrons trapped in the LI centeis. It is shown that Intensification of the HE under the action of NAR of 10 s duration depends in the main on the hole component. Results obtained in studies of the HE for photomaterials with different types of chemical and spectral sensitization as well as after their treatment with chemical reagents specifying the kinetics of free charge carriers on surface of emulsion microcrystals permit to refine the notion about their part in processes of LI formation. 1.

Silver-halide sensitized gelatin (SHSG) processing method for pulse holograms recorded on VRP plates

One of the most important area of holograph applications is display holography. In case of pulse recording the requirement for vibration stability is easier than compared to CW exposure. At the same time it is widely known that the behavior of sliver-halide holographic materials strongly depends on the exposure duration. In particular the exposure sensitivity drastically decreases under nanosecond pulse duration. One of the effective ways of the diffraction efficiency improvement is SHSG processing method. This processing scheme is based on high modulation of refractive index due to microvoids appearance inside emulsion layer. It should be mentioned that the SHSG method was used earlier only in the cases when the holograms were recorded by use of CW lasers. This work is devoted to the investigation of SHSG method for pulse hologram recording on VRP plates. We used a pulsed YLF:Nd laser with pulse duration of 25 nanoseconds and wavelength of 527 nm. Both transmission and reflection holograms were recorded. The different kinds of bleaching as well as developing solutions were investigated. Our final processing scheme includes the following stages: 1) development in non-tanning solution, 2) rehalogenating bleach, 3) intermediate alcohol drying, 4) uniform second exposure, 5) second development in diluted developer, 6) reverse bleaching, 7) fixing and 8) gradient drying in isopropyl alcohol. Diffraction efficiency of transmission holograms was of about 60 percent and reflection mirror holograms was of about 45 percent. Thus we have demonstrated the SHSG processing scheme for producing effective holograms on VRP plates under pulse exposure.

Recording and reconstruction of reflection and transmission holograms with a cw-laser diode

We present results of investigations of modern cw-laser diodes, emitting in the red spectral range from 635 nm to 670 nm with power from 5 mW to 100 mW for recording and reconstructing reflection and transmission holograms. High- quality reflection holograms were recorded in silver halide materials and in DuPont photopolymers. We demonstrated a brilliant reconstruction of transmission holograms with a depth of image up to 3 m.

Improved processing for silver halide pulse holography

Using of an improved developer with optical latensification allowed to significantly increase exposure sensitivity of currently in use silver halide materials. Transmission large-scale holograms (30 X 40 cm2) of diffused objects have been recorded under pulse exposure of about 6.5 X 10-6 J/cm2 for VRP and of about 2 X 10-6 J/cm2 for Agfa-Gavaert 8E56HD, in both cases without appreciable contrast deterioration. Results of the first experiments on pulse reflection holography are also discussed.

Sensitivity of silver-halide emulsions at exposure durations 10 2 -10 -13 seconds

The sensitivity of a fine-grained silver halide VRP photoplates exposed by laser radiation over a wide range of durations (102 - 10-3 sec) is studied. The drastic deviation of sensitivity in the time range from 10-9 sec to 10-13 sec is found and discussed.