Recording of dynamic holograms by nanosecond and picosecond laser pulses in solid-state fullerene-containing matrices

The results of a complex investigation of the recording of dynamic holograms by pulsed radiation with a duration of 20 ns and 300 ps in fullerene-containing media based on porous glasses and polymethyl methacrylate matrices are reported. Spectral analysis of these media in the range 300–700 nm was performed. The efficiency of hologram recording was found to relate with the occurrence of a band at 330 nm in the absorption spectrum of a medium. It is shown that dynamic holograms can be recorded in the fullerene-containing media by nanosecond and picosecond pulses. In the latter case, holograms arise mainly due to a change in the electronic polarizability of fullerene molecules, which is almost inertialess. The results obtained can be used in the development of ultrafast switching devices based on dynamic holograms.     

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.     

The diffraction efficiency of hologram grating recorded in an absorptive medium

The profile of the hologram grating is described considerating the absorption of the recording medium and its diffraction efficiency is calculated for special cases using the coupled wave theory. The maximum diffraction efficiency obtainable is not affected by the absorption of the recording medium in the case of transmission holograms, while it decreases with increasing absorption in the case of absorptive reflection holograms.     

Zum Beugungswirkungsgrad von Volumenhologrammen. Teil II. Reflexionshologramme

In this paper we give an exact solution of the coupled differential equation system as developed by Kogelnik [1] for the case of symmetrical recording without neglecting the second differentials for the reflection volume hologram. This solution is applicable to dielectric, absorption and so-called mixed volume holograms. There are some remarkable distinctions between our results and those got by Kogelnik for the case of absorption and mixed holograms. It is shown, that under special assumptions and approximations or for special combinations of the material parameters we get the same relations as Kogelnik.     

Polarization volume holograms in layers of polymethylmethacrylate with phenanthrenequinone

Polarization volume holograms are recorded in the polymethylmethacrylate layers that contain phenanthrenequinone at a molar content of 2.5–3%. The effect of the polarization of recording beams on the kinetics of diffraction efficiency and properties of holograms is analyzed. Polarization hologram recording in the polymethylmethacrylate layers with phenanthrenequinone and a relatively high optical stability of the holograms are demonstrated.     

Angle-multiplexed hologram storage in LiNbO(3):Tb, Fe

We have performed hologram multiplexing with a cw laser at lambda=532 nm in a near-stoichiometric LiNbO(3) :Tb, Fe crystal that exhibits a visible absorption band induced by UV light. When 50 plane-wave holograms were angle multiplexed from the UV preexposed state, the recording sensitivity gradually decreased, owing to bleaching of the induced absorption. However, a conventional recording schedule of multiplexing many holograms of equal diffraction efficiency can be used in this photochromic material. The gradual decrease in recording sensitivity throughout multiplexing can be compensated for by the increased erasure-time constants of later-written holograms. An M/# of 1.73 was obtained in a crystal of 3.3-mm thickness.     

Efficient and flexible laser beam scanners constructed from volume holograms

We combine the scan flexibility of computer-generated holographic laser beam scanners with the high diffraction efficiency of volume phase holograms to produce a new type of “holo-scanner”. The scanner-hologram consists of numerous, small, volume hologram facets recorded in dichromated gelatin films and produces an arbitrary output pattern with greater than 90% light efficiency. Experimental results from discrete point, continuous line, and 3-D scanners are shown. Multi-wavelength scanners are also considered. This paper is based on the concepts presented in the preceding paper on “computer-interferometric holograms used for laser beam scanners”.     

Dynamic holograms and phase conjugation in multilevel resonant media

The generation of dynamic holograms and four-wave phase conjugation in resonant media has been investigated under conditions of interaction between radiation and excited singlet and triplet states. Two mechanisms of optical control of resonant media non-linearities using independent pump-up to increase the diffraction efficiency of dynamic holograms have been considered. The peculiarities of non-linear recording of holograms, and a variant of quadratic recording, have been investigated. The dependence of the efficiency of diffraction by dynamic holograms on the intensity of interacting waves and the spectroscopic characteristics of the medium has been analysed.     

Holography with guided optical waves

Waveguide holograms are recorded in a storage material layer covering a planar dielectric waveguide with a guided mode as reference wave. They are also read-out with a guided mode. In the storage material, assumed to have a lower refractive index than the waveguiding film, the fields of the reference and of the read-out wave are evanescent waves. We describe the preparation of the epoxy resin (Araldit) waveguides on glass substrates, their coating with a dichromated gelatin (DCG) layer as storage material, the processing of the DCG, and the recording and reconstruction techniques. Waveguide holograms of good quality with a size of several square centimeters have been realized for the first time. The holograms were recorded and read-out with wavelength λ=488 nm. They have a length of about 25 mm and a width of 17 mm. To obtain holograms that wide a special prism coupler had to be used which allowed to couple in a laser beam of elliptical cross section, and thus to excite a guided reference or read-out mode with a width of 17 mm.     

Aberration-free lateral shear holographic interferometry

Lateral shear interferometry is considered as a possible means for optical correction of wave fronts reconstructed from singly and doubly exposed holograms. Optical aberrations are eliminated in a moiré pattern by superposing two lateral shear interferograms using waves diffracted by original holograms. It is shown that the singly exposed hologram allows compensation for only optical inhomogeneities due to the substrate, while the doubly exposed hologram also excludes aberrations due to the recording system. The experimental results supporting the efficiency of the method as applied to imperfect substrates of holograms are presented.     

On the possibility of writing thin amplitude-phase holograms in the near infrared range (λ=1315 nm) using polyimide-based fullerene-containing conjugated organic structures

The process of writing thin amplitude-phase holograms in polyimide-based fullerene-containing conjugated organic media using an iodine laser operating at λ=1315 nm was studied. It is shown that such polymeric structures are promising media for reversible optical data recording in the IR spectral range.     

模压全息图的颜色设计及其记录方法

目前模压全息广泛地应用于商品标识、卡通、贺卡等，如何制作出色彩鲜艳、亮度高、清晰的模压全息图是至关重要的。本文从两束光干涉的简单模式讨论模压全息图的颜色设计，给出几种实用的和可能用的浮雕全息图的记录方法，并介绍常用光致抗蚀剂记录材料的特性及其处理工艺。     

Image reconstruction from a dielectric volume hologram

The phenomenon of image reconstruction from an absorptionless volume hologram is analyzed using coupled-wave diffraction theory. Reconstruction efficiency formulas are derived, which apply when the hologram intermodulation component is negligible and when no extraneous diffracted orders of significant amplitude are generated. Both transmission and reflection holograms are considered, and the analysis is developed for diffraction geometries in which polarization effects are appreciable.     

New azo-dye-doped polymer systems as dynamic holographic recording media

Polymer materials show their impact on optical storage technology for developing high information density and fast access-type memories with a high read-out efficiency. New azo-dye-doped polymer materials have been developed and used for recording dynamic holograms. Dynamic holograms with reasonably high diffraction efficiency have been recorded at 468 nm, and the efficiency of the Write, Read and Erase (WRE) cycle in these azo-dye-doped polymer materials was determined. Significant observations in these materials are: (i) there is no need to change the polarization of the writing beam to erase the recorded holograms, (ii) the whole WRE cycle is very fast (3–6 s) and (iii) recording of more than 250 WRE cycles without any fatigue of the recording materials is possible.     

三维动画显示体积全息图的研究与制作

根据体积全息图的角度复用特性,在一张卤化银干版上记录了多幅图像,再现时轮流显示不同画面从而实现动画显示的效果。设计记录波长632.8nm,再现波长532nm。通过记录和检测光栅确定全息图的处理工艺,从理论上分析了因乳胶收缩导致的光栅结构变化问题,计算得到全息图的记录和再现条件,消除了再现像"左右跳动"的现象,在一张干版上记录了4幅子图。设计并制作完成了自动控制电路和展示装置,实现了三维动画显示效果。     

Influence of light polarization on the diffraction efficiency of TIR holograms

Normally when forming a TIR hologram two interference gratings are stored in the recording medium. The object beam interferes with the incoming and with the reflected reference beam. An appropriate selection of the polarization orientations of the interfering light beams leads to the suppression of one of the grating systems. Even to reconstruct TIR hologram it is not all the same in which orientation the reconstructing laser beam is polarized. With the proper selection of the polarization orientations of the forming and reconstructing laser light the diffraction efficiency for TIR holograms can be optimized.     

Investigations of As-S-Se thin films for use as inorganic photoresist for digital image-matrix holography

As-S-Se chalcogenide thin films are successfully employed in classical and dot-matrix holography as inorganic photoresists for obtaining a relief-phase hologram. However using these films for image-matrix hologram recording has not been studied due to some features of image-matrix technology. For the applied research of the optical properties of As-S-Se films an experimental device of digital image-matrix holographic recording based on 100 mW 405 nm semi-conductor laser and Spatial Light Modulator (SLM) has been created. The device has the following main parameters: 140 × 105 μm frame size; laser intensity during exposure 10 W/cm². With the help of this device diffraction grating and security holograms were recorded on As-S-Se thin films. The work reported herein presents results of an experimental study of how diffraction efficiency (DE) of the received relief-phase holographic gratings depends on an exposure and period. Diffraction grating profiles and speed of etching corresponding to different exposure doses are shown. Hologram samples with DE = 65% have been received which allows for using chalcogenide film as alternative to organic photoresists in applied dot-matrix and image-matrix holography.     

Dynamic reflection holograms in CdF2 crystals with bistable centers

The diffraction efficiency and the recording and relaxation times of dynamic reflection holograms, recorded in CdF₂ crystals with bistable centers are studied experimentally in the temperature range 20–100°C. In the model experiments which measured the quality of the wave reflected from the hologram, the dynamic wavefront distortions are demonstrated to be efficiently compensated using a holographic corrector based on these crystals. CdF₂ crystals with bistable centers are likely to be useful in solving problems of correction of laser light wavefront and image correction in observation telescopes with nonideal primary mirrors.     

Holographic recording on the basis of forbidden singlet-triplet electronic transitions

The possibility of recording holograms in thick layers of a photopolymeric material on the basis of a forbidden singlet-triplet transition of a sensitizing dye, erythrosine, is theoretically substantiated and experimentally confirmed. A single hologram and 16 superimposed holograms are recorded with a low-power He-Ne laser (632 nm) at high concentrations of the sensitizing dye and high optical densities in the range of its main absorption. The diffraction efficiency of the single hologram is ～50%. The dependence of the increase in the diffraction efficiency of a transmission grating in samples of photopolymeric material on the intensity of incident radiation of a Kr⁺ laser (647 nm) is studied. The observed linear dependence of the maximal rate of increase in the diffraction efficiency in the photopolymer on the incident light intensity is explained by the manifestation of a two-step excitation of the dye (T ₁←S ₀, T ₂←T ₁) in the samples studied.