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1.
In the present study, the process of formation of holographic transmission diffraction gratings in photopolymer media is investigated
at low contrasts with allowance for self-diffraction of recording waves. A theoretical model for the first spatial harmonics
of the refractive index grating is constructed based on a solution of the coupled kinetic photopolymerization and diffraction
equations. The temporal dynamics of amplitude and phase spatial profiles of harmonics, diffraction efficiency, and angular
selectivity of recorded gratings is theoretically investigated. The calculated and experimental data are compared.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 35–42, November, 2006. 相似文献
2.
In the present study, record and readout of holographic transmission diffraction gratings in photopolymer media are investigated
with allowance for an arbitrary degree of nonlinearity of photopolymerization, contrast of interference patterns, and absorption
and arbitrary relative contributions of polymerization and diffusion recording mechanisms. A theoretical model of (N + 1) 3-D harmonics of the refractive index grating, based on a solution of the coupled kinetic photopolymerization equations,
allows the time dynamics of harmonic amplitudes, 3-D refractive index profile, diffraction efficiency, and angular selectivity
of the recorded gratings to be investigated.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 56–63, May, 2005. 相似文献
3.
Dynamic analysis of holographic gratings in amulti-wavelength visible light sensitive photopolymer 下载免费PDF全文
A dynamic theoretical model of photochemistry and
hologram formation in holographic photopolymer is established, and
the dynamic development process of holographic gratings in the
photopolymer is discussed with the model. A novel multi-wavelength
visible light sensitive photopolymer for holographic storage is
prepared. The influence of exposure wavelength on holographic
storage characteristics is analysed. By fitting the experimental
data of transmittance and diffraction efficiency to a function of
time with different exposure intensities and wavelengths, the
variations of dynamic parameters of photochemistry and
photopolymerization diffusion are presented. 相似文献
4.
Photopolymer systems can produce good image quality holograms that does not require any post-processing and are environmentally stable with good diffraction efficiency. The present work reports the development of a methylene blue-sensitized polyvinyl alcohol acrylamide (MBPVA/AA) photopolymer system for recording white light reflection holograms. Reflection gratings were recorded in the photopolymer films with different concentrations of methylene blue (MB). Various parameters affecting the holographic properties of the samples were also studied. The holographic performance of the material is found to depend on its chemical composition and the recording parameters. 相似文献
5.
Manuel Ortuño Elena Fernandez Sergi Gallego Augusto Beléndez 《Optics Communications》2006,268(1):133-137
The behaviour of a hydrophilic acrylamide photopolymer, with and without crosslinker (N,N′-methylene-bis-acrylamide), in solid layers 700 μm thick is analyzed. Slanted diffraction gratings are multiplexed at constant and variable exposure. Variable exposure time scheduling, with increased exposure time by steps is used in order to determine the effect on the dynamic range and the homogenization of diffraction efficiency values. This scheduling results in a greater dynamic range compared with constant time multiplexing. For crosslinked photopolymer, those exposure times are excessive (higher energetic sensitivity) and there is overlapping of the individual angular response curves for each stored diffraction grating. 相似文献
6.
Manuel Ortuño Andrés Márquez Sergi Gallego Inmaculada Pascual 《Optics Communications》2008,281(6):1354-1357
Unslanted diffraction gratings are recorded in a 900 μm thick acrylamide photopolymer by means of peristrophic multiplexing. A solid state Nd:YAG (λ = 532 nm) laser is used as the recording beam, with a total incident intensity of 5 mW/cm2, and a He-Ne laser as the reconstruction beam. The dye concentration in the photopolymer is optimized so that it does not limit the dynamic range. Nine holograms are recorded using constant exposure time scheduling and variable exposure time scheduling. From the results obtained it may be deduced that optimization of the dye allows us to work in the linear response region of the photopolymer and at the same time obtain high values of diffraction efficiency for each hologram. An exponential increase in exposure time as the number of holograms increases enables the values of diffraction efficiency to be homogenized with regard to the case of constant exposure scheduling. In this way, better use is made of the dynamic range of acrylamide hydrophilic photopolymer. 相似文献
7.
The filter made up of two gratings performs as a two-dimensional non-spatial filtering. This paper reports that the volume Bragg gratings are fabricated by interfering two collimated coherent laser beams in photopolymer. Diffraction efficiency of a single grating is up to 78% in Bragg's condition, then a two-dimensional non-spatial filter, which consists of two volume Bragg gratings and a half-wave plate, enables the laser beam filtered in two dimensions with the diffraction efficiency of 54%. The Bragg's condition and effect of polarisation on performances of the two-dimension filter are also discussed. 相似文献
8.
A method for the holographic determination of the chemical kinetic order of irradiance in linear-chain polymerization rates
using phase gratings recorded over dry photopolymer films is derived. This method, based in the initial slope of the recorded
diffraction efficiency, does not depend on any model of the grating growth, and it allows to collect information on the kinetic
mechanisms involved in the polymerization. An acrylamide-based linear-chain photopolymer is analysed.
Received: 2 August 1999 / Published online: 8 March 2000 相似文献
9.
10.
The temporal dynamics of harmonic amplitudes and refractive index grating profiles is modeled numerically for the theoretical
model of the (N+1)th spatial harmonic of the refractive index grating constructed on the basis of the solution of coupled
kinetic photopolymerization equations derived in [1] with allowance for the absorption for N = 2. Solutions of the self-consistent
diffraction problem [1] are used to analyze numerically the diffraction efficiency and angular selectivity of recorded gratings.
Model parameters of the experimentally investigated photopolymer material are estimated by means of a comparison of the experimental
data on the diffraction kinetics and angular selectivity with the results of model calculations presented in [1].
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 85–92, July, 2005. 相似文献
11.
Data are presented from studies of the temperature dependence of the diffraction efficiency and radiation resistance of volume
phase hologram/transmission gratings. The reversible diffraction efficiencies are described by the phase equilibrium diagram
for the polymer-diffusate system. The radiation resistance of these hologram/gratings is determined by the thresholds for
photothermolytic decay of the diffusate, bromonaphthalene, that was used. Composites containing diffusates with high thresholds
for photolysis and thermolysis are studied. As a result, modified versions of the photopolymer recording medium with radiation
resistances exceeding 200 MW/cm2 are proposed.
Zh. Tekh. Fiz. 68, 105–110 (June 1998) 相似文献
12.
一种核黄素敏化的宽带全息记录材料 总被引:2,自引:1,他引:1
制备了一种核黄素敏化的以聚乙烯醇为基质的新型全息存储材料,并研究了材料的全息特性.用Ar+激光器激发的488 nm的蓝光对材料曝光,结果表明该材料具有较高的衍射效率和曝光灵敏度,衍射效率高达53%,灵敏度为3.3 cm2/J,折射率调制度为4.5×10-4.研究了材料的透过率与随时间和入射角度变化的关系,说明在曝光记录过程中有噪音光栅生成.在存储介质膜中存储了全息图像,再现图像较为清晰,说明该材料适合用作高密度全息存储介质. 相似文献
13.
<正>Diffraction efficiency of volume Bragg grating,whose period is in the same order as the incident wavelength, is related to the polarization direction of the incident linear polarized beam.When two linearly polarized recording beams with the same polarization direction are used for recording volume Bragg gratings in a photopolymer with diffusion amplification,the azimuth of polarization of the reconstruction beam influences the diffraction efficiency of the grating.When the probe beam is linearly polarized and oriented orthogonally to the grating vectors,the±1-order diffraction beams are also linearly polarized with polarization direction parallel to that of the probe beam.According to the results,a two-dimensional nonspatial optical filter consisting of the volume Bragg gratings would achieve significantly higher efficiency. 相似文献
14.
在Polyacrylic Acid(PPA)光聚合物中用双光束相干的方法成功地写入了全息光栅,用He-Ne 激光器作为探测光对光栅的写入过程进行了实时监测.分两种情况重点研究了温度对光栅成栅过程的影响,一是在不同的温度下写入光栅;二是在室温下写入光栅,待光栅强度达到最高时再改变温度来研究温度对光栅的影响.实验中温度的变化范围为25 ℃~100℃. 相似文献
15.
16.
Experimental study of multiplexed holographic gratings recorded in a photopolymerizable silica glass
A. Murciano L. Carretero S. Blaya R.F. Madrigal A. Fimia 《Applied physics. B, Lasers and optics》2006,83(4):619-622
Recently the capability of photopolymerizable sol–gel materials to angular multiplex holographic gratings has been demonstrated [1, 2]. In this study, holographic transmission gratings were recorded using angular multiplexing in a silica glass doped photopolymer holographic recording material. The time interval between exposures and the angular selectivity were analyzed, in particular their effects on the dynamic range. By using the optimal parameters gratings of similar response were achieved with values of M/#=4.8, as well as good values of diffraction efficiency with high photosensitivity. PACS 42.40.Pa; 42.70.Ln 相似文献
17.
Dark diffusional enhancement of holographic multiplexed gratings in phenanthrenequinone doped poly(methyl methacrylate) photopolymer 下载免费PDF全文
In this paper, we experimentally investigate the dark diffusional enhancement of the optimized multiplexed grating in the phenanthrenequinone doped poly (methyl methacrylate) (PQ-PMMA) photopolymer. The possibility of improving the holographic characteristics of the material through the dark enhancement is demonstrated. The optimal preillumination exposure and the optimal time interval between exposures are extracted to obtain the optimized diffraction efficiency, and their values are 3.4×103 mJ/cm2 and 2 min, respectively. The dark enhancement of the multiplexed grating is presented as an effective method to improve the response region and the dynamic range and to prevent saturation of the material. The dependence of the phenanthrenequinone concentration on the increment of the refractive index modulation is quantitatively studied, which provides a significant basis for improving the homogeneity in the multiplexed gratings using a quantitative strategy. Finally, a simple experimental procedure using the dark enhancement is introduced to improve the homogeneity of the diffraction efficiency and to avoid the complex schedule exposure. 相似文献
18.
Kotakonda Pavani Izabela Naydenova Jallapuram Raghavendra Vincent Toal 《Optics Communications》2007,273(2):367-369
Surface relief patterns are one of the promising possibilities for the fabrication of liquid crystal (LC) electro-optical devices. Optically recorded surface relief gratings in an acrylamide based photopolymer were filled with the liquid crystal to fabricate liquid crystal diffraction gratings. E49 liquid crystals were used in this work. The switching behaviour of the diffraction grating was investigated by measuring the intensity in the first order when an electric field was applied. 相似文献
19.
V. V. Shelkovnikov E. V. Vasil’ev T. N. Gerasimova E. F. Pen A. I. Plekhanov 《Optics and Spectroscopy》2005,99(5):806-815
The dynamics of recording holographic diffraction gratings in photopolymer material using 10-ns pulses of Nd:YAG laser radiation (532 nm) was investigated. The formation of permanent and intermediate gratings was observed. Optimization of the photopolymer composition for pulsed recording was performed. The kinetic photopolymerization models taking into account the mechanisms of radical destruction due to recombination and by impurities are verified. Measurement of the recording kinetics at different recording angles showed that diffusion does not affect the hologram formation for times of the same order of magnitude as the recording duration (0.1 s) at a length of the grating half-period. Samples of the photopolymer composition in triethanolamine were investigated and diffusion of oligomeric acrylamide molecules was revealed. The diffusivity was found to be 1.1 × 10?9 cm2/s. 相似文献