一种全可见光敏感的光致聚合物全息特性研究

制备了一种对整个可见光波段都敏感的光全息存储材料,并研究了该材料的透过率、衍射效率、灵敏度等全息特性.用He-Ne激光器633 nm和Ar+ 激光器514 nm,488 nm,476 nm四种波长的光曝光,材料的饱和衍射效率最大为66%,最小为48%;最高灵敏度为8.06×10－3 cm2/mJ.最高折射率调制度为4.22×10－4.用多波长存储时,不同波长的光可存储多幅全息图,且再现图像清晰.结果表明,该材料是较好的高密度数字全息存储材料.     

A wideband sensitive holographic photopolymer

A novel wideband sensitive dry holographic photopolymer sensitized by rose bengal (RB) and methylene blue (MB) is fabricated, the holographic storage characteristics of which are investigated under different exposure wavelengths. The result shows that the sensitive spectral band exceeds 200 nm in visible light range, the maximum diffraction efficiency under different exposure wavelengths is more than 40% and decreases with the decrease of exposure wavelength, the exposure sensitivity is not change with the exposure wavelength.This photopolymer is appropriate for wavelength multiplexing or multi-wavelength recording in digital holographic storage.     

新型双染料敏化的宽带光聚物全息特性研究

报道了一种新型、两种染料共同敏化的宽带响应光聚物材料.该材料使用孟加拉玫瑰红和亚甲基蓝作为联合光敏剂,由于混合染料的加入,使材料的感光光谱范围大大加宽.用四种波长的光对样品进行曝光,衍射效率均大于40%,最高可达80%,适合于多波长存储,分别用不同波长的激光在样品同一位置存储了四幅不同的图像,其再现图像效果良好,表明该材料是一种较理想的多波长全息存储材料.     

一种核黄素敏化的宽带全息记录材料

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.     

基于体全息技术的波分解复用(WDM)器件研究

为了寻求更高质量和密集度的WDM器件，对体全息技术制作WDM器件的新方法进行了研究。利用耦合波理论讨论了光折变多重体全息光栅作为波长滤波器实现波长解复用的基本原理。通过理论分析得出了最大衍射效率、最佳写入光强比与耦合强度大小的关系表达式。考虑有效电光系数和空间电荷场随写入光路几何组态的变化关系，以及各信道衍射光波长、衍射角等因素对曝光时序的影响，利用递推法推导出更为精确的曝光时序。采用高亮度溴钨灯代替价格昂贵的大功率可调谐激光器作为波长解复用光源，设计出基于体全息技术的16通道波分解复用器的实验方案。理论分析表明，该器件可将波长相隔0.8nm的谱线分开约1.0mm，这有助于实现密集波长的解复用。     

The changes of holographic characteristics of photopolymer induced by temperature

The changes of holographic characteristics of photopolymer induced by temperature are studied experi-mentally. The results show that the exposure sensitivity increases with the increase of temperature. Themaximum diffraction efficiency and the final maximum diffraction efficiency increase with the increaseof temperature when the temperature is lower than Tg (glass transition temperature), while they decreasewith the increase of temperature when the temperature is higher than Tg. The effect of the change oftemperature on the saturation refractive index modulation is very weak.     

导致光聚物全息存储布喇格偏移因素的研究

研究了光聚物高密度全息存储材料在全息记录过程中曝光量、曝光时间、厚度收缩比例、折射率调制度及记录角度等因素对布喇格偏移的影响规律,结果表明:曝光量一定时,布喇格偏移与曝光时间的关系不大,当曝光量不一定时布喇格偏移随曝光时间增加缓慢增加最后达到饱和;而布喇格偏移随厚度收缩比例和折射率调制度的增加以接近正比例的关系增加;记录光栅的倾斜度越大则布喇格偏移也越大.这些结论对光聚物高密度全息存储研究具有重要的意义.     

Dynamic analysis of holographic gratings in amulti-wavelength visible light sensitive photopolymer

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.     

Optimization of multiplexed holographic gratings in PQ-PMMA for spectral-spatial imaging filters

Holographic gratings formed in thick phenanthrenquinone- (PQ-) doped poly(methyl methacrylate) (PMMA) can be made to have narrowband spectral and spatial transmittance filtering properties. We present the design and performance of angle-multiplexed holographic filters formed in PQ-PMMA at 488 nm and reconstructed with a LED operated at approximately 630 nm. The dark delay time between exposure and the preillumination exposure of the polymer prior to exposure of the holographic area are varied to optimize the diffraction efficiency of multiplexed holographic filters. The resultant holographic filters can enhance the performance of four-dimensional spatial-spectral imaging systems. The optimized filters are used to simultaneously sample spatial and spectral information at five different depths separated by 50 microm within biological tissue samples.     

Rainbow holographic interferometry

A one-step rainbow holographic process is applied to holographic interferometry. Experimental demonstrations of double exposure and time-average interferograms are included. Comparison is made with the conventional holographic process. We found that the rainbow process provides better equality and less speckle noise.     

番红花红T光敏感光致聚合物全息存储材料

制备了一种以番红花红T为光敏剂的新型全息存储材料,主要用Ar⁺激光器的514.5nm波长的绿光研究材料的全息特性.研究表明,该材料具有较高的衍射效率、曝光灵敏度和较大的折射率调制度,衍射效率近40%,灵敏度为7.22×10^-4cm²/mJ,折射率调制度为3.65×10^-4,同时,在读出时必须考虑布拉格偏移对全息存储的影响.在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. 关键词： 全息存储 光致聚合物 衍射效率 布拉格偏移     

利用偏振全息记录可重复擦写的偶氮相位光栅

利用偏振全息技术在偶氮苯侧链聚合物薄膜上进行了记录全息相位光栅的研究.从理论和实验两方面分析了不同的偏振全息模式、偶氮高分子聚合物材料和全息曝光时间对相位光栅生成的影响.通过实验比较,确定了最佳的实验条件,在形成折射率相位光栅的同时,最大限度的避免了由于大分子运动而导致的表面起伏对相位光栅的破坏,并在此基础上,记录了可重复擦写的全息相位光栅.这种全息光栅制作比较方便,光栅系数可以方便的调整,在室温下非常稳定并且能用圆偏振光完全擦除后重复写入.     

Comparative accuracy of holographic interferometry and speckle photography for out-of-plane deformation measurement

Out-of-plane deformation of a surface can be measured either by recording a double exposure hologram, or by taking a double exposure speckle photograph with the camera deliberately de-focused. In the latter case the local surface tilt is measured, and the profile change subsequently obtained by integration. It is shown that errors can arise in speckle photography due to focusing the camera incorrectly, whereas the holographic method is not affected instrumentally. The sensitivity of the speckle method can approach that of holographic interferometry, but without requiring the same interferometric stability of recording apparatus.     

Holographic properties of Fe3O4 nanoparticle-doped organic–inorganic hybrid photopolymer

An organic–inorganic hybrid photopolymer doped with sodium-citrate-coated Fe₃O₄ nanoparticles was fabricated. The experimental results showed that the maximum diffraction efficiency could be increased from 69 to 90%, and the maximum refractive index modulation improved from 1.386 × 10⁻³ to 2.083 × 10⁻³. It also found that the volume shrinkage during holographic exposure was noticeably suppressed without affecting the optical quality of the photopolymer.     

掺杂TiO2纳米颗粒的抗缩皱光致聚合物全息特性的研究

报道了一种掺杂亲水性TiO₂纳米颗粒的丙烯酰胺基光致聚合物厚膜的全息特性.实验结果表明,掺杂TiO₂纳米颗粒后的聚合物材料不仅在曝光过程中厚度缩皱有了明显的降低,而且衍射效率和其他性能参数都有了一定的改善,同时存在一个最佳的掺杂浓度,使得材料的最大衍射效率可以达到92.3%,最大折射率调制度达到2.09×10^-3,体积缩皱降低至0.80%. 关键词： 全息 光致聚合物 衍射效率 布拉格偏移     

铌酸锶钡晶体的光存储实验研究

通过全息存储光路调整,采用适当的曝光时间,在铌酸锶钡晶体中得到清晰的全息存储图象,并通过高压固化存储图象,测得全息存储时间衰减曲线.     

The choice of beamsplitter for minimum exposure time in photoresist holography

It is shown that for a linear holographic recording material in which a dc intensity level in fringes of contrast less than unity does not affect the maximum attainable diffraction efficiency, the minimum exposure time is obtained when the available power is divided equally into reference and object beams at the beamsplitter. Certain photoresists when appropriately processed approach this ideal. It is shown that for particular photoresists (Shipley AZ-1300 series), nonlinearities cause the optimum power ratio at the beamsplitter to be other than 1 : 1, and it is shown how the optimum power ratio may be determined.     

Image magnified lensless holographic projection by convergent spherical beam illumination

In liquid crystal spatial light modulator(SLM)-based holographic projection, the image is usually displayed at a distant projection screen through free space diffraction from a computer-generated hologram(CGH). Therefore,it allows for removing of the projection lens for the sake of system simplification and being aberration free, known as the "lensless holographic projection". However, the maximum size of the optical projected image is limited by the diffraction angle of the SLM. In this Letter, we present a method for the implementation of image magnification in a lensless holographic projection system by using convergent spherical wave illumination to the SLM.The complete complex amplitude of the image wavefront is reconstructed in a lensless optical filtering system from a phase-only CGH that is encoded by the off-axis double-phase method. The dimensions of the magnified image can break the limitation by the maximum diffraction angle of the SLM at a given projection distance.Optical experiment results with successful image magnification in the lensless holographic projection system are presented.     

采用空间—角度复用的盘式三维全息存储

提出基于空间－角度复用技术的盘式三维全息存储方案，给出这一技术的基本原理，并采用简化的光线分析方法对该方案的可行性进行分析。研究表明，这是一种能提供高密度和高数据传输率，而读写系统又相对简单的盘式三维全息存储方案，具有潜在的应用前景。     

制作具有预期位相调制度的卤化银乳胶位相型薄全息光栅的研究

提出了一种制作具有预期位相调制度的卤化银乳胶位型薄全息光栅的方法。它通过分析所拍摄的第一张全息光栅的数据来获得最佳曝光参量，从而使继后的拍摄，在同样的实验条件下能获得所预期的位相调制度。文中给出了这方法的理论分析和某些应用。