接触法复制全息图的实验

接触法复制全息图需要使母全息图与感光干板的乳胶面相向紧密接触,对母全息图进行透射照明,经冲洗处理后的曝光干板即为普通的全息图.采用低压钠灯为光源,对菲涅耳全息图进行复制实践,复制全息图的再现像清晰度比母全息图要差,但就像的质量而言层次很分明.     

浅谈全息图的复制

简要介绍了将原全息图再现和接触复制法两种全息图复制的原理与方法.进一步采用接触复制法的方法,利用激光作为光源进行了全息图的复制实验研究.实验结果表明复制的全息图再现像图像比较清晰,层次分明.     

激光全息照相实验探讨

1962年由杰尼休克提出的反射全息图的制法至今还是实验教学的一个内容。本文介绍对干版仅仅曝光一次的条件下,将白光反射再现全息图和激光透射再现全息图同时记录于同一干版上的实验。由此得到的全息照片不仅可在白光下再现。而且可在激光下再现,且两次再现的像既可相同也可不同。图1为实验光路图。如将图中物Ⅱ去掉,该图即变成记录激光透射再现全息图的光路;而将物     

超短脉冲激光选通电子学全息成象系统研究

本文介绍了最早到达光概念，分析了超短脉冲激光电子学全息实现选通最早到达光成象的原理．用超短脉冲激光拍摄全息图，相当于用多色光记录全息图，当用单色光再现这种全息图时，会给再现象造成一个模糊量．在一般全息理论中，只讨论了采用单色光记录全息图，复色光再现所造成的模糊量．因此，本文中讨论的是一个与此相反的问题，即用多色光记录全息图，单色光再现的情况，并且着重讨论了超短脉冲激光记录全息图的情况．最后得出结论，在用超短脉冲激光拍摄全息图时，最好采用象面全息术．     

一种制作多色彩全息图的新方法

本文首先提出了一种制作二维透射物彩虹全息图的新方法，即利用一专门设计的全息光学元件──色编码板，采用单光束制作所需物体的彩虹全息图；在此基础上，通过对色编码板的进一步理论设计，制作了一组对应不同主波长的色编码板，实现了记录物体的多色彩虹再现全息图。实验结果表明，此方案简便易行，光路布置灵活性高，且能有效地消除纵向色差的影响，特别适合于模压全息图制造中母全息图的拍摄，并降低了对环境稳定性的要求。     

白光再现激光全息照相的实验研究

以光的干涉和衍射为基础,讨论白光再现激光全息照相的原理,设计拍摄不同物体白光再现全息图的光路,探索能成功拍出白光再现反射全息图的条件和方法,并通过实验证明其可行性。     

浮雕全息图的转印复制技术研究

采用光学树脂作为转印介质复制浮雕全息图,适于将全息图复制到硬质基底材料上.对光敏型及热敏型两种树脂用于复制浮雕全息图进行了试验,实验结果表明：复制品的衍射效率、空间频率均接近原版全息图,并具有良好的环境稳定性.运用独特的一次转移复制工艺,工艺流程简单、设备投资少,在批量化复制生产中具有实用价值.     

全息图模压复制技术(Ⅲ)——模压复制及热冲压转印技术

模压复制是形成全息产品的最后一道工序,它类似凸版印刷,因而可以实现机械化大规模生产。本文介绍了平压、滚压工艺过程及所用的原材料及设备,同时还介绍了将模压全息图应用到别的载体材料上的热冲压转印技术。     

银盐干板的皱缩控制及其在彩色反射全息上的应用

分析了影响全息干板银盐乳胶在处理过程中收缩的几个因素，并通过实验，找出了在拍摄及处理体积反射全息图过程中，曝光量、漂白液温度及脱水的方式对乳胶收缩影响的规律.在此基础上提出控制乳胶的收缩，即控制反射全息图衍射波长的方法，从而达到彩色反射全息图的实现.实验结果表明该方法做出的全息图效果良好.     

二步法大景深反射全息图

以开拓反射全息图的景深表达能力为目的,从反射全息图的共轭物像关系出发,利用反射全息图的均匀介质耦合波理论和布拉格条件,对其白光再现像模糊作了具体的分析和讨论,得到色模糊和线模糊的表达式.指出反射全息图上不同各点对任意白光再现像点的色模糊和线迷糊的影响均存在差异,给出反射全息图白光再现像的景深表达式.实验利用二步法制作了一张景深为83 cm的反射全息图,与大景深彩虹全息图再现像相比,其再现像的立体感更加强烈.理论分析和实验结果表明,光源的再现角度和观察距离对反射全息图的再现像景深大小影响显著.在再现光垂直于反射全息图平面照明情况下,反射全息图具有最好的景深表达能力.     

利用光致聚合物的真彩色反射全息图

本文用Ar~+-Kr~+激光器的红光(647.1nm)、绿光(574.5nm)和蓝光(488.0nm)分别对准全色的光致聚合物干板制作反射光栅,给出各个反射光栅的光谱透射率曲线,由此可得最小透射率随曝光量、再现波长随曝光量变化的情况.并采用Ar~+-Kr~+激光器全谱线输出和减色滤光片一次曝光成功地拍摄了真彩色反射全息图.本文还讨论了彩色反射全息图再现像的色度坐标和彩色控制.     

A compact holographic interferometer with a single optical element

A compact holographic interferometer is presented. A key feature of the instrument is the minidiffuser used as a single optical element. Divergent diffuse waves formed on illumination of the minidiffuser by a narrow beam from a continuous wave (CW) laser are shown to be well suited for obtaining high-quality reflection holographic interferograms and holograms.     

二维彩虹全息图母版的非相干光拷贝技术

描述一种用非干光制作二维彩虹模压全息图母版的新技术。该技术用紫外灯作为记录光不原,记录系统中不用任何光学元件。记录过程不需防振条件,色彩编码 狭缝像的“彩虹版”上进行条纹复制而获得。彩虹版可以无数次重复使用,所以全息图母版的记录十分简单。该技术投资少、效率高,制出的全息图质量好,对大批量模压全息图制造有很高的实用价值。     

高精度激光参数测量系统中衰减系统的研究与评价

 分析了楔形镜和中性玻璃衰减片组对光束的衰减原理，采用反射式楔形镜作为无像差定量衰减器，并同时使用中性玻璃衰减片组微调光束能量。实验测量了LD泵浦激光模式发生器基模和高阶模条件下激光束的M­²因子,结果表明：楔形镜反射式衰减器对光束质量无显著影响，将楔形镜第一次表面反射作为无像差定量衰减，入射角在0~55°范围内，单棱镜表面反射光束能量为入射光能量的4.3%，通过多块组合可以得到更大的衰减；可采用中性玻璃衰减片组对激光光束的衰减进行精细控制，使其满足CCD探测器动态范围要求。该结论可为高精度激光参数测量装置光衰减系统的研制提供理论依据。     

Dynamic holography in alkali metal vapour

Problems of dynamic hologram recording on resonant absorption lines of alkali metal vapour are discussed. Light beams and media parameters are determined that are necessary for hologram recording with usable efficiency. The effects of thermal atomic motion and the radiative transport of excitation influence on the spatial frequency transfer function of two-level media are investigated. Results of hologram recording in vapour of Rb (780.0 nm) and Cs (852.1 nm) using low-power CW-lasers are presented. Transmission holograms in the volume media and reflection holograms near the boundary of the resonant vapour and the dielectric are compared. For transmission holograms the advantage of collinear read-out when using pure vapour in comparison with a counterpropagating read-out is shown, and this makes it possible to achieve higher values of hologram efficiency over a wide range of atomic density. It is shown that reflection hologram recording is characterized by higher resolution, as compared with hologram recordings in the volume of extended media. Problems of metal vapour hologram usage for laser parameter control are discussed. The feasibility of holograms in Cs-vapour usage as a spectral-selective real-time feedback element in a semiconductor laser external cavity is shown.     

利用傅里叶变换全息图实现彩色胶片存储

本文提出一种利用傅里叶变换全息图存储彩色胶片的方法.在参考光路和透明片后置入采栅,以红、绿、蓝三种波长记录+1级谱的点全息图.当三色光分别照明各自的全息图时,可再现两个真彩色图像.     

Assessment of acoustic pressure holograms from membrane velocity measurements

The aim of this paper is to demonstrate experimentally the possibility of acquiring acoustic pressure holograms using a light membrane and a scanning laser vibrometer. The velocity of a light membrane placed in an acoustic field can be measured without contact by means of a laser vibrometer. The ideal membrane must be optically reflective, acoustically transparent (having as little mass as possible), impermeable, and mounted without tension. The measured velocity is equal for continuity reasons to the normal acoustic velocity, but differs from the acoustic velocity without the membrane because the membrane is never completely transparent to acoustic waves. The effect of the mass of the membrane can be taken into account to correct this difference. Then, acoustic pressure holograms can be deduced from velocity holograms using the 2D Discrete Fourier Transform. An experimental validation is carried out; acoustic pressures derived from laser measurements are compared with microphone measurements, with a very satisfying match over a wide frequency range.     

Role of recording geometry in the performance of spectral diversity filters with spherical beam volume holograms

We present experimental demonstrations of spectral diversity filters with spherical beam volume holograms for multimodal multiplex spectroscopy. Major properties of filters under diffuse-light illumination are discussed. The comparisons of spectral diversity between the transmission geometry holograms and the reflection geometry holograms are also studied. The results show that there is a trade-off between the degree of the spatial coherence of the source and the spectral diversity of the filter. We also conclude that the reflection geometry holograms have better spectral diversity and less sensitivity to the spatial coherence of the source.     

Comparison of the laser ablation process on Zn and Ti using pulsed digital holographic interferometry

Pulsed digital holographic interferometry has been used to compare the laser ablation process of a Q-switched Nd-YAG laser pulse (wavelength 1064 nm, pulse duration 12 ns) on two different metals (Zn and Ti) under atmospheric air pressure. Digital holograms were recorded for different time delays using collimated laser light (532 nm) passed through the volume along the target. Numerical data of the integrated refractive index field were calculated and presented as phase maps. Intensity maps were calculated from the recorded digital holograms and are used to calculate the attenuation of the probing laser beam by the ablated plume. The different structures of the plume, namely streaks normal to the surface for Zn in contrast to absorbing regions for Ti, indicates that different mechanisms of laser ablation could happen for different metals for the same laser settings and surrounding gas. At a laser fluence of 5 J/cm², phase explosion appears to be the ablation mechanism in case of Zn, while for Ti normal vaporization seems to be the dominant mechanism.     

Hologram multiplexing in acrylamide hydrophilic photopolymers

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.