Computer-generated holograms using (Se,S)-based chalcogenide amorphous film

New computer-generated holograms using As-Se-S-Ge chalcogenide amorphous film are presented. The chalcogenide film is sensitive to an electron beam and has a high resolution (3000 lines/mm). Utilizing a fine focused electron beam and a high resolution of the amorphous film, full size computer-generated holograms can be directly fabricated without reducing process, and thus a real-time process is possible. Computer-generated holograms with 64 × 64 cells have been experimentally demonstrated in 560 μm × 560 μm hologram size.     

全息图模压复制技术(Ⅰ)——浮雕型彩虹全息图的形成

浮雕型彩虹全息图是全息图模压复制的基础,它从根本上决定了最后成品的质量和性能。本文在介绍普通彩虹全息图和2D/3D彩虹全息图的基础上,着重介绍了我们在实验中总结出的两种形成浮雕全息图的工艺技术,即用国产的BP-212紫外正型光致抗蚀剂制造浮雕全息图和用银盐感光材料PD法制造浮雕全息图的技术。     

Hologram recording in glass and direct reconstruction using visible-wavelength laser beam

We propose a method of hologram recording in a glass plate by corona charging. The holographic recording materials used in this study are conventional soda-lime glass and azobenzene polymer film. A Fourier transform hologram on an azobenzene polymer film coated on the glass plate is recorded in the glass plate by corona charging. After removing the polymer film, the hologram recorded in the plate can be reconstructed using a visible-wavelength laser beam. The first-order diffraction efficiency of the hologram at a wavelength of 532 nm is 0.03%; the efficiency depends on the depth of the surface relief structure on the azobenzene polymer film and the corona-charging time. The hologram recorded in the glass plate has high environmental resistance.     

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。     

三维漫射体单波长真彩色彩虹全息术

提出一种新的三维漫反射物体真彩色彩虹全息术,在普通一步法真彩色彩虹全息术的基础上,用单波长激光逆光路再现,可在同一种记录介质上一次曝光记录三维物体的真彩色全息图.因而特别适合于制作光致抗蚀剂模压全息母板.     

The use of commercial fine-grain films for computer-generated holograms

The possible use of commercial fine-grain films for computer-generated binary holograms is described. Three different types of film are used. Image quality improves with film resolution but if the resolving power is higher than a minimum value needed for the phase level resolution, the contrast (γ value) of the film has a pronounced effect on the quality of the image reconstructed optically from the hologram. The possible generation of binary holograms by computers with reduced central memory is also studied.     

Holographic properties of chalcogenide-metal photosensitive materials

A new type of photosensitive material using a chalcogenide-metal system can be used for recording holograms. This hologram is thin, recorded by amplitude and/or phase variations; a relief hologram is also available. It is shown that this material does not require development and fixation procedures and can be used for real-time holographic interferometry.     

Un correlateur optique par filtrage chromatique fonctionnant en temps reel et en source etendue de lumiere blanche

Relief-type holograms were copied on PVC sheets from a master made on a photosensitive As-Se-Ge amorphous film. One hundred hologram copies could be printed successively without degradation of the reconstructed image quality. Typical diffraction efficiency of the copied hologram was about 2%.     

Hologram Recording in Various Glass Plates by Corona Charging

We propose techniques of hologram replication in glass plates and reconstruction on another film by corona charging. A surface relief hologram on an azobenzene polymer film was recorded in the form of electric polarization in glass plates that include alkali cations by corona charging at high temperature. The hologram recorded in the glass plate is stable for more than 1 month at room temperature. After removal of the azobenzene polymer film from the plate, poly(methyl methacrylate) (PMMA) film was spin-coated onto the plate. The hologram recorded in the plate was reconstructed with the same surface relief structure on the PMMA film by corona charging again at 110°C.     

Hologravure as a computer-generated and laser engraved scratch hologram

We presented “hologravure” as the generalization of a scratch hologram, generated by computer from a three-dimensional (3D) model by using an appropriate software, and laser-drawing with a conventional engraver-laser system. For making this type of computer-generated hologram, neither diffractive optics, nor mask pattern or photo-reduction of a transparency onto a high resolution film plate is needed. The shape of a 3D virtual object is encoded in a two-dimensional (2D) multiple circular-scratch drawing. A computer program was created for generating the holograms. Hologravures representing several 3D models are engraved on different materials, and the quality of the lines traced by the CO₂ laser is considered. Sheets of acrylic, polycarbonate, glass and thermo-resistant pieces of acetate were tested. Reconstructed images of all this computer-generated and laser engraved holograms and also of computer assisted and hand-drawn scratch holograms, synthesized by means of the same software are shown.     

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.     

Binary computer-generated holograms for security applications from a synthetic double-exposure method by electron-beam lithography

We have developed a new multiplexing method for producing binary computer-generated holograms (CGH's) for security applications. This method is based on double recording of two types of coding method upon binary CGH's. The CGH synthesized by the proposed method can have multiple image planes from the region close to the hologram (image region) to infinity (Fraunhofer region) without severe degradation of reconstructed images in the image region. A CGH containing simultaneous image- and Fourier-type holograms is fabricated by electron-beam lithography. Some experimental results are presented.     

室外自然场景体视彩虹全息图的制作方法研究

本文介绍了一种用连续激光制作室外自然场景体视彩虹全息技术. 先用自制的透镜线阵照相机拍摄室外自然场景经透镜所成像的初级体视图，然后用连续激光照明初级体视图，原光路返回，透镜线阵此时不仅起到成像作用，而且起到了彩虹全息术中的狭缝作用. 这种技术也适用于室外动态物体. 本文制作了室外自然场景的体视彩虹全息图，并给出了实验结果.     

Fast reconstruction of multiple off-axis holograms based on a combination of complex encoding and digital spatial multiplexing

An algorithm is proposed for the fast reconstruction of off-axis digital holograms based on a combination of complex encoding(CE) and spatial multiplexing(SM). In this algorithm, every two off-axis holograms recorded in sequence are first assembled into a CE hologram using the CE method, and then four of the CE holograms are again encoded into one complex spatial multiplexing(CSM) hologram based on the SM algorithm. It is demonstrated that the eight holograms encoded into such one CSM hologram can be quickly reconstructed by performing a two-dimensional(2D) Fourier transform(FT) on the CSM hologram. Using this method, the eight 2D FTs required for the reconstruction of the eight holograms in the conventional spatial filtering methods can be simplified to a process with only one 2D FT, which can largely improve the computation efficiency with the     

复杂三维场景数字全息图隐藏面问题研究

从数字全息图制作原理出发,分析了隐藏面对数字全息图再现像的影响,得出在制作复杂场景数字全息图时必须进行消隐.在此基础上提出了一种消隐方法,通过寻找连接全息面上每一采样点与场景中每一采样点之间的虚拟光线与场景的交点中到全息面距离最短的交点集来消隐.最后给出了这种方法的原理和计算机模拟结果.     

向列相液晶动态全息存储特性的研究

研究了C60掺杂向列相液晶中全息光栅的形成, 实验中我们利用了一种特殊的全息再现方法：即低电压记录, 高电压再现, 观察到清晰的全息再现像. 实验结果表明样品具有良好的全息存储能力. 分析了电压对实验结果的影响, 实验表明：为了避免动态散射的出现应使用较低的记录电压, 而再现时应采取高电压以重新激发隐藏的光栅, 提高再现的质量.     

Computer-Generated Image Holograms for 3D-Display

Computer-generated image holograms are particularly useful for 3D-display applications. We discuss the properties of the reconstructions obtained with this hologram type. Conditions are given which must be fulfilled to ensure a disturbance free reconstruction. A new efficient algorithm is presented which implements the hidden surface effect for synthetic image holograms.Presented at the International Commission for Optics Topical Meeting, Kyoto, 1994.     

双视三维动态反射全息图合成技术研究

在综合了白光反射全息、像全息、体视对全息和合成全息等多种技术的基础上 ,提出了一种制作双视三维动态反射全息图的合成技术 ,给出了制作该类全息图有关参数的设计方法 ,成功地制作了一种适于近距离观察的双视三维动态反射全息图样品 ,有效消除了用双眼观察普通动态全息图时常出现的像混淆现象 ,其清晰的三维立体图像、生动而逼真的动态艺术效果 ,具有较高的艺术欣赏和防伪价值 ,为该类全息产品的开发探索了一条可行途径     

High speed holocinematography using spatial multiplexing for image separation

Up to eight holograms are successively recorded at maximum repetition rates of 20kHz. A multiply Q-switched ruby laser is used to produce the series of coherent light pulses for hologram exposure. All holograms are recorded on the same plate. Image separation of different holograms is achieved by spatial multiplexing using a rotating disk with apertures directly in front of the holographic plate. The performance of the technique is demonstrated by reconstructions of a hologram series taken of laser produced cavitation bubbles following optical breakdown in water.