Pal Greguss

Experiments in holographic video imaging

Reduction of the information content of a hologram to the minimum necessary to support strong spatial perception makes possible the interactive computation, transmission, and display of three-dimensional animated holographic images.

Holographic optical security systems

One of the most successful applications of Holography,in recent years,has been its use as an optical security technique.Indeed the general publics awareness of holograms has been greatly enhanced by the incorporation of holographic elements into the VISA and MASTERCHARGE credit cards.Optical techniques related to Holography,are also being used to protect the currencies of several countries against the counterfeiter. The mass production of high quality holographic images is by no means a trivial task as a considerable degree of expertise is required together with an optical laboratory and embossing machinery.This paper will present an overview of the principal holographic and related optical techniques used for security purposes.Worldwide, over thirty companies are involved in the production of security elements utilising holographic and related optical technologies.Counterfeiting of many products is a major criminal activity with severe consequences not only for the manufacturer but for the public in general as defective automobile parts,aircraft components,and pharmaceutical products, to cite only a few of the more prominent examples,have at one time or another been illegally copied.

Optical tomography by heterodyne holographic interferometry

Investigations of transparent objects like stationary plasmas on the basis of hologra- phic interferometry are difficult because of the relatively small fringe shift caused by these phase objects. For tomographic reconstruction procedures the phase shifts derived from the interferograms have to be particularly accurate , otherwise the reconstruction of the refrac- tive index distribution of the inhomogeneous plasmas is not reliable. The highly resolved phase profiles can be obtained by the use of spatial heterodyning, providing an accuracy of 2n/20 in the determination of the phase. A test of the optical arrangement and the computer-tomographic reconstruction algorithms is performed. The method is applied to diagnostics of different plasmas, such as high frequency plasmas and dc-glow-discharges. A special feature of these investigations is the use of resonance interferometry, in order to determine spatial distributions of particle densities of certain atoms in distinct states.

Automated systems for quantitative analysis of holograms

In this paper, fundamentals of hologram interferometry are discussed, procedures for recording and recon- struction of holograms are presented, methods for quantitative interpretation of holographic data are outlined, and representative systems for automated holographic analysis are described. In these discussions, emphasis is placed on quantitative analysis of holographic data. Selected applications are illustrated with representative examples.

A collection of personal notes on Dennis Gabor

What follows are anecdotes and remarks offered to me on the person of Dennis Gabor by participants of this conference. They reveal the human and intellectual sides of him not found in his formal publications. These notes are quoted verbatim.

Difference holographic interferometry: an overview

The difference holographic interferometry (DHI) may be used for direct optical compa- rision of two nominally identical objects (master and test) and to display the re- sults of the comparision in form of interference pattern related to the difference in deformation, shape or refractive index change of the two objects. After a general discussion of concepts the main techniques of the DHI will be intro- duced, and typical applications presented.

Display and applied holography in culture development

The analysis of possible applications of the modern science achievements in various spheres of culture is one of the important and rather actual prob- lems of the present. In this respect optical holography, as a new method of recording and reconstruction of light fields, affords extraordinary potentia- lities to be applied in the domain of culture, viz, in art and museology, un- common to optics and quantum electronics. These possibilities are analyzed in the presented paper. It is also connected with the idea to show for the museo- logists, who are not very much acquainted with this new field, the real achie- vements in holography, different aspects of their applications in the museum life and to discuss these possibilities by the rather simple way.

Reducing and magnifying holograms

Reduced and magnified holography by telescope and zoom-like system have been proved to be aberration-free. Theoretical and experimental details are analyzed either in continuous and pulse holography.

Holography and education

It is altogether fitting that in this commemorative conference, we celebrate the one application of holography that would have pleased Dennis Gabor the most, its contribution to culture and education. Among the many uses of holography, the most frequently lauded are display, interferometry, HOE, and a myriad of other technical applications. Seldom mentioned is its important contribution to culture and education, the theme of this conference. Herein we wish to argue this case, and detail the steps we have taken to implement it to a broad spectrum of the U. S. public over the last twenty years. With the consolidated effort of colleagues around the world, we expect the subject of holography to become an integral part of basic education, starting from elementary school.

Theoretical background and practical processing techniques for art- and technical-work in dichromated gelatin holography

In this paper the steps necessary for plate making and processing for dichromated gelatin holography will be discussed.. This article will refer to work of other people as well as work done in my own laboratory. When dichromated gelatin is used as a recording-medium special effects will occur. These effects are not, or not in the same extension, present when other recording-media are used. Mostly these effects are caused by the difference in which the recording is stored in the photo-sensitive layer. Whereas, in the case of silverhalide, the change of refractive-index of the silver-molecules embedded in gelatin is used, in the case of dichromated gelatin the change of retractive- index of the gelatin itself is used. This difference has a major influence on parameters such as efficiency, spectral replay response and resolution.