on Optical information systems 

About: on Optical information systems is an academic journal. The journal publishes majorly in the area(s): Fourier transform & Holography. It has an ISSN identifier of 0886-5809. Over the lifetime, 181 publications have been published receiving 624 citations.

Comparison of fitness scaling functions in genetic algorithms with applications to optical processing

Abstract: Many optical or image processing tasks reduce to the optimization of some set of parameters. Genetic algorithms can optimize these parameters even when the functions they map are fairly complicated, but they can only do so the point where the fitness functions they are given can differentiate between good results and the best result. This can occur when the optimal point is in a region (in a three dimensional example) such as a plateau, where all the surrounding points are of very nearly the same fitness. If there are multiple peaks in close proximity, all of nearly the same fitness but with very deep divides, the algorithm will have trouble 'hopping' from one to the other. One way to overcome these obstacles is to scale the fitness values given by the fitness function, thereby gently modifying the fitness function from the point of view of the algorithm, thus rewarding the more fit solutions to a higher precision than would naturally occur. Four such scaling methods will be compared based upon their handling of a sample set of optical processing data. Success will be determined by comparing the variance over time, selection pressure over time, and best of generation graphs.

Reconfigurable video

Abstract: The problem of efficient access to full-motion video resource materials in an educational context is explored. Reconfigurable VideoTM is a software technology designed to assist in the organization and delivery of visual databases on optical videodisc. A prototype project is described which integrates a relational database of documentary video, audio transcripts, and expert analysis into a multi-media educational research tool for the humanities and social sciences. \"Marital Fracture,\" a case study of a divorce by Dr. Rosalyn Gerstein, serves as a model for future interactive video resources. Specialized software allows for the creation of electronic pages which incorporate video \"footnotes\", and the synchronization of text to video. A graphical user-interface for editing and restructuring the movie materials is presented. Introduction to the Problem The last decade has seen a tremendous increase in the use of video materials in curriculum, with few corresponding developments in technologies which allow simple and effective management of video resources by the people who use them. At universities all over the country, case-study videotape is becoming the preferred mode of teaching the complexities of decision-making and behavior: in medicine, business, law, and psychology. Paper case-studies are hindered by the layers of interpretation that separate students from the situation being examined. The language used to present the paper casestudy is already layered with judgments that students must accept at face value; analysis becomes a game of manipulating words and abstract concepts. The critical phase of translating one's own perceptions into a personally insightful viewpoint is undermined. In contrast, video presentation is capable of simulating or actually documenting the characters and situations in a case study, in a way that allows students to extract information using their own senses, and to arrive at judgments using their own mental processes. This is not to say that video is an \"objective\" medium, only richer and more realistic than printed materials. Unfortunately, videotape is found lacking in several areas. Chief among these complaints is that viewer's simply can't get what they want when they want it. Videotape as a medium consists of the serial delivery of information; programs never divulge their agenda to their viewers because direct access to content isn't possible, preventing individual exploration and access. It is impossible to provide a 'table of contents\" for a videotape, due to the lack of addressing capability on all but the most expensive professional equipment. Hence the viewer can neither browse nor annotate, but must passively receive the information in the order in which it was originally assembled. Another difficulty is the inability to render high-density supplementary textual information in limited NTSC video resolution. Videotape also deteriorates rapidly with use, requiring special care to maintain archival quality. Finally, videotape presentations are incapable of being rearranged even slightly without a complete reconstruction. Yet the teaching power of moving video is undeniable, especially in applications which require students to perceive phenomena directly and develop their own interpretations. Professionals and academics have responded enthusiastically to the innovative quality of Dr. Rosalyn Gerstein's work with documentary video case studies. The power of video comes from its ability to render actual people and situations, so that we realize that these aren't just raw statistics we're talking about, that these are complicated decisions in which there are rarely any easy answers... [In mediation] for example, I find the body language of negotiating parties to be an invaluable clue to their emotional state, and you just can't get that kind of richness out of a paper case-study. Attorney Michael Wheeler MIT Department of Urban Studies Dr. Gerstein's interests in visual ethnography and the social application of media technology led her to document a couple's marital separation, and edit a portion of the ethnography for interactive videodisc in 1982. It was the perception of the potential of these video case studies that led the author to collaborate with Dr. Gerstein in 1983 on a 2-year project at the MIT Media Laboratory, exploring alternative technologies to overcome the limitations of the videotape medium for case-study curricula. The product of this effort is Marital Fracture: A Moral Tale. As I continued to work with pictures and words, I realized that videodisc was πthe ideal distribution medium which combined television and text. Although it had never been used for portraiture or documentary before, I was excited by the application to my own material... Documentary creates a vivid record which appears to capture all one needs to re-explore meanings. The contribution of this work is in the [provision] of sufficient material (and means of access) so that viewers can study the construction and better understand the influences which make up a visual account. Dr. Rosalyn Gerstein PhD, Communication Technology and Culture

Multi-wavelength digital holographic metrology

Abstract: A digital holographic metrology technique is described for measuring the three-dimensional shape of manufactured parts. The technique uses optical fibers to set up a near equal path interferometer, steps through multiple frequencies with a tunable laser, steps through multiple phases using a fiber based phase shifter, uses an off-axis parabolic mirror to collimate the light, and generates a digital hologram that leads to surface flatness measurements accuracies better than 1 micron over large surfaces. An example result for an automobile engine part is given using a Coherix Inc., Shapix TM 2000 instrument.

RF spectrum analysis in spectral hole burning media

Abstract: We propose a novel, wideband spectrum analyzer based on spectral hole burning (SHB) technology. SHB crystals contain rare earth ions doped into a host lattice, and are cooled to cryogenic temperatures to allow sub-MHz hole burning linewidths. The signal spectrum is recorded in an SHB crystal by illuminating the crystal with an optical beam modulated by the RF signal of interest. The signal's spectral components excite those rare earth ions whose resonance frequencies coincide with the spectral component frequencies, engraving the RF spectrum into the crystal's absorption profile. Probing this altered absorption profile with a low power, chirped laser while measuring the transmitted intensity results in a time-domain readout of the accumulated RF signal spectrum. The resolution of the spectrum analyzer is limited only by the homogeneous linewidth of the rare earth ions ( 20 GHz.

Image encryption techniques based on the fractional Fourier transform

Abstract: The fractional Fourier transform, (FRT), is a generalisation of the Fourier transform which allows domains of mixed spatial frequency and spatial information to be examined. A number of method have recently been proposed in the literature for the encryption of two dimensional information using optical systems based on the FRT. Typically, these methods require random phase screen keys to decrypt the data, which must be stored at the receiver and must be carefully aligned with the received encrypted data. We have proposed a new technique based on a random shifting or Jigsaw transformation. This method does not require the use of phase keys. The image is encrypted by juxtaposition of sections of the image in various FRT domains. The new method has been compared numerically with existing methods and shows comparable or superior robustness to blind decryption. An optical implementation is also proposed and the sensitivity of the various encryption keys to blind decryption is quantified. We also present a second image encryption technique, which is based on a recently proposed method of optical phase retrieval using the optical FRT and one of its discrete counterparts. Numerical simulations of the new algorithm indicates that the sensitivity of the keys is much greater than any of the techniques currently available. In fact the sensitivity appears to be so high that optical implementation, based on existing optical signal processing technology, may be impossible. However, the technique has been shown to be a powerful method of 2-D image data encryption.