A Knowledge Based System For Electron Beam Fabrication Of Computer Generated Holograms

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A Knowledge Based System For Electron Beam Fabrication Of Computer Generated Holograms

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Author : Hamid Farhoosh
language : en
Publisher:
Release Date : 1991

A Knowledge Based System For Electron Beam Fabrication Of Computer Generated Holograms written by Hamid Farhoosh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with categories.

E Beam Written Computer Generated Holograms

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Author : Steven M. Arnold
language : en
Publisher:
Release Date : 1983

E Beam Written Computer Generated Holograms written by Steven M. Arnold and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with categories.

This final report describes a three-year research program to investigate computer generated holograms produced by electron beam lithography. Because they are light weight and can create wavefronts of arbitrary complexity, computer generated holograms are attractive for applications such as optical data processing and optical testing. To be practical, these elements must have large space-bandwidth products, and have the qualities of high diffraction efficiency, low scattering, low aberration and low cost, as compared to conventional optics. Developed have been generalized encoding algorithms and fabrication techniques for producing e-beam computer generated holograms having submicron feature sizes, distortion-free resolution of better than 0.4 micron, and space-bandwidth products in excess of 10 to the 7th power. E-beam lithography is superior to optical plotting for writing computer generated holograms and, with further refinement, could be extended to produce holograms having space-bandwidth products as large as 10 to the 11th power, comparing favorably with interferometrically recorded holograms.

Selected Papers On Computer Generated Holograms And Diffractive Optics

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Author : Sing H. Lee
language : en
Publisher:
Release Date : 1992

Selected Papers On Computer Generated Holograms And Diffractive Optics written by Sing H. Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Computer graphics categories.

An important feature of computer generated holograms (CGHs) is to create wavefronts that may be defined only mathematically. Since A. W. Lohmann and his colleagues invented CGHs in 1966 for spatial filtering in image processing, the applications of CGHs have multiplied to include 3-D display, optical testing, diffractive/binary optics, bifocal intraocular lenses, wavefront transformations for material processing, pickup heads for optical disks, focal plane array detection, coherent laser addition, beam steering, and optical interconnects for parallel computing and neural computing. Today, the applications of CGHs continue to expand. This book features a selection of papers that examine different aspects of the development of CGHs from the 1960s through 1990, because there is no substitute for reading the original papers on any subject, even if that subject is mature enough to have many single-aspect monographs and textbooks. It is hoped that this selection of papers will be valuable additions to many working libraries on this expanding, expansive subject.

Modeling Design And Optimization Of Computer Generated Holograms With Binary Phases

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Author : Jing Wang
language : en
Publisher:
Release Date : 2019

Modeling Design And Optimization Of Computer Generated Holograms With Binary Phases written by Jing Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.

The computer-generated hologram (CGH) has been demonstrated to play an important role, since its invention by Lohmann in 1960s, in many applications such as wavefront engineering, structured illumination and optical display, etc. In this thesis, the modeling, design and optimization of CGH with binary phases are studied. We considered a practical projection image system with certain working specification, e.g. working distance of 40 cm, depth of field of 10 cm and a diffraction angle of 53 degree for 632 nm working wavelength, and then designed and optimized a binary-phase hologram by direct binary search for this image system. The hologram was fabricated by E-beam lithography. To achieve the required diffraction angle, we discussed the optical architecture in holographic projection image system. The designed CGH and holographic projection image system were validated experimentally by optical reconstruction. Since the pixels will eventually cluster to form polygonal apertures in hologram, which can be seen clearly during the process of direct binary search, we proposed a new approach to directly design polygonal apertures based on triangular layout in CGH of a large number of pixels. The diffraction of aperture was calculated by analytical Abbe transform. The reconstructed image can be expressed as a coherent addition of diffraction patterns from all the straight edges of different orientations and lengths. A two-step optimization including genetic algorithm with local search for encoding binary phases of apertures, followed by direct search for floating covertices of the elementary triangular apertures was developed. We further proposed a quadrilateral aperture layout, which provides more degrees of freedom and can form more diverse polygonal apertures in holograms. The parallel genetic algorithm with local search was adopted to assign binary phases in the first step, and direct search was then used to optimize of locations of covertices of quadrilateral apertures in the second step. Three different schemes for the two-step algorithm were discussed to provide flexible ways to balance the optimization performance and time cost.

Application Of Diffractive Optics To Free Space Optical Interconnects

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Author : Kristopher S. Urquhart
language : en
Publisher:
Release Date : 1992

Application Of Diffractive Optics To Free Space Optical Interconnects written by Kristopher S. Urquhart and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with categories.

Optical Interconnections For Vlsi Computational Systems Using Computer Generated Holography

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Author : Michael R. Feldman
language : en
Publisher:
Release Date : 1989

Optical Interconnections For Vlsi Computational Systems Using Computer Generated Holography written by Michael R. Feldman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.

Scientific And Technical Aerospace Reports

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Author :
language : en
Publisher:
Release Date : 1994

Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Aeronautics categories.

Wavefront Analysis And Calibration For Computer Generated Holograms

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Author : Wenrui Cai
language : en
Publisher:
Release Date : 2013

Wavefront Analysis And Calibration For Computer Generated Holograms written by Wenrui Cai and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.

Interferometry with computer generated holograms (CGH) has evolved to be a standard technology for optical testing and metrology. By controlling the phase of the diffracted light, CGHs are capable of generating reference wavefronts of any desired shape, which allows using of interferometers for measuring complex aspheric surfaces. Fabrication errors in CGHs, however, cause phase errors in the diffracted wavefront, which directly affects the accuracy and validity of the interferometric measurements. Therefore, CGH fabrication errors must be either calibrated or budgeted. This dissertation is a continuation and expansion of the analysis and calibration of the wavefront errors caused by CGH in optical testing. I will focus on two types of error: encoding error and etching variation induced errors. In Topic one, the analysis of wavefront error introduced by encoding the CGH is discussed. The fabrication of CGH by e-beam or laser writing machine specifically requires using polygon segments to approximate the continuously smooth fringe pattern of an ideal CGH. Wavefront phase errors introduced in this process depend on the size of the polygon segments and the shape of the fringes. We propose a method for estimating the wavefront error and its spatial frequency, allowing optimization of the polygon sizes for required measurement accuracy. This method is validated with both computer simulation and direct measurements from an interferometer. In Topics two, we present a new device, the Diffractive Optics Calibrator (DOC), for measuring etching parameters, such as duty-cycle and etching depth, for CGH. The system scans the CGH with a collimated laser beam, and collects the far field diffraction pattern with a CCD array. The relative intensities of the various orders of diffraction are used to fit the phase shift from etching and the duty cycle of the binary pattern. The system is capable of measuring variations that cause 1 nm peak-to-valley (P-V) phase errors. The device will be used primarily for quality control of the CGHs. DOC is also capable of generating an induced phase error map for calibration. Such calibration is essential for measuring freeform aspheric surfaces with 1 nm root-mean-square (RMS) accuracy.

Design Fabrication And Evaluation Of Computer Generated Holograms

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Author : Mouna Nakkar
language : en
Publisher:
Release Date : 1993

Design Fabrication And Evaluation Of Computer Generated Holograms written by Mouna Nakkar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Diffraction categories.

American Doctoral Dissertations

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Author :
language : en
Publisher:
Release Date : 1990

American Doctoral Dissertations written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Dissertation abstracts categories.