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Although the basic idea may be traced back to the earlier X-ray diffraction studies of Sir W. L. Bragg, the holographic method as we know it was invented by D. Gabor in 1948 as a two-step lensless imaging technique to enhance the resolution of electron microscopy, for which he received the 1971 Nobel Prize in physics. The distinctive feature of holography is the recording of the object phase variations that carry the depth information, which is lost in conventional photography where only the intensity (= squared amplitude) distribution of an object is captured. Since all photosensitive media necessarily respond to the intensity incident upon them, an ingenious way had to be found to convert object phase into intensity variations, and Gabor achieved this by introducing a coherent reference wave along with the object wave during exposure. Gabor's in-line recording scheme, however, required the object in question to be largely transmissive, and could provide only marginal image quality due to unwanted terms simultaneously reconstructed along with the desired wavefront. Further handicapped by the lack of a strong coherent light source, optical holography thus seemed fated to remain just another scientific curiosity, until the field was revolutionized in the early 1960s by some major breakthroughs: the proposition and demonstration of the laser principle, the introduction of off-axis holography, and the invention of volume holography. Consequently, the remainder of that decade saw an exponential growth in research on theory, practice, and applications of holography. Today, holography not only boasts a wide variety of scientific and technical applications (e.g., holographic interferometry for strain, vibration, and flow analysis, microscopy and high-resolution imagery, imaging through distorting media, optical interconnects, holographic optical elements, optical neural networks, three-dimensional displays, data storage, etc.), but has become a prominent am advertising, and security medium as well. The evolution of holographic optical memories has followed a path not altogether different from holography itself, with several cycles of alternating interest over the past four decades. P. J. van Heerden is widely credited for being the first to elucidate the principles behind holographic data storage in a 1963 paper, predicting bit storage densities on the order of 1/lambda(sup 3) with source wavelength lambda - a fantastic capacity of nearly 1 TB/cu cm for visible light The science and engineering of such a storage paradigm was heavily pursued thereafter, resulting in many novel hologram multiplexing techniques for dense data storage, as well as important advances in holographic recording materials. Ultimately, however, the lack of such enabling technologies as compact laser sources and high performance optical data I/O devices dampened the hopes for the development of a commercial product. After a period of relative dormancy, successful applications of holography in other arenas sparked a renewed interest in holographic data storage in the late 1980s and the early 1990s. Currently, with most of the critical optoelectronic device technologies in place and the quest for an ideal holographic recording medium intensified, holography is once again considered as one of several future data storage paradigms that may answer our constantly growing need for higher-capacity and faster-access memories.

Although the basic idea may be traced back to the earlier X-ray diffraction studies of Sir W. L. Bragg, the holographic method as we know it was invented by D. Gabor in 1948 as a two-step lensless imaging technique to enhance the resolution of electron microscopy, for which he received the 1971 Nobel Prize in physics. The distinctive feature of holography is the recording of the object phase variations that carry the depth information, which is lost in conventional photography where only the intensity (= squared amplitude) distribution of an object is captured. Since all photosensitive media necessarily respond to the intensity incident upon them, an ingenious way had to be found to convert object phase into intensity variations, and Gabor achieved this by introducing a coherent reference wave along with the object wave during exposure. Gabor's in-line recording scheme, however, required the object in question to be largely transmissive, and could provide only marginal image quality due to unwanted terms simultaneously reconstructed along with the desired wavefront. Further handicapped by the lack of a strong coherent light source, optical holography thus seemed fated to remain just another scientific curiosity, until the field was revolutionized in the early 1960s by some major breakthroughs: the proposition and demonstration of the laser principle, the introduction of off-axis holography, and the invention of volume holography. Consequently, the remainder of that decade saw an exponential growth in research on theory, practice, and applications of holography. Today, holography not only boasts a wide variety of scientific and technical applications (e.g., holographic interferometry for strain, vibration, and flow analysis, microscopy and high-resolution imagery, imaging through distorting media, optical interconnects, holographic optical elements, optical neural networks, three-dimensional displays, data storage, etc.), but has become a prominent am advertising, and security medium as well. The evolution of holographic optical memories has followed a path not altogether different from holography itself, with several cycles of alternating interest over the past four decades. P. J. van Heerden is widely credited for being the first to elucidate the principles behind holographic data storage in a 1963 paper, predicting bit storage densities on the order of 1/lambda(sup 3) with source wavelength lambda - a fantastic capacity of nearly 1 TB/cu cm for visible light The science and engineering of such a storage paradigm was heavily pursued thereafter, resulting in many novel hologram multiplexing techniques for dense data storage, as well as important advances in holographic recording materials. Ultimately, however, the lack of such enabling technologies as compact laser sources and high performance optical data I/O devices dampened the hopes for the development of a commercial product. After a period of relative dormancy, successful applications of holography in other arenas sparked a renewed interest in holographic data storage in the late 1980s and the early 1990s. Currently, with most of the critical optoelectronic device technologies in place and the quest for an ideal holographic recording medium intensified, holography is once again considered as one of several future data storage paradigms that may answer our constantly growing need for higher-capacity and faster-access memories.

A new tape product has been developed for optical data storage. Laser data recording is based on hole or pit formation in a low melting metallic alloy system. The media structure, sputter deposition process, and media characteristics, including write sensitivity, error rates, wear resistance, and archival storage are discussed.

A new tape product has been developed for optical data storage. Laser data recording is based on hole or pit formation in a low melting metallic alloy system. The media structure, sputter deposition process, and media characteristics, including write sensitivity, error rates, wear resistance, and archival storage are discussed.

Because they produce small spot size, near-field techniques are applied to optical data storage systems in order to increase recording density. For data storage, the optical near field is defined in terms of evanescent coupling between the system used to read data and the recording layer. Two practical implementations that use evanescent energy are aperture probes and solid immersion lenses (SILs). In this paper, the basic characteristics of these systems are reviewed, and some considerations for improving performance are discussed. Combinations of SILs and apertures could produce data storage systems with ultra-fine resolution and good detection characteristics.

Current optical data storage is challenging to increase its memory capacity and data transfer rate for realizing high-quality image and rapid service in the coming digital, multimedia and network era. To actualize more effective and simple data storage, a novel parallel near-field optical system has been proposed using vertical cavity surface emitting laser (VCSEL) microprobe arrays. The new parallel optical system is based a multibeam recording head consisting of a VCSEL array with apertures of nanometer size as a near-field wave exit. We have developed some candidates for the parallel recording head, including the direct aperture formation on the VCSEL emitting surface and the preparation of microprobe arrays with flat-tip structure. The new flat-tip microprobe array has advantages for improving the optical efficiency and stabilizing the contact head system with optical media since it is prepared from semiconductor materials of high refractive index. Silicon nano-aperture probe array has been prepared successfully with the aperture size of 150 to 500 nm using micro-fabrication techniques. We have also investigated the integrated microprobe array by the direct fabrication of flat-tip probes on the substrate of bottom emitting VCSEL arrays. Finally the reading mechanism has been studied theoretically using a finite difference time domain (FDTD) simulation and an optical feedback effect of semiconductor lasers for the integrated microprobe VCSEL array. We believe this nano-aperture VCSEL probe array is sufficiently effective to be applied to the parallel recording head for the near-field optical data storage of a high data capacity and fast transfer rate.

ICI has developed a unique and novel method of certifying a Terabyte optical tape. The tape quality is guaranteed as a statistical upper limit on the probability of uncorrectable errors. This is called the Corrected Byte Error Rate or CBER. We developed this probabilistic method because of two reasons why error rate cannot be measured directly. Firstly, written data is indelible, so one cannot employ write/read tests such as used for magnetic tape. Secondly, the anticipated error rates need impractically large samples to measure accurately. For example, a rate of 1E-12 implies only one byte in error per tape. The archivability of ICI 1012 Data Storage Tape in general is well characterized and understood. Nevertheless, customers expect performance guarantees to be supported by test results on individual tapes. In particular, they need assurance that data is retrievable after decades in archive. This paper describes the mathematical basis, measurement apparatus and applicability of the certification method.

ICI has developed a unique and novel method of certifying a Terabyte optical tape. The tape quality is guaranteed as a statistical upper limit on the probability of uncorrectable errors. This is called the Corrected Byte Error Rate or CBER. We developed this probabilistic method because of two reasons why error rate cannot be measured directly. Firstly, written data is indelible, so one cannot employ write/read tests such as used for magnetic tape. Secondly, the anticipated error rates need impractically large samples to measure accurately. For example, a rate of 1E-12 implies only one byte in error per tape. The archivability of ICI 1012 Data Storage Tape in general is well characterized and understood. Nevertheless, customers expect performance guarantees to be supported by test results on individual tapes. In particular, they need assurance that data is retrievable after decades in archive. This paper describes the mathematical basis, measurement apparatus and applicability of the certification method.

The design and analysis of a hybrid diffractive/refractive achromat for optical data storage is presented, beginning with a discussion of the construction and diffraction efficiency of surface relief diffractive lenses. The phase function, which defines a diffractive lens in much the same manner as a surface sag equation defines a refractive lens, is examined. The thin lens, or Sweatt, model of a diffractive lens is discussed, and equations are provided that allow conversion to and from the phase model. The thin lens model provides a good method to design diffractive lenses using conventional lens design software. This model also provides a convenient means of deriving the third-order aberrations of a diffractive lens. A wave propagation approach is used to discuss how decentering or tilting one of the elements with respect to the other will affect the PSF and MTF of a doublet. Two examples of achromat design are presented. First, a conventional refractive achromat with no spherical aberration or coma is designed, and the method is then extended to design a hybrid diffractive/refractive achromat. Finally, design constraints and performance goals for a hybrid diffractive/refractive achromat for use in an optical data storage system is presented. Two figures of merit used to evaluate the performance of the achromat are the Strehl ratio, which should remain greater than 0.96 over a 1 deg half field of view, and the ratio of focal length change per wavelength change, which should remain less than 0.1 micrometers/nm over the wavelength band. An optimized hybrid achromat is presented, and design tolerances with respect to fabrication errors-element misalignment, thickness errors, diffractive surface zone radii errors, blaze height errors, and mask misalignment error--are discussed.

Available from National Technical Information Service, Springfield, Va

Available from National Technical Information Service, Springfield, Va

Available from National Technical Information Service, Springfield, Va

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external-cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normal associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external-cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normal associated with intrinsically frequency-selective materials.

Optical data storage tape is now a commercial reality. The world's first successful development of a digital optical tape system is complete. This is based on the Creo 1003 optical tape recorder with ICI 1012 write-once optical tape media. Flexible optical media offers many benefits in terms of manufacture; for a given capital investment, continuous, web-coating techniques produce more square meters of media than batch coating. The coated layers consist of a backcoat on the non-active side; on the active side there is a subbing layer, then reflector, dye/polymer, and transparent protective overcoat. All these layers have been tailored for ease of manufacture and specific functional characteristics.

A compact optical image correlator using orthogonal, wavelength multiplexed Fourier transform holograms recorded in a photorefractive crystal has been demonstrated. Cross-correlation and auto-correlation measurements were obtained using randomly selected test images against the set of reference images stored in the orthogonal data storage volume hologram. Over 40 holograms were written in the 645 to 651 nm wavelength range with 2% diffraction efficiency and 1.5 A wavelength separation. A low power tunable external cavity semiconductor laser was used for readout, further demonstrating the portability of this approach. The input image translation tolerances on the correlation output and the effect of using partial images during readout were also investigated. Optical image correlation, Pattern recognition, Optical memory, Volume holography, Optical data storage

A new technology developed at Optex Corporation out-performs all other existing data storage technologies. The Electron Trapping Optical Memory (ETOM) media stores 14 gigabytes of uncompressed data on a single, double-sided 130 mm disk with a data transfer rate of up to 120 megabits per second. The disk is removable, compact, lightweight, environmentally stable, and robust. Since the Write/Read/Erase (W/R/E) processes are carried out photonically, no heating of the recording media is required. Therefore, the storage media suffers no deleterious effects from repeated W/R/E cycling. This rewritable data storage technology has been developed for use as a basis for numerous data storage products. Industries that can benefit from the ETOM data storage technologies include: satellite data and information systems, broadcasting, video distribution, image processing and enhancement, and telecommunications. Products developed for these industries are well suited for the demanding store-and-forward buffer systems, data storage, and digital video systems needed for these applications.

The utilization of polymers as media for optical data storage offers many potential benefits and consequently has been widely explored. New developments in thermal imaging are described, wherein high resolution lithography is accomplished without thermal smearing. The emphasis was on the use of poly(ethylene terephthalate) film, which simultaneously serves as both the substrate and the data storage medium. Both physical and chemical changes can be induced by the application of heat and, thereby, serve as a mechanism for high resolution optical data storage in polymers. The extension of the technique to obtain high resolution selective metallization of poly(ethylene terephthalate) is also described.

Preprints are presented from the recent 1992 Optical Data Storage meeting in San Jose. The papers are divided into the following topical areas: Magneto-optical media (Modeling/design and fabrication/characterization/testing); Optical heads (holographic optical elements); and Optical heads (integrated optics). Some representative titles are as follow: Diffraction analysis and evaluation of several focus and track error detection schemes for magneto-optical disk systems; Proposal for massively parallel data storage system; Transfer function characteristics of super resolving systems; Modeling and measurement of a micro-optic beam deflector; Oxidation processes in magneto-optic and related materials; and A modal analysis of lamellar diffraction gratings in conical mountings.

Optical data storage tape is now a commercial reality. The world's first successful development of a digital optical tape system is complete. This is based on the Creo 1003 optical tape recorder with ICI 1012 write-once optical tape media. Several other optical tape drive development programs are underway, including one using the IBM 3480 style cartridge at LaserTape Systems. In order to understand the significance and potential of this step change in recording technology, it is useful to review the historical progress of optical storage. This has been slow to encroach on magnetic storage, and has not made any serious dent on the world's mountains of paper and microfilm. Some of the reasons for this are the long time needed for applications developers, systems integrators, and end users to take advantage of the potential storage capacity; access time and data transfer rate have traditionally been too slow for high-performance applications; and optical disk media has been expensive compared with magnetic tape. ICI's strategy in response to these concerns was to concentrate its efforts on flexible optical media; in particular optical tape. The manufacturing achievements, media characteristics, and media lifetime of optical media are discussed.

Optical data storage tape is now a commercial reality. The world's first successful development of a digital optical tape system is complete. This is based on the Creo 1003 optical tape recorder with ICI 1012 write-once optical tape media. Several other optical tape drive development programs are underway, including one using the IBM 3480 style cartridge at LaserTape Systems. In order to understand the significance and potential of this step change in recording technology, it is useful to review the historical progress of optical storage. This has been slow to encroach on magnetic storage, and has not made any serious dent on the world's mountains of paper and microfilm. Some of the reasons for this are the long time needed for applications developers, systems integrators, and end users to take advantage of the potential storage capacity; access time and data transfer rate have traditionally been too slow for high-performance applications; and optical disk media has been expensive compared with magnetic tape. ICI's strategy in response to these concerns was to concentrate its efforts on flexible optical media; in particular optical tape. The manufacturing achievements, media characteristics, and media lifetime of optical media are discussed.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

The results of a comprehensive study of optical interactions with frequency-selective recording materials are reported along with ancillary results related to high-speed tuning and reference-free stabilization of associated lasers. Frequency-selective recording materials provide the physical basis for time-space or 4D holography wherein the full spatial and temporal information contained in an optical signal can be stored and/or processed. It is shown that 4D holographic recall signals can be substantially stronger than previously believed possible. Innovative external cavity diode laser designs supportive of very high-speed laser tuning and dynamic stabilization are also reported. Preliminary work on the use of composite grating devices to emulate the functionality normally associated with frequency-selective materials is also presented. Composite grating devices provide a basis for robust optical signal processing operative over extensive ranges of bandwidths and are entirely free of the constraints normally associated with intrinsically frequency-selective materials.

Under this grant, our objective was to test the feasibility of realizing holographic optical memory.

From the bitsavers.org collection, a scanned-in computer-related document. santaClaraUniversity :: IIST :: Data Storage Tutorial on Magnetic and Optical Recording 199203

Thin silver oxide films used as mask layers in super-Resolution Nearfield Structure (super-RENS) disks for high density optical data storage were reactively sputter-deposited and their composition was determined by spectroscopic means. We found that the stoichiometry of the films changed with the oxygen content in the sputtering gas atmosphere. With a stepwise increase in the percentage of O2 from 0 - 100%, the corresponding layers consist of Ag, mixtures of Ag and Ag2O, Ag2O, mixtures of Ag2O and AgO and AgO. Laser activation of such oxidic phase containing deposits results in the decomposition of the material and excitation of strong local plasmons in the remaining silver clusters. This was confirmed by acquiring surface enhanced Raman spectra (SERS) of benzoic acid (BA), copper phthalocyanine (CP) and internal carbon impurities on silver oxide substrates. From this data, we conclude that the sub-wavelength resolution obtained in super-RENS disks is mediated by local surface plasmons on small silver particles forming in the mask layer.

Extensive progress was made in the following areas: Demonstration of room temperature spectral hole burning in CdS quantum dot samples. Fabrication of the first quantum dot slab and channel waveguides and measurements of femtosecond pulse propagation in these waveguides. Fabrication of the first circular grating in a quantum dot waveguide.

Although the basic idea may be traced back to the earlier X-ray diffraction studies of Sir W. L. Bragg, the holographic method as we know it was invented by D. Gabor in 1948 as a two-step lensless imaging technique to enhance the resolution of electron microscopy, for which he received the 1971 Nobel Prize in physics. The distinctive feature of holography is the recording of the object phase variations that carry the depth information, which is lost in conventional photography where only the intensity (= squared amplitude) distribution of an object is captured. Since all photosensitive media necessarily respond to the intensity incident upon them, an ingenious way had to be found to convert object phase into intensity variations, and Gabor achieved this by introducing a coherent reference wave along with the object wave during exposure. Gabor's in-line recording scheme, however, required the object in question to be largely transmissive, and could provide only marginal image quality due to unwanted terms simultaneously reconstructed along with the desired wavefront. Further handicapped by the lack of a strong coherent light source, optical holography thus seemed fated to remain just another scientific curiosity, until the field was revolutionized in the early 1960s by some major breakthroughs: the proposition and demonstration of the laser principle, the introduction of off-axis holography, and the invention of volume holography. Consequently, the remainder of that decade saw an exponential growth in research on theory, practice, and applications of holography. Today, holography not only boasts a wide variety of scientific and technical applications (e.g., holographic interferometry for strain, vibration, and flow analysis, microscopy and high-resolution imagery, imaging through distorting media, optical interconnects, holographic optical elements, optical neural networks, three-dimensional displays, data storage, etc.), but has become a prominent am advertising, and security medium as well. The evolution of holographic optical memories has followed a path not altogether different from holography itself, with several cycles of alternating interest over the past four decades. P. J. van Heerden is widely credited for being the first to elucidate the principles behind holographic data storage in a 1963 paper, predicting bit storage densities on the order of 1/lambda(sup 3) with source wavelength lambda - a fantastic capacity of nearly 1 TB/cu cm for visible light! The science and engineering of such a storage paradigm was heavily pursued thereafter, resulting in many novel hologram multiplexing techniques for dense data storage, as well as important advances in holographic recording materials. Ultimately, however, the lack of such enabling technologies as compact laser sources and high performance optical data I/O devices dampened the hopes for the development of a commercial product. After a period of relative dormancy, successful applications of holography in other arenas sparked a renewed interest in holographic data storage in the late 1980s and the early 1990s. Currently, with most of the critical optoelectronic device technologies in place and the quest for an ideal holographic recording medium intensified, holography is once again considered as one of several future data storage paradigms that may answer our constantly growing need for higher-capacity and faster-access memories.

Although the basic idea may be traced back to the earlier X-ray diffraction studies of Sir W. L. Bragg, the holographic method as we know it was invented by D. Gabor in 1948 as a two-step lensless imaging technique to enhance the resolution of electron microscopy, for which he received the 1971 Nobel Prize in physics. The distinctive feature of holography is the recording of the object phase variations that carry the depth information, which is lost in conventional photography where only the intensity (= squared amplitude) distribution of an object is captured. Since all photosensitive media necessarily respond to the intensity incident upon them, an ingenious way had to be found to convert object phase into intensity variations, and Gabor achieved this by introducing a coherent reference wave along with the object wave during exposure. Gabor's in-line recording scheme, however, required the object in question to be largely transmissive, and could provide only marginal image quality due to unwanted terms simultaneously reconstructed along with the desired wavefront. Further handicapped by the lack of a strong coherent light source, optical holography thus seemed fated to remain just another scientific curiosity, until the field was revolutionized in the early 1960s by some major breakthroughs: the proposition and demonstration of the laser principle, the introduction of off-axis holography, and the invention of volume holography. Consequently, the remainder of that decade saw an exponential growth in research on theory, practice, and applications of holography. Today, holography not only boasts a wide variety of scientific and technical applications (e.g., holographic interferometry for strain, vibration, and flow analysis, microscopy and high-resolution imagery, imaging through distorting media, optical interconnects, holographic optical elements, optical neural networks, three-dimensional displays, data storage, etc.), but has become a prominent am advertising, and security medium as well. The evolution of holographic optical memories has followed a path not altogether different from holography itself, with several cycles of alternating interest over the past four decades. P. J. van Heerden is widely credited for being the first to elucidate the principles behind holographic data storage in a 1963 paper, predicting bit storage densities on the order of 1/lambda(sup 3) with source wavelength lambda - a fantastic capacity of nearly 1 TB/cu cm for visible light! The science and engineering of such a storage paradigm was heavily pursued thereafter, resulting in many novel hologram multiplexing techniques for dense data storage, as well as important advances in holographic recording materials. Ultimately, however, the lack of such enabling technologies as compact laser sources and high performance optical data I/O devices dampened the hopes for the development of a commercial product. After a period of relative dormancy, successful applications of holography in other arenas sparked a renewed interest in holographic data storage in the late 1980s and the early 1990s. Currently, with most of the critical optoelectronic device technologies in place and the quest for an ideal holographic recording medium intensified, holography is once again considered as one of several future data storage paradigms that may answer our constantly growing need for higher-capacity and faster-access memories.

Optical disk-based information systems are being used in private industry and many Federal Government agencies for on-line and long-term storage of large quantities of data. The storage devices that are part of these systems are designed with powerful, but not unlimited, media error correction capacities. The integrity of data stored on optical disks does not only depend on the life expectancy specifications for the medium. Different factors, including handling and storage conditions, may result in an increase of medium errors in size and frequency. Monitoring the potential data degradation is crucial, especially for long term applications. Efforts are being made by the Association for Information and Image Management Technical Committee C21, Storage Devices and Applications, to specify methods for monitoring and reporting to the user medium errors detected by the storage device while writing, reading or verifying the data stored in that medium. The Computer Systems Laboratory (CSL) of the National Institute of Standard and Technology (NIST) has a leadership role in the development of these standard techniques. In addition, CSL is researching other data integrity issues, including the investigation of error-resilient compression algorithms. NIST has conducted care and handling experiments on optical disk media with the objective of identifying possible causes of degradation. NIST work in data integrity and related standards activities is described.

The increased sophistication and complexity of new weapon systems have generated an exponential growth in the associated technical support documentation. This data explosion impacts several data management issues including: the exorbitant costs associated with the initial development and distribution of this required information; the massive weight, environmental and space considerations attributable to the storage of this data; and the complex task of publishing and distributing revisions to previously disseminated documentation. This research serves as a preliminary feasibility study, analyzing the optical media storage and presentation alternatives applicable to Naval Aviation technical manual publication and distribution methodologies. The research includes a synopsis of the DOD/DON directives and programs aimed at data automation and digitization processes with particular emphasis on the Naval Aviation environment. This thesis concludes with the recommendation to continue investigation of the optical mass storage alternatives. Furthermore, this study recommends research emphasis of the CD-ROM format due to its standardization lead, technological maturation, economy to scale advantages resulting from the audio compact disc success and the environmental and transportable benefits associated with this medium. Keywords: Theses, Aviation maintenance.

The increased sophistication and complexity of new weapon systems have generated an exponential growth in the associated technical support documentation. This data explosion impacts several data management issues including: the exorbitant costs associated with the initial development and distribution of this required information; the massive weight, environmental and space considerations attributable to the storage of this data; and the complex task of publishing and distributing revisions to previously disseminated documentation. This research serves as a preliminary feasibility study, analyzing the optical media storage and presentation alternatives applicable to Naval Aviation technical manual publication and distribution methodologies. The research includes a synopsis of the DOD/DON directives and programs aimed at data automation and digitization processes with particular emphasis on the Naval Aviation environment. This thesis concludes with the recommendation to continue investigation of the optical mass storage alternatives. Furthermore, this study recommends research emphasis of the CD-ROM format due to its standardization lead, technological maturation, economy to scale advantages resulting from the audio compact disc success and the environmental and transportable benefits associated with this medium. Keywords: Theses, Aviation maintenance.

The increased sophistication and complexity of new weapon systems have generated an exponential growth in the associated technical support documentation. This data explosion impacts several data management issues including: the exorbitant costs associated with the initial development and distribution of this required information; the massive weight, environmental and space considerations attributable to the storage of this data; and the complex task of publishing and distributing revisions to previously disseminated documentation. This research serves as a preliminary feasibility study, analyzing the optical media storage and presentation alternatives applicable to Naval Aviation technical manual publication and distribution methodologies. The research includes a synopsis of the DOD/DON directives and programs aimed at data automation and digitization processes with particular emphasis on the Naval Aviation environment. This thesis concludes with the recommendation to continue investigation of the optical mass storage alternatives. Furthermore, this study recommends research emphasis of the CD-ROM format due to its standardization lead, technological maturation, economy to scale advantages resulting from the audio compact disc success and the environmental and transportable benefits associated with this medium. Keywords: Theses, Aviation maintenance.

The increased sophistication and complexity of new weapon systems have generated an exponential growth in the associated technical support documentation. This data explosion impacts several data management issues including: the exorbitant costs associated with the initial development and distribution of this required information; the massive weight, environmental and space considerations attributable to the storage of this data; and the complex task of publishing and distributing revisions to previously disseminated documentation. This research serves as a preliminary feasibility study, analyzing the optical media storage and presentation alternatives applicable to Naval Aviation technical manual publication and distribution methodologies. The research includes a synopsis of the DOD/DON directives and programs aimed at data automation and digitization processes with particular emphasis on the Naval Aviation environment. This thesis concludes with the recommendation to continue investigation of the optical mass storage alternatives. Furthermore, this study recommends research emphasis of the CD-ROM format due to its standardization lead, technological maturation, economy to scale advantages resulting from the audio compact disc success and the environmental and transportable benefits associated with this medium. Keywords: Theses, Aviation maintenance.

The increased sophistication and complexity of new weapon systems have generated an exponential growth in the associated technical support documentation. This data explosion impacts several data management issues including: the exorbitant costs associated with the initial development and distribution of this required information; the massive weight, environmental and space considerations attributable to the storage of this data; and the complex task of publishing and distributing revisions to previously disseminated documentation. This research serves as a preliminary feasibility study, analyzing the optical media storage and presentation alternatives applicable to Naval Aviation technical manual publication and distribution methodologies. The research includes a synopsis of the DOD/DON directives and programs aimed at data automation and digitization processes with particular emphasis on the Naval Aviation environment. This thesis concludes with the recommendation to continue investigation of the optical mass storage alternatives. Furthermore, this study recommends research emphasis of the CD-ROM format due to its standardization lead, technological maturation, economy to scale advantages resulting from the audio compact disc success and the environmental and transportable benefits associated with this medium.

A CMOS circuit capable of storing optically transmitted data from a holographic read only memory (ROM) is described. The investigation focuses on combining optical and electronic circuit technology to rapidly transfer data in parallel fashion from a ROM to an array of static random-access memory (SRAM) cells. The proposed optoelectronic SRAM cells have an optical detection components as well as electrical read and write functions. Development of the optoelectronic memory circuit is based on research in several areas. A design method is described which applies MOS inverter transfer characteristics to the six-transistor CMOS SRAM cell. Circuit diagrams, layouts, and models are presented for photodetection devices adapted to integrated CMOS circuits. These devices are fabricated in standard CMOS processes for silicon. Performance characteristics are provided for photodetection devices with different load circuits. The optical data transfer technology is extended to other systems in which high speed and parallelism are essential. An array of the optoelectronic cells and many related devices and circuits have been designed, fabricated, and tested. Simulation and experimental results are given for circuits applicable to optical detection and electronic storage of data. The optical data transfer concept has been verified with a 16-bit optoelectronic SRAM. Data contained in a parallel array of 16-bit optoelectronic SRAM. Data contained in a parallel array of 16 light beams with an average power of 3.35 microwatts per bit were successfully transferred to the SRAM.

A CMOS circuit capable of storing optically transmitted data from a holographic read only memory (ROM) is described. The investigation focuses on combining optical and electronic circuit technology to rapidly transfer data in parallel fashion from a ROM to an array of static random-access memory (SRAM) cells. The proposed optoelectronic SRAM cells have an optical detection components as well as electrical read and write functions. Development of the optoelectronic memory circuit is based on research in several areas. A design method is described which applies MOS inverter transfer characteristics to the six-transistor CMOS SRAM cell. Circuit diagrams, layouts, and models are presented for photodetection devices adapted to integrated CMOS circuits. These devices are fabricated in standard CMOS processes for silicon. Performance characteristics are provided for photodetection devices with different load circuits. The optical data transfer technology is extended to other systems in which high speed and parallelism are essential. An array of the optoelectronic cells and many related devices and circuits have been designed, fabricated, and tested. Simulation and experimental results are given for circuits applicable to optical detection and electronic storage of data. The optical data transfer concept has been verified with a 16-bit optoelectronic SRAM. Data contained in a parallel array of 16-bit optoelectronic SRAM. Data contained in a parallel array of 16 light beams with an average power of 3.35 microwatts per bit were successfully transferred to the SRAM.

A CMOS circuit capable of storing optically transmitted data from a holographic read only memory (ROM) is described. The investigation focuses on combining optical and electronic circuit technology to rapidly transfer data in parallel fashion from a ROM to an array of static random-access memory (SRAM) cells. The proposed optoelectronic SRAM cells have an optical detection components as well as electrical read and write functions. Development of the optoelectronic memory circuit is based on research in several areas. A design method is described which applies MOS inverter transfer characteristics to the six-transistor CMOS SRAM cell. Circuit diagrams, layouts, and models are presented for photodetection devices adapted to integrated CMOS circuits. These devices are fabricated in standard CMOS processes for silicon. Performance characteristics are provided for photodetection devices with different load circuits. The optical data transfer technology is extended to other systems in which high speed and parallelism are essential. An array of the optoelectronic cells and many related devices and circuits have been designed, fabricated, and tested. Simulation and experimental results are given for circuits applicable to optical detection and electronic storage of data. The optical data transfer concept has been verified with a 16-bit optoelectronic SRAM. Data contained in a parallel array of 16-bit optoelectronic SRAM. Data contained in a parallel array of 16 light beams with an average power of 3.35 microwatts per bit were successfully transferred to the SRAM.

A CMOS circuit capable of storing optically transmitted data from a holographic read only memory (ROM) is described. The investigation focuses on combining optical and electronic circuit technology to rapidly transfer data in parallel fashion from a ROM to an array of static random-access memory (SRAM) cells. The proposed optoelectronic SRAM cells have an optical detection components as well as electrical read and write functions. Development of the optoelectronic memory circuit is based on research in several areas. A design method is described which applies MOS inverter transfer characteristics to the six-transistor CMOS SRAM cell. Circuit diagrams, layouts, and models are presented for photodetection devices adapted to integrated CMOS circuits. These devices are fabricated in standard CMOS processes for silicon. Performance characteristics are provided for photodetection devices with different load circuits. The optical data transfer technology is extended to other systems in which high speed and parallelism are essential. An array of the optoelectronic cells and many related devices and circuits have been designed, fabricated, and tested. Simulation and experimental results are given for circuits applicable to optical detection and electronic storage of data. The optical data transfer concept has been verified with a 16-bit optoelectronic SRAM. Data contained in a parallel array of 16-bit optoelectronic SRAM. Data contained in a parallel array of 16 light beams with an average power of 3.35 microwatts per bit were successfully transferred to the SRAM.

This report summarizes the research results obtained on NASA Ames Grant NAG 2-878 entitled 'Investigations of Bacteriorhodopsin Films for Optical Signal Processing and Data Storage.' Specifically we performed research, at Texas Tech University, on applications of Bacteriorhodopisin film to both (1) dynamic spatial filtering and (2) holographic data storage. In addition, measurements of the noise properties of an acousto-optical matrix-vestor multiplier built for NASA Ames by Photonic Systems Inc. were performed at NASA Ames' Photonics Laboratory. This research resulted in two papers presented at major optical data processing conferences and a journal paper which is to appear in APPLIED OPTICS. A new proposal for additional BR research has recently been submitted to NASA Ames Research Center.

Our objectives are threefold: (1) to accurately characterize optical data storage films by MeV ion-beam analysis (IBA) for ODSC collaborators; (2) to develop new and/or improved analysis techniques; and (3) to expand the capabilities of the IBA facility itself. Using H-1(+), He-4(+), and N-15(++) ion beams in the 1.5 MeV to 10 MeV energy range from a 5.5 MV Van de Graaff accelerator, film thickness (in atoms/sq cm), stoichiometry, impurity concentration profiles, and crystalline structure were determined by Rutherford backscattering (RBS), high-energy backscattering, channeling, nuclear reaction analysis (NRA) and proton induced X-ray emission (PIXE). Most of these techniques are discussed in detail in the ODSC Annual Report (February 17, 1987), p. 74. The PIXE technique is briefly discussed in the ODSC Annual Report (March 15, 1991), p. 23.

Scattering effects in a two-photon optical data storage system are numerically studied. Surface scattering analysis using a scalar, beam propagation model is performed. The problem is analyzed by computing scattering from randomly varying surfaces, and also by Fourier surface decomposition. Scattering induced by propagation through pages of randomly recorded data marks is also studied using a hybrid finite difference time domain angular spectrum model. Both surface and bulk scattering are shown to influence the spatial properties of the optical beam. Results and some possible implications are presented.