bluuebunny/crossref_metadata_2025 huggingface dataset:
Digital Magneto-Optic Storage System
Authors: Sander I.
Published: February 2023

A small - potentially low-cost - magneto-optic digital recorder with up to 10 MByte of erasable storage capacity on a 50-mm (2") disk has been investigated as an alternative to the well-known floppy disk or Winchester digital storage systems.
Magneto-optical Memory Experiments on Chromium Dioxide Flexible Disk
Authors: Nomura Tatsuo , Tokumaru Haruki , Nakagawa Shozo
Published: February 2023

Optical data storage has many advantages, particularly high packing density, high reliability and short access time. Various optical recording systems and numerous media have been proposed and are still being developed.
Digital Optical Recording in Infrared-Sensitive Organic Polymers
Authors: Howe Dennis G.
Published: February 2023

Organic dye/polymer high density optical recording materials designed to be written with 800-850 nm light and read out via 633 nm light or 800-850 nm light have been developed. A schematic cross section of the medium is shown in Fig. 1. The recordable dye/polymer (called Laser Write and Read or LWR material) layer is coated over a reflective metal film which is vacuum deposited on a substrate treated with a proprietary surfacer coating. Although the LWR material has only moderately high absorption at the desired recording wavelength, the interference bilayer structure shown in Fig. 1 absorbs strongly over the 800-850 nm wavelength range.1 Steep-walled, flat-bottomed "pits" having constant depth are instantaneously formed in the upper portion of the LWR layer during recording via a complex process.2 Recording sensitivity is such that ~ 0.6 μm wide pits can be written at scan velocities of 20 m/s using only 10 mW of light focused onto the medium with a well-corrected 0.65 NA lens.
Morphology Dependent Contrast Measurements of Microscopically Textured Germanium Films
Authors: Suh S. Y. , Craighead H. G. , Howard R. E. , Schiavone L. M.
Published: February 2023

Textured surfaces have been studied for application to optical storage media (1) and represent an alternative mechanism to the usual ablative hole-opening process. The important advantage of the textured media is that the slope, S=dC/dE, in the contrast, C, vs writing power, E, curve can be easily altered by adopting various etching conditions in the texturing process. The contrast ratio is defined as
C=|Ra−Rb|Ra+Rb, where Ra and Rb are the reflectivity before and after pit formation respectively. The theoretical analysis (2) and a preliminary experimental result indicate that the writing threshold energy for textured media is determined by the energy required to melt a spot in the medium. This represents a significant sensitivity improvement and a great deal of simplification in the material selection. In this paper, we are concerned mainly the former characteristics of the texture media.
Noise Properties of Semiconductor Lasers in Simulated Conditions of Optical Playback
Authors: Small M.B. , Stubkjaer K.E.
Published: February 2023

As semiconductor lasers are being used in more advanced optical systems, the noise properties of the light output are of increasing importance. We present an experimental analysis of noise due to feedback into index guided lasers. Our measurement set-up reproduces that in which the laser may be used for reading information from a mechanically unstable reflecting surface, as for example an optical disk. The analysis includes the dependence of noise on output power level, proportion of the reflected light returned to the laser, external cavity length and modulation level. Finally, the noise performance of different lasers, with and without modulation, is compared in a simple analysis of the requirements of optical disk systems.
Experimental Measurements on Long-Term IR Readout of Data Recorded in Organic Optical Storage Media
Authors: Kay David , Strome Forrest , Wrobel Joseph
Published: February 2023

This paper presents the results of two studies on long-term readout of organic optical recording media: (a) bit error measurements from digital data tracks read 106-107 times from a rotating disk versus IR read power and (b) simulations of a very large number of readouts (108-109) using a pulsed IR read source to interrogate stationary pits. The second technique is used to provide data at a number of read cycles too time consuming for the first method, thus providing an efficient means to evaluate novel media.
Erasable disk memory using Te-TeO2 thin film
Authors: Yamashita Tadaoki , Takenaga Mutsuo
Published: February 2023

There are two types of recordable disk media : the one using an ablative film forming pits through a process of melting or ablation1−4), the other that displays critical changes in its reflectivity and transmission absorbing the diode laser light power5−6). The latter type has a feasibility to be improved as an erasable medium if it satisfies some conditions for an erasable disk medium.
Optical Data Storage and Electronic Publishing
Authors: Lippman Andrew B.
Published: February 2023

Fundamentally, one can equate radio, television and print as being technically different versions of broadcast communications. They use different channels and have different descriptive modes, but they all follow a one-to-many paradigm. Powerful local computing and storage can change this, transforming a broadcast into a dialogue, a presentation into a conversation. This is a basic change in the notion of publication, with technical and intellectual ramifications. This paper will describe two ongoing research projects that address the evolution of publishing brought about by large-scale personal optical storage. In each, read-only and read/write analogue devices are used to jointly and simultaneously store images and related data, permitting distribution of a superset of information in compact, machine readable form. The significance of the work is that optical storage is integrated into the more general storage heirarchy of the computer as opposed to being a flexible peripheral.
The Storage Technology 7640 Access And Control Systems*
Authors: McIntosh Robert P.
Published: February 2023

Implementation of the control systems required for the Storage Technology 7640 Optical Storage Unit consists of a combination of transducers, optical components and precision servomechanisms. The major functions include spin, focus, coarse and fine seeking, track following and write alignment systems.
Use of Optical Fiber Heads for Optical Disks
Authors: Barnes Frank S. , Lee K.S. , Smith Archibald W.
Published: February 2023

The ability to generate high quality lenses on the end of single mode optical fibers makes it possible to consider a large number of design changes in the development of a head for an optical disk system. It is these potential design changes which we wish to explore in discussing characteristics of a fiber optics head for an optical disk mass storage system.
Design Consideration of Optical Pregroove Dimensions
Authors: Yamamoto Manabu , Watabe Akinori , Ukita Hiroo
Published: February 2023

Pregrooved optical disks have the advantage of making the tracking servo easy when writing data and enabling the disk to be exchanged. In pregrooved disks, push-pull tracking servo signals are detected by a change in the intensity distribution of the diffracted beam. Both tracking and focusing servo signal can be obtained by the same photo diode placed in a far field. However, interference between tracking error signals and focusing error signals makes the focusing servo unstable, and the decrease in light intensity due to groove diffraction causes a reduction in signal amplitude. These problems depend not only on the width and the depth but also on the gradient of the edge of a pregroove.
Plastic Substrate for Optical Memory Disk
Authors: Onisawa Yoshio , Tokuhara Shinji , Hiramatsu Taiji , Toba Hirotaka
Published: February 2023

Polymethylmethacrylate(PMMA) and Polycarbonate(PC) was usually used for the materials for the substrate of optical disks. PMMA is used for the commercialized disk substrates larger than 20cm in diameter because of the excellent optical properties, especially low level of birefringence. But the substrate of PMMA has a fault, that warping takes place more easily than PC by heat and water absorption. On the other hand PC is not liable to warp but has generally poorer moldability and higher birefringence. Thus PC is used only for compact disk of 12cm diameter. PC is superior to PMMA if the birefringence can be decreased. We reported on the topical meeting at Montrey last year that 20cm diameter PC substrate with low birefringence was obtained by optimum selection of conditions for injection molding. It was possible to keep the retardation of the recordable area of PC 20cm diameter substrates within 40nm(double pass). Furthermore we investigated the molding conditions for PC 30cm diameter substrates and succeeded in molding substrates of low birefringence(retardation) as shown in Fig.1. We used a special mold which has several pressure sensors in the cavity and optimized the molding conditions, using the correlation between pressure distribution and birefringence. The environmental durability of optical disks is very important from the viewpoint of actual usage of optical disks as optical recording media. We found that the depth of tracking pregrooves engraved on plastic substrates by injection molding changes depending on environmental conditions. Generally, the substrates for optical disk have groove of submicron size. In the process of injection molding of disk substrate molten polymer is injected into mold cavity with high flow rate and pressed on the stamper by cavity pressure. Then pregrooves and pits on the stamper is replicated to molten polymer. The change of cylinder position, ram pressure and pressure of mold cavity during injection is shows in Fig.2. The time for the process from the injection of the hot molten polymer to the rise of pressure in a mold cavity is only a few milliseconds.
Present Status and Future Trends in Erasable Optical Memories
Authors: Tsunoda Yoshito
Published: February 2023

During the past few years, several write-once type optical disk file memory products have been introduced to the market and are establishing a stable rising curve of the optical memory era.
Characteristics of Magneto-Optical Disk with Media Sandwiched between Protective Layers
Authors: Kawabata H. , Yamamoto K. , Birukawa M. , Miyatake N. , Shimizu T. , Fukai M.
Published: February 2023

RE-TM amorphous ferri-magnetic film, a magneto-optical (M-O) material (1~3), is the promising erasable optical mass memory medium. Compared with other erasable optical memory materials, the film offers particularly excellent erasability, as proven by repeated recording, reading and erasing over 107 times without measurable degradation (4).
CD-ROM System
Authors: Sako Yoichiro , Suzuki Tadao
Published: February 2023

The CD-ROM ( Compact Disc Read Only Memory), based on the digital audio Compact Disc system[1], is designed as a data storage device for computers. With a 540M-byte capacity, and a high-speed, random-access capability, the CD-ROM offers a wide range of storage applications and greatly expands the potential uses of computers.
Organic Dye Materials For Optical Recording Medium
Authors: Oba H. , Abe M. , Umehara M. , Sato T. , Ueda Y. , Kunikane M.
Published: February 2023

Organic dyes, which are utilized for optical recording medium, have some excellent characteristics such as anti-oxidizing, non-toxic, high resolution, and so on. And some kind of dyes show such a high reflectivity like metals near the wavelength region corresponding to the absorption.
Volume Production of Plasmon Optical Discs
Authors: Gardner K , Helfet PR , Longman RJ
Published: February 2023

The success of any product intended for use as a high capacity digital storage medium depends critically on the quality control procedures adopted during manufacture. This requires that simple test methods which can be routinely applied during volume manufacture should be developed. The Plasmon disc is unique in its construction and lends itself to simple monitoring which can be used not only to control the Moth Eye texture but to provide invaluable data on the satisfactory operation of all stages in the production process..
Disk Drive Optics: Design Factors Affecting Manufacturing and Cost in Volume.
Authors: Westney Ronald , Swaby Basil
Published: February 2023

High performance beamsplitting, polarizing and beam-steering optics used in optical disk drive heads have some requirements which are not always compatible with the low cost goal which is mandatory for high volume.
Physical optics analysis of the focusing grating coupler optical data head
Authors: Lawrence George , Cronkite Patrick , Sweatt William
Published: February 2023

The focusing grating coupler (FGC) has been developed for application to optical data storage.1 This device is of considerable interest for low-cost highly stable optical heads. Figure 1 shows an optical schematic of the device. A laser diode is optically coupled to a slab laser wave guide. The light in the slab propagates to the FGC where it leaves the slab and focuses to a point. After reflection from the surface of the optical recording media, the light returns to the FGC as a diverging beam. After a second diffraction from the FGC, the light again propagates in the slab -- this time in the reverse direction. A linear grating is used to diffract part of the return illumination into orders that focus to either side of the laser diode.
Reversible Optical Data Storage Materials Optical Properties of Several Chalcogenide Compounds
Authors: Edgerton Robert F.
Published: February 2023

The use of chalcogenide alloys for reversible optical data storage was first reported by Ovshinsky in 1970.1 The design of an optimal system requires a thin film design with the active material as part of a thin film structure.2 The optical properties of the material in both the recorded (amorphous) and erased (crystalline) is required to calculate the performance of a particular design. Several chalcogenide compounds (TeSe, Te3Sb2, Te3As2, Te2Sb2Se) were deposited as amorphous thin films on quartz with a nominal thickness of 100nm. Two films from the same deposition were used in each study and one the films was crystallized by heating appropriately in an oven.
Charge Constrained (1,7) Code For Magneto Optic Recording
Authors: Shinn Charles E.
Published: February 2023

Modulation codes are used in disc memory applications to limit the distance between transitions, control the spectral distribution of the data stream, and to maximize the data capacity. Because of their high density ratios the class of codes known as Run Length Limited (RLL) codes have become dominant in the magnetic disc recording industry.
Magneto-optical Disks Using PC Substrates
Authors: Okada M. , Nakada M. , Toki K. , Gokan H. , Iwanaga T. , Inada H.
Published: February 2023

Magneto-optical disk is one of the most promising candidates for erasable optical media.1)2) Considering mass production, optical disks using resin substrates have the advantage of simple pre-groove formation. Among several resins applicable for use in optical disks substrates, Polycarbonate (PC) has superior injection molding characteristics, good humidity resistance and excellent thermal resistance. However, the noise arising from birefringence is the most significant drawback. On the other hand, it is necessary to use excellent protective films since the magneto-optical films are rapidly oxidized in the air. For this reason, various kinds of protective films have been studied for magneto-optical disks.3)4)5) This paper discusses the characteristics of magneto-optical disks using the noise reduced PC substrates and excellent protective films.
Antireflection Structures for Magneto-Optic Recording
Authors: Bell Alan E.
Published: February 2023

Antireflective thin film structures(1) have been used advantageously in write – once(2)(3) and reversible phase change(4) materials design to provide increased sensitivity, better marking contrast and to amplify the optical effects of small laser-induced marking effects. The same structures may be used in magneto-optic recording to increase the shot-noise-limited figure of merit R½ΘK for Kerr readout. Previous reports have analyzed the effects of single quarter-wave overlayers(5) and more powerful approaches such as the encapsulated trilayer (quadrilayer)(6). This paper will present a comprehensive analysis of the various approaches to antireflection structures and their relative enhancement capabilities for shot noise limited magneto-optic readout.
Magneto-optical Recording Readout Performance Evaluation
Authors: Iwanaga Toshiaki , Sugaya Satoshi , Inada Hiroshi , Nomura Tadashi
Published: February 2023

Important factors in read and write processes for magneto­optical disk are that readout carrier to noise ratio (C/N) is high, readout signal envelope is smooth,optical efficiency is high, head size is compact and head weight is light. This paper summarizes results from many studies on optical retardation influence in magneto-optical head and disk substrate. Improvements in a magneto-optical head and disk drive system are presented.
Analysis of Signal to Noise Ratio in Magneto-Optical Disk Using a Polarization Simulator
Authors: Toda Tsuyoshi , Shigematsu Kazuo , Yoshihiro Masafumi , Ojima Masahiro , Tsunoda Yoshito
Published: February 2023

Magneto-optical (M-0) disk is an erasable and large capacity memory which has been actively developed by many companies in the world. One of the most serious problem in developing M-0 disk is to guarantee the signal to noise (SN) ratio . In the M-0 disk, Kerr effect is utilized to reproduce the recorded data on the disk. However, Kerr effect is usually so small that the SN ratio is considerably small comparing with that of the write-once optical disk. Moreover, the SN ratio decreases in association with the retardation of disk substrate because of the degradation of the polarization state of the laser beam. Consequently, a precise analysis of the SN ratio taking retardation of disk substrate into account is significantly important for designing M-0 disk system. In this paper, retardation of the policarbonate substrate is precisely investigated and quantitative relations between the SN ratio and the retardation of disk substrate are particularly studied by the polarization simulator which traces polarization state of the laser beam.
Write-Once Phase-Change Recording in GaSb
Authors: Tongeren H. v. , Sens M.
Published: February 2023

This paper deals with phase-change recording of EFM-modulated data according to the standard for the signals of the Compact Disc system. Application of GaSb sensitive layers allows a simple single-sided disc construction. Recording is based on locally transformation of the as-deposited amorphous state to the crystalline state.
90-mm Optical Disk Subsystem Using High-Speed Digital Control Techniques
Authors: Saito Minoru , Takeda Toru , Itao Kiyoshi
Published: February 2023

There is a demand for small optical mass storage devices for personal computers. Although a 130-mm rewritable optical disk subsystem has already been developed with large capacity and high-speed access1, a 90-mm rewritable optical disk subsystem would suit personal computers, electronic mail, and electronic publishing.
Overwriting on a magneto-optical disk with magnetic triple layers by means of the light intensity modulation method
Authors: Aratani Katsuhisa , Mutoh Yoshihiro , Kaneko Masahiko , Watanabe Kenjirou , Makino Hiroshi
Published: February 2023

Magneto-optical disk systems have recently been put into the market, featuring large capacity of 600 MB on a double-sided 5.25 inch disk.1 However the system does not have a function of direct overwriting, i.e., erasing operation must be carried out before writing. There is an increasing demand for direct overwriting to obtain an effectively high data transfer rate. Various methods2 for achieving overwriting have been investigated, including the magnetic field modulation method3 and the light intensity modulation method.4 Two light intensity levels P
U
and P
L
are used in the light intensity modulation method. It has the advantages in terms of a high transfer rate and a wide magnet-disk spacing compared with the magnetic field modulation method. The light intensity modulated overwriting was successfully reported by Saito et. al.4 using an exchange-coupled double layer film.
Dependence of Laser-Feedback Noise on Optical-Path Length
Authors: Call David E. , Finkelstein Blair I.
Published: February 2023

Laser-feedback noise in a GaAIAs laser was investigated as a function of optical-path length and modulation frequency. Laser-feedback noise was discovered to be a strong function of the phase difference between the modulated irradiance of the laser and the reflected light intensity. With proper selection of the high frequency of the laser current, satisfactory laser-noise suppression can be achieved for any optical-path length.
Ultra-High Density Optical Memory by Photochemical Hole Burning (PHB) and Multi-Layered PHB System
Authors: Yoshimura Motomu , Nishimura Tetsuya , Tsukada Noriaki
Published: February 2023

(1) Photochemical Hole Burning (PHB) has a possibility to offer us an optical memory with ultra-high data storage density of more than 1011 bits/cm2 theoretically1). Such high data density can be achieved by multiplexing the information additional wavelength dimension besides the x-y spatial domain. The multiplexing of the information is realized by burning a sequence of narrow spectral holes as signals in the spectrum of a PHB material. Then the degree of information multiplexing depends on the degree of the multiple holes in the spectrum. The most essential subject for PHB memory is how densely and how many multiple holes can be formed without any interaction between any two holes.
Melt-Erasing Method of Single Beam Overwrite of Phase Change Optical Disk
Authors: Gotoh Norio , Ishigaki Masaji , Fukui Yukio , Andoh Hisashi , Maeda Yoshihito
Published: February 2023

We introduced a melt-erasing method of single beam overwrite of a phase-change optical disk. A examination on this method was done using a newly developed In-Sb-Te phase-change optical disk. The carrier to noise ratio (CNR) more than 50dB and the erasing ratio more than 40 dB were obtained. The high CNR and the good erasability were due to the In-Sb-Te phase-change optical disk and the melt-erasing method.
Long Life 12” W–Q Type Optical Disks
Authors: Gotoh Akira , Nakamichi Shuhei , Horigome Shinkichi
Published: February 2023

Because of the large memory capacity, optical disks are required to be more reliabl compared with other recording media. Especially, 12” write-once type optical disks are mainly used for archival applications. Therefore, it is important that they can preserve recorded data for a very long time. To keep long term reliability for recorded data, it is essential that initial error rate is low enough and that the error rate dose not increase for a long time. In order to meet the above demand, a series of automated clean processes have been developed for production of air sandwiched type ternary alloy (Te–Se–Pb) recording media 1), 2) in which glass substrates covered with 2P resin are used.
A theoretical analysis for media life estimation using error rate
Authors: Okazaki Hideki , Sasaoka Tatsuya , Nakane Yasuaki , Kiyomiya Tadashi , Makino Hiroshi , Aoki Tokuei
Published: February 2023

Optical data storage systems have been commercially available as computer peripherals. For practical use, long media life is one of the most important key issues in the media qualification. Although there are many degradation mechanisms on the media such as mechanical, physical and chemical changes, these all are reflected in byte error. It is most suitable to estimate the media life by byte error rate (BER), but this estimation method has not been established yet.
High-Power Diode Laser Arrays
Authors: Bartolini Robert A.
Published: February 2023

Semiconductor diode lasers have been the preferred recording source for virtually every optical data storage system since their first reported use nearly a decade ago.1,2,3 Highly reliable, low-power devices are in wide use in consumer CD players while higher-power versions are used in write-once-read-many-times systems. With the emergence of Magneto-Optic media, higher demands are being placed on the power requirements for these devices due to the addition of the media erase cycle. In addition, there has always been a desire and, in many systems, a pressing need to improve the performance of the semiconductor diode laser in such areas as wavelength; mode stability and coherence (both spatial and temporal); beam divergence; power efficiency; and multiple sources on a single monolithic chip.4 The techniques and structures used to achieve diode laser performance improvements in these areas will be reviewed and discussed. In particular, a new class of grating surface emitter lasers5 allows one- and two-dimensional array geometries,6 with inherent stable, single-frequency operation imparted by the grating. These devices offer the advantages of narrow beam divergence, as well as the possibility of electronic steering of the beam. These properties may lead to new classes of high-performance, compact recording systems.
5-channel Magneto-optical Recording Using a Laser Diode Array
Authors: Nishimura Kazutoshi , Murata Setsuko
Published: February 2023

Multichannel recording is the most effective way of increasing the data transfer rate in optical disk drives. Recently, 3- and 4-channel recording have been studied using laser diode (LD) arrays and write-once disks.1,2 However, multichannel recording characteristics in magneto-optical (MO) disks, which have more severe signal and noise problems, have not been reported. This paper investigates the read and write characteristics of an experimental 5-channel MO disk drive with a monolithic LD array. The data transfer rate is 5 MByte/s, which ranks with that of conventional large magnetic disk drives.
Progress in the development of a high data rate, high capacity Optical Disk Buffer
Authors: Levene Martin L.
Published: February 2023

Development of high data rate, high capacity optical disk buffer technology has reached demonstration of the basic modular breadboard. Test and operational data are presented.
Optical Recording Properties of In47Se51Pb2 Thin Films
Authors: Hou L.S. , Jiamg F.S. , Gan F.X.
Published: February 2023

The optical recording properties of In47Se51Pb2 thin films are investigated. The effects of pb on the erase rate, the difference in relectivity between amorphous and crystalline states, and the write/erase cycling number of the above thin films are discussed.
STM Analysis of Pit Formation In Organic Worm Media
Authors: Goldberg H. A. , Onorato F. J. , Chiang K. , Jamieson M. , Li Y. Z. , Piner R. , Reifenberger R.
Published: February 2023

In order to develop a low cost, high performance write once optical data storage media, Hoechst Celanese has been developing organic thin films which can be spin coated directly onto polycarbonate and which can be marked with both 830 nm and 780 nm diode lasers. In this paper we discuss the optical and laser marking properties of this media, paying special attention to information obtained using Scanning Tunneling Microscopy (STM) for evaluating surface topography.
Directions in Optical Storage
Authors: Jipson Victor B.
Published: February 2023

Optical data storage has developed as an industry over the last several years. Starting with large form factor write-once products in the early eighties and more recently evolving to small form factor rewritable products, it has "proven to be an attractive alternative to other storage technologies in the areas of automated libraries for nearline storage and as a workstation peripheral. The principal advantage of optical storage is its relatively high storage capacity on a removable disk. Furthermore, a single optical device can support multiple media types which allows it to provide multiple functions to the user. The relative penetration of optical recording within the storage hierarchy will critically depend on the pace of improvement in the technology that reduces the cost/byte stored, while improving device performance and maintaining removability and functional advantages.
Direct Overwritable Magneto-Optical Exchange Coupled Multilayered Disk by Laser Power Modulation Recording
Authors: Saito Jun , Akasaka Hideki
Published: February 2023

In 1987, we presented a direct overwritable Magneto-Optical exchange coupled multilayered (DOW-MO-ECML or DOW) disk by laser power modulation recording.1) The direct overwriting method could be summarized as follows.

(a) The ECML thin film has at least two layers as shown in Fig. 1. The upper layer, memory layer has higher coercivity at ambient temperature and lower Curie temperature than the lower layer, writing layer.

(b) Laser power is modulated as shown in Fig. 2. Ph irradia tion records new marks. Pl irradiation erases prerecorded marks. Pr means reading power.

(c) The initializing field, Mini is applied to the disk in ad dition to the bias field, Hb for recording.
Direct overwriting system by light intensity modulation using triple-layer disks
Authors: Maeda Fumisada , Arai Masayuki , Owa Hideo , Takahashi Hiroo , Kaneko Masahiko
Published: February 2023

Direct overwriting using light intensity modulation can achieve a high data transfer rate on a double-sided disk. As far as the media is concerned the initializing field strength and the total thickness of the magnetic layer have been reduced by adopting the magnetic triple-layer structure1,2,3. On the other hand, though the system is said to be theoretically compatible with the conventional ISO system, there are some problems still unsolved. The way of initializing the disk is one of them. We have developed an external magnet assembly for a triple layer disk and investigated the feasibility of the direct overwriting system.
Tracking Method of an Optical Tape Recorder Using Acousto-Optic Scanning
Authors: Narahara Tatsuya , Kumai Satoshi , Nakao Takashi , Ozue Tadashi
Published: February 2023

There are many methods to scan laser spots on an optical tape to record and reproduce data. CREO threem RCA A high data transfer rate is one of the most important parameters for digital data storage systems. It is difficult to control a mechanical scanner at a high scanning velocity in a way that the laser spot can trace a high density data pattern precisely. We used an acousto-optic deflector(AOD) for scanning. The advantage of using an AOD over a slide motor or a polygonal mirror or a rotary drum is that the laser spot can be deflected at a high speed with simple and compact hardware. An AOD does not need a precise mechanical actuator nor a position sensor, it only needs optics and an electronic controller. In this paper a precise tracking method using an electronically controlled AOD is discussed.
Optical Memory Using Localized Photoinduced Anisotropy in Synthetic Dye-Polymer
Authors: Kuo Chai Pei
Published: February 2023

The search for proper materials for all-optical data storage has become a critical issue in the development of a practical system that would provide high capacity and high accessing speed operation. In order to characterize a material to determine whether it is a candidate for optical information storage, three basic properties that deal with the material's light/matter interaction response (its ability to retain information, the driving power requirements for light/matter interaction, and the material's response speed) must be considered as a whole, balancing one property against another. Recent developments have shown certain materials that utilize photochromic two-photon absorption phenomena[1] and time-domain frequency selective storage (TDFSS) methods[2,3] are superb in performing three-dimensional, ultra-high capacity, and ultra-high speed data storage. Nevertheless, the two-photon materials need always be driven by a very powerful laser source due to the inherent low absorption cross-section of the two-photon process and the fact that TDFSS is constrained by the required cryogenic cooling operation. In this paper, we present a novel erasable and nonvolatile optical memory based on the application of high-efficiency polymeric material with reversible photoinduced birefringence. All the disadvantages of the two-photon absorption and TDFSS mechanisms are invisible to the synthetic polymer because its storage does not rely on quantum mechanic state excitation but on fast photoinduced electric dipole rotation.
Optical Data Storage in Photosensitive Fibres
Authors: Campbell R. J. , Kashyap R.
Published: February 2023

There is considerable interest in exploiting photosensitivity in germanosilicate optical fibres for application in the areas of optical communication and sensors. Hill et al [1] first observed permanent optically-induced changes of the refractive index of optical fibres in 1978. In their experiment coherent radiation at 514.5nm, reflected from the fibre ends, generated a standing wave in the fibre which induced a periodic refractive index change along its length. This formed a high reflectivity Bragg grating in the fibre which has a peak at the wavelength of the incident beam. Since then numerous studies into the grating growth mechanism and photosensitive fibres have been carried out [2],[3]. However, the mechanism which results in the perturbation to the refractive index of the fibre core is not fully understood. The spectral region where the fibre is photosensitive has been found to range from the uv to around 500nm.
Reversible phase-change optical recording using micro-cellular GeSbTeCo recording film
Authors: Okamine Shigenori , Terao Motoyasu , Andoo Keikichi , Miyauchi Yasushi
Published: February 2023

Single-beam overwriting up to 105 times has been achieved in phase-change optical discs with GeSbTeCo recording films.1 Major limiting factors of the number of overwriting cycles include local thickness change and void generation in recording films.2 This indicates that the film's melted material gradually flows along the recording trucks owing to the repetitions of laser irradiation.
Superresolution in a magneto-optical disk with an active mask
Authors: Fukumoto Atsushi , Yoshimura Shunji , Udagawa Toshiki , Aratani Katsuhisa , Ohta Masumi , Kaneko Masahiko
Published: February 2023

In the conventional optical disk systems, the optical cut-off frequency is limited by the numerical aperture(NA) of the objective lens and the wavelength of the light source due to the diffraction.
Compact Magneto-Optical Disk Head Integrated with Chip Elements
Authors: Yamanaka Y. , Katayama R. , Komatsu Y. , Ishikawa S. , Itoh M. , Ono Y.
Published: February 2023

Recently, a 3.5" magneto-optical disk drive has been developed for a compact data storage peripheral. In such a compact drive, a small optical head having a sufficient read out C/N ratio is necessary. Several types of compact head, using hybrid assembly technique, were proposed for a read only disk 1),2). These optics consist of a few optical parts. A hybrid integration is used for a laser diode chip and a photodetector chip. Because the fluctuation range in optical parts position and the contributed parts number are small, stable operation is expected. For a magneto-optical disk head, however, there has been no report published on a hybrid assembly, owing to the complicated data signal detection optics required.
A 10 MM Thick Head Mechanism for a Stacked Optical Disk System
Authors: Seya Eiichi , Matsumoto Kiyoshi , Moriyama Shigeo , Nakamura Shigeru , Mita Seiichi , Nihei Hideki , Ichikawa Kouji
Published: February 2023

Optical library systems are used for applications which require large storage capacities. However, their access times are too long, sometimes exceeding 10 seconds, for active read/write uses. Recently, a stacked disk system with a head mechanism re-positionable on different disk surfaces1) have realized faster access. Nevertheless, their access times are still too long for random access jobs.
Optical Fibers for Magneto-optical Recording
Authors: Opsasnick Michael N. , Stancil Daniel D. , White Sean T. , Tsai Ming-Horn
Published: February 2023

The performance of present magneto-optical disk devices is limited by the relatively large size and weight of the optical head. The use of optical fibers has been proposed as one technique for reducing the size and weight of optical heads used with contrast media.1 In this paper, we extend this idea and propose a scheme for using single-mode polarization preserving (SMPP) fibers in magneto-optical recording heads. In addition to reducing the size and weight, optical fibers are well suited to achieving simultaneous access to multiple channels.
Fast Laser Power Control for High Density Optical Disk Systems
Authors: Satoh Hiroharu , Kinoshita Yoshio , Okao Keiichi , Tanaka Masahiko , Nagatani Hiroyuki , Honguh Yoshinori
Published: February 2023

In order to increase the recording density in optical disks, it is effective to adopt mark-edge recording with a short-wavelength laser. A powerful visible lasing light as short as 670 nm is now available using a InGaAlP diode 1). The power of the laser, however, includes too much noise to be used in a high density optical disk system. In mark-edge recording, still more distorted marks induce more bit error than in conventional pit position recording. It is, therefore, indispensable to precisely control the laser power level in mark-edge recording. The authors have developed a new optical head and a new fast laser power control electro-optics which reduces much of the laser noise, and, at the same time, rapidly controls the laser power enough to follow the reference laser power signals. In an experiment using this technique, the laser noise decreased by 10 dB and RIN could be reduced to–126 dB/Hz at 10 MHz without a high frequency superimposition. Mark shapes were obtained by simulation based on thermal analysis.
Differential Spot-Size Focus Servo
Authors: Milster Tom D. , Froehlich Fred F. , Wang Mark S. , Treptau Jeff P. , Erwin J. Kevin
Published: February 2023

There are several techniques that can be used for focus-error detection in an optical data storage device. Astigmatic, knife-edge, critical-angle prism, pupil obscuration, and spot-size detection are common techniques (1)(2)(3). These methods sense the focus error by manipulating reflected light from the disk and creating an electrical focus-error signal (FES) with sectioned detectors. If a continuously pregrooved disk is used, the reflected light also contains diffracted orders that are used to provide a tracking-error signal (TES). It is difficult to completely separate the focuserror information from the tracking-error information, regardless of the focus-error detection method. The residual amount of TES observed in the FES is called cross talk. Prikryl (4) has modeled the sensitivity of several focus-error detection methods to sources of cross talk. Stahl (5) has modeled the sensitivity of astigmatic focus-error detection. The works of Prikryl and Stahl indicate that spot-size focus-error detection is probably a good method for eliminating cross talk. In this paper, we discuss the characteristics of a differential spot-size measurement technique, which has better cross-talk rejection than the single-detector spot-size measurement technique. Similar differential techniques have been presented in the literature (6), but they have not been analyzed with respect to cross talk.
Tracking Servo Signal Simulation from STM Surface Profiles
Authors: Karis T.E. , Best M.E. , Logan J.A. , Lyerla J.R. , Lynch R.T. , McCormack R.P.
Published: February 2023

Certain optical data systems rely upon the ability of the laser to accurately track along grooves in the substrate. The topography and physical properties of the substrate, laser beam characteristics (wavelength, spot size), and physical optics of the optical head all play a role in determining whether tracking is possible on a given optical disk. The effects of each of these variables can be found by modelling the disk as a phase surface which modulates the phase of the incident laser light. Scalar diffraction thcory[l,2] can be used to predict the reflected light intensity as a function of position across the disk for a given system. It is then possible to predict the servo signals which are used for tracking. The primary substrate parameters which affect these tracking signals are the groove depth, the relative widths of the groove and land (duty cycle), the track pitch, the refractive index, and the groove topography. All of these disk properties, excluding the refractive index, are found using Scanning Tunneling Microscopy (STM)[3]. This gives a detailed three dimensional surface profile for the disk which is then used in the theoretical calculation of the tracking servo signals. These calculated values are compared to actual experimental data obtained using an optical disk tester. Disks were measured which have varying depth and varying track pitch at fixed depth.
Magnetic and Electronic Properties of Co/Pd Superlattices
Authors: Victora R. H.
Published: February 2023

Recently, there has been considerable interest in the properties of Co/Pd superlattices. Much of this interest stems from their proposed use as a high density magnetooptical recording medium: they possess enhanced Kerr effect at short wavelengths (~4000 A) relative to the currently used amorphous transition metal alloys. Large perpendicular anisotropies K can be obtained by combining thin Co layers (1-2 monolayers) with thicker Pd layers. This combination also produces saturation magnetizations Ms much smaller than that of pure Co, which leads to anisotropy fields (hk = 2 K/Ms) much greater than the demagnetizing field 4πms, and, consequently, perpendicular hysteresis loops possessing squarenesses near 1. Finally, Pd layer thickness can be adjusted to place the Curie temperature at values appropriate for the available laser power.
DyFeCo Magneto-Optical Disks with Ce-SiO2 Protective Film
Authors: Naito Kazunori , Numata Takehiko , Nakashima Kazuo , Maeda Miyozo , Koshino Nagaaki
Published: February 2023

The 130-mm magneto-optical disk has already been marketed, and experimental 90-mm drives have been fabricated to develop compact, extremely efficient low-cost models. Such disks are now being used by individual customers and, in such cases, must be available at a low price. Magneto-optical disks mainly use TbFeCo for their recording material. The magneto-optical disk we developed uses DyFeCo film, which is about two-thirds less expensive than TbFeCo because dysprosium is less expensive than terbium. It had been thought that DyFeCo had a lower Curie temperature and smaller perpendicular magnetic anisotropy than TbFeCo, leading to questions about signal quality and recording bit stability. Unfortunately, no reports on the practicality of DyFeCo have been published thus far. The practical disk we developed has an optimized DyFeCo composition and configuration. For the protective film, we originally developed a very efficient Tb-SiO2 film [1], but replaced it with cerium, which is less expensive. The Ce-SiO2 film was as protective as the Tb-SiO2 film, which we have already reported.
Optimization of Quadralayer Structures for Various Magneto-Optical Recording Materials
Authors: He Ping , McGahan William A. , Woollam John A.
Published: February 2023

Computer simulation of magneto-optical responses as a function of wavelength (300 - 800 nm), thicknesses, and material were made, based on the scattering matrix formulation for the calculation of optical and magneto-optical response of multilayer systems.1 Results from the following MO materials systems are presented: bismuth substituted garnets, TbFeCo, PtMnSb, and NiMnSb. Silicon nitride and silicon carbide were the dielectrics used in the simulations, and aluminum was assumed for the reflector. The optimum structure for each of these materials systems has been found. The Kerr rotation, ellipticity, reflectance, and figures of merit for recording were calculated.
High Speed, Large Capacity Optical Disk, Using Pit-edge Recording and MCAV Method
Authors: Maeda Takeshi , Saitoo Atushi , Sugiyama Hisataka , Ojima Masahiro , Arai Shinichi , Shigematu Kazuo
Published: February 2023

A large size optical disk (for example, in 300 mm diameter) has been applied to document files and archived coded data files. Recently, demands for larger capacity and higher speed are growing greatly. Therefore, we developted a write once optical disk (300 mm in diameter), which adopts the pit-edge recording(1)method and the MCAV (modified constant angular velocity) method to achieve high linear density. No optical disk system combining the above two methods has yet been developed. In addition, new techniques must still be developed to satisfy the requirements of large capacity and high speed using these two methods. In this paper, new techniques we have developed are discussed.
CD-R and the compatibility with CD
Authors: Heemskerk Jacques , Kablau Hans
Published: February 2023

In November 1990 Philips and Sony published the first draft of the "Orange Book", the standard for recording in CD format. Here, we will concentrate on part II of the "Orange Book", the standard for Write Once recording: CD-R.
Wavelength Dependency of CD-R
Authors: Inoue Akiyoshi , Muramatsu Eiji
Published: February 2023

The CD-R System is currently gaining popularity in the Audio and Data field. During the course of development, it is important to comprehend the wavelength dependency of CD-R discs using organic dye material as one of the technological elements.(1)
CD Error Characterization; Differences Between CD-ROM and Writable CD
Authors: Howe Dennis G.
Published: February 2023

Read only Compact Discs (CDs), such as the CD-ROM and Digital Audio CD, are made by concurrently forming the plastic disc and the spiral track of pits that represent the data carried on the surface of the disc via an injection molding operation, and subsequently applying a reflective metal layer in a vacuum coating step and a protective polymer layer via spin coating. The original data that is replicated on these "pressed" CDs is carefully written on a master disc (that is used to form the injection molding tool) using a precision master laser writer that is housed in a very clean environment. On the other hand, writable CDs, such as the CD-R and PhotoCD, are made by first using injection molding to form a plastic disc that has a continuous spiral (tracking) groove on one surface and then sequentially coating that grooved surface with a vacuum deposited dielectric layer, a spin coated organic "pit-forming" layer, a vacuum coated metal reflector layer and a spin coated organic protective layer. Although the spiral tracking groove that is replicated on the surface of the writable CD's molded plastic substrate is initially written on a master disc using essentially the same precision laser writer that was used to create the pressed CDs' master discs, the marks that correspond to the user digital data carried by the writable CD are written one at a time via an optical CD disc drive that is housed in an ordinary environment.
Types of Diode Lasers Now Available for Use in Optical Data Storage Systems
Authors: Scifres D.R. , Major J. , Zucker E.P. , Craig R.R. , Geels R.S. , Welch D.F.
Published: February 2023

One of the largest applications for semiconductor lasers is optical data storage and retrieval systems. Optical data storage applications are expanding rapidly beyond the simple compact disk player requiring a few milliwatt 780 nm laser. This talk will discuss the wide range of laser diode options presently available for optical data storage applications as well as future technical advances which may improve such systems.