Optical Disk Recording Research Articles

Optical disc writing strategy for analog signal recording

Optical discs are being sought as low-cost, earth-friendly storage candidates in response to increasing data volumes. To increase the recording density of optical disc, analog recording technique such as the Orthogonal Frequency Division Multiplexing (OFDM) method has been investigated. Since bitwise information is recorded on optical discs, it is necessary to create a column of marks corresponding to the analog signal for the OFDM method. The Delta-Sigma Modulation (DSM) is known as an analog to digital conversion method in the area of audio. This method transfers efficiently an analog signal to a binary sequence with a simple circuit. In this paper, the application of the method for analog signal recording and the simulation results of the mark recording process on the optical disc are described. The optical disc recording utilizes temperature rise of a multilayer film stack in recording process that is triggered by light focusing. A simplified, 2.5-dimension, thermal analysis is applied to do the large-scale simulation of recording mark sequence.

Signal processing methods in telecommunication field applied to optical disc systems

The main topic in the telecommunication field is to increase the capacity of information transformation with a limited channel bandwidth. Since the readout and recording bandwidths are also limited in optical disc systems, many technologies in communication systems should be applied to them. In this study, two examples of such technologies, orthogonal frequency division multiplexing (OFDM) and divergence detection methods, were applied to optical disc systems to achieve a higher recording density. I studied optical disc recording and reproduction using the OFDM method, and showed the sample calculation of an approximately 1.5-fold recording density for a BDXL™ system using 5-band multiplexing and 64-quadrature amplitude modulation (64-QAM). Typically, optical disc systems have additional readout channels for objective lens control signals. A dual-phase partial response (PR) signal detection method is demonstrated using an additional signal called tangential push–pull. The calculation result of the method indicates a smaller normalized two-dimensional signal deviation than that of the conventional PR detection method.

Japanese 2011 nationwide survey on complications from spine surgery.

BackgroundThe Japanese Society for Spine Surgery and Related Research (JSSR) previously carried out two nationwide surveys in 1994 and 2001 on complications from spine and spinal cord surgery. More than 10 years have now elapsed since 2001. Rapidly ageing populations have major impacts on society, particularly in the medical field. The purpose of this study was therefore to examine the present situation for spine surgery in Japan.MethodsThe JSSR research team prepared a computerized questionnaire made up of two categories in order to capture clinicopathological information and surgical information. A recordable optical disc for data storage was sent to surgeons who were certified for spine surgery by JSSR. The data was analyzed.ResultsThe JSSR carried out a nationwide survey of complications of 31,380 patients. Patients aged 60 years or older comprised 63.1 % of the overall cohort. This was considerably higher than observed in previous surveys. Degenerative spinal diseases increased 79.7 %. With regard to surgical approach, the incidence of anterior surgery has decreased, while that of posterior surgery has increased compared to the earlier surveys (both p < 0.05). Spinal instrumentation was applied in 30.2 % cases, compared to 27.0 and 34.0 % cases in the 1994 and 2001 surveys, respectively. Intraoperative and postoperative complications were reported in 10.4 % and were slightly increased compared to 8.6 % in the earlier surveys (both p < 0.05). Diseases associated with a high incidence of complication included intramedullary tumor (29.3 %) and primary malignant tumor (22.0 %). The highest incidence of complication was dural tear (2.1 %), followed by neurological complication (1.4 %).

Effects of specific key environmental factors on the life expectancy of optical data carriers

ABSTRACTIn recent years, the concept of content preservation rather than carrier preservation has become the norm with regard to long-term digital preservation. Nonetheless, the life expectancy of digital carriers is important because, in addition to other digital system parameters, it determines the migration time of digital content. In general, a cleaner, cooler, drier, and more stable environment extends the life expectancy, and appropriate protection of individual types of carriers is based on understanding the vulnerability of the carrier and consequently on providing optimal storage conditions and appropriate handling. This paper presents the effects of specific environmental factors (i.e., temperature, humidity, and light) on the life expectancy of physical digital recording media, with an emphasis on optical media. Although optical discs are just one of the various methods of digital data storage today, they continue to be a popular archive medium. It should be noted that optical discs are not permanent recording media, as is often wrongly believed, and that their life expectancy is significantly influenced by environmental factors. At the ZRC SAZU Institute of Ethnomusicology, an experiment was conducted to analyze the durability of digital records saved on CD-Rs that were exposed to light in everyday working conditions. The results showed that exposing recordable optical discs to light, especially direct sunlight, can result in complete destruction of the data recorded within a few days or weeks. This confirmed the importance of careful handling, appropriate storage, and regular testing of digital carriers.

International Standards and off Line Archiving Through the use of Recordable Optical Discs

What does the phrase &#x201C;CD-R, DVD-R Recordable Optical Discs&#x201D; bring to mind? Does it have negative connotations like &#x201C;old technology&#x201D;, &#x201C;limited capacity&#x201D; or &#x201C;unreliable archiving?&#x201D; If it does, then you need to take another look at this technology. Recordable optical disc technology is an established technology that is widely regarded as a state-of-the-art solution used on servers, medical instrumentation and for &#x201C;must not be altered&#x201D; data storage needed for trials and law enforcement records. Furthermore, DVD-R capacity (4.7 GB) is enough to store approximately 20,000 PDF pages, assuming 250 KB per page (up to 50,000 pages with compression). It is also enough capacity for 120 minutes of digital master sound data (24-bit, 96 kHz). DVD-R's are an excellent storage solution and provide sufficient capacity when organization size and purpose is taken into consideration. DVD-R is also a solution for long-term archiving. We will discuss three extremely important things you should know about archiving using recordable optical discs.

Archiving Solution with Optical Disc

Ever since the dawn of human being, variety of media such as stone, parchment, bamboo, woods, paper, magneto, optical and electric has been used for recording information. Among those, the optical discs initially started from audio CD in early 1980s, has 12 cm diameter, still playing prominent roles for long term with its stable format, despite the continued evolution of electronic products. The recordable optical discs has also been used for data storage and data distribution for more than 20 years showing its continued strong demand over 10 billion discs every year. Its applications are broadly ranged such as audio, video, PC and digital information.Though optical discs have less capacity and slower transfer rate than hard disk drives and magnetic tape, they have great deal of potential for application of long term archiving.This report discusses the use of optical discs as archiving media and trends in its standardization towards it. As an example, this paper also examines the recovery of discs damaged by the Great East Japan Earthquake.

New Edge-Shift Detection Method for Write Strategy Optimization in High-Density Optical Disc Recording

New Edge-Shift Detection Method for Write Strategy Optimization in High-Density Optical Disc Recording

New Edge-Shift Detection Method for Write Strategy Optimization in High-Density Optical Disc Recording

We propose a sophisticated edge-shift detection method based on the partial response maximum likelihood technology for high-density optical disc recordings. One of the major features is the capability of detecting the edge shifts of short marks that cannot be optically resolved. Another feature is that measured values are not affected by the signal-to-noise ratio in a readout signal. This ensures drive compatibility. Furthermore, the edge-shift values are sorted and evaluated corresponding to the write pulse control parameters for simplifying write strategy optimization. These features make write strategy optimization possible under an areal recording density of over 30 Gbyte/layer.

Perfect Tracking Control System with Prediction State Observer for Next-Generation Optical Disks

Recently, the capacity of optical disk recording systems has been increasing. Optical disk drive systems must realize high-precision tracking control. For this purpose, we previously proposed a tracking control system that is composed of both a robust feedback controller and a zero-phase-error feedforward tracking controller. The proposed feedforward tracking control system effectively suppresses the tracking error caused by track eccentricity. However, it is sometimes difficult for conventional feedforward tracking control systems to realize higher precision in their tracking control. Hence, in this paper we propose a new perfect tracking control (PTC) system with a prediction state observer for next-generation optical disks. The experimental results confirm that the proposed system suppresses the tracking error at a disk rotation speed of 8000 rpm. Therefore, the proposed system realizes high-precision tracking control.

Recording Characteristics of 10-Layer Recordable Optical Disc and a Prospect for Over 500 Gbyte Recording

A 10-layer recordable optical disc with an inorganic recording material, Bi–Ge–O, was fabricated and the recording characteristics were measured using a Blu-ray Disc-based apparatus with a wavelength of 405 nm and a numerical aperture of 0.85. Practical signal quality was obtained from all the layers at densities of 25 and 32 Gbyte per layer. A 16-layer recordable optical disc was also fabricated and measured. Practical signal quality was also obtained from both the 1st layer and the 16th layer.

Error Prediction Robust Tracking Control System Suppressing Harmonics Disturbance for Optical Disk Recording System

Recently, the memory capacity of media for the optical disk recording system has been increasing. The disk rotation speed has been increasing depending on the large memory capacity. However, the optical disk recording system has both periodic primary disturbance and periodic harmonics disturbance. Hence, the tracking control of the optical disk recording system is requested to maintain a high-precision tracking performance. We have proposed the robust tracking controller and zero-phase error tracking feed-forward control systems. Results of our study show that the primary disturbance is well suppressed by our conventional method, but it is difficult for our conventional method to suppress the harmonics disturbance. To overcome this problem, in this paper, we propose a new error prediction robust tracking control system suppressing harmonic disturbance. The experimental results show that the proposed tracking control system has a precise tracking response against both periodic primary disturbance and periodic harmonics disturbance.

Robust Feedforward Tracking Control Suppressing Harmonics Disturbance and DC Offset for Optical Disk Recording System

This paper proposes a new robust feedforward tracking control system suppressing tracking error including harmonics disturbance and DC offset for optical disk recording system. The proposed tracking control system consists of triple compensation loops of tracking error which are the robust feedback control loop, a new harmonics disturbance suppression loop based on Zero Phase Error Tracking(ZPET) feedforward control and a new additional DC offset compensation loop. The feedback controller is the most inner loop which is based on the high gain servo system. The harmonics disturbance suppression loop based on ZPET control is the middle loop which suppresses the influence of many periodic disturbances. The final outer loop is a new additional DC offset compensation loop which suppresses the DC offset caused by ZPET feedforward control. The experimental results point out that the proposed system well realizes the fine tracking performance for optical disk recording system.

Achievement method of high‐speed response of error prediction tracking control for optical disk system

AbstractThis paper proposes the new design method of error‐prediction control systems combining the ZPET control and the robust feedback control. The error‐prediction control system based on ZPET control can reduce the tracking error caused by periodic disturbances more efficiently than the conventional repetitive control technique. However, the proposed tracking servo system does not reduce the residual tracking error caused by the low‐pass filter of the feedforward compensation and by the long sampling time. In order to overcome this problem, this paper proposes the new structure of the feedforward tracking control system. The modified ZPET control tracking servo system for optical disk recording system does not include the low‐pass filter and its sampling time becomes faster. On the other hand, the sudden disturbance observer reduces the influence of nonperiodic disturbances. The experimental results point out that the proposed tracking servo system has a precise tracking response against both the periodic disturbances and the nonperiodic disturbances. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 51–59, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20800

Microstructure and recording mechanism of Bi–Fe–(N) layer for high-density write-once optical disk

Bi–Fe–(N) thin film as the recording layer of high density digital versatile disk recordable optical disk was developed. For the disk sample with optimized layer structure, maximum partial response signal to noise ratio of 21.1 and minimum simulated bit error rate of 5×10−7 were achieved at the write power=5.7mW. Transmission electron microscopy characterization illustrated that the separation of Bi and Fe elements to form the coarse granular structure in the mark regime during laser irradiation comprised of the recording mechanism.

高速光ディスク装置のための高性能エラー予測型ロバストトラッキング制御系

高速光ディスク装置のための高性能エラー予測型ロバストトラッキング制御系

Trend of High-Power Laser Diodes for Recordable Optical Disc Drive

Historical development trend of high-power laser diodes for recordable optical disc as CD-R and DVD-R is explained in a view point of not only how to realize highly reliable high-power operation but also how to adopt laser diodes into optical disc drives.

Scalar diffraction modeling in optical disk recording using wave function assembling

A new scalar diffraction modeling method for simulating the readout signal of optical disks is described. The information layer is discretized into pixels that are grouped in specific ways to form written and unwritten areas. A set of 2D wave functions resulting from these pixels at the detection aperture is established. A readout signal is obtained via the assembly of wave functions from this set according to the content under the scanning spot. The method allows efficient simulation of jitter noise due to edge deformation of recorded marks, which is important at high densities. It is also capable of simulating a physically irregular mark, thereby helping to understand and optimize the recording process.

Investigation on Life Expectancy of High-Speed Recordable Optical Disks

This study is intended to establish a standard technique for measuring high-density optical disk life expectancy. The life expectancy of archival performance for high-speed recordable optical disks [digital versatile disc-recordable (DVD-R) disk] was examined using two acceleration test models, namely, the Arrhenius and Eyring models, and an analysis of statistical techniques based on the ISO method. Results demonstrate that the statistical distribution of failure time using both acceleration test models follows a lognormal distribution. Thus, we can estimate a standard life expectancy of 95% survival probability with a 95% confidence level for each acceleration test model.

Auto-write strategy system for optical disc recording

Optical disc recording technology using many types of write strategy (WS) has been developed for optical discs. The optimum WS for each disc is determined based on the material of recordable layer, recording speed, specification of the optical heads and so on. Parameters of WS should be determined by accurate tuning for each optical disc. It has been strongly desired to develop an actual auto-write strategy (AWS) technology to reduce the time for preparing WSs. A new AWS system to optimize the WS for 2times-speed recording on DVD-R discs was developed. This system can detect the pulse widths and signal level of RF signals, and can get better parameters of WS by calculation. As a result, optimum WS can be obtained for optical discs. In this paper, we introduce our new AWS system along with the experimental result of the effectiveness of this system for the optical discs in the actual market.

Standardized Life Expectancy of High-Speed Recordable Optical Disks

This study examined a life expectancy of high-speed recordable optical disks (DVD-R). It is based on the Eyring acceleration model and statistical analysis. The statistical distribution of life data for the optical disk assumed a lognormal distribution. Analysis of statistical techniques based on the ISO standard is proposed as a life expectancy prediction method for CD-R disks. The results demonstrated that the statistical distribution of failure time data using the PI error number criterion can accommodate a lognormal distribution. We can estimate a standardized life expectancy of a high-speed DVD-R as the minimum lifetime of 95% survival probability at 25 degC/50%RH with a 95% confidence level