Shinichi Arai

High-speed large-capacity optical disk using pit-edge recording and MCAV method

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 developed a write once optical disk (300 mm in diameter), which adopts the pit-edge recording method and the MCAV (modified constant angular velocity) method to achieve higher linear density. On 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 were have developed are discussed.

Basic Characteristics and Predicted Lifetime of Stacked Volumetric Optical Disks

A stacked volumetric optical disks (SVOD) system has been developed to achieve an over 1 Tbytes cartridge capacity using a commercialized drive and conventional recording layers. To confirm the reliability of thin optical disks in SVOD, several feasibility tests were conducted. The recording power margin, tilt margin and read stability of the thin optical disks were measured, and the lifetime of the thin optical disks was estimated. The results were similar to those of conventional 1.2-mm-thick optical disks regardless of the disk thickness.

Analysis of Leading Edge/Trailing Edge Independent Detection Method in Optical Disk

The effects of independent detection of leading edge / trailing edge on edge-shift and jitter are investigated for typical heat-mode recording processes using read-out pulse width, recording timing measurements and thermal simulation. In addition, in order to investigate the edge-shift reduction limit for this new method, a method is proposed to analyze what causes the edge-shifts; it statistically evaluates the relative edge intervals between adjacent edges of a particular worst-case recording pattern. Our results clarify that the new method is effective for reducing edge-shifts and jitter.

Electro Magnetic Compatibility Noise Free Endoscope Using Optical Fiber Communication Technology

Recently, the number of pixels for an image sensor has exceeded more than 1 megapixel in the field of video endoscopes, while analog signal transmission bands that use existing electric wires will face physical limitations from the perspective of signal bandwidth and electro magnetic compatibility (EMC) noise. In order to solve these problems, we have developed a bi-directional digital optical communication endoscope system that employs both an image sensor and a single line optical fiber. In addition, due to the fibers high-speed image signal transmission, we have incorporated a digital circuit for serial modulation and deserial demodulation. Consequently, we confirmed that transmission speeds of a 1 Gbps downlink image signal and a 110 kbps uplink control signal were achieved as a result of simultaneous communication. We also designed and tested a compact, co-axial bi-directional optical transmitter and receiver module that can be built into the distal side of a scope. The optical communication module size is less than 4×10 mm2. It was confirmed that this module could be installed in the distal tip of a current endoscope.

Feedback Coupling Module of Optical Transceiver Using Projection Core Fiber

We propose a unique type optical transceiver with a lens position feedback control system to preserve a high optical coupling efficiency between a laser diode and a single-mode fiber (SMF). In this method, accurate alignment or welding is eliminated in the assembly of optical components. This system is also free from a long-term optical power change caused by optical component displacement with environmental variation in temperature and oscillation. In this study, we investigated an optical coupling system, where the position of an optical axis is tuned by active feedback control detecting the optical diffractive pattern from a projecting core fiber (PrCF). By this method, the optical transceiver enabled a lens position control of less than 0.3 µm in a noise environment of 100 Hz–0.25G (G-forces), and was able to maintain optical transmission.

WRITE-ONCE OPTICAL DISK SYSTEM MEASURING 300 MM USING HIGH-DENSITY, PIT-EDGE RECORDING

To meet the requirement for a second-generation digital optical disk with a larger capacity and a higher speed, the new 300-mm, write-once optical disk system described here uses pit-edge recording and the modified-constant-angular-velocity method [Maeda et al., Trans. IEICE E74, 951 (1991)]. New techniques that can use these methods together and are suitable for interchangeability-data composition and independent detection of the leading and trailing edges-have resulted in the most reliable data-storage system ever produced, we believe. The concept of this system, the characteristics of the new techniques, and the optimization of system performance are described.