Yoshihiro Okino

Ultrahigh accuracy 3-D profilometer

An ultrahigh accuracy 3-D profilometer using a laser heterodyne interferometer has been developed. The profiles of aspheric lenses and their molds have been measured. It can measure not only the rectangular coordinates but also the polar coordinates of the surface profile. The measuring accuracy of each of the three axes is 0.01-0.05 microm if the inclination of the investigated surface is less than +/-25 degrees . The accuracy of the polar coordinate measurement is also better than 0.05 microm when the inclination of the aspheric surface is less than +/-55 degrees . The dynamic range of the X-Y-Z measurement is 40 x 40 x 20 (mm).

Reproducing-only and recordable-reproduceable optical discs and common optical disc player therefor

The combination of recordable-reproduceable optical discs and reproducing-only optical discs and an optical disc player which is capable of reproducing recorded signals both from the recordable-reproduceable optical disc possessing pregrooves and the reproducing-only optical disc possessing recording pits by means of a common optical system. The common optical system has a common laser for irradiating both types of discs with a laser beam used for reading the discs. The wavelength of the laser is λ and the depth or height of the pregrooves of the recordable-reproduceable optical disc is made equal to or less than λ/8n, and the depth or height of the recording pits of the reproducing-only optical disc is made equal to or greater than λ/8n but less than λ/4n, wherein n is the refractive index of the substrate of the disc or the protective layer provided on the surface thereof.

Developments In Fabrication Of Optical Disks

To establish the high density disc system, the most important point is how discs are produced stably on high rate of yield. From the point of this view we developed a new laser cutting machine of master disc and a novel duplicator of replica disc. This cutting machine which is compactly designed has a improved optical system which are stabel against temperature fluctuation and other environmental disturbance. And we can produce high quality discs at high rate of index time by our disc duplicator using liquid photo-polymer resin which is cured by ultra-violet ray.

Speckle reduction by double recorded holograms.

A method of speckle reduction in holography for 2-D objects with minimum recording area is presented. The image is incoherently synthesized from the hologram double recorded with a set of random phase plates.

A New Approach for Estimating the Life Expectancy of Optical Disk for Digital Archival Storage

In this study, we examine a lifetime estimation method for optical disks using the Eyring acceleration model and statistical analysis. The standardized life expectancy of an optical disk is defined as its minimum lifetime at a 95% survival probability and a 95% confidence level under disk conditions in terms of its degree of usage. We confirmed the capability of this method of estimating life expectancy by considering the stresses of temperature and relative humidity, and providing a confidence level.

Video And Audio Disk File System

A new disk format and a new recorder were developed, based on the still picture disk file system which was put on the market a few years ago, whereby a video disk system that permits concurrent continuous recording of video and audio signals has been developed. In order to achieve a prolonged. recording time, the disk track pitch was narrowed from the conventional 2.5 μm to 1.6 μm and a contrivance was also made circuit-wise to eliminate the resulting cross talk interference. Because of these innovations, 13.3 minutes (24,000 frames) of continuous recording is now realized on a disk 20 cm in diameter. For a continuous recording of sound signals, a continuous track is necessary. To solve this problem, a spiral track was developed in lieu of the conventional concentric track. To indicate addresses, this track is locally interrupted. Such interruptions would normally interfere with sound recording but such interferences could be prevented by selecting the optimum relation between, the length of interruptions and the sound carrier frequency.

Life Time Test of Rewritable Mini Disc (MD) Media.

The lifetime test of optical media is discussed on the rewritable Mini Disc media for consumer use. The experiments were applying the method conventionally used for the data storage optical disc. Judging from some respects of the experimental results, the lifetime of the recording layer of rewritable MD media presently available in the market is deemed to be sufficiently long. In order to establish a measurement method to determine the reliability or lifetime of rewritable MD media, it is necessary to discuss the issues from view points except degradation of recording layer.

Analog Video Signal Recording and Playback Characteristics of Magneto-optical Memory Disk

For real time recording of analog video signals, we developed a high performance RE-TM magneto-optical disk by the technique of alloy target sputtering and a new optical pickup based on the principle of Brewster angle. Real time recording of analog video signals with SNR of 45 dB and estimated life time of more than 10 yerars was achieved.

Recording and Playing (R/P) System Having a Compatibility with Mass Produced Replica Disc

It has now been several years since the first laser video disc system made its debut on the market and the years since then have seen the development of many new applications utilizing various features of the system. The most outstanding features of the laser video disc system are high recording density, high speed of information retrieval, and high speed of copying of information.