• Alex Savin
• March 10, 2022
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Blu Ray Disc Technology

In the past year technology has been developing so fast and all with the goal of making our lives easier. With that idea in mind, blu ray disc was developed. Lots of information, memories, and various data can be stored on this small object which is still constantly being developed. Read on to find out how the Blu-Ray disc technology has evolved.

Basics of Blu-Ray disc technology

Blu-ray Disc (official abbreviation BD) is an optical disc storage medium designed to supersede the DVD format. The disc diameter is 120 mm and the disc thickness is 1.2 mm plastic optical disc, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB (23.31 GiB) per layer, with dual-layer discs (50 GB) being the norm for feature-length video discs. Triple-layer discs (100 GB) and quadruple layers (128 GB) are available for BD-XL Blu-ray re-writer drives. Currently, movie production companies have not utilized the triple or quadruple layer discs; most consumer-owned Blu-ray players will not be able to read the additional layers, while newer Blu-ray players may require a firmware update to play the triple and quadruple sized discs.

Blu-ray Discs are recorded and read with a blue-violet 405 nm laser through a high numerical aperture 0.85 objective lens. The main application of Blu-ray Discs will be high-definition television (HDTV) recording. Future demand for a major capacity increase within the Blu-ray Disc family is anticipated by the development of multi-layer technology. However, the optical and thermal characteristics of the currently used phase-change materials restrict the number of layers to two. Such a dual-layer re-writable disc still allows for design choices, which affect system performance. First, we describe the spacer technology we have used for making our dual-layer disc. The two recording layers are based on stack designs with fast-growth materials.

A new recording mechanism that generates well-defined cavities in recording pits is found to satisfy essential performance criteria for high-density, high-speed recordable dye media. A 0.1mm cover layer with a web-coated protective layer is shown to have satisfactory resistance to abrasion and scratching, and to offer ease of fingerprint removal.

A practical way of realizing cartridge-free Blu-ray disc using nanocomposite UV-curable resin as a hard coat on a laser incident surface of the disc is described. The hard coat is a composite material of UV-curable acrylic resin and nanoparticles of silica. A lubricant that exhibits oil repellency, as well as a low friction coefficient, was added to the hard coat in order to facilitate the removal of fingerprints. It effectively prevents abrasions, scratches, and problems with fingerprints on the disc surface. Abrasion and scratch resistance and ease of fingerprint removal were evaluated and compared with those of a polycarbonate surface and a conventional UV-curable hard coat.

The liquid immersion mastering technique has been successfully applied to the mastering of read-only memory (ROM) discs for the Blu-ray disc (BD) system. Replicated discs with a density corresponding to 25 GB in a single layer on a 12 cm disc showed a bottom jitter of less than 5%. Results concerning process latitude and disc uniformity are presented. A full-format 25 GB ROM disc containing over 2 h of high-definition video content has been mastered according to the BD target specification. The results obtained for a reduced channel bit length show the potential of liquid immersion mastering for densities beyond 31 GB per layer.

This paper describes a front-end processor for Blu-Ray Disc (BD) recorder applications. It integrates a partial response maximum likelihood (PRML) block, a data processor (DP) block, and a servo block. The PRML includes an analog-to-digital converter (ADC) and two digitally controlled oscillators (DCO) for data phase-locked loop (PLL) and wobbles PLL. A nonlinear equalizer is designed to compensate for high-frequency signal components without increasing inter-symbol interference (ISI). A Teaklite DSP, an ADC, and a digital-to-analog converter are embedded for servo controls. The functions of the 17PP modem and error correction code (ECC) are also implemented. Due to the proposed nonlinear equalizer in PRML, less than 2 × 10-4 of symbol-error rate (SER), defined in the Blu-ray Disc format book, is achieved with a tangential tilt margin of ±0.5°. This system on a chip (SOC) is fabricated in 0.18-μm one-poly five-metal CMOS technology. It contains 12 million transistors in a 50-mm2 die and consumes 0.9 W with a channel clock of 132 MHz in 2× playback mode.

The usage of pulsed cooling for mold temperature to improve the molding process has been gaining increasing attention. In this study, Blu-ray Disc substrates, adapted for the commercial format media, were injection molded by combining pulsed-cooling technology. When applying pulsed cooling, coolant circulation is usually stopped during the melt-filling process and the mold opening and closing period. This leads to the additional cavity surface temperature increase and may vary part qualities. The correlations of mold temperature, cycle time, and pulse cooling duration with microgroove duplication accuracy and substrate qualities such as warpage in different directions were investigated in detail. Measured results were also compared with those of injection-compression molded Blu-ray Disc using conventional cooling. The experiments showed that by using pulsed cooling in a proper manner one may manufacture Blu-ray Discs with lower warpage, higher accuracy in microgroove replication meanwhile reducing coolant temperature by 8 °C and shortening the cycle time by10% as compared to the conventional-cooling process. The usefulness of pulsed cooling and its potential in improving part quality and reducing cycle time during injection molding has been successfully demonstrated.

Conclusion

With all its usefulness the inventors of blu ray are continuing to perfect it. The newest project is to develop a Blu-ray 3D with the goal to respond to the demands of the film industry and consumer electronics. All us laymen can do is wait for the new surprises coming from blu ray and they are coming fast.