Paul Louis Marie Put

Resolution Limit of Optical Disc Mastering.

With the increase of the information density on optical discs, it becomes increasingly necessary to improve the quality and the resolution of the optical disc mastering process. The obvious approach is to reduce the size of recorded structures by reducing the λ/ NA ratio of the recorder. Indeed, mastering at UV wavelengths has been put into practice by several companies. This paper deals with an additional route towards higher resolution. It is shown that the combination of improved photoresist processes and better exposure techniques can lead to a clear reduction of the smallest achievable pit size. Combining such techniques with UV mastering, pit lengths below 200 nm should be well within reach of classical optical disc mastering.

Prototype Optical Tape Recorder

In 1994 a new concept for an optical tape recorder, based on a very fast spinning polygon, was presented. Since then, a prototype tape recorder has been developed on the basis of this technology. In order to reduce the complexity of the system, the optical configuration was redesigned. Also, a new polygon with 10 facets was developed. Finally, the tape transport mechanism was modified in order to further decrease the access time. The result is a smaller recorder consisting of fewer components and having better performance than the original one. Typically, a storage capacity on the order of 50–100 Gbyte is possible in a small cassette. Bit rates are up to 25 Mbit/s. An access time of less than 3 s was realized for 50 Gbytes of storage capacity.

Evaluation of photolithographic processes for high-density optical disc mastering

An investigation into the fundamental properties of the photolithographic optical disc mastering process is presented. It is shown that, despite the extreme differences in processing conditions, some of the models used in IC-lithography are valid for this process. This opens the possibility of introducing some of the techniques for resolution enhancement, proposed in IC-lithography, into the optical disc mastering process.

Compact optical tape recording system

A new optical tape recorder, based on a very fast rotating polygon is described. This system combines a high data rate with a high storage density and fast access. The recorder is compact and, apart from the polygon, requires only simple mechanics.