Characteristics of scanning laser and electron beams in bulk data storage

The fundamental practical factors of data recording by the modulation of focused spots formed by electron beams or by laser light are compared in terms of usefulness in applications for data storage and retrieval. The basic factors include: spot formation, focal sensitivity, noise, scanning speed, beam deflection, and media environment. As photographic recording systems, both have maximum utility for high-speed serial data recording and readout and less utility for rapid-access memories. In electron beam systems continuous data rates as high as 300 Mbit/s are feasible. Such rates will also be attainable in laser systems utilizing parallel track recording. Bit densities of 10⁷/in²are possible with either system. A projected estimate of pertinent parameters is indicated.