An optical-card reader/writer optical and electronic breadboard system, developed by SRI International under contract to Drexler Technology, is described. The optical card, which is the same size as a credit card, can contain more than 2 megabytes of digital user data, which may also include preformatted tracking information and preformatted data. The data layout on the card is similar to that on a floppy disk, with each track containing a header and clocking information. The design of this optical reader/writer system for optical cards is explained. Design of the optical card system entails a number of unique issues: To accommodate both laser-recorded and mass-duplicated information, the system must be compatible with preencoded information, which implies a larger-than-normal spot size (5 gm) and a detection system that can read both types of optical patterns. Cost-reduction considerations led to selection of a birefringent protection layer, which dictated a nonstandard optical system. The non-polarization-sensitive optics use an off-axis approach to detection. An LED illumination system makes it possible to read multiple tracks.

Date Published: 2 June 1988
PDF: 3 pages
Proc. SPIE 0899, Optical Storage Technology and Applications, (2 June 1988); doi: 10.1117/12.944600

Published in SPIE Proceedings Vol. 0899:
Optical Storage Technology and Applications
Donald B. Carlin; Albert A. Jamberdino; Yoshito Tsunoda, Editor(s)