Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation; by modifying optical properties or the physical structure; , reproducing using an optical beam at lower power; by sensing optical properties; Record carriers therefor
Structures for detection, control, recording operation or replay operation; Special shapes or structures for centering or eccentricity prevention; Arrangements for testing, inspecting or evaluating; Containers, cartridges or cassettes
