| 摘要 |
1441175 Recording and playback PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 31 Aug 1973 [2 Sept 1972 5 Sept 1972] 41111/73 Heading G5R A playback beam of radiation B from a source 5, e.g. a laser, impinges on a record carrier 1 in a spot V 1 wider than the track 2 being scanned and is diffracted on encountering any elements of recorded information b, e.g. pits of depth #/4 or optical marks; the path of the radiation from the record carrier 1 to a detector D includes a limiting aperture, e.g. a lens L, such that a part of any diffracted radiation falls outside it and does not affect the detector D. |
