| 摘要 |
1462791 Television recording and playback MCA DISCO-VISION Inc 15 Feb 1974 [20 Feb 1973] 7021/74 Heading G5R A video recording made by a modulated laser beam is read by a second laser beam distinguished from the recording beam by having a different wavelength. As shown, a beam 40 from an argon ion laser 30 is modulated by video signals in a Pockels cell 32 and passes via a Glan prism 38 and a microscope objective lens 14 on an air bearing 16 to melt a pattern of holes in a bismuth film on a rotating record disc 18. A lower-power HeNe laser 52 sends a reading beam 54 through the same lens 14 at an angle to the recording beam so as to read the record about 2 Ám. downstream of the recording spot. A filter 66 stops any of the argon ion recording beam that may have been reflected from the record with the reading beam. The path of the reading beam includes a polarizing beam-splitter 56 and a quarter-wave plate 62, as described in Specification 1,462,792. |
