| 摘要 |
PURPOSE:To make accurate recording of information bits possible by reading out the guide grooves on a recording medium, making the clock of a period corresponding to a bit string out of this signal, and making a modulating signal from the data signal to be recorded and the clock. CONSTITUTION:An optical disc 66 having guide grooves (guide bits) rotates in an arrow direction around a shaft 71. The light beam shown by the diagonal line radiated from a semiconductor laser 81 via an optical system 82 reflects on the disc 66, again returned to the optical path and returns to the laser 81. Then, the quantity of the light emitted from the laser 81 is modulated by the light returning from the disc 66. Hence, the light come out from one end of the laser 81 is detected with a photodetector 80, by which the signal on the disc 66 is read out. |
