| 摘要 |
PURPOSE:To improve recording density and an information transfer rate by constituting an information track of two strings of information pits. CONSTITUTION:When a light beam is radiated on a position where the information pits do not exist in the right information pit string PR and the information pit string 1L exists in the left information pit string PL so as to form a beam spot 2C, a strong diffracted light occurs in the right edge of the information pit string 1L and the intensity of the reproduced spot of a photodetector is set on the side of right detection part side. A signal SR obtained from the right detection part goes to 'H' and a signal SL obtained from the left detection side goes to 'L'. When the light beam is radiated on the position where the information pits do not exist in the left and right information pit strings PL and PR so as to form the beam spot 2D, most of light beam is reflected and the light receiving quantity in the detection part is much in the photodetector, so that obtained signals SL and SR go to 'H' together. Thus, the existence of the information pits in the left and right information pit strings PL and PR can be detected and information signals can be reproduced from the respective information pit strings, so that the bit density of information and the information transfer rate can be improved. |
