| 摘要 |
PURPOSE:To prevent the invasion of a reflected light corresponding to a side lobe and to prevent noise of a signal reproducing system and the deterioration in the servo characteristic of an error detection system by providing a side lobe eliminating optical system to both a signal reproducing optical system and an error signal detection optical system. CONSTITUTION:A light from a light source 1 is shaped by a beam shaping prism 3, the light around the center is shut by a light intensity modulator 4 and the resulting light irradiates a recording medium 7. The reflected light transmits through a beam splitter 5, and is collected by a condenser lens 8 again and only a main lobe component is selected by a slit 9 provided to its focal face. Then the light is split into lights for a signal reproducing system and an error detection system by a splitter 11. The main lobe component of the signal reproducing system is collected by a photodetector 14, and the main lobe component of the error detection system is separated by a splitter 16 into a focus error and a track error and detected by photodetectors 18,19. Thus, the invasion of the reflected light corresponding to the side lobe to a signal detector as noise is prevented and an excellent reproducing signal and an error detection signal are obtained. |
