| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time required for an adjustment by arranging a transparent roughly flat plate on either a focus error detection system or a tracking error detection system and magnifying a light spot being on a light receiving part for tracking error signal generation to facilitate the adjusting of the photodetector of an optical head. SOLUTION: After the reflected luminous flux R reflected on an information recording surface passes through an objective lens 5 and is reflected in a beam splitter 27, it is made to become a converged luminous flux by a condenser lens 31. Next, this luminous flux R is divided by a beam splitter 32 so that a transmission light becomes a luminous flux to the tracking error detection system and the light reflected two times in the internal parts of the beam splitter 32 becomes a luminous flux to the focus detection system and a reproduced signal detection system. Here, in an ordinary optical system, a transparent member whose thickness is, for example, the order of 0.1∼1.0mm is arranged on the light incident end surface of a photodetector 36, however, an optically transparent roughly flat plate 35 different from this optically transparent member is provided in this head and the tracking error detection system is made to have the magnifying power of a light spot for tracking error detection of not less than, for example, 20%. |
