| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost by constituting the optical pickup without necessity of adjusting an input/output characteristic of an APC circuit for the purpose of keeping a signal output level at a prescrived level. SOLUTION: In the optical pickup having a light receiving photodiode 4 for transducing reflected light from a disk 100 into current signal, a light receiving I/V converter 5 for converting the current signal outputted. by the light receiving photodiode 4 into a voltage signal, a monitor photodiode 6 for transducing a part of emitting light from a light source (a semiconductor laser chip) 1 into a current signal and the APC circuit 7 for feedback control on the light source 1 based on the current signal outputted by the monitor photodiode 6, two photodiodes having the same efficiency of transducing the optical signal into the current signal are used as the light receiving photodiode 4 and the monitor photodiode 6. |
