| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head for changing a position for reading optical information according to the kind of an optical information recording medium, which is realized at a low cost and capable of employing a low output light source and reading optical information at a high speed. SOLUTION: An intermediate lens 5 and an objective lens 4 are disposed on the optical axis of a laser beam from a semiconductor laser 1 reflected by a beam splitter 2. The intermediate lens 5 is moved toward the objective lens 4 by a specified distance by conducting power to a driving coil 8 and laser beams are collected in the moved condition thereof. Thus, the light collecting position of the objective lens 4 is located in the focal position (optical information recording surface of CD) of the objective lens 4 when the intermediate lens 5 is in a normal position while the light collecting position thereof is located before the focal position (optical information recording surface of DVD) when the intermediate lens 5 is moved. Thus, the optical information of the CD and the DVD can be read by a photodetector 10. |
