| 摘要 |
PURPOSE:To miniaturize the optical element constituted while assuring the function capable of making high-density recording and to reduce the size and weight over the entire part of the device by disposing a beam expander into the optical path where the optical element is disposed. CONSTITUTION:This optical head consists of a semiconductor laser 1a as a light beam radiating source, a collimating lens 2, a beam splitter 3, the beam expander 100, a rising mirror 4a, an objective lens 5-1, a condenser lens 5-2, and a photodetector 6-1. The laser beam radiated from the semiconductor laser 1a is projected through a transparent film 11 to the recording surface 10 of the optical disk 12. Since the beam expander 100 exists, the miniaturization of the optical elements, such as the collimating lens 2, the beam splitter 3 and the condenser lens 5-2, is possible. The recording and reproducing device which can make recording and reproducing of information with the small size and weight and at the high speed while maintaining the recording and reproducing functions is obtd. in this way. |
