| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head which is capable of performing recording and reproduction on two optical recording media different in recording reproduction wavelength and has excellent optical use efficiency regarding an outgoing beam from each light source. <P>SOLUTION: By providing a dichroic beam expander 207 which forms N steps or a blaze of a saw-toothed pattern on both sides of a substrate between the respective light sources 201 and 202 and an objective lens 209, light flux diameters from the two light sources different in wavelength is wavelength-selectively expanded or reduced. Thus, it is possible to gain the use efficiency of a laser beam from the respective light sources with high efficiency. Also, as effective light flux diameters to the light from the respective light source are different in the optical head capable of recording and reproducing optical disks (mainly CD and DVD) of a plurality of standards differing in light source wavelength, inconvenience that the light use efficiency regarding the light of narrow effective light flux diameter has reduced can be eliminated. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
