| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head device capable of reproducing two kinds of disks whose substrate thicknesses are different, capable of obtain satisfactory S/N and jitter at the time of reproduction and capable of obtain a sufficient light output and peak intensity at the time of recording. SOLUTION: This optical device is provided with the optical system 11 of one side and the optical system 12 of other side outputting and receiving laser beams whose wavelengths are different and is equipped with a light multiplexing/demultiplexing means (interference filter) 13 which multiplexes outgoing lights from semiconductor lasers of respective optical systems and which also demultiplexes a reflected light from an optical recording medium 16 (or 17) to guide it to either of photodetectors. Moreover, a wavelength selecting phase plate 14 having a character changing a phase distribution with respect to other wavelength in wavelengths of one side and other side from the first and second semiconductor lasers is equipped in between the interference filter 13 and an objective lens 15. |
