| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the number of components of an optical pickup device. <P>SOLUTION: An optical pickup device 10 comprises a light source 12, polarizing elements 18 and 20, beam splitter optical elements 22 and 24, a lens 26 for lighting, a lens 32 for detection, a detector 34, a reflecting wavelength plate 40 and an objective optical system 30. The reflecting wavelength plate 40 has a structure in which a reflector 42 and a 1/4 wavelength plate 44 are integrated with each other. The 1/4 wavelength plate 44 has a period as short as a half or less of a wavelength of target light and employs a periodic grating structure for performing conversion between linear polarization and circular polarization. In order to use the optical wavelength plate commonly for light of a plurality of wavelengths, the dimension and the refractive index of the periodic grating structure are set so that a difference between a phase difference of one wavelength and a phase difference of the other wavelength may be an integral multiple of (π/4) in a wavelength-phase difference characteristic of birefringence characteristics. <P>COPYRIGHT: (C)2012,JPO&INPIT |
