Optical pickup device and wavelength selective diffraction grating
US6181668A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1998 |
| Grant date | Jan 30, 2001 |
| Priority date | — |
| Expiry date | Aug 28, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/13727
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The optical pickup device includes a two wavelength semiconductor laser (23) selectively generating a laser beam having the wavelength of 635 nm and laser beam having the wavelength of 780 nm, a collimator lens (24), a hologram (25) formed on a surface of collimator lens (24), a polarizing glass (22) having an annular polarizing region (40) and an objective lens (21). Hologram (25) does not diffract the laser beam having the wavelength of 635 nm, and diffracts outward the laser beam having the wavelength of 780 nm. Therefore, virtual light source of the laser beam having the wavelength of 780 nm comes closer to the collimator lens (24) than the light source of the laser beam having the wavelength of 635 nm. Therefore, objective lens (21) focuses the laser beam having the wavelength of 635 nm on a recording surface of a transparent substrate (31) of a DVD, and focuses the laser beam having the wavelength of 780 nm on a recording surface of a transparent substrate (32) of a CD-R. Accordingly, the optical pickup device is capable of reproducing both DVD and CD-R having transparent substrates of different thicknesses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.