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Optical pickup using an optical phase plate
| Details |
Inventors: Yoo, Jang Hoon; Lee, Chul Woo; Chung, Chong Sam; Seong, Pyong Yong; Cho, Kun Ho; Choi, Hyun Seob; Lee, Yong Hoon; Kim, Tae Kyung; Park, No Kyong;
Assignee: Samsung Electronics Co., Ltd. (Kyungki-do, KR)
Primary Examiner: Edun; Muhammad
Assistant Examiner:
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak & Seas, PLLC
An optical pickup apparatus having compatibility with a recodable compact disk (CD-R) and a digital video disk (DVD), which uses a wavelength of one of a first light beam and a second light beam according to the recording medium to be used. In the optical pickup apparatus, laser light sources emit a first light beam having a relatively shorter wavelength for the DVD and a second light beam having a longer wavelength for the CD-R, respectively. An objective lens has a predetermined focal length in accordance with the position of an information recording surface in the DVD. An optical path control unit controls the path of light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit. A phase shift unit which is located between the optical path control unit and the objective lens, shifts the phase of the second light proceeding from the optical path control unit to the objective lens, to thereby reduce the size of a beam spot which is formed on a position of the information recording surface in the CD-R. |
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DETAILED DESCRIPTION An object of the present invention is to provide an optical pickup apparatus which is compatible with a digital video disk and a recordable compact disk by removing a spherical aberration using a phase plate.
To accomplish the above object of the present invention, there is provided an optical pickup apparatus for at least two optical recording media, which are different in distance from an optical pickup to information recording surfaces and uses light beams of different wavelengths for recoding and reading information, the optical pickup apparatus comprising: a plurality of laser light sources for emitting a first light beam having a relatively shorter wavelength and a second light beam having a relatively longer wavelength, respectively; an objective lens having a predetermined focal length in which the focal point of the objective lens according to the first light beam coincides with the position of the information recording surface in a first optical recording medium having the information recording surface closer to the objective lens; optical detection means; means for controlling an optical path so that the light beam emitted from the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection means; and phase shift means, coupled between the optical path control means and the objective lens, for shifting the phase of the second light beam proceeding from the optical path control means to the objective lens, thereby reducing the size of a beam spot which is formed on the position of information recording surface in the second optical recording medium having the information recording surface farther from the objective lens by the second light beam focussed by the objective lens, wherein a wavelength of one of the first light and second light beams is used according to the optical recording medium used.
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Optical Systems 
