Optical pickup using an optical phase plate and which is compatible with optical recording media of dirrerent types
First Claim
1. An optical pickup apparatus for at least two optical recording media, which are different in distance from an optical pickup to an information recording surface and using light beams having different wavelengths for recording 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 a focal point of said objective lens according to the first light beam coincides with a position on the information recording surface in a first optical recording medium wherein the information recording surface is closer to said objective lens;
means for optical detection;
means for controlling an optical path so that at least one of the first and second light beams emitted from one of the laser light sources is directed to said objective lens and light output from said objective lens is directed to said optical detection means; and
means for phase shifting, located between said optical path control means and said objective lens, for shifting the phase of the second light beam proceeding from said optical path control means to said objective lens, thereby reducing a size of a beam spot which is formed on the position of the information recording surface in the second optical recording medium having the information recording surface which is positioned farther from said objective lens by the second light beam focussed with said objective lens, wherein the wavelength of one of the first and second light beams is chosen according to the optical recording medium to be used.
0 Assignments
0 Petitions
Accused Products
Abstract
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.
51 Citations
26 Claims
-
1. An optical pickup apparatus for at least two optical recording media, which are different in distance from an optical pickup to an information recording surface and using light beams having different wavelengths for recording 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 a focal point of said objective lens according to the first light beam coincides with a position on the information recording surface in a first optical recording medium wherein the information recording surface is closer to said objective lens;
means for optical detection;
means for controlling an optical path so that at least one of the first and second light beams emitted from one of the laser light sources is directed to said objective lens and light output from said objective lens is directed to said optical detection means; and
means for phase shifting, located between said optical path control means and said objective lens, for shifting the phase of the second light beam proceeding from said optical path control means to said objective lens, thereby reducing a size of a beam spot which is formed on the position of the information recording surface in the second optical recording medium having the information recording surface which is positioned farther from said objective lens by the second light beam focussed with said objective lens, wherein the wavelength of one of the first and second light beams is chosen according to the optical recording medium to be used. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 25, 26)
-
-
20. An optical pickup apparatus for at least two optical recording media, which are different in distance from an optical pickup to an information recording surface and using light beams having 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 a focal point of said objective lens according to the first light beam coincides with a position on the information recording surface in a first optical recording medium wherein the information recording surface is closer to said objective lens;
means for optical detection;
means for controlling an optical path so that at least one of the first and second light beams emitted from one of the laser light sources is directed to said objective lens and light output from said objective lens is directed to said optical detection means; and
means for varying the aperture, located between said optical path control means and said objective lens, having a first region for transmitting both of the first and second light beams entered from said optical path control means, and a second region for transmitting only the second light beam entered therefrom, wherein the first and the second regions have a same optical axis as that of said objective lens, and wherein the wavelength of one of the first and second light beams is chosen according to the optical recording medium to be used. - View Dependent Claims (21, 22, 23, 24)
-
Specification