Optical pickup apparatus
First Claim
1. An optical pickup apparatus for reading recorded information from an optical recording medium, said optical pickup apparatus including and optical system which comprises:
- light intensity detection means having quartered light receiving surfaces;
two semiconductor lasers for emitting light beams of different wavelengths;
an objective lens for directing each of said light beams onto an optical recording medium to form a light spot on a recording surface; and
first and second holographic optical elements located between said quartered light receiving surfaces and said objective lens,wherein one of said two semiconductor lasers is arranged to direct the light beam to said first and second holographic optical elements in a manner that a main axis of said light beam is normal to said first and second holographic optical elements, and the other one of said two semiconductor lasers is arranged at a position that its light beam incident into said first and second holographic optical elements emerges therefrom at right angles; and
wherein said first holographic optical element eliminates coma aberration and spherical aberration of a light beam of a first wavelength from said one of said semiconductor lasers, reflected by said recording surface, thereby generating a predetermined amount of astigmatism, andsaid second holographic optical element eliminates coma aberration and spherical aberration of a light beam of a second wavelength from the other one of said semiconductor lasers, reflected by said recording surface, thereby generating a predetermined amount of astigmatism.
1 Assignment
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Accused Products
Abstract
An optical pickup apparatus which can be designed compact while having a plurality of semiconductor lasers. The optical pickup apparatus, which reads recorded information from an optical recording medium, comprises an optical system including light intensity detection means having a quarter-split light receiving surface, two semiconductor lasers for emitting light beams of different wavelengths, an objective lens for directing each of the light beams onto an optical recording medium to form a light spot on a recording surface, and first and second holographic optical elements located between the quarter-split light receiving surface and the objective lens, whereby the first holographic optical element eliminates coma aberration and spherical aberration of a light beam of a first wavelength from one of the semiconductor lasers, traveled through the recording surface, thereby generating a predetermined amount of astigmatism, and the second holographic optical element eliminates coma aberration and spherical aberration of a light beam of a second wavelength from the other one of the semiconductor lasers, traveled through the recording surface, thereby generating a predetermined amount of astigmatism.
69 Citations
16 Claims
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1. An optical pickup apparatus for reading recorded information from an optical recording medium, said optical pickup apparatus including and optical system which comprises:
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light intensity detection means having quartered light receiving surfaces; two semiconductor lasers for emitting light beams of different wavelengths; an objective lens for directing each of said light beams onto an optical recording medium to form a light spot on a recording surface; and first and second holographic optical elements located between said quartered light receiving surfaces and said objective lens, wherein one of said two semiconductor lasers is arranged to direct the light beam to said first and second holographic optical elements in a manner that a main axis of said light beam is normal to said first and second holographic optical elements, and the other one of said two semiconductor lasers is arranged at a position that its light beam incident into said first and second holographic optical elements emerges therefrom at right angles; and wherein said first holographic optical element eliminates coma aberration and spherical aberration of a light beam of a first wavelength from said one of said semiconductor lasers, reflected by said recording surface, thereby generating a predetermined amount of astigmatism, and said second holographic optical element eliminates coma aberration and spherical aberration of a light beam of a second wavelength from the other one of said semiconductor lasers, reflected by said recording surface, thereby generating a predetermined amount of astigmatism. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification