Optical pickup with improved collimating lens for use with long and short wavelength laser beams

An optical pickup comprising:

• first and second light sources, which correspond to first and second media, respectively, to generate laser beams of different wavelengths;
• an objective lens to focus the laser beams from said first and second light sources onto the first and second media, respectively;
• first and second photodetectors to receive the laser beams emitted from said first and second light sources and reflected from the first and second media, respectively;
• and
• a collimating lens arranged on the optical path of one of the laser beams having a relatively short wavelength, said collimating lens including a diverging lens with diverging power and a focusing lens with focusing power,
• wherein said collimating lens satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the diverging lens.

An optical pickup comprising:

• an objective lens selectively arranged opposite first and second media;
• a first light source arranged on the optical path of said objective lens;
• a beam splitter arranged between said objective lens and said first light source;
• a second light source arranged on the optical path of the light reflected from said beam splitter;
• a first photodetector to receive light emitted from said first light source and reflected from the first medium;
• a second photodetector to receive light emitted from said second light source and reflected from the second medium;
• and
• a collimating lens arranged between said objective lens and said beam splitter, said collimating lens including a diverging lens with diverging power and a focusing lens with focusing power,
• wherein said collimating lens satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the diverging lens.

An optical pickup comprising:

• an objective lens selectively arranged opposite first and second media;
• a first light source arranged on the optical path of said objective lens, to emit a laser beam toward the first medium;
• first, second and third beam splitters arranged on the optical path at predetermined positions from said first light source toward said objective lens;
• a second light source arranged on the optical path of the light reflected by the first beam splitter, to emit a laser beam through the first beam splitter toward the second medium;
• a first photodetector arranged on the optical path of the light reflected by the third beam splitter, to receive the laser beam emitted from said first light source and reflected from the first medium;
• a second photodetector arranged on the optical path of the light reflected by the second beam splitter, to receive the laser beam emitted from said second light source and reflected from the second medium;
• and
• a collimating lens arranged between the second and third beam splitters, said collimating lens including a diverging lens with diverging power and a focusing lens with focusing power,
• wherein said collimating lens satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the diverging lens.

An optical pickup comprising:

• an objective lens selectively arranged opposite first and second media;
• a first light source arranged on the optical path of said objective lens, to emit a laser beam toward the first optical disk;
• first, second and third beam splitters arranged on the optical path at predetermined positions from said first light source toward said objective lens;
• a second light source arranged on the optical path of the light reflected by the first beam splitter, to emit a laser beam through the first beam splitter toward the second medium;
• a first photodetector arranged on the optical path of the light reflected by the third beam splitter, to receive the laser beam emitted from said first light source and reflected from the first medium;
• a second photodetector arranged on the optical path of the light reflected by the second beam splitter, to receive the laser beam emitted from said second light source and reflected from the second medium;
• and
• a collimating lens arranged between said objective lens and the third beam splitter, said collimating lens including a diverging lens with diverging power and a focusing lens with focusing power,
• wherein said collimating lens satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the diverging lens.

An optical pickup comprising:

• a light source to generate a first light beam with a wavelength within a range of wavelengths under 500 nm for use with recording and/or reproducing with respect to a first medium and a second light beam with a wavelength outside of the range and which is roughly 650 nm for use with recording and/or reproducing with respect to a second medium other than the first medium;
• an optical element to focus a generated one of the first and second light beams onto a received one of the first and second media;
• a detector to detect the generated light beam reflected from the received one medium;
• and
• a collimating lens arranged in an optical path between said light source and said optical element, the collimating lens having a diverging lens with a diverging power sufficient to allow the optical element be capable of:
• focusing the first light beam for each of the wavelengths within the range onto the first medium with negligible aberration, and
• focusing the second light beam with the wavelength of roughly 650 nm onto the second medium with negligible aberration.

An optical pickup comprising:

• a light source to generate a light beam with a wavelength between roughly 400 nm and 650 nm;
• an optical element to focus the light beam onto a medium;
• a detector to detect the light beam reflected from the medium;
• and
• a collimating lens arranged in an optical path between said light source and said optical element, wherein:
• the optical pickup focus the light beam onto the medium with negligible aberration, and
• said collimating lens comprises a surface with a diverging power, and satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the surface with diverging power.

An optical pickup comprising:

• light sources to emit respective light beams of different wavelengths, wherein one of the wavelengths is within a range that is less than roughly 500 nm and another one of the wavelengths is more than roughly 500 nm;
• an optical element to focus the light beams onto respective media;
• detectors to detect respective light beams reflected from the corresponding media;
• and
• a collimating lens arranged between said light sources and said optical element, wherein said collimating lens comprises a surface with a diverging power, wherein:
• the optical pickup focuses the light beams emitted from the light sources and having passed through the collimating lens onto respective media with negligible aberration, and
• the diverging power is sufficient to allow the optical pickup to focus the one light beam for each of a plurality of wavelengths within the range below 500 nm onto the respective medium with negligible aberration and also to allow the optical pickup to focus the another light beam having the wavelength above roughly 500 nm onto the respective medium with negligible aberration.

An optical pickup comprising:

• light sources to emit respective light beams of different wavelengths, wherein one of the wavelengths is less than roughly 500 nm;
• an optical element to focus the light beams onto respective media;
• detectors to detect respective light beams reflected from the media;
• and
• a collimating lens arranged between said light sources and said optical element, wherein said collimating lens comprises a surface with a diverging power, wherein:
• the optical pickup focuses light beams onto respective media with negligible aberration, and
• said collimating lens satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the surface with diverging power.

An optical system comprising:

• light sources to emit a light beam having a wavelength within a range under 500 nm and another light beam having a wavelength suitable for recording and/or reproducing data with respect to a digital versatile disc;
• an optical element to focus the light beams onto respective media;
• detectors to detect a respective light beam reflected from the media;
• and
• a collimating lens arranged between said light source and said optical element, wherein said collimating lens comprises a surface with a diverging power, wherein:
• the optical system focuses each of the light beams emitted from the light sources and having passed through the collimating lens onto respective media with negligible aberration, and
• the diverging power is sufficient to allow the optical pickup to focus the one light beam for each of a plurality of wavelengths within the range below 500 nm onto the respective medium with negligible aberration and also to allow the optical pickup to focus the another light beam onto the digital versatile disc with negligible aberration.

An optical system comprising:

• a light source to emit a light beam of less than roughly 500 nm;
• an optical element to focus the light beam onto a respective medium;
• a detector to detect the light beam reflected from the medium;
• and
• a collimating lens arranged between said light source and said optical element, wherein said collimating lens comprises a surface with a diverging power, wherein:
• the optical system focuses the light beam onto the respective medium with negligible aberration, and
• said collimating lens satisfies the relationship −1.5>f/fn, where f is a total focal length of said collimating lens, and fn is a focal length of the surface with diverging power.