Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
196 words
An optical pickup head comprising: a semiconductor laser source (1) for emitting a coherent or semi-monochromatic beam; an imaging optics (8) for receiving the beam from said source and focussing it to a micro-spot on an optical memory medium (4); a holographic optical element (6) for receiving a beam reflected from said optical medium and generating diffraction beams; and a photodetector unit (5) for receiving the diffraction beams from said holographic element and delivering photoelectric currents, wherein said source and said photodetector unit are housed in the same package (2), said package has input/output terminals (101) for connecting said source and photodetector unit housed in said package to external circuits, said photodetector unit is comprised of a plurality of photodetectors (501-508) formed on the same semiconductor substrate, said photodetector unit is disposed at a position which is remoter from said holographic optical element than a first plane (113) containing a light emitting point (10) of said source and being vertical to the optical axis thereof, and said holographic optical element has a function of substantial concave lens to permit detection of a focus error signal by means of the light receiving surface of said photo-detector unit.
Claim 2
Dependent Claim
196 words
An optical pickup head comprising: a semiconductor laser source (1) for emitting a coherent or semi-monochromatic beam; an imaging optics (8) for receiving the beam from said source and focussing it to a micro-spot on an optical memory medium (4); a holographic optical element (6) for receiving a beam reflected from said optical medium and generating diffraction beams; and a photodetector unit (5) for receiving the diffraction beams from said holographic element and delivering photoelectric currents, wherein said source and said photodetector unit are housed in the same package (2), said package has input/output terminals (101) for connecting said source and photodetector unit housed in said package to external circuits, said photodetector unit is comprised of a plurality of photodetectors (501-508) formed on the same semiconductor substrate, said photodetector unit is disposed at a position which is remoter from said holographic optical element than a first plane (113) containing a light emitting point (10) of said source and being vertical to the optical axis thereof, and said holographic optical element has a function of substantial concave lens to permit detection of a focus error signal by means of the light receiving surface of said photo-detector unit.
Claim 3
Dependent Claim
52 words
An optical pickup head according to Claim 1, wherein said photodetector unit further includes a photodetector (513) for receiving a beam emitted from a second emission surface of said source opposing, through said source, a first emission surface of said source from which the beam directed to said optical medium is emitted.
Claim 4
Dependent Claim
18 words
An optical pickup head according to Claim 1, wherein said holographic optical element is mounted on said package.
Claim 5
Dependent Claim
73 words
An optical pickup head according to Claim 1, wherein said holographic optical element reconstructs double diffraction beams (81, 82) of different focal points (P1, P2), and said focal points of diffraction beams respectively lie after and before the upper surface of said photodetector unit so that said diffraction beams may have substantially the same size on said photodetector unit when the beam emitted from said source is in-focus on said optical memory medium.
Claim 6
Dependent Claim
32 words
An optical pickup head according to Claim 1, wherein part of said holographic optical element is formed with different diffraction gratings, holograms or non-holographic areas which are spatially independent or of multi-layer.
Claim 7
Dependent Claim
20 words
An optical pickup head according to Claim 1, wherein said photodetector unit is disposed to the bottom of said package.