Apparatus and method for dynamic tracking and focus in an optical tape system
First Claim
1. In an optical storage system, an apparatus for focussing a light beam onto a recording medium, said apparatus comprising:
- a modulator for modulating said light beam to produce a modulated light beam;
an objective lens for focussing said modulated light beam onto said recording medium;
a focus detector for generating an electrical signal corresponding to a degree of focus of said modulated light beam in reference to said recording medium;
a beamsplitter for directing said modulated light beam to said objective lens and directing a reflected light beam from said recording medium to said focus detector;
a focus actuator placed in close proximity to said modulator, said actuator having a mirrored surface for reflecting said modulated light beam to said beamsplitter, wherein said focus actuator is moved in an optical axis responsive to said electrical signal generated by said focus detector.
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Accused Products
Abstract
In an optical storage system, an apparatus for focussing a light beam onto a recording medium. A light source generates a light beam which is modulated by a thin-film PLZT modulator array. A beamsplitter is used to direct the modulated light beam to an objective lens which focuses the modulated light beam onto the recording medium. The light reflected back from the recording medium is directed by the beamsplitter to a focus detector which generates an electrical signal corresponding to a degree of focus of the modulated light beam in reference to the recording medium. A focus actuator is placed in close proximity to the modulator, wherein the focus actuator has a mirrored surface for reflecting the light beam to the beamsplitter. By moving the focus actuator in an optical axis according to the electrical signal generated by the focus detector, a high bandwidth servo loop can be closed about the focal position.
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Citations
17 Claims
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1. In an optical storage system, an apparatus for focussing a light beam onto a recording medium, said apparatus comprising:
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a modulator for modulating said light beam to produce a modulated light beam; an objective lens for focussing said modulated light beam onto said recording medium; a focus detector for generating an electrical signal corresponding to a degree of focus of said modulated light beam in reference to said recording medium; a beamsplitter for directing said modulated light beam to said objective lens and directing a reflected light beam from said recording medium to said focus detector; a focus actuator placed in close proximity to said modulator, said actuator having a mirrored surface for reflecting said modulated light beam to said beamsplitter, wherein said focus actuator is moved in an optical axis responsive to said electrical signal generated by said focus detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In an optical storage system, a method for focussing a light beam onto a recording medium, said method comprising the steps of:
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modulating said light beam to produce a modulated light beam by using a modulator; focussing said modulated light beam onto said recording medium by using an objective lens; generating an electrical signal corresponding to a degree of focus of said modulated light beam in reference to said recording medium by using a focus detector; directing said modulated light beam to said objective lens; directing a reflected light beam from said recording medium to said focus detector; moving a focus actuator placed in close proximity to said modulator, said actuator having a mirrored surface for reflecting said modulated light beam to a beamsplitter which directs said modulated light beam to said objective lens, wherein said focus actuator is moved in an optical axis responsive to said electrical signal generated by said focus detector. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification