Optical pickup

Details Optical pickup Optical pickup

2006-05-23

2006-05-23

Korzuch, William (Department: 2653)

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

C369S112240

Reexamination Certificate

active

07050378

ABSTRACT:
Disclosed is such an optical pickup controlling an aberration even if optical axes of an objective lens and another optical system are shifted from each other. The optical pickup is a device for recording or reproducing an information signal by irradiating light along a track of a rotating optical disk, including a light source, a beam expander for changing a parallelism of light emitted from the light source, and an objective lens33for collecting the light emitted from the beam expander along the track of the optical disk and for irradiating the collected light thereonto, wherein the beam expander is comprised of a concave lens31and a Fresnel lens32, and a focal distance fnof the diffraction lens exists in a range satisfying the following inequality:in-line-formulae description="In-line Formulae" end="lead"?f1<fn<f2,in-line-formulae description="In-line Formulae" end="tail"?wherein-line-formulae description="In-line Formulae" end="lead"?f1=((λ2/λ1)−1)f0v0in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?f2=(1−(λ2/λ1))bin-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?b=−f0(f0+Δ)/Δin-line-formulae description="In-line Formulae" end="tail"?λ1and λ2are a designed lower limit wavelength and a designed upper limit wavelength, respectively,f0and v0are a focal distance and a partial dispersion of the objective lens, respectively, andΔis a difference between focal distances corresponding to the wavelengths λ1and λ2.

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patent: 2002/0097504 (2002-07-01), Kitamura et al.
patent: 1 154 417 (2001-11-01), None
patent: 1 276 104 (2003-01-01), None

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