§
Luxuse
Patent Intelligence
Sign In
← Back to Patent Explorer
EP0260569A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Optical pick-up device

Assignee: Sony Corp
•
Filing: 1987-09-07
•
Granted: —
•
Expires: 2007-09-07
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract An optical pick-up device comprises a light beam source (1), an object lens system (4) for causing a light beam emitted from the light beam source (1) to impinge upon a record medium (D) and receiving a reflected light beam from the record medium (D), an intermediate lens system (20) composed of a single lens element for causing the light beam emitted from the light beam source (1) to be slightly converged and enter into the object lens system (4) and receiving the reflected light beam having passed through the object lens system (4), a beam splitter (2) for separating the reflected light beam having passed through both the object lens system (4) and the intermediate lens system (20) from the light beam emitted from the light beam source (1) to enter into the intermediate lens system (20), and a photodetector (6) for detecting the reflected light beam having passed through the beam splitter (2). A spherical aberration brought forth by the intermediate lens system (20) on the light beam passing through the intermediate lens system (20) and the object lens system (4) to the record medium (D) is cancelled at the object lens system (4).

Inventors

  • 👤 Akira Nakamura

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 16:32
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1372

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 214 words
An optical pick-up deivice comprising, a light beam source (1), object lens means (4) for focusing a light beam from said light beam source to cause the same to impinge on a record medium (D) and receiving a reflected light beam coming from the record medium, intermediate lens means (20) for causing the light beam emitted from said light beam source to enter into said object lens means and for receiving the reflected light beam having passed through said object lens means, said intermediate lens means comprising a single lens ele­ment beam splitting means (2) for separating the reflected light beam having passed through both of said object lens means and said intermediate lens means from the light beam emitted from said light beam source to enter into said intermediate lens means, and photodetecting means (6) for detecting the reflected light beam having passed through said beam splitting means, characterized in that said intermediate lens means (20) is adapted to converge the light beam emitted from said light beam source (1) slightly as compared with a parallel light beam, so that a spherical aberration brought forth by said intermediate lens means (20) on the light beam passing through said intermediate lens means and said object lens means is cancelled at the object lens means.
Claim 2
Dependent Claim 214 words
An optical pick-up deivice comprising, a light beam source (1), object lens means (4) for focusing a light beam from said light beam source to cause the same to impinge on a record medium (D) and receiving a reflected light beam coming from the record medium, intermediate lens means (20) for causing the light beam emitted from said light beam source to enter into said object lens means and for receiving the reflected light beam having passed through said object lens means, said intermediate lens means comprising a single lens ele­ment beam splitting means (2) for separating the reflected light beam having passed through both of said object lens means and said intermediate lens means from the light beam emitted from said light beam source to enter into said intermediate lens means, and photodetecting means (6) for detecting the reflected light beam having passed through said beam splitting means, characterized in that said intermediate lens means (20) is adapted to converge the light beam emitted from said light beam source (1) slightly as compared with a parallel light beam, so that a spherical aberration brought forth by said intermediate lens means (20) on the light beam passing through said intermediate lens means and said object lens means is cancelled at the object lens means.
Claim 3
Dependent Claim 74 words
An optical pick-up device according to claim 1, wherein said intermediate lens means (20) is provided in an optical path between said light beam source (1) and said object lens means (4) to be so located that a principal plane of said single lens element is distant by a distance (Lx) slightly longer than the focal distance (Lf₀) of said single lens element from a light emitting point of said light beam source (1).
Claim 4
Dependent Claim 56 words
An optical pick-up device according to claim 2, wherein said intermediate lens means (20) is so positioned that the light beam entering into said object lens means (4) is converged by said intermediate lens means so slightly as to be focused by said object lens means in substantially the same manner as a parallel light beam.
Claim 5
Dependent Claim 19 words
An optical pick-up device according to claim 1, wherein said intermediate lens means comprises a single plano-convex lens element.

References Cited (Backward Citations)

No citation records indexed.

USPTO Annuity & Maintenance Windows

Maintenance schedule is calculated for granted US utility patents.

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag