Objective lens, optical head device, optical information device, and optical disk system

Patent metadata

Field	Value
Publication number	US-2021304793-A1
Application number	US-201916963575-A
Country	US
Kind code	A1
Filing date	Oct 23, 2019
Priority date	Nov 30, 2018
Publication date	Sep 30, 2021
Grant date	—

Abstract

Provided is an objective lens which is used so that more information can be accumulated in a large-capacity optical disk and which has a further enhanced numerical aperture NA. The objective lens is a single lens having the numerical aperture NA and a refractive index n, and is configured so as to satisfy: NA≥0.91 and 1.61≤n<1.72.

First claim

1 . An objective lens which is a single lens having a numerical aperture NA and a refractive index n that satisfy NA≥0.91 and 1.61≤n<1.72.

2 . The objective lens according to claim 1 , wherein the objective lens is a biconvex lens a sag amount of each surface of which always varies in the same direction from the optical axis toward a lens outer circumference of the biconvex lens.

3 . The objective lens according to claim 1 , wherein a focal length f of the objective lens falls in a range of 1 to 1.3 mm.

4 . The objective lens according to claim 1 , wherein a working distance Wd of the objective lens falls in a range of 0.2 to 0.3 mm.

5 . The objective lens according to claim 1 , wherein NA 0.94 is satisfied.

6 . An optical head device comprising:
a laser light source configured to emit a light beam; the objective lens according to claim 1 configured to receive the light beam emitted from the laser light source and to focus the light beam into a small spot on a recording surface of an optical disk; and an optical detector formed of a photodetecting unit configured to receive a light beam reflected from the recording surface of the optical disk and to output an electrical signal according to a light quantity of the received light beam.

7 . An optical information device comprising:
the optical head device according to claim 6 ; a motor configured to rotate the optical disk; and an electric circuit configured to receive a signal produced by the optical head device and to control and drive the motor, the objective lens, and the laser light source.

8 . An optical information device comprising:
an optical head device; a motor configured to rotate an optical disk; and an electric circuit configured to receive a signal produced by the optical head device and to control and drive the motor and an objective lens and a laser light source of the optical head device, wherein the optical head device comprises:
a first light source configured to emit a blue light beam having a wavelength λ 1 ;
the objective lens according to claim 1 configured to receive the light beam emitted from the first light source and to focus the light beam into a small spot on a recording surface of the optical disk through a base material layer having a base material thickness t 1 ;
an optical detector formed of a photodetecting unit configured to receive a light beam reflected from the recording surface of the optical disk and to output an electrical signal according to a light quantity of the received light beam; and
an actuator configured to perform focusing so that the small spot is formed on the recording surface of the optical disk by driving the objective lens in an optical axis direction of the objective lens;
wherein the optical head device is configured to detect, from the optical detector, an electrical signal for detection of a focusing error signal; and wherein the optical head device is configured to perform focusing so that the small spot is formed on the recording surface of the optical disk by driving the objective lens in the optical axis direction of the objective lens by the actuator.

9 . An optical disk system comprising:
the optical information device according to claim 7 ; an input device or an input terminal configured to input of information; a computing device configured to perform computation based on information received from the input device or information reproduced from the optical information device; and an output apparatus or an output terminal configured to display or output of the information received from the input device, the information reproduced from the optical information device, or a result of the computation by the computing device.

10 . An optical disk system comprising:
the optical information device according to claim 7 ; and an information-to-image decoder configured to convert an information signal acquired from the optical information device into an image.

11 . An optical disk system comprising:
the optical information device according to claim 7 ; and an image-to-information encoder configured to convert image information into information to be recorded by the optical information device.

12 . An optical disk system comprising:
the optical information device according to claim 7 ; and an input/output terminal for exchange of information with the outside.

13 . An optical disk system comprising:
the optical information device according to claim 8 ; an input device or an input terminal configured to input of information; a computing device configured to perform computation based on information received from the input device or information reproduced from the optical information device; and an output apparatus or an output terminal configured to display or output of the information received from the input device, the information reproduced from the optical information device, or a result of the computation by the computing device.

14 . An optical disk system comprising:
the optical information device according to claim 8 ; and an information-to-image decoder configured to convert an information signal acquired from the optical information device into an image.

15 . An optical disk system comprising:
the optical information device according to claim 8 ; and an image-to-information encoder configured to convert image information into information to be recorded by the optical information device.

16 . An optical disk system comprising:
the optical information device according to claim 8 ; and an input/output terminal for exchange of information with the outside.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Komma Yoshiaki
• Kobayashi Yasushi
• Minami Kazuhiro

Classifications

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B3/00

  Simple or compound lenses · CPC title

• G11B2007/0006

  adapted for scanning different types of carrier, e.g. CD & DVD · CPC title

• G11B7/1374 Primary

  Objective lenses {(optical objectives per se G02B9/00)} · CPC title

• G11B7/1275 Primary

  Two or more lasers having different wavelengths · CPC title