# US 7,612,323 B2 · Optical element for condensing incident light

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- Number: US 7,612,323 B2
- Document ID: US7612323B2
- Status: Granted
- Kind: B2
- Application number: 11/239,694
- Filed: 2005-09-28
- Published: 2006-04-20
- Granted: 2009-11-03
- Earliest claimed: 2004-10-01
- Assignees: Konica Minolta Opto, Inc.
- Inventors: Masahiro Okitsu; Kazuyuki Ogura; Kenji Konno; Hiroshi Hatano
- Web page: https://patentgrep.com/patent/US7612323B2

## CPC

- G11B 7/1374: Objective lenses {(optical objectives per se G02B9/00)}
- G11B 7/1387: using the near-field effect
- G11B 7/08505: {Methods for track change, selection or preliminary positioning by moving the head}
- Y10S 977/862: Near-field probe
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

To obtain an optical element for generating near-field light which can accurately detect positions of a plurality of minute structures formed on a metallic thin film provided to a condensing surface, and a method of adjusting an optical spot position of the optical element. The metallic thin film is formed on the condensing surface of the optical element that condenses incident light so as to generate near-field light smaller than an condensing spot B near a condensing point, and a plurality of openings (minute structure) for generating the near-field light are formed into a matrix matter on the metallic thin film, and position detecting structures are formed on positions that partitions the openings is formed. Scanning in X and Y directions is carried out by a light beam, and its reflected light is detected so that the positions of the openings are detected.

## Claims

### Claim 1

A method for adjusting the position of a condensing spot relative to a near-field light generating minute structure formed near the condensing position of an optical element, comprising the steps of:
scanning a surface of the optical element perpendicular to an optical axis by a light beam;
detecting the position of position detecting minute structures formed outside of the near-field light generating minute structure; and
detecting the position of the near-field light generating minute structure based on a change of reflectance of incident light, the near-field light generating minute structure, which includes:
a first area configured to provide a high reflectance of the incident light; and
an opening within the first area configured to provide a slightly lower reflectance of the incident light than is provided by the first area; wherein
the change of reflectance of the incident light from the position detecting minute structures to the first area, and from the first area to the opening, facilitates detecting the position of the near-field light generating minute structure.

### Claim 2 (depends on 1)

A method of adjusting of claim 1, wherein the scanning is carried out in two directions perpendicular to each other.

### Claim 3 (depends on 1)

A method of adjusting of claim 1, wherein the near-field light generating minute structures are arranged so as to be positioned at approximately center of the position detecting minute structures.