US4658148A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inspection method for magnetic head utilizing the Kerr effect
Assignee: Fujifilm Holdings Corp
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Filing: 1984-12-27
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Granted: 1987-04-14
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Expires: 2004-12-27
Abstract
Abstract A light beam is made to impinge upon a light reflecting section of a magnetic head provided with a magnetic layer having the light reflecting section on the surface. A change in characteristics of the light beam reflected by the light reflecting section, which is caused by the Kerr effect in accordance with a change in internal magnetization of the magnetic layer, is detected photoelectrically. Magnetic characteristics of the magnetic head are measured on the basis of the detected change in characteristics of the reflected light beam.
Inventors
- 👤 Hiroichi Naito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 19:15
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/455; G01; G01R; G01R33/00; G01R33/02; G01R33/032; G01R33/0325; G11B11/00; G11B11/10; G11B11/105; G11B33/00; G11B33/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
95 words
An inspection method for a magnetic head, which comprises the steps of: (i) making a light beam impinge upon a light reflecting section of a magnetic head provided with a magnetic material layer having the light reflecting section on the surface, (ii) photoelectrically detecting a change in characteristics of said light beam reflected by said light reflecting section, which is caused by the Kerr effect in accordance with a change in internal magnetization of said magnetic material layer, and (iii) measuring the magnetic characteristics of said magnetic head on the basis of the detection output.
Claim 2
Dependent Claim
95 words
An inspection method for a magnetic head, which comprises the steps of: (i) making a light beam impinge upon a light reflecting section of a magnetic head provided with a magnetic material layer having the light reflecting section on the surface, (ii) photoelectrically detecting a change in characteristics of said light beam reflected by said light reflecting section, which is caused by the Kerr effect in accordance with a change in internal magnetization of said magnetic material layer, and (iii) measuring the magnetic characteristics of said magnetic head on the basis of the detection output.
Claim 3
Dependent Claim
40 words
A method as defined in claim 1 wherein a laser beam is used as said light beam, and the internal magnetization of each minute region of said magnetic head is measured by scanning the minute region by the laser beam.
Claim 4
Dependent Claim
42 words
A method as defined in claim 1 or 2 wherein said magnetic head is a magnetic thin film head, and said internal magnetization is the internal magnetization generated when a current is applied to a coil of said magnetic thin film head.
Claim 5
Dependent Claim
29 words
A method as defined in claim 1 or 2 wherein said change in characteristics of said reflected light beam is a change in intensity of said reflected light beam.
Claim 6
Dependent Claim
32 words
A method as defined in claim 1 or 2 wherein said change in characteristics of said reflected light beam is a rotation of the plane of polarization of said reflected light beam.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-13 | 1990-10-13 | 1991-04-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-13 | 1994-10-13 | 1995-04-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-13 | 1998-10-13 | 1999-04-14 | $7700.00 | Window Closed / Lapsed |