Inspection method for magnetic head utilizing the Kerr effect

• US 4,658,148 A
• Filed: 12/27/1984
• Issued: 04/14/1987
• Est. Priority Date: 12/29/1983
• Status: Expired due to Term

• Current Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Naito, Hiroichi
• Primary Examiner(s): Westin, Edward P.
• Application Number:
  US06/686,529
• Time in Patent Office: 838 Days
• Field of Search: 250/571, 250/231 R, 250/225, 250/559, 324/244, 324/96, 324/260, 324/210, 324/212, 356/364, 356/369
• US Class Current: 250/225
• CPC Class Codes: G01R 33/0325 using the Kerr effect
• CPC Class Codes: G11B 11/105 using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
• CPC Class Codes: G11B 33/10 Indicating arrangements; Warning arrangements G11B15/04, G11B19/04, G11B27/34, G11B27/36 take precedence
• CPC Class Codes: G11B 5/455 Arrangements for functional testing of heads; Measuring arrangements for heads

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.

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.