Patent ID: 11860248
Assignee: SONY GROUP CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 12:
13. A method for manufacturing a magnetic recording medium, the method comprising:
applying a first magnetic field to a continuously moving magnetic recording medium to magnetically saturate the magnetic recording medium, applying a first polarized light to a surface of the magnetic recording medium to which the first magnetic field is being applied, and measuring a light polarization state of a first reflected light that is reflected;
applying a second magnetic field having an opposite direction of the first magnetic field to the continuously moving magnetic recording medium to magnetically saturate the magnetic recording medium, applying a second polarized light to the surface of the magnetic recording medium to which the second magnetic field is being applied, and measuring a light polarization state of a second reflected light that is reflected;
applying a third magnetic field having an opposite direction of the second magnetic field to the continuously moving magnetic recording medium, applying a third polarized light to the surface of the magnetic recording medium to which the third magnetic field is being applied, and measuring a light polarization state of a third reflected light that is reflected;
adjusting a strength of the third magnetic field so that a measurement value of the light polarization state of the third reflected light is a mean value of a measurement value of the light polarization state of the first reflected light and a measurement value of the light polarization state of the second reflected light, and obtaining, as a coercive force, the strength of the third magnetic field when the measurement value of the light polarization state of the third reflected light becomes equal to the mean value; and
adjusting a film formation condition for the continuously moving magnetic recording medium on a basis of the coercive force obtained.