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

Claim 15:
16. 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 light to the surface of the continuously moving magnetic recording medium, and measuring a light polarization state of a third reflected light that is reflected;
obtaining a squareness ratio by calculating a ratio (ΔA20/ΔA10) of a difference ΔA20 (=A2−A0) between a mean value A0 of measurement values of the light polarization states of the first reflected light and the second reflected light and a measurement value A2 of the light polarization state of the third reflected light to a difference ΔA10 (=A1−A0) between the mean value A0 and the measurement value A1 of the light polarization state of the first reflected light; and
adjusting a film formation condition for the continuously moving magnetic recording medium on a basis of the squareness ratio obtained.