US 11,860,248 B2
Method for measuring magnetic characteristics, apparatus for measuring magnetic characteristics, and method for manufacturing magnetic recording medium
Akifumi Ono, Tokyo (JP); and Yasunori Imai, Tokyo (JP)
Assigned to Sony Corporation, Tokyo (JP)
Appl. No. 17/277,190
Filed by Sony Corporation, Tokyo (JP)
PCT Filed Sep. 13, 2019, PCT No. PCT/JP2019/036123
§ 371(c)(1), (2) Date Feb. 1, 2022,
PCT Pub. No. WO2020/059662, PCT Pub. Date Mar. 26, 2020.
Claims priority of application No. 2018-174246 (JP), filed on Sep. 18, 2018.
Prior Publication US 2022/0221531 A1, Jul. 14, 2022
Int. Cl. G01R 33/032 (2006.01); G01N 27/72 (2006.01); G01R 33/12 (2006.01)
CPC G01R 33/0325 (2013.01) [G01N 27/72 (2013.01); G01R 33/1223 (2013.01)] 16 Claims
OG exemplary drawing
 
6. An apparatus for measuring magnetic characteristics, the apparatus comprising:
a first measurement section configured to apply a first magnetic field to a continuously moving magnetic recording medium to magnetically saturate the magnetic recording medium, apply a first polarized light to a surface of the magnetic recording medium to which the first magnetic field is being applied, and measure a light polarization state of a first reflected light that is reflected;
a second measurement section configured to apply 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, apply a second polarized light to the surface of the magnetic recording medium to which the second magnetic field is being applied, and measure a light polarization state of a second reflected light that is reflected;
a third measurement section configured to apply a third magnetic field having an opposite direction of the second magnetic field to the continuously moving magnetic recording medium, apply a third polarized light to the surface of the magnetic recording medium to which the third magnetic field is being applied, and measure a light polarization state of a third reflected light that is reflected; and
a control section configured to control the third measurement section to adjust 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 obtain 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.