JPS60233533A - Instrument for measuring magnetic domain - Google Patents

Abstract

PURPOSE:To obtain a distinct magnetic domain pattern and to enable exact measurement of the magnetic characteristic of a magnetic film by scanning the laser beam of a laser generating means, polarizing linearly the laser beam, condensing the beam to a system to be measured and imaging the beam passed therethrough. CONSTITUTION:Optical deflectors 2a, 2b scan two-dimensionally the laser beam having several mum or below spot diameter from a laser oscillator 1 over a 100mum square region at 100kHz frequency. A condenser lens 4 projects the linearly polarized beam on a magnetic film B of a system to be measured after stopping down the spot diameter to several mum or below. The beam transmitted through the film B is rotated with the plane of polarization according to the direction of the magnetization of the film B. The transmitted light is converted to a difference in the quantity of light by passing through a polarizing plate 6 and is inputted to a photoelectric transducer 7, by which the beam is converted to a video signal and is displayed on a CRT, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic domain measuring device, and particularly relates to a magnetic garnet film or rare earth film used in bubble memory, magneto-optical memory, etc.
The present invention relates to a measuring device for observing magnetic domains, which is necessary for evaluating the magnetic properties of transition metal amorphous films, etc.

[Prior art and its problems]

Conventionally, a polarizing microscope has been used to observe magnetic domains in stromal films used in bubble memories, magneto-optical memories, and the like.

However, when observing magnetic domains using such a polarizing microscope, if the Faraday rotation angle of the film to be observed is small or the light transmittance is small, the contrast of the image obtained is low, and therefore it is difficult to accurately obtain accurate magnetic properties. [Means for solving the problem] A laser generating means, a scanning means for scanning a laser beam from the laser generating means, and a polarizing means for linearly polarizing the laser beam. , a focusing means for focusing the laser beam on the system to be measured, and an imaging means for forming an image of the laser beam that has passed through the system to be measured.

〔Example〕

FIG. 1 is a schematic explanatory diagram of one embodiment of the magnetic domain measuring device according to the present invention, and FIG. 2 is a photograph of the magnetic domain pattern of a magnetic garnet film obtained by this measuring device.

Surface M-1 is a low-power He such as Ichiyuki 1 u25mWk.
-Ne gas laser oscillator.

2a and 2b are optical deflectors for scanning a laser beam from the laser oscillator using an acousto-optic element such as LiNbO3, and sb is an optical deflector 2a,
2b is a device in which a laser beam is two-dimensionally deflected and scanned at a frequency of 100 KHz, and a laser beam having a condensed spot diameter of several μm or less is scanned over an area of, for example, 100 μm square. 2a is an optical deflector in the X-axis direction, and 2b is an optical deflector in the X-axis direction.

3 is a first polarizing plate, and this first polarizing plate 3 is for obtaining a linearly polarized laser beam.

4 is a condensing lens (objective lens for a microscope, ×53), and this condensing lens 4 focuses the linearly polarized laser beam produced by the first polarizing plate 3 so that its spot diameter is several μm or less. It is something.

The spot diameter of the linearly polarized laser beam is set to several μm or less on the magnetic film B, which is the system to be measured.

Similarly, lenses 4b and 4c are also condensing lenses, and these lenses 4b and 4c are provided on the optical path between the optical deflectors 2a and 2b and the first polarizing plate 3, and converge the laser beam. This is for converging the light within the optical diameter of the optical lens 4.

Reference numeral 5 denotes a projection lens (objective lens for a microscope, ×53), and this projection lens 5 is used to focus and image a laser beam transmitted through the magnetic film B on the surface of a photoelectric conversion element, which will be described later.

6 is a second polarizing plate, and the plane of polarization of the linearly polarized laser beam transmitted through the magnetic film B rotates according to the direction of magnetization of the magnetic film B (Faraday effect). The transmitted light whose polarization plane has been rotated according to the direction is converted into a difference in light amount by passing through the second polarizing plate.

7 is a photoelectric conversion element such as a solid-state image sensor of COD, MOS, or BBD type.
The electrical signal obtained by this method is converted into a video signal and displayed on a CRT or the like.

Unlike conventional polarizing microscopes, which use a white light source such as a nitrogen lamp or a mercury lamp as a light source, the laser beam type magnetic domain measuring device configured as described above uses a magnetic film as shown in FIG. The contrast of the magnetic domain pattern is extremely high. The photograph shown in Figure 3 shows the magnetic domain pattern of the magnetic garnet film taken using a conventional polarizing microscope.

That is, since the device of the present invention makes it possible to obtain clear magnetic domain turns, it is possible to accurately determine the limit of recording density from the exact width of the magnetic domain pattern.
Furthermore, the moving speed of the bubble domain can be accurately determined based on the response of the domain to the application of an external magnetic field, and the access time as a memory can be accurately determined.

〔effect〕

It is now possible to accurately characterize the magnetic domain patterns of magnetic films such as magnetic garnet films and rare earth-transition metal amorphous films used in bubble memories and magneto-optical memories.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of one embodiment of the magnetic domain measuring device according to the present invention, FIG. 2 is a photograph of a magnetic domain pattern of a magnetic garnet film by the device of the present invention, and FIG. 3 is a photograph of a magnetic garnet film measured by a conventional device. This is a photograph of the magnetic domain pattern. 1... Laser oscillator (laser generation means), 2a,
2b... Optical deflector (scanning means), 3... First polarizing plate (polarizing means), 4... Condensing lens (condensing means), 5
... Projection lens, 6... Second polarizing plate, 7... Solid-state image sensor. Procedural amendment (method) August 23, 1980 Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 88500/1982 2. Name of the invention Magnetic domain measuring device a. Person making the amendment Relationship to the case Patent applicant Victor Japan Agent for ζ Co., Ltd. July 11, 1980 & Subject of amendment 7, Contents of amendment (1) ", Figure 2... Photograph" on page 2 of the specification, lines 18 to 19 delete. (2) Page 5 of the specification, lines 3-4 [, Figure 2・-
・・・Delete J. (3) [t#1, line 5 to 7 on page 5 of the specification]
·····be. ” to be deleted. (4) Page 6 of the specification, lines 3 to 6, “, 2nd...
...Delete the photo. (5) Figures 2 and 3 in the drawings are deleted.

Claims (1)

[Claims] a laser generating means, a scanning means for scanning a laser beam from the laser generating means, a polarizing means for linearly polarizing the laser beam, a focusing means for focusing the laser beam on a system to be measured, 1. A magnetic domain measuring device comprising: imaging means for imaging a laser beam that has passed through the system.