JPH02116765A - Magnetization observing apparatus - Google Patents

Abstract

PURPOSE:To obtain a magnetic domain image with a better contrast with no magnetic field applied thereto by determining a differential image between observation images as obtained when a wavelength plate adapted to generate a phase difference of a 1/2 wavelength is added or not to an optical system of a magnetic Kerr effect observing device. CONSTITUTION:A mechanism 13 is operated by a signal of a computer 14 and a 1/2 wavelength plate 7 is moved onto or out of an optical path to record an observation image for each action on an image processor 11. It is so arranged that when the wavelength plate 7 is moved onto the optical path, an optical axis thereof becomes parallel with or vertical to a direction of polarization of an analyzer 8 when it is in a crossed nicol positional relationship. At this point, a polarization plane of reflected light is turned by a magnetic Kerr effect. This causes an inversion in contrast of light between magnetic domains opposite in the direction thereof. Reflected light with no turning of the polarization plane as caused by reflection from a foreign matter or the like is equal in contrast. Thus, when the device 11 is used to determine a differential image of the observation image depending on the presence of the wavelength plate 7, the contrast is stressed double.

Description

[Detailed description of the invention] Ru.

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

In Figure 1, 1 is a light source, 2 is a collector lens, 3 is a polarizer, 4 is a reflecting mirror, 5 is an objective lens, 6 is a sample to be measured, 7 is a wavelength plate that produces a phase difference of % wavelength, and 8 is a An analyzer, 9 is an imaging lens, 10 is a camera, and 11 is an image processing device that has both the function of recording a plurality of observation images taken by the camera IO and the function of obtaining a difference image between the plurality of observation images, - An example is a device that has a memory for recording images and a processing function for calculating differences between multiple images. 12 is a lens barrel. Reference numeral 13 denotes a mechanism for moving the wavelength plate 7, which causes a phase difference between the local wavelengths, to take it in and out of the optical path.An example is a mechanism in which a hole is provided in the lens barrel and the wavelength plate 7 is moved in and out with a plunger. Reference numeral 14 denotes a computer, which controls the insertion and removal of the 1/2 wavelength plate 7 from the optical path by the image processing device 11 and mechanism 13. Reference numeral 15 indicates light ``hh'' from the objective lens 5 and the imaging lens 9.

Light from a light source 1 becomes a focused beam by a collector lens 2, becomes linearly polarized light by a polarizer 3, and enters one corner of an objective lens 5 by a reflecting mirror 4 in a lens barrel 12. The light incident on the objective lens 5 is reflected by the surface of the sample to be measured 6,
An image is formed by an imaging lens 9 on a camera IO via an objective lens 5 and an analyzer 8. At this time, the analyzer 8 is arranged so that a part of the magnetic domain in the magnetic domain observation image becomes dark.

The polarization plane of the reflected light from the sample to be measured 6 differs depending on the magnetization. Therefore, the analyzer 8 is
Even if a magnetic domain image is placed, a magnetic domain image with a different magnetization will not become dark, and a contrast between light and dark will occur. computer 14
The mechanism 13 is operated by the signal to move the 1/2 wavelength plate 7 in and out of the optical path. The observed image when taken out from the road is recorded in the image processing device 11 linked to the mechanism 13 via the computer 14. When placed on the optical path, the frequency plate 7 is arranged so that its optical axis is parallel or perpendicular to the polarization direction of the analyzer 8 in crossed Nicols. At this time, due to the magnetic Kerr effect, the plane of polarization of the reflected light from the magnetic domain of the sample to be measured 6 is rotated relative to that of the incident light. The plane of polarization of reflected light from magnetic domains with opposite magnetization directions is symmetrical with respect to the plane of polarization of incident light.

Further, due to the arrangement of the polarizer 31, the local wavelength plate 7, and the analyzer 8, when the local wavelength plate 7 is placed on the optical path, the polarization plane of the reflected light rotates symmetrically with respect to the polarization plane of the incident light. That is, when the frequency plate 7 is placed in the optical path, magnetic domains whose direction of magnetization is opposite to those that appear dark when the wavelength plate 7 is taken out appear dark.

In this way, the contrast between magnetic domains with opposite directions of magnetization is reversed in brightness and darkness between the observed image when the wavelength plate 7 is taken out from the optical path and the image when it is put in.

At this time, the direction of the reflected light whose polarization plane has not been rotated due to the 6n Kerr effect due to reflection by a foreign object or the like is the same as the direction of the polarization plane of the incident light, so that the former and the latter have the same contrast. That is, when the local wavelength plate is taken out from the optical path and when it is put in, the contrast due to the magnetic Kerr effect is opposite in brightness and darkness, and the contrast other than the magnetic Kerr effect is the same. When the difference image between the former observed image and the latter observed image is obtained using the image processing device ALL, the contrast of the observed image is doubled, contrast not due to the magnetic Kerr effect is canceled, and the S/N ratio is also improved. do.

In order to reduce contrast noise, it is effective to obtain a plurality of difference images and add them. This can be achieved by adding a function to the image processing device 11 to obtain a summation image of the plurality of images. In observational snowmaking in which this function is added to the image processing device 11, it is possible to obtain a summation image of the plurality of difference images and automatically perform the work of reducing noise.

In the above embodiments, linearly polarized light is created using a polarizer, but it goes without saying that if a linearly polarized laser is used as the light source, the light source can be monochromatic and the structure can be simplified.

Effects of the Invention] As described above, according to the present invention, it is possible to enhance contrast in a magnetically non-destructive manner in observing a magnetic domain structure, and furthermore, it is also possible to automate contrast enhancement.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention. 5... Objective lens, 6... Sample to be measured, 7... Wave plate that produces a phase difference between circumferential wavelengths, 8...
Analyzer, 9... Imaging lens, 10... Camera, II... Image processing device, 12... Lens barrel, 13... Mechanism for moving the wavelength plate 7 in and out of the optical path, 14. ··Computer. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Scope of Claims] 1) A microscope optical system including at least a polarizer, a half-wave plate, and an analyzer in the same optical path; and recording a plurality of observation images observed by the microscope optical system; an image processing means for forming a difference image between the observed images obtained by the observation, and a control means for controlling the insertion and removal of the 1/2 wavelength plate from the optical path in conjunction with the image processing means, The optical axis of the half-wave plate when the wavelength plate is on the optical path is parallel or perpendicular to the polarization direction of the analyzer when the polarizer and analyzer are in a crossed Nicols positional relationship. A magnetization observation device characterized by: