JPH0656749B2 - Image display device for electron microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention displays a marker by superimposing it on a Fourier-transformed image in an apparatus for performing, for example, two-dimensional Fourier transform and inverse Fourier transform on an image obtained by an electron microscope. Thus, the present invention relates to an image display device of an electron microscope, which allows an operator to easily extract a desired frequency region.

[Prior Art] An image of a sample obtained by an electron microscope has S / N deteriorated due to aberrations, astigmatism, amplifier noise of an electron lens, etc. In addition, when the sample has periodicity, , It is very difficult to interpret the image obtained from the sample due to the diffraction effect.

As a method of coping with such a case, the obtained image is subjected to two-dimensional Fourier transform to represent the image in a frequency space, and a mask pattern is applied to the transformed image (hereinafter, this image is referred to as a Fourier transform image). A method is known in which a Fourier transform image having only a necessary frequency region is created to obtain a desired image by performing a two-dimensional inverse Fourier transform on the Fourier transform image.

This example will be described with reference to FIG. The image of the sample obtained by the electron microscope 12 is stored in the image memory 13. When this image is displayed on the CRT monitor 17 by the image display memory 15, the image as it is obtained by the electron microscope 12 is displayed. The image of the sample stored in the image memory 13 is Fourier transformed by the Fourier transform / inverse transform circuit 14 and stored in the image memory 13 as a Fourier transformed image. The Fourier transform image thus obtained is displayed on the CRT monitor 17 by the image display memory 15. An example is shown in FIG.
Shown in. The DC component is at the center of the figure, and becomes a high frequency component toward the periphery. In the case of an image having a regular pattern on the entire screen, the Fourier transform image has a ring shape, and noise appears in the low frequency component. Therefore, according to FIG. 5A, it can be seen that there is some regularity pattern from the ring-shaped pattern A, and that B is a noise component. Therefore, if the operator wants to remove noise and observe only the image corresponding to the ring A, the operator creates a mask pattern A '(FIG. 5b) corresponding to A in the mask pattern generation circuit 16 and Is weighted appropriately, for example, 1, and the image display memory 1
The Fourier transform image stored in 5 is multiplied. As a result, the Fourier transform image as shown in Fig. 5c is obtained as A ". The Fourier transform image thus obtained is stored in the image memory 13, and further Fourier inverse transform is performed by the Fourier transform / inverse transform circuit 14. The image obtained by the inverse Fourier transform is stored in the image memory 13. If this image is displayed on the CRT monitor 17 by the image display memory 15, the operator can observe the image in which only the desired frequency region is extracted. You can

[Problems to be Solved by the Invention] However, in the conventional art, when trying to apply a mask pattern to a Fourier transform image, the operator compares the original image and the Fourier transform image one by one, and determines the size of the mask pattern, The shape and position had to be determined, and if the result thus obtained was inappropriate, the mask pattern had to be recreated. Specifically, assuming that it is theoretically known that the pitch of the observed crystal is 5.3Å, a mask pattern corresponding to the pitch is generated. However, since the size of the ring of the Fourier transform image changes depending on the magnification, it is not easy to generate a mask pattern corresponding to the pitch, and it requires skill.

The present invention is to solve the above-mentioned problems, and to provide an image display device of an electron microscope capable of easily creating a mask pattern by superimposing and displaying a marker on a Fourier transform image. With the goal.

[Means for Solving the Problems] In order to achieve the above object, the image display device of the electron microscope of the present invention transforms an image obtained by the electron microscope into a frequency domain, and obtains the image by the transformation. When the image is displayed on the display device, a marker representing a frequency or a wavelength is superimposed and displayed on the image obtained by the conversion.

Examples Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an image display device for an electron microscope according to the present invention, in which 1 is an electron microscope, 2 is an image memory, 3 is a Fourier transform / inverse conversion circuit, 4 is an image display memory, 5 is a mask pattern generation circuit, 6 is a CRT monitor,
Reference numeral 7 is a magnification control circuit, 8 is an image frequency calculation circuit, and 9 is a marker generation circuit.

This configuration is such that a magnification control circuit 7, an image frequency calculation circuit 8 and a marker generation circuit 9 are added to that of FIG. 4, and the functions of other circuits are the same as those of FIG. The magnification control circuit 7 sets the magnification of the electron microscope 1 by key input and outputs the magnification information to the image frequency calculation circuit 8. The image frequency calculation circuit 8 determines the image frequency, that is, CR from the magnification information and the resolution per pixel which is known in advance.
On the T screen, how much length and what frequency is calculated. The marker generation circuit 9 includes the image frequency calculation circuit 8
Based on the calculation result of, the pattern including the scaled crosshairs 10 and the length markers 11 as shown in FIG. 2 is generated. The scaled crosshair 10 and the length marker 11 are linked to the image frequency. The pattern obtained by the marker generation circuit 9 is stored in the image display memory 4, and the Fourier transform image already stored in the image display memory 4 and the CRT monitor 6 are superimposed and displayed as shown in FIG.

As a result, the operator can know the frequency of the image while referring to the scaled crosshairs 10 and the length marker 11, so that the mask pattern can be easily generated.

Although the image frequency is calculated in the above description, the wavelength which is the reciprocal of the image frequency may be calculated and the marker of the wavelength may be displayed. Further, FIG. 2 shows a crosshair with a scale. However, a concentric pattern may be used. Various such patterns are conceivable. Further, the Fourier transform / inverse transform is taken as the conversion method of the image into the frequency domain, but the invention is not limited to this and the present invention can be applied as long as the image is handled in the frequency domain.

[Effects of the Invention] As is apparent from the above description, in the present invention, since the marker representing the frequency or the wavelength is superimposed and displayed on the image in which the image is represented in the frequency domain, the desired image frequency can be selected. This is extremely easy, and as a result, the mask pattern can be easily generated.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of an image display device for an electron microscope according to the present invention, FIG. 2 is a diagram showing an example of a scale pattern, and FIG. 3 is a superimposed display of a Fourier transform image and a scale pattern. 4 and FIG. 4. FIG. 4 is a diagram showing one configuration example of a conventional image display device of an electron microscope, and FIG. 5 is a diagram showing a conventional example of a method of extracting a frequency region by a mask pattern. 1 ... Electron microscope, 2 ... Image memory, 3 ... Fourier transform / inverse conversion circuit, 4 ... Image display memory, 5 ... Mask pattern generation circuit, 6 ... CRT monitor, 7 ... Magnification control circuit, 8 ... Image frequency calculation circuit, 9 ... Marker generation circuit.

Claims (1)

[Claims] 1. An image display device of an electron microscope for converting an image obtained by an electron microscope into a frequency domain and displaying the image obtained by the conversion on a display device. An image display device for an electron microscope, which displays a marker indicating a wavelength in a superimposed manner.