JPS60143749A - Automatic electron ray diffraction image measuring apparatus - Google Patents

Abstract

PURPOSE:To elevate the accuracy by arranging an electron microscope, a camera, an analog-digital conversion section, an image processing section and an analysis section which performs analysis and others of crystal structure and azimuth of a sample based on basic data of point-to-point distance in a diffraction image and the like determined by an arithmetic processing section. CONSTITUTION:An analog image signal from an image input section 1 comprising an electron microscope 1a and a camera 1b is converted into digital at a gray tone level of 256 by an analog-digital conversion section 2 while two or more pictures are piled one upon another at a high speed to be converted into a digital image. An image processing section 3 extracts transmission spots, diffraction spots, diffraction rings and Kikuchi lines and an arithmetic processing section 4 determines basic data of distance and angle between spots, radius of the rings and distance between the Kikuchi lines and the like. In addition, an analysis section 5 determines parameters for surface interval and the like from basic data to fix a sample material based thereon while basic data, parameters and the like are outputted from an output section 6. This can reduce effect of noise.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron diffraction image analyzer, and particularly an electron diffraction image analyzer that can automatically measure lattice spacing, plane index, etc. with high precision and high speed by image processing an electron diffraction image. This relates to an automatic line diffraction image measuring device.

When observing the microstructure of a metal using an electron microscope, precipitates and matrices can be identified by analyzing electron diffraction images.

Conventionally, when performing this analysis, a diffraction image is photographed, this photograph is enlarged and projected using an optical magnifying device such as a projector, and the distance between the transmitted beam spot and the diffraction spot is calculated on this projected image. In order to analyze the electron beam channeling pattern, the angle between the diffraction spot and the transmitted spot, the radius of the diffraction ring, and even the distance between lines and the angle formed by the lines are manually measured. . Such manual measurements require a great deal of effort and time, and are extremely inefficient. Furthermore, analysis can only be carried out after photographing, and it is impossible to identify substances while observing them, which has many disadvantages in electron microscopy observation.

In order to improve such problems, an automatic electron diffraction image analysis system has been developed, and was presented, for example, in the 39th Academic Conference of the Japanese Society of Electron Microscopy, page 6 (May 1981). However, this automatic analysis system uses an expensive high-sensitivity television imaging device called an image carrier to improve accuracy, making the entire system expensive. Furthermore, although the time required for analysis is on the order of several minutes, in practice it is necessary to process on the order of several seconds when considering sample contamination.

Furthermore, since a high-sensitivity television imaging device is used, if noise occurs for some reason, it will also be captured with high sensitivity, which may seriously affect the analysis and is cumbersome to handle. There is a drawback.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, to be able to analyze electron beam diffraction images with high precision without being affected by noise, to process quickly in the order of several seconds, and to have a simple configuration. The purpose of this invention is to provide a simple and inexpensive automatic electron diffraction image measuring device.

The automatic measuring device for electron beam diffraction images of the present invention includes an electron microscope that forms an electron beam diffraction image of a sample, an imaging device that captures this electron beam diffraction image and outputs an analog image signal, and a An analog-to-digital converter that converts into a digital image signal at the translation level and can superimpose images of two or more screens, and converts the digital image signal output from the analog-to-digital converter into a point 1 circle and a line element. an image processing section that extracts features such as, and records a diffraction image; an arithmetic processing section that extracts basic data such as the distance between points of this diffraction image, angle, radius, and distance between lines; The present invention is characterized by comprising an analysis section that analyzes the crystal MIJ structure and crystal orientation of the sample based on the basic data collected.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a miniature diagram showing the overall configuration of an automatic electron beam diffraction image measuring device according to the present invention. The image input section 1 is an electron microscope 1
a, and an imaging device 1b that captures an electron beam diffraction image projected on a fluorescent plate, and supplies an analog image signal output from the imaging device 1b to an analog-to-digital converter 2. This analog-digital converter 2 is the most characteristic part of the device of the present invention, and converts analog image signals into digital signals at 64 levels or higher, preferably at a translation level of 256 levels, and superimposes images on two or more screens at high speed. can be converted into a digital image. That is, it is possible to obtain a digital image signal for one screen by sequentially capturing several screens using the imaging device 1b and averaging the translation level digital values of each pixel of these screens. Such an analog-to-digital converter 2 includes, for example, an analog-to-digital converter, a gray memory that can store digital values at the translation level for one screen, and a digital value output from the analog-to-digital converter for each pixel. and a circuit for calculating an average value between the digital value and the digital value stored in the gray memory, and this average value is stored in the gray memory. Alternatively, the analog-digital transformation section 2 may be configured to determine that signals having a difference of more than a certain value for the same pixel are noise, and perform superposition to remove the signals. In this specification, the analog-to-digital conversion section is assumed to be capable of performing analog-to-digital conversion and superimposition of screens in this manner. By using the analog-to-digital converter 2 that allows such superimposition, it is possible to suppress noise in diffraction images with extremely low brightness and contrast, and to strengthen gray information at intermediate brightness. In other words, the original image appears in the same position every screen, so it becomes a large value by tightening it, whereas noise occurs randomly and does not appear in the same position every screen, so when averaged, it will not reach a large value. It won't happen. In this way, an electron diffraction image with extremely low brightness and contrast can be input with high precision without being affected by noise. However, it has become possible to analyze electron beam diffraction images with low Iζ contrast at high speed, which are impossible to analyze using conventional apparatuses.

The image signal converted into a digital quantity with the brightness difference, that is, the contrast emphasized, as described above is supplied to the image processing section 3, where a transmitted image and a circular or point-like diffraction image are found.

In addition, line elements are extracted in the channeling pattern or Kikuchi pattern. This image processing is also a feature of the present invention, and the processing method will be explained below. First, a case will be described in which a diffraction image having a pattern of 1 to 1 is processed. In this case, first locate the center of the transmission spot l-. Since this transmission spot appears as a density gap with a certain spread, its center of gravity is temporarily overlapped with the center point of the transmission spot. On the other hand, the diffraction spot can be detected separately from the transmission spot 1 by utilizing the characteristic that the concentration gap has a relatively small expansion compared to the transmission spot. The center of gravity of the diffraction spot created in this way is regarded as a diffraction spot point.Next, select a spot point near the point that is symmetrical to the tentatively created transmission spot 1~ point.In this way, We found diffraction spot points that were symmetrical to the tentative transmission spot points in the set of fine lines we had prepared, and
The intersection of the straight lines connecting the ~ points is the true transparent sub-point 1~.

Transmission spot points and diffraction spot points can be found in the above manner.

Furthermore, in the case of a ring-shaped diffraction image, since there is a very large density gap on the ring, this is detected, these points are regarded as points on the ring, and circular approximation is performed.

In the case of channeling or Kikuchi patterns, line element tracing filter processing is used to extract Kikuchi lines, which are thin parallel black and white lines. Generally, the Kikuchi pattern has extremely low contrast, but in the device of the present invention, several screens are superimposed in a blurred manner (above), so the contrast is emphasized and the Kikuchi line can be detected accurately.

Image processing is performed as described above (extracting transmitted spot points, diffraction spot points, diffraction rings, and Kikuchi lines).
The image signal supplied from the analog-digital converter 2 has an S/N ratio with enhanced contrast and suppressed noise.
Since the image quality is high, image processing can be performed in a short time, and the image processing time is about 3 to 15 seconds.

Next, the diffraction image extracted by the image processing section 3 is processed by the arithmetic processing section 4.
Here, basic data such as the distance between the transmission spot point and the diffraction spot point, the angle between the diffraction spot points, the radius of the ring, and the distance between the Kikuchi lines are calculated. next,
The basic data regarding the diffraction image thus obtained by the arithmetic processing section 4 is sent to the analysis section 5. The analysis section 5 calculates parameters such as surface spacing and surface index from these basic data, and identifies the sample material based on these parameters. The configuration is such that the measurement results, basic data, parameters, etc. can be outputted by the output section 6 as appropriate.

Next, a measurement example performed by the above-mentioned automatic electron diffraction image measurement apparatus of the present invention will be explained.

FIG. 2 shows the result of circular approximation by the image processing section 3 of a ring-shaped electron beam diffraction image obtained using the vapor deposited film as a sample in A. As a result of processing this circular approximation pattern by the arithmetic processing unit 4 and the analysis unit 5, the electron microscope 1a in this case is
The lens length was found to be 556.1 mm. The processing time for such a ring-shaped electron beam diffraction image was completed in about 1 second. Furthermore, by processing such a ring-shaped electron beam diffraction image, the lattice spacing of each crystal constituting the polycrystal can be determined.

FIG. 3 shows the result of processing an electron beam diffraction pattern obtained when covering a single crystal of pure iron with a sample in the image processing unit 3 to find transmission spots and diffraction spots. As described above, the transparent spot points are the intersections of straight lines connecting pairs of diffraction spot points. Next, from the result of image processing, the distance between the transmission spot point and the diffraction spot point and the angle between the diffraction spot points are determined by the calculation processing unit 4, and the analysis unit 5 calculates the distance between the planes of pure iron and the index. The results are shown in Tables 1 and 2, respectively. Incidentally, transmission spot point 0 and diffraction spot point P1 to P4 representing the interplanar spacings 11 to r4 and angles in these tables are shown in FIG. 4, which correspond to those shown in FIG. 3.

As is clear from Tables 1 and 2 above, the measured values and the theoretical values almost match, indicating that it is possible to identify substances with high accuracy. Note that this process was completed in about 8 seconds.

FIG. 5 shows the results of processing a Kikuchi pattern formed from a steel thin film as a sample by the image processing unit 3. Further, FIG. 6 shows the orientation analyzed by the arithmetic processing section 4 and the analysis section 5 based on the image shown in FIG. 5. This process was completed in about 10 seconds.

As mentioned above, according to the device of the present invention, surface spacing, angle, index, direction, etc. can be measured at high speed and with high precision, but this is largely due to the overlapping of the screens in the analog-digital converter 2. This effect is shown in FIGS. 7 and 8.

That is, FIG. 7 shows the Kikuchi pattern when no superimposition is performed, and FIG. 8 shows the Kikuchi pattern when two screens are superimposed. As is clear from comparing these images, it can be seen that by overlapping two or more screens, noise is removed and the contrast between light and dark is emphasized, resulting in a clear image.

The invention is not limited to the embodiments described above, but can be modified in many ways. For example, in the above-mentioned embodiment, the electron beam diffraction image formed on the fluorescent plate of the electron microscope was directly converted into a silver image by the Il imager, but the electron beam diffraction image was taken on -H photographic film and developed. The film may be imaged by a photographing device. Further, the number of screens to be superimposed by the analog-to-digital converter may be arbitrary as long as it is two or more, and in reality, it is preferable to configure the system so that the optimum number can be selected by determining various situations.

As is clear from the above, according to the automatic electron diffraction image measurement device of the present invention, the image signals obtained by repeatedly capturing electron diffraction images with an imaging device are superimposed and converted into digital signals. A high S/N image is obtained with the effects of noise removed, and by processing this in the image processing section, the lower points of transmission spots, diffraction spots, diffraction rings, thin background lines, etc. are extracted at high speed and with high precision. Based on this, useful data such as surface spacing, surface index, orientation, etc. can be obtained in a short period of time, and materials can be identified with high precision. Furthermore, since an image pickup device with normal sensitivity can be used, the entire device can be constructed at low cost and is easy to handle.

[Brief explanation of drawings]

Fig. 1 is a miniature diagram showing the configuration of an embodiment of the automatic electron diffraction image measuring device of the present invention, Fig. 2 is a diagram showing the result of processing a ring-shaped diffraction image by the device of the present invention, and Fig. 3 is a spot Figure 4 is a diagram showing the results of processing a spherical diffraction image, Figure 4 is a diagram to explain the interplanar spacing and angle measurement method, Figure 5 is a diagram showing the results of processing a Kikuchi pattern, and Figure 6 is a diagram showing the results of processing a Kikuchi pattern. Diagrams showing the analysis results, Figure 7 is a diagram showing the Kikuchi pattern without superimposition, and Figure 8 is a diagram showing the Kikuchi pattern when two screens are superimposed. 1... Image input jll la... Electron microscope 1b.
...Imaging device 2...Analog-digital converter 3...Image l! Processing unit 4... Arithmetic processing unit 5... Analysis unit 6... Output unit. Patent applicant: Kawasaki Steel Corporation Applicant: Japan Regulator Co., Ltd. Figure 2 Figure 3 Figure 4 Figure 7 Figure 8 Procedural amendment (method) % formula % 1. Indication of the case 1982 Patent Application No. 25oaoΦ 2. Title of invention: Electron diffraction image automatic measurement device 3. Person making the amendment. Relationship to the case. Patent applicant (125) Kawasaki Steel Co., Ltd. Japan Regulator Co., Ltd. August 27th, i=v-sz, +, bulge goo 1 snow-1□71, "Ani" in the first line of page 10 of the specification is corrected to "Au". 2. "Figure 2 shows a ring shape" in line 8 of page 14 of the same page was corrected to "Figure 2 shows a ring shape obtained by using a metal structure made of a 71u vapor deposited film as a sample." In the line 14 of the same page, ``Figure 8 shows the shape of a spot F'' was corrected to ``Figure 3 shows the shape of a spot obtained from a metal structure made of a single crystal of pure iron.'' In line 14 of the same page, ``Figure 6 shows the shape of a spot.''"Kikuchipattern" has been corrected to "Figure 6 is a Kikuchi pattern obtained using a metal structure made of a thin film of steel as a sample", and in line 16 of the same page, "7v!J is Kikuchi when no overlapping". "Figure 7 is the Kikuchi obtained as a sample of the metallographic structure of a steel thin film without superimposition," and in line 18 of the same page, "Figure 8 is the Kikuchi obtained when the two images are superimposed."'' should be corrected to ``Figure 8 shows Kikuchi obtained as a sample of the metallographic structure of thin steel films without overlapping.''

Claims (1)

[Scope of Claims] 1. An electron microscope that forms an electron diffraction image of a sample, an imaging device that captures this electron diffraction image and outputs an analog image signal, and converts this analog image signal into a digital image at the translation level. An analog-to-digital converter that can convert images into signals and superimpose images on two or more screens, and a point from the digital image signal output from this analog-to-digital converter. An image processing unit that extracts features such as circles and wire elements and creates a diffraction image;
It is characterized by comprising an arithmetic processing section that stores basic data such as line distance, and an analysis section that analyzes the crystal structure and crystal orientation of a sample based on the basic data obtained by this arithmetic processing section. Automatic electron diffraction image measurement device.