JPS587024B2 - Image display devices such as electron microscopes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image display device such as an electron microscope, and particularly to a device that can obtain images with improved image quality.

Conventionally, in a scanning electron microscope or a transmission electron microscope equipped with an image pickup tube, the obtained image signal is supplied to a display means such as a cathode ray tube to obtain a sample image. The aim is to improve image quality.

For example, a contour correction processing circuit using a differential circuit as shown in FIG. 1A is known.

That is, when a video signal with a distorted waveform is applied to the input terminal as shown in FIG.

The other signal is sent to the differentiating circuit D and is differentiated, so that the output signal of the differentiating circuit D is a differentiated signal as shown in FIG.

The differential signal is then sent to the rectifier circuit R, where it is rectified and converted into a signal as shown in Figure d, in which the negative portion is folded back.

The signal shown in FIG. 1d obtained in this way is sent to the adding circuit A, where it is added to the original video signal shown in FIG. 1b, so that the output of the adding circuit A is In this case, a modified video signal is obtained in which the changing portion of the signal is emphasized, as shown in FIG.

Therefore, by sending the modified video signal to a display means such as a cathode ray tube, a sharp image with enhanced outlines can be obtained.

However, even if such a video signal processing circuit is used to improve image quality, the effect can only be expected in one direction, that is, one-dimensionally.

For example, using a scanning electron microscope, a sample having a contrast as shown in Figure 2a is scanned with an electron beam in the direction of the arrow, and an image signal obtained is transmitted through the processing circuit shown in Figure 1a. When sent to a cathode ray tube, in the sample image obtained on the screen of the cathode ray tube shown in FIG. Sides L3 and L4, which are in a nearly parallel relationship, are not emphasized, and therefore the sample image obtained can only be incomplete.

The present invention has been made in view of the above points.
By scanning in two different directions, applying the same signal processing to the multiple types of video signals obtained from each scan to improve image quality, and superimposing images based on the multiple types of video signals. An object of the present invention is to provide an image display device such as an electron microscope that can obtain images with improved image quality in all directions, that is, in two dimensions.

The embodiment shown in FIG. 3 will be described in detail below. In FIG. 3, reference numeral 1 denotes an electron gun, and an electron beam 2 generated from the electron gun is focused onto a sample 4 by a focusing lens 3.

The electron beam 2 is two-dimensionally scanned over the sample 4 by the X-direction deflection coil 5X and the Y-direction deflection coil 5Y.

Scanning signals (horizontal and vertical) generated by a scanning circuit 6 are supplied to the deflection coils 5X, 5Y via changeover switches 7, 8.

Electrons generated from the sample 4 by electron beam projection are detected by a detector 9, and the resulting video signal is sent to an amplifier 10 and a video signal processing circuit 11 (hereinafter referred to as a processing circuit) having a configuration as shown in FIG. 1a, for example. ) through a cathode ray tube 12
(hereinafter abbreviated as CRT) is sent to grid G.

Horizontal and vertical scanning signals generated from the scanning circuit 6 are supplied to the X-direction deflection coil 13X and Y-direction deflection coil 13Y of the CRT 12 via changeover switches 14 and 15, respectively.

The changeover switches 7, 8, 14, and 15 are switched in response to a command from the scanning circuit 6 each time the electron beam 2 scans the scanning area once.

In the above-described configuration, the scanning circuit 6 repeatedly emits constant horizontal and vertical scanning signals, and switches the changeover switch 78 every time the electron beam 2 scans the scanning area once. The scanning direction of is shown in Fig. 4 a, b.
As shown in , the angle differs by 90° for each scan.

The video signal obtained by scanning in the husband's direction is processed by a processing circuit 11 and then sent to a CRT 12 where it is scanned in synchronization with the electron beam 2.

At this time, the scanning signals supplied to the deflection coils 13X and 13Y of the CRT 12 are also switched by the changeover switches 14 and 15 in conjunction with the changeover switches 7 and 8, so that the screen of the CRT 12 ends up with the image shown in FIG. 4a. A first sample image obtained by scanning and whose contour in one direction is emphasized by the processing circuit 11, and a first sample image obtained by scanning and enhanced by the processing circuit 11 shown in FIG. A second sample image with an enhanced outline is displayed alternately.

Therefore, to the naked eye, a sample image in which both are superimposed, that is, a correct sample image with emphasized contours in all directions is displayed.

Incidentally, the scanning area of the electron beam on the sample may be square or roughly rectangular as in the above embodiment.

In this case, 9 is displayed alternately on the CRT 12 screen.
The center part where two images with different 0° scanning directions overlap becomes the correct sample image with the outline emphasized in all directions, and the image with the outline emphasized in only one direction is displayed at the edge of the screen as before. However, since it is in the corner of the screen, it is not a practical problem at all.

If this is a problem, make the display area of the CRT 12 sufficiently narrower than the electron beam scanning area and display only a part of it.In other words, the electron beam scanning area is smaller than the CRT 12 display area. If you make it thick enough to scan extra, what will be displayed on the CRT 12 will be only the central part of the overlap between the two images taken in 900 different scanning directions, and the outlines in all directions will be emphasized over the entire screen. The correct sample image can be displayed.

Furthermore, in the above-described embodiment, if the scanning speed using a normal CRT is slow, an accumulation type CRT may be used.

Further, in the above-mentioned embodiments, a scanning electron microscope using a contour correction processing circuit has been described, but the present invention is not limited to this, and other correction processing circuits (for example, a processing circuit for improving contrast) may be used. As described above, according to the present invention, by superimposing two images that differ by 90 degrees in the scanning direction, the effect of image correction processing can be obtained in all directions, and in terms of structure, a changeover switch can be added to the deflection system of the conventional device. The present invention can be carried out simply by providing the following, and its effects are extremely large.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing an example of a contour correction processing circuit and diagrams for explaining the operation of the circuit, and FIG. 3 is a block diagram showing an embodiment of the present invention. FIG. 4 is a diagram for explaining the operation of the embodiment shown in FIG. 3. 1... Electron gun, 3... Focusing lens, 4
...Sample, 5X, 5Y, 13X, 13Y...
...deflection coil, 6...scanning circuit, 7,8,
14, 15... changeover switch, 9...
Detector, 11...Video signal processing circuit, 12...
...Cathode ray tube.

Claims (1)

[Claims] 1. An electron gun, a focusing lens for narrowly focusing the electron beam generated from the electron gun onto the sample, a deflection means for scanning the electron beam on the sample in the horizontal and vertical directions, and an electron beam irradiation device. A detection means for detecting information generated from the sample, a signal processing circuit for processing the video signal obtained from the detection means, and a cathode ray tube display device to which the video signal extracted from the processing circuit is supplied. and a switching means for changing the scanning direction of the electron beam on the sample by 90 degrees;
An image display device such as an electron microscope, characterized in that a switching device is provided for changing the scanning direction of the cathode ray tube display device by 90 degrees, and the two switching devices are switched for each screen scan.