JPH0360149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a detector that detects the amount of signal change from a sample irradiated with an electron beam and outputs the signal related to this detection as a video signal, and a detector that outputs the detected signal as a video signal. The present invention also relates to an electron beam scanning sample image display apparatus comprising: and a video display system that displays a sample image on a video screen by scanning with a sweep signal in the Y-axis direction.

Some detectors used in X-ray microanalyzers and scanning electron microscopes have drift signals that exceed the normal signal change amount. When using such a detector, a sample image cannot be clearly displayed using a conventional image display system. In order to solve this problem, conventionally, a very expensive lock-in amplifier and a signal synchronization mechanism are incorporated into the image display system to display the sample image. However, the synchronization frequency in a lock-in amplifier can only be raised to about 10 kHz at most, so in order to display a smooth sample image, the X-axis sweep period must be set to several tenths or several hundredths of the synchronization frequency. must be lowered to For this reason, there was a major inconvenience in that a very long time had to be spent before obtaining a sample image.

The present invention eliminates the above-mentioned disadvantages, eliminates the need to use an expensive lock-in amplifier, and simply adds a simple circuit to a conventional video display system, thereby eliminating the need for a long time even when the video signal has a large drift. The purpose is to obtain a clear sample image without any distortion.

In order to achieve the above object, the present invention mixes a blanking signal for X-ray sweep with a video signal from a detector, always clamps the blanking signal in this mixed signal to a constant level, and performs X-axis sweeping. By making the period shorter than the drift change time, the amount of drift change can be kept to an apparently small amount, so that a clear sample image can be obtained without spending a long time even if the video signal has a large drift in conventional video display systems. It is composed of

Next, the configuration of the present invention will be specifically explained with reference to the drawings in terms of embodiments.

FIG. 1 is a block circuit diagram of an embodiment of the present invention. An electron beam 2 is irradiated from an electron beam generator 1 toward a sample 3 . The electron beam 2 is deflected by deflection coils 4 and 5 on the X axis (for example, horizontal scanning direction) and the Y axis (vertical scanning direction), respectively. The detector 6 (for example, an infrared semiconductor detector) is used while being cooled with liquid nitrogen until immediately before activation, and detects changes in the amount of light generated from the sample 3 irradiated with the electron beam depending on the composition. At the same time, a signal having a waveform as shown in FIG. 2a related to the detection is outputted as a video signal. The adder 7 adds and mixes the blanking signal of a constant amplitude whose generation period is shorter than the drift change time as shown in FIG. , outputs a mixed signal as shown in FIG. 2d. The pulse clamp circuit 9 outputs a signal clamped by the X-axis sweep blanking signal and the mixed signal so that the blanking signal included in the mixed signal is always at a constant level, as shown in FIG. 2e. Therefore, the video signal of FIG. 2a,
As is clear from a comparison with the clamped video signal in FIG. 2e, the large drift included in the video signal in FIG.
It will be pressed down to a small size within the scan. In this way, the clamped video signal is transferred to the video amplifier 10.
The brightness signal is input to the luminance signal input terminal of the video display 11 via. In addition, 12 is a magnification adjuster, and 1
3 is a deflection coil of the image display 11, 14 is an X-axis sweeper, 15 is a Y-axis sweeper, 1
6 is an offset adjuster. Further, FIG. 2d shows the output waveform of the X-axis sweeper 14. In this way, by clamping the blanking signal, making the drift component change relatively slow, and making the operation time (sweep period) in the X-axis direction shorter than the drift change time, the video signal with large drift can be suppressed to a small drift. image and convert it to a stable image.
The video signal related to this conversion makes it possible to display a clear sample image.

As explained above, according to the present invention, the X-axis sweep blanking signal and the video signal from the detector are mixed, the blanking signal in the mixed signal is clamped to be always constant, and the Since the axis sweep period is configured to be shorter than the drift change time, a video signal with large drift can be output from the detector by simply adding a simple circuit to a conventional video display system without using an expensive lock-in amplifier. It is possible to convert into a stable video signal even when the image quality is low, and therefore it is possible to obtain a clear sample image without spending a long time with an inexpensive configuration.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, and FIG. 2 is a signal waveform diagram for explaining its operation. 1...Electron beam generation circuit, 3...Sample, 6...Detector, 7...Adder, 8...X-axis oscillator, 9...
Pulse clamp circuit, 10...Video amplifier, 11
...Video display.

Claims (1)

[Claims] 1 A detector that detects the amount of signal change from a sample irradiated with an electron beam and outputs a video signal, and a detector that scans this video signal with a sweep signal in the X-axis and Y-axis directions of the video screen to create a sample image. In an electron beam scanning sample image display device comprising a video display system for displaying on a video screen, a means for mixing an X-axis sweep blanking signal and a video signal from the detector, and mixing from the mixing means. and means for clamping the blanking signal contained in the signal so that it is always at a constant level, and the video display system uses the output signal from the clamping means as a video signal, and the X-ray sweep period is changed by drift. 1. An electron beam scanning sample image display device, characterized in that the time is shorter than that of an electron beam scanning sample image display device.