JP2000243339A - Image display device for electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breakage of the image pickup tube itself of a TV camera by providing a safety mechanism for preventing the current selection of a diffraction image mode and a television observation mode. SOLUTION: An operator console 14 is provided with an image mode selecting switch 14a of a TEM image or a diffraction image and an observation mode selecting switch 14b for fluorescent screen observation or TV observation. In the TV observation mode, the image information formed on the front face of an image pickup tube 11 and inputted to the image pickup tube 11 is read out by the scanning signal from a TV camera body 12, and its image signal is displayed on an image display device 13 via the TV camera body 12. The diffraction image and the TEM image are switched in the image mode by a excitation condition change of an image forming lens system 5. When the diffraction image is observed by the TV camera, the light receiving face of the image pickup tube 11 is damaged by the concentration of a high-energy electron beam Eb. To prevent this from occurring, a central control device judges the mode state when the image mode and the observation mode are selected and controls the image forming lens system 5 to prohibit the concurrent selection of the diffraction image and the TV observation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety mechanism such as an electron microscope having an image pickup means.

[0002]

2. Description of the Related Art In an electron microscope, an image pickup tube of a television camera device (hereinafter, referred to as a TV camera) is arranged at a position where a sample image is formed, a sample image is photographed, and the video signal is transmitted through an image processing device. It has been generalized to supply an image display device (for example, a cathode ray tube) to display an image and observe a sample image. As this sample image, in addition to projecting a normal transmission electron microscope image (hereinafter, referred to as a TEM image) on the front surface of the imaging tube, the excitation of the imaging lens system (objective lens and projection lens) is adjusted, and diffraction is performed. There is a case where an image is projected on the front surface of an imaging tube and a diffraction image is observed on an image display device.

[0003]

By the way, in an electron microscope equipped with such an image display device, in an ultra-high voltage electron microscope having an acceleration voltage as high as 1000 KV or more, an electron beam has a high brightness and a high energy. Electrons having energy enter the fluorescent screen and the TV camera. Conventionally used fluorescent screens have a sufficiently high allowable electron beam energy value, so when observing these TEM images or diffraction images, there is almost no damage to the fluorescent screen by electron beams having high energy, It can be used similarly to a normal electron microscope (acceleration voltage is not more than 300 KV). On the other hand, the TV camera has a lower allowable energy value than the fluorescent screen, so care must be taken when handling it. Nevertheless, when a normal TEM image is observed with a TV camera, the electron beam is dispersed and incident on the entire light receiving surface of the image pickup tube. (KV or less).

However, when a diffraction image in which electron beams having high energy are concentrated is observed by a TV camera, the light receiving surface of the image pickup tube may be damaged by the electron beam energy. In the case of a diffraction image, the pattern is as shown in FIG. 2 (b), and there is a direct spot of a small spot of high brightness and high energy at the center of the pattern. Electron beams of high energy diffraction spots appear concentrated. As shown in FIG. 2A, the direct spot at the center of this diffraction image has extremely high brightness. Therefore, the high-energy electric charge is accumulated in the small area of the light receiving surface of the image pickup tube of the TV camera when the electron beam of the direct spot of the high energy and small spot is intensively irradiated. As a result, on the light receiving surface of the image pickup tube, discharge occurs toward the area where the high-energy accumulated electric charge of this small spot area has a low surrounding potential or a low potential inside the light receiving surface. The trajectory of the discharge remains, and the image pickup tube itself is damaged.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide an electron microscope provided with a safety mechanism capable of preventing damage to an image pickup tube itself of a TV camera.

[0006]

According to the present invention, there is provided an imaging lens system for projecting an electron beam transmitted through a sample onto an imaging portion, and an electron microscope image formed by the imaging lens system. Image mode selection switching means for selectively switching between a mode and a diffraction image mode, a fluorescent plate and an image pickup means selectively disposed on an electron beam path of the imaging section, a fluorescent plate observation mode using the fluorescent plate, and the image pickup means In the electron microscope provided with the observation mode selection switching means for selectively switching between the television mode and the television observation mode, the selection of the diffraction image mode by the image mode selection means and the selection of the television observation mode by the observation mode selection switching means are simultaneously performed. It has a safety mechanism that is not performed.

[0007]

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

FIG. 1 is a block diagram showing an embodiment of an image display device for an electron microscope according to the present invention. In the figure, an electron beam Eb generated and accelerated from an electron gun 1 is irradiated on a sample 8 by a converging lens 2. The electron beam Eb passing through the sample 8 is
The light is radiated to an image forming portion Z via an image forming lens system 5 including an objective lens 3 and a projection lens 4 (including an intermediate lens). Imaging part Z
Is provided with a fluorescent plate 9 for receiving the irradiated electron beam Eb and an image pickup tube 11 for receiving the electron beam Eb when the fluorescent plate 9 comes off the electron beam path. The imaging lens system 5 is controlled by a central controller 7 via an imaging lens control circuit 6. Further, the fluorescent screen 9 of the image forming section Z is controlled by the central control device 7 via the fluorescent screen driving mechanism 10.

On the console 14, an image mode selection switch 14a for a TEM image or a diffraction image is provided.
An observation mode selection switch 14b for V observation is provided. Each mode signal set by these mode selection switches 14a and 14b is input to the central control unit 7.
On the other hand, in the TV observation mode, image information formed on the front surface of the imaging tube 11 and input to the imaging tube 11 is read out according to a scanning signal from the TV camera body 12, and the read out video signal is , Is supplied to the image display device 13 via the TV camera body 12, and is displayed as an image on the image display device 13. The operation of such a configuration will now be described.

The switching between the image modes of the diffraction image and the TEM image can be performed by changing the excitation conditions of the imaging lens system 5. However, as described above, when the diffraction image of the ultra-high voltage electron microscope is observed by the TV camera, the light receiving surface 11a of the imaging tube 11 is damaged due to the concentration of the electron beam Eb having high energy. .

The present invention is characterized by including a safety mechanism for preventing the image pickup tube 11 of the TV camera from being damaged by the above-mentioned diffraction image. The safety mechanism determines the state of each mode when the image mode and the observation mode are selected by the central control device 7, and controls so that the simultaneous selection of the diffraction image and the TV observation is prohibited. Hereinafter, this safety mechanism will be described.

First, observation of a normal TEM image is performed first by using the fluorescent screen 9.
Next, a description will be given of the observation of a fluorescent plate by a TV camera and the TV observation by a TV camera. First, when a normal TEM image of a fluorescent plate is observed, the image mode selection switch 14a of the console 14 is set to a TEM image, and the observation mode selection switch 14b is set to a fluorescent plate observation. These mode signals are input to the central control unit 7 as a TEM image and a mode signal for observing a fluorescent screen. Since the central control device 7 is not a combination of the diffraction image and the TV observation, the imaging lens system 5 is set to the TEM image based on the TEM image and the mode signal for instructing the observation of the fluorescent plate, and the fluorescent plate 9 is set in the imaging portion Z. Deploy.

The electron beam Eb generated from the electron gun 1 and accelerated
Is irradiated on the sample 8 by the converging lens 2. The electron beam Eb that has passed through the sample 8 is imaged as a TEM image on the surface of the fluorescent screen 9 by the imaging lens system 5 set in the TEM image mode by the central controller 7.

Next, in order to change the observation mode of the TEM image from the fluorescent plate observation to the TV observation, the operator sets the observation mode selection switch 14b of the console 14 from the fluorescent plate observation to the TV observation. Upon receiving a signal for switching the observation mode to the TV observation mode, the central control device 7 switches the fluorescent plate 9 from the broken line to the solid line in the drawing and removes the fluorescent plate 9 from the imaging unit Z via the fluorescent plate driving mechanism 10. Therefore, the electron beam Eb is formed as a TEM image on the light receiving surface 11a of the imaging tube 11, and the information of the TEM image input to the imaging tube 11 is T
Read out according to the scanning signal from the V camera body 12,
The read video signal is supplied to the image display device 13 via the TV camera main body 12 and is displayed on the image display device 13.
It is displayed as an EM image. To return the TV observation to the fluorescent screen observation, the image observation on the fluorescent screen 9 can be performed again by setting the selection switch 14b of the console 14 to the fluorescent screen observation rather than the TV observation as the reverse operation.

As described above, when a TEM image is observed with a TV camera, the electron beam Eb is dispersed and incident on the front surface of the light receiving surface 11a of the image pickup tube 11, so that even with an ultra-high voltage electron microscope, a normal electron microscope (acceleration) can be used. An image can be observed almost in the same manner as described above (voltage is not more than 300 kV). As a result, in the case of a TEM image, the observation mode can be switched to the fluorescent plate observation and the TV observation at any time for observation.

On the other hand, a case where the image mode is switched to a diffraction image from a state where a normal TEM image is observed on a TV will be described. First, the operator selects the image mode selection switch 14a of the console 14 from a TEM image to a diffraction image. The central controller 7 determines whether or not the observation mode signal set to the TV observation and the image mode signal of the diffraction image input and selected this time satisfy the prohibition condition. Then, the central control device 7 determines that the diffraction image and the TV observation are prohibited conditions that are set at the same time, and performs control so that selection of the diffraction image is not accepted. Accordingly, the central control unit 7 sends a prohibition signal indicating that the mode cannot be switched to the diffraction image mode to the console 14, and simultaneously holds the state of the TEM image. The console 14 that has received the prohibition signal displays on the monitor (not shown) a character saying “switching to the diffraction image mode is not possible”,
The display unit (for example, a lamp or the like, not shown) of the image mode selection switch 14a and the observation mode selection switch 14b blinks for a certain period of time to indicate that mode switching has not been accepted.

Next, the case where the observation mode is switched from the state of observing the diffraction image to the fluorescent screen to the mode of TV observation will be described. When the operator switches the observation mode selection switch 14b of the console 14 from the fluorescent screen observation to the TV observation,
The central control device 7 determines whether or not a prohibition condition is satisfied based on the image mode signal set as the diffraction image and the observation mode signal of the TV observation selected and input this time. The central control device 7 determines that the diffraction image and the TV observation are prohibited conditions that are set at the same time, and performs control so that selection of the TV observation is not accepted. Accordingly, the central control unit 7 sends a prohibition signal to the console 14 and at the same time holds the state of the fluorescent plate observation up to now.
The console 14 having received the prohibition signal displays on the monitor (not shown) the characters "cannot be switched to the TV observation mode", and displays the image mode selection switch 14a and the observation mode selection switch 14b (for example, A lamp or the like (not shown) blinks for a certain period of time to indicate that mode switching has not been accepted.

As described above, in the present invention, when setting the imaging mode and the observation mode by the operator, the safety mechanism automatically operates so as to avoid realizing the state of observing the diffraction image on the TV, As a result, damage to the TV camera is prevented.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above, and various modifications are possible. For example, when the acceleration voltage is lower than a predetermined voltage, the above-described safety function is released, and each mode can be switched freely. Further, when the imaging mode is the diffraction image, the TV observation of the switching display of the observation mode on the console 14 may be deleted so that the selection cannot be performed. Similarly, when observing in the TV mode, the diffraction image of the choice of the imaging mode of the console 14 may be erased and the selection may not be possible.

[0020]

As is apparent from the above description, in the present invention, when setting the imaging mode and the observation mode, a safety mechanism is provided so as to avoid realizing the state of the TV observation of the diffraction image. It operates automatically, and as a result, damage to the TV camera due to a diffraction image having high energy can be prevented.

[0021]

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an image display device for an electron microscope of the present invention.

FIG. 2 is a diagram showing a diffraction image and its signal intensity.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Converging lens, 3 ... Objective lens, 4 ... Projection lens, 5 ... Imaging lens system, 6 ... Imaging lens control circuit, 7 ... Central controller, 8 ... Sample, 9 ... Fluorescent plate, 10 …
Fluorescent plate drive mechanism, 11: imaging tube, 12: TV camera body, 13: image display device, 14: console

Claims (4)

[Claims] 1. An imaging lens system for projecting an electron beam transmitted through a sample onto an imaging section, and an image mode selection switching means for selectively switching the imaging lens system between an electron microscope image mode and a diffraction image mode. A fluorescent plate and an imaging unit selectively disposed on the electron beam path of the image forming unit; and an observation mode selection switching unit for selectively switching a fluorescent plate observation mode by the fluorescent plate and a television observation mode by the imaging unit. An electron microscope comprising: a safety mechanism in which selection of a diffraction image mode by the image mode selection means and selection of a television observation mode by the observation mode selection switching means are not performed at the same time. . 2. The safety mechanism according to claim 1, wherein when the television mode is previously selected by the observation mode selection switching means, the safety mechanism is prohibited from selecting the diffraction image mode later by the image mode selection switching means. Claim 1.
Electron microscope as described. 3. The safety mechanism according to claim 1, wherein when the diffraction image mode is previously selected by the image mode selection switching means, the safety mechanism is prohibited from selecting the television observation mode later by the observation mode selection switching means. The electron microscope according to claim 1, wherein: 4. The electron microscope according to claim 1, wherein the safety mechanism operates when an acceleration voltage of the electron beam is equal to or higher than a predetermined value.