JPS63168949A - Electron microscope - Google Patents

Abstract

PURPOSE:To neutralize and remove the electric charge on charged recording media in the camera room of an electron microscope by connecting an ion producing means mixing positive and/or negative ions in gas to a gas introducing device for introducing of gas to the camera room at the breaking of the vacuum of the said room. CONSTITUTION:When the magazine 14 for supply or the magazine 20 for receiving is put on or off, at first the leaking of the vacuum of the camera room 19 is performed, and as soon as the door 21 or 23 is opened dried air 43 of higher pressure than the atmosphere is sent in the camera room 19 from a compressed air tank 37. At that time, dried nitrogen gas 39 and dried air 43 are both passed through an ionizing device 51 so that a part of them is changed to positive or negative ions and sent into the camera room 19. Thereby the negative charge on the accumulative fluophor sheet 12 due to the irradiation of the electron beam 2 or the rubbing of the sheet 12 against each other or of the sheet 12 and the transfer means 40 can be neutralized by the positive ions.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention prevents dirt, dust, etc. from adhering to an electron microscope image recording medium placed in an electron microscope, particularly in a camera room, due to electrostatic attraction. This relates to an electron microscope that has been made possible.

(Prior Art) Conventionally, an electron microscope has been known that obtains an enlarged image of a sample by refracting an electron beam transmitted through a sample using an electric field or a magnetic field. In many cases, this electron microscope is equipped with a camera room, and an electron microscope image of the sample is recorded on the recording medium such as photographic film placed in the camera room by irradiating the electron beam that has passed through the sample. S (shooting) is now possible. The recording medium is taken in and taken out through a door provided in the camera room. As is well known, when recording an electron microscope image, the camera chamber onto which the electron beam is projected is maintained in a vacuum state.

(Problems to be Solved by the Invention) By the way, especially when a two-dimensional sensor such as a stimulable phosphor sheet disclosed in Japanese Patent Application Laid-Open No. 61-51738 by the present applicant is used as the recording medium, Since this recording medium is irradiated with an electron beam during image recording (photography), the medium may be negatively charged. When the recording medium charged in this manner is taken out of the camera room, it tends to attract dirt and dust in the air due to electrostatic attraction. If dirt, dust, etc. adhere to the recording medium, it will appear as noise in the recorded image. In addition, the two-dimensional sensor mentioned above can be used many times by repeatedly erasing the image, so
If the camera absorbs dust or the like in this way, the dust or the like will be brought into the camera chamber the next time it is used. This dirt, dust, etc. tend to adhere to the valves and the like of the exhaust passage when the camera chamber is evacuated to bring the camera chamber into a vacuum state. If this happens to a large extent, the attached dirt, dust, etc. may cause valves to malfunction, causing abnormal vacuum generation within the camera chamber.

In addition, the two-dimensional sensors described above are often subjected to electron microscope image reading in batches, but if these two-dimensional sensors are charged as described above, they may attract each other due to electrostatic attraction. Two sheets are transported during reading, which may cause transport troubles in the sensor transport system or lead to reading errors.

Note that the above-mentioned charging of the recording medium is caused not only by the electron beam irradiation, but also by the sensors rubbing against each other or the sensor transport system, particularly when the two-dimensional sensor is used.

Furthermore, although we have mainly explained the case where a two-dimensional sensor such as a stimulable phosphor sheet is used as the electron microscope image recording medium, silver halide photographic film, which has been widely used in the past, is used as the electron microscope image recording medium. Even if
If the film is handled in a bare state, or if it is automatically fed one by one from a stack of many films and transported to the electron microscope image recording section, the problem of charge-3 is also applied. occurs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electron microscope that can prevent dirt, dust, etc. from adhering to the two-dimensional sensor or a recording medium such as a photographic film due to electrostatic attraction, or from adhering recording media to each other. It is something to do.

(Means for Solving the Problems) The electron microscope of the present invention is an electron microscope equipped with a camera chamber as described above, and has a gas introduction system that introduces gas into the chamber when breaking the vacuum state of the camera chamber. , is characterized in that an ion generating means for mixing positive and/or negative ions into the gas is connected.

(Function) When positively charged and/or negatively charged ions are sent into the camera chamber as described above, the charge on the recording medium that has been charged in the chamber is neutralized and the charge is removed.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows an electron microscope according to an embodiment of the present invention. - For example, this electron microscope is configured to record (photograph) an electron microscope image on a two-dimensional sensor that accumulates electron beam energy, as shown in Japanese Patent Application Laid-Open No. 61-517.38 by the present applicant. It is something that The mirror body 1 of the electron microscope includes an electron gun 3 that emits an electron beam 2 at a uniform velocity, and at least one focusing lens 4 consisting of a magnetic lens, an electrostatic lens, etc. that narrows the electron beam 2 to a sample surface. , a sample stage 5, an objective lens 6 similar to the focusing lens 4,
and a projection lens 7. The electron beam 2 transmitted through the sample 8 placed on the sample stage 5 is refracted by the objective lens 6 to form an enlarged scattered image 8a of the sample 8. This enlarged scattered image 8a is projected onto a formed image 9 by the projection lens 7 (8b in the figure).

An electron microscope image recording device 10 is arranged below the mirror body 1 of the electron microscope. This electron microscope image recording device 10 includes a stimulable photosensitive sheet 1 as a two-dimensional sensor.
a sensor supply section 16 in which a supply magazine 14 containing a large number of 2 sheets, a recording section 18 formed to include the image forming surface 9, and a receiving magazine 20 similar to the supply magazine 14 described above. It has a sensor accommodating part 22 in which is housed. These sensor supply section 16, recording section 18, and sensor receiving section 22 are provided in a camera chamber 19 that is maintained in a vacuum state during operation of the electron microscope. The supply magazine 14 and the receiving magazine 20 can be taken in and out through the door 2) of the camera room 19, respectively. 23 will be opened. The stimulable phosphor sheet 12 stores and records the energy of the electron beam irradiated thereon, and when it is subsequently irradiated with excitation light, it emits stimulated luminescence light with an intensity corresponding to the energy of the electron beam. The specific structure is disclosed in detail in, for example, the aforementioned Japanese Patent Laid-Open No. 61-51738. On the other hand, an erasing light source 24 is provided between the sensor supply section 16 and the recording section 18. A horizontally movable sheet supply table 26 is provided across the sensor supply section 16 and the recording section 18.

A rack 30 that meshes with a gear 28 is fixed to the sheet supply table 2θ, and when the gear 28 is rotated, the sheet supply table 26 moves in the left-right direction in the figure. Further, the sensor receiving section 22 holds the stimulable phosphor sheet 12 in the recording section 18, and a receiving magazine 20 is provided.
A sheet delivery arm 32 is provided which is dropped into the container. Note that between the mirror body 1 and the electron microscope image recording device 10, there are shutters 3 that are movable in the six directions of arrows in the figure.
4 and a fluorescent screen 36 are provided, and these shutter 34 and screen 36 are each operated by a lever (not shown). Further, above the shutter 34, an observation window 38 made of lead glass, for example, is provided on the peripheral wall of the mirror body 1.

While the electron microscope is in operation, the interior of the mirror body 1 and the camera chamber 19 are maintained in a vacuum state by a known exhaust system. A blocking member (not shown) is provided, and by blocking the inside of the mirror body 1 and the inside of the camera chamber 19 from each other, it is possible to install the supply magazine 14 and take out the receiving magazine 20. Furthermore, even if the vacuum in the camera chamber 19 is destroyed, the interior of the mirror body 1 can be maintained in a vacuum state.

When recording electron microscope images, close the door 2). 23 is opened, a supply magazine 14 containing a large number of stimulable phosphor sheets 12 is stored in the sensor supply section 16, and an empty storage magazine 20 is stored in the sensor receiving section 22. Ru. The shutter 34 and the fluorescent screen 36 are set at a position where they block the electron beam 2 (horizontal position in the figure).

Further, the gear 28 is rotated clockwise in the figure, the sheet supply table 26 is moved to the right in the figure, and the lowest stimulable phosphor sheet 12 in the supply magazine 14 is sent to the recording section 18. When the stimulable phosphor sheet 12 is fed in this way, the erasing light source 24 is turned on and the erasing light 58 is irradiated onto the sheet 12, so that the sheet 12 undergoes erasure of residual radiation energy. Sheet supply table 26 supplies sheet 1
2 is located on the imaging plane 9, it is stopped. The electron beam 2 hits the fluorescent screen 36 and generates fluorescence, so that the enlarged scattered image 8a carried by the electron beam 2 appears on the observation window 3.
Observed through 8. In this way, the fluorescent screen 36
After the focus, magnification and viewing range of the enlarged scattered image 8a are determined by observing the image, the shutter 34 and the fluorescent screen 3
6 is flipped up to a position where it does not block the electron beam 2 by operating the aforementioned lever. In this way, electron beam 2
reaches the stimulable phosphor sheet 12 set in the recording section 18, and the electron beam energy carrying the enlarged scattered image 8b is accumulated and recorded on the sheet 12.

After opening the shutter 34 and performing electron beam exposure as described above, the shutter 34 is closed. The stimulable phosphor sheet 12 on which the enlarged scattered image 8b has been stored and recorded is then dropped into the receiving magazine 20 by the sheet delivery arm 32. Then, the sheet supply table 26 is returned to the sensor supply unit 16 by reversing the gear 28, and the stimulable phosphor sheet 12 in the supply magazine 14 is loaded in the same manner as described above in preparation for the next electron microscope image recording. One sheet is supplied to the recording section 18.

When the above operation is repeated, the stimulable phosphor sheets 12 on which electron microscope images have been recorded are collectively stored in the receiving magazine 20. When the series of electron microscope image recording is completed, open the door 23 and open the receiving magazine 2.
0 from the sensor receiving section 22, and the stimulable phosphor sheet 12 is subjected to electron microscope image reading. FIG. 2 shows an example of an image reading device for reading the electron microscope image. In this device, the stimulable phosphor sheet 12 is transported by a sheet conveying means 40 consisting of, for example, an endless belt.
placed on top. Then, an excitation light beam 44 emitted from an excitation light source 42 such as a He-Ne laser tube is deflected by an optical deflector 46 such as a galvanometer mirror, and the stimulable phosphor sheet 12 is scanned in the direction of arrow X by the beam 44. (main scan). At the same time, the sheet conveying means 40
As a result, the stimulable phosphor sheet 12 is moved in the Y direction substantially perpendicular to the main scanning direction (sub-scanning). As a result, the entire surface of the stimulable phosphor sheet 12 is irradiated with the excitation light beam 44.

By this excitation light irradiation, the stimulable phosphor sheet 12 emits stimulated luminescence light 48 at a level corresponding to the accumulated and recorded electron beam energy. This stimulated luminescence light 48 enters into the light collecting body 50 from the incident end surface 50a of the light collecting body 50.
The emitted light travels through the zero through repeated total reflection and exits from the exit end face 50b, is received by a photodetector 52 such as a photomultiplier connected to the exit end face 50b, and the amount of stimulated luminescence light is read photoelectrically. The electrical signal output from the photodetector 52 indicates the level of the electron beam energy, and this electrical signal is sent to the image processing circuit 54 where necessary image processing is performed, and then input to the image reproduction device 56. be done. This image reproducing device 56 may be a display such as a CRT, or may be a recording device that performs optical scanning recording on a photosensitive film. By outputting an image using the electric signal corresponding to the amount of stimulated luminescence light in this manner, the enlarged scattered image 8b carried by the stimulated luminescence light 48 is reproduced.

Next, a mechanism for preventing dirt, dust, etc. in the air from entering the camera room 19 will be explained.

A gas supply pipe 25 is opened in the camera room 19, and the gas supply pipe 25 is connected to two branch pipes, namely a nitrogen gas supply pipe 27 and an air supply pipe 29. Nitrogen gas supply pipe 2
7. The air supply pipe 29 is connected to a nitrogen gas cylinder 35 and a compressed air tank 37, respectively, via on-off valves 31 and 33, which are M magnetic valves, for example. Note that an ionization device 51, which will be described in detail later, is interposed between the on-off valve 31 and the nitrogen gas cylinder 35. The nitrogen gas cylinder 35 is filled with compressed dry nitrogen gas 39 .

On the other hand, a compressor 41 is installed in the dry pressure/compressed air tank 37.
Dry compressed air 43 is fed in by. The nitrogen gas 39 is reduced to atmospheric pressure by a pressure reducing valve 40, and the dry compressed air 43 is increased to above atmospheric pressure by, for example, automatically operating the compressor 41 upon detection of a pressure drop in the compressed air tank 37. I'm under pressure.

On the other hand, door 2) of camera room 19. Opening/closing sensors 45.47 such as limit switches are provided to detect the open/closed states of the gas supply valve 23, and signals S1 and S2 outputted from these opening/closing sensors 45.47 are input to the gas supply control circuit 49. There is.

In order to take in and out the supply magazine 14 or the receiving magazine 20, first, the camera chamber 19 is vacuum leaked. At that time, the valve opening signal S3 is sent to the on-off valve 31 to open the valve 31, and dry nitrogen gas 39 is sent into the camera room 19. Then, when door 2) or door 23 is opened after the leak is completed,
The opening/closing sensor 45 or the opening/closing sensor 47 sends a signal indicating the door open state to the gas supply control circuit 49. The gas supply control circuit 49 receives a signal indicating this door open state from the open/close sensor 45.4.
7, the valve opening signal S4 is sent to the on-off valve 33 to open the on-off valve 33. As a result, when the door 2) or the door 23 is opened, dry air 43 at atmospheric pressure or higher is sent into the camera room 19 from the compressed air tank 37. Here, both the dry nitrogen gas 39 and the dry air 43 pass through the ionization device 51, and some of them become positive or negative ions and are sent into the camera chamber 19.

If the dry air 43 is sent to the camera room 19 as described above, the dry air 43 will flow out of the camera room 19 from the opened m2) or door 23, so the air outside the camera room 19 will flow into the camera room 19. Never. Therefore, dirt, dust, etc. do not enter the camera room 19 from outside the camera room 19, and humid air does not enter the camera room 19.

Furthermore, as described above, when the stimulable phosphor sheet 12 is irradiated with the electron beam 2 during recording (photography) using an electron microscope, or when the sheets 12 rub against each other or against the conveyance means 40, the stimulable phosphor sheet 12 12
may be negatively charged, but in this case, the charge is neutralized by positively charged ions, and the sheet 12 is neutralized. Therefore, when the stimulable phosphor sheet 12 is taken out of the camera room 19, dirt, dust, etc. in the air will not be attracted to the sheet 12 due to electrostatic attraction. Further, since the sheets 12 accumulated in the receiving magazine 20 are not attracted to each other by electrostatic attraction, when the above-mentioned image reading is performed by the image reading device shown in FIG.
This prevents sheet 12 from being conveyed while being adsorbed, causing sheet conveyance troubles or reading errors.

It is preferable that the ionization device 51 is configured to automatically stop ionization when static elimination of the sheet 12 is completed.

In addition, when the leak in the camera room is completed and the pressure reaches atmospheric pressure, the dry nitrogen gas 39 is switched to dry compressed air 43.
There is no possibility that a large amount of the dry nitrogen gas 39 flowing out from the camera room 19 will fill the electron microscope installation room and cause difficulty in breathing for the electron microscope operator.

Also, as mentioned above, first dry nitrogen gas 39 is applied to the camera room 1.
Since the nitrogen molecules are allowed to flow into the interior of the camera chamber 19, nitrogen molecules become adsorbed on the inner wall of the camera chamber 19. Such a nitrogen molecule is
Next, when the inside of the camera room 19 is evacuated, the camera room 19 can be easily removed.
However, if oxygen molecules or water molecules are adsorbed to the inner wall of the camera chamber 19, they will not easily detach from the inner wall when exhausting air. Therefore, if the nitrogen gas 39 is first sent into the camera room 19 as in this example, then when the inside of the camera room 19 is evacuated, the vacuum state can be created easily and in a short time.

In the present invention, it is not necessarily necessary to switch between two types of gas and send them to the camera room 19 as described above, and for example, the vacuum leak means and the gas supply means may be used both. In addition to the nitrogen gas mentioned above, an inert gas such as argon gas is preferably used as the gas to be sent to the camera room 19 other than air.

Further, although an embodiment in which the present invention is applied to an electron microscope that performs recording on the stimulable phosphor sheet 12 has been described above, the present invention is not limited to such an electron microscope.
Of course, the present invention can also be applied to an electron microscope configured to record an electron microscope image on a silver halide photographic film.

(Effects of the Invention) As described above in detail, according to the present invention, dirt, dust, etc. are prevented from adhering to a recording medium such as a charged stimulable phosphor sheet and entering the camera chamber of an electron microscope. Since this can be reliably prevented, noise caused by the influence of dirt, dust, etc. will not be generated on the recording staff. Furthermore, it is possible to avoid problems such as malfunctioning valves in the camera chamber exhaust system, and to greatly improve the reliability of the electron microscope. Furthermore, according to the present invention, since it is possible to reliably prevent recording media such as stimulable phosphor sheets and photographic films from adhering to each other due to electrostatic attraction, it is possible to reliably prevent recording media such as stimulable phosphor sheets and photographic films from being attracted to each other by electrostatic attraction, so that it is possible to reliably prevent recording media such as stimulable phosphor sheets and photographic films from being attracted to each other by electrostatic attraction. At the same time, it is possible to avoid troubles caused by adhesion of recording media to each other, and it is also possible to improve the reliability of the reading process, etc. Furthermore, since it is possible to prevent moist air from entering the camera room, the time required to create a vacuum can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an electron microscope according to an embodiment of the present invention, and FIG. 2 is a diagram showing how an electron microscope image is read and reproduced from a stimulable phosphor sheet on which an electron microscope image has been recorded using the electron microscope according to the above embodiment. FIG. 2 is a schematic diagram showing the device.

Claims (2)

[Claims] (1) In an electron microscope configured to place a recording medium in a camera chamber maintained in a vacuum state, and record an electron microscope image of the sample by irradiating the recording medium with an electron beam that has passed through the sample, An electronic device characterized in that ion generation means for mixing positive and/or negative ions into the gas is connected to a gas introduction system that introduces gas into the camera room when breaking the vacuum state of the camera room. microscope. (2) The gas introduction system includes a gas supply source that sends gas into the camera room, and a gas supply source that supplies the gas to the camera room when the door is opened in conjunction with the opening and closing of the door of the camera room. 2. The electron microscope according to claim 1, further comprising gas supply control means for stopping the gas supply when the door is closed.