JPH062201Y2 - Imager in electron microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an imaging apparatus in an electron microscope, and more particularly to an imaging apparatus capable of reducing electron beam damage to a sample in an imaging process.

[Prior Art] Conventionally, an apparatus having a configuration as shown in FIG. 3 is known as a photographing apparatus in an electron microscope. In FIG. 3, 1 is an electron microscope housing, 2 is a projection lens, 3 is an electron microscope image observation fluorescent plate, 4 is an electron microscope image recording medium, 5 is a shutter, 6 is a shutter drive mechanism, and 7 is an ammeter. When the electron microscope image is photographed by the apparatus having such a structure, the photograph is taken by the process shown in FIG. In FIG. 4, (a) shows the timing of opening and closing the fluorescent plate 3,
(B) shows the opening / closing timing of the shutter 5.

Step A: The operator first projects a desired photographing position (image) on the electron microscope image observing fluorescent plate 3 to perform focusing and the like.

Step B: After that, in order to determine the exposure time for giving the optimum exposure amount of the electron beam for the sensitivity of the image recording medium 4, the fluorescent plate is irradiated with an ammeter 7 connected to the fluorescent plate 3. The electron beam current is measured. Then, an appropriate exposure time t of the electron beam is obtained based on the measured value of the electron beam current, and the shutter drive mechanism 6 is exposed to the exposure time t.
(Shutter speed) is set.

Step C: Next, the shutter 5 is temporarily closed by the shutter driving mechanism 6, and Step D: While the electron beam is blocked by the shutter 5, the fluorescent plate 3 is rotated about the axis Q to be an electron beam. Removed from the passage.

Step E: Then, the shutter drive mechanism 6 opens the shutter 5 for the set exposure time t, the electron beam is exposed on the electron microscope image recording medium, and the shutter 5 is closed after the exposure is completed.

Step F: When the shutter 5 is closed, the fluorescent plate 3 is rotated in the opposite direction to the previous direction and inserted into the electron beam passage, and Step G: the closed shutter 5 is opened again and the electron microscope image is again displayed. It is projected on the fluorescent screen 3.

Further, when the electron microscope images are continuously photographed, the photographing steps A to G are repeated as shown in FIGS. 4 (a) and 4 (b).

[Problems to be Solved by the Invention] In observation of an electron microscope image, an observation sample may be damaged by irradiation with an electron beam. It is known that the degree of the electron beam damage changes depending on the amount of electron beam irradiation to the sample, and therefore it is desired to shorten the electron beam irradiation time to the sample as much as possible.

Now, in the photographing process of the electron microscope image, the sample is always irradiated with the electron beam. Considering the irradiation amount of the electron beam to the sample in the photographing process, FIGS. 4 (a) and 4 (b) are considered. In the entire imaging process as shown in Fig. 6, the electron beam exposure time (process E) to the main image recording medium is short, but other focusing and field of view (process A) and electron beam current measurement are performed. The electron beam is irradiated to the sample for a relatively long time (stroke B) and the opening / closing stroke of the fluorescent plate 3 (open stroke D, closed stroke F). In particular, since the fluorescent plate 3 has a large area capable of projecting the entire magnified electron microscope image, it is difficult to insert it into and remove it from the electron beam passage at a high speed, and the opening and closing process takes the longest time. Therefore, the sample is most damaged by the electron beam during the opening and closing process.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging device capable of reducing electron beam damage to a sample in an imaging process.

[Means for Solving the Problems] The present invention is directed to a fluorescent plate for projecting an electron microscope image, a shutter detachably arranged in an electron beam passage near a crossover point of a projection lens, and an electron microscope image. In a photographing device in an electron microscope equipped with an electron microscope image recording medium arranged below the fluorescent plate for recording, a sensor for detecting an electron beam and converting the electron beam into an electric signal is attached to the shutter. The position is an electron beam irradiation position on the shutter when the electron beam is cut off, and a calculation unit that calculates an electron beam exposure time to the image recording medium based on a detection signal of the sensor, and an output of the calculation unit. A means for controlling the opening time of the shutter based on a signal is provided.

[Operation] In the present invention, the shutter is equipped with a sensor that detects an electron beam and converts it into an electric signal, and the mounting position is an electron beam irradiation position to the shutter when the electron beam is blocked. By providing a calculating means for calculating the electron beam exposure time to the image recording medium based on the detection signal of the sensor and a means for controlling the opening time of the shutter based on the output signal of the calculating means, the photographing process is performed. Is shortened, and electron beam damage to the sample is reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 is a device configuration diagram for explaining an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are diagrams for explaining the opening / closing timing of a fluorescent screen and the opening / closing timing of a shutter. In FIG. 1, the same components as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 1, 10
Is a sensor that detects an electron beam and converts it into an electric signal, and the sensor 10 is attached to a position where the shutter 5 receives the electron beam when the shutter 5 blocks the electron beam. Reference numeral 11 is a processor that calculates the electron beam exposure time to the image recording medium 4 based on the detection signal of the sensor 10, and the shutter drive mechanism 1 that controls the opening time of the shutter based on the output signal of the processor 11.
2 is controlled.

When the electron microscope image is photographed by the apparatus having such a configuration, the photographing is performed by the following steps.

Step I: First, a desired photographing position (image) is projected on the fluorescent plate 3 for observing an electron microscope image to perform focusing and the like.

Step J: Next, the shutter 5 is the shutter drive mechanism 12
Is closed and the electron beam is blocked. At this time, the electron beam is detected by the sensor 10 provided on the shutter and converted into an electric signal. The signal is the processor 1
1, the exposure time t for giving the optimum exposure amount of the electron beam to the sensitivity of the image recording medium 4 is calculated. Then, the output signal of the processor 11 is supplied to the shutter drive mechanism 12, and the exposure time is set in the drive mechanism.

Step J ′: While the electron beam is blocked by the shutter 5, the fluorescent plate 3 is rotated around the axis Q and removed from the electron beam passage.

Step K: Then, the shutter driving mechanism 12 opens the shutter 5 for the set exposure time t (shutter speed), the electron beam is exposed to the electron microscope image recording medium, and the shutter 5 is closed after the exposure is completed. Then, a series of shooting process is completed.

Here, in the case of continuously photographing electron microscope images, as shown in FIGS. 2 (a) and 2 (b), after completing the series of photographing steps, the steps J and K are repeated. That is, when the shutter 5 is closed after the exposure is completed, the electron beam is detected by the sensor 10 provided on the shutter, the exposure amount t1 of the electron beam necessary for the next photographing is calculated, and the driving mechanism is exposed. Time is set (process J). Then, the exposure time t1 set by the shutter drive mechanism 6 is set.
The shutter 5 is opened over and the electron beam is exposed to the electron microscope image recording medium.
Is closed and the shooting process is completed (process K).

By doing so, it is not necessary to insert and remove the fluorescent plate for each photographing to measure the electron beam current as in the conventional case, so that the entire photographing process can be extremely shortened.

The above-described embodiment is only one embodiment of the present invention, and the present invention can be modified and implemented. For example, by using a two-dimensional sensor as the sensor provided in the shutter in the above-described embodiment, while calculating the electron beam exposure time based on the detection signal of the two-dimensional sensor,
It is also possible to set the brightness based on the detection signal and display an electron microscope image on an image display device or the like.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the shutter is equipped with a sensor for detecting an electron beam and converting it into an electric signal, and the mounting position is the position when the electron beam is cut off. An electron beam irradiating position on the shutter, a calculating means for calculating an electron beam exposure time to the image recording medium based on a detection signal of the sensor, and a shutter opening based on an output signal of the calculating means. By providing a means for controlling the time, it is no longer necessary to insert and remove the fluorescent plate for each photographing to measure the electron beam current as in the conventional case,
The shooting process can be shortened. Therefore, it is possible to realize an imaging device in an electron microscope that can reduce electron beam damage to a sample in the imaging process.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the present invention, and FIGS. 2A and 2B are timings of opening and closing a fluorescent plate and opening and closing timings of a shutter in the apparatus according to an embodiment of the present invention. FIG. 3 is a diagram for explaining a conventional example, and FIGS. 4 (a) and 4 (b) are diagrams showing the opening / closing timing of the fluorescent plate 3 and the opening / closing timing of the shutter 5 in the conventional apparatus. 1: electron microscope housing 2: projection lens 3: electron microscope image observation fluorescent plate 4: electron microscope image recording medium 5: shutter 10: sensor 11: processor 12: drive mechanism

Claims (1)

[Scope of utility model registration request] 1. A fluorescent plate for projecting an electron microscope image,
A photographing device in an electron microscope equipped with a shutter that is removably arranged in the electron beam passage near the crossover point of the projection lens, and an electron microscope image recording medium arranged below the fluorescent plate for recording the electron microscope. In the above, a sensor for detecting an electron beam and converting it into an electric signal is attached to the shutter, and the attachment position is an electron beam irradiation position to the shutter at the time of blocking the electron beam. A photographing means for an electron microscope, which is provided with a calculating means for calculating an electron beam exposure time to the image recording medium based on the above, and a means for controlling an opening time of the shutter based on an output signal of the calculating means. apparatus.