JPH10148235A - Vibration preventing device for microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a vibration preventing device for a microscope whereby an influence due to a noise can be prevented. SOLUTION: In an acoustic signal detected by a microphone 4, after amplified by an amplifier 5, only a signal of specific frequency is supplied to a control circuit 7 by a filter circuit 6. In the control circuit 7, a signal of reverse phase to the supplied signal is generated, the signal of this reverse phase is supplied to a speaker 9 through an amplifier 8. The speaker 9, based on a supplied acoustic signal, generates a sound. This acoustic wave is directed toward a sample chamber 2 or a part of a mirror cylinder 3 of a scanning electron microscope main unit approaching the microphone 4. As a result, in the sample chamber 2 and the mirror cylinder 3, a noise is transmitted to generate vibration, but by supplying an acoustic wave of reverse phase to this noise, in a part of the sample chamber 2 and the mirror cylinder 3, two kinds of sounds are negated each other, vibration by the sound of the sample chamber 2 and the mirror cylinder 3 is remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing vibration of a microscope such as a transmission electron microscope or a scanning electron microscope, which prevents the influence of vibration due to sound.

[0002]

2. Description of the Related Art In a transmission electron microscope or a scanning electron microscope,
As the resolution increases, it has become important to reduce the blurring of the image due to external vibration. For this reason, for example, seismic isolation technology that absorbs mechanical vibration from the floor on which the electron microscope is installed, or vibration that detects this vibration and cancels the vibration positively is applied to the main body of the electron microscope. Active control devices have been developed to eliminate the effects of turbidity.

[0003]

In addition to the above-mentioned mechanical vibration, transmission electron microscopes and scanning electron microscopes also generate vibrations due to noise, which affects the image and hinders high-resolution image observation. ing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to realize a vibration preventing device for a microscope which can prevent the influence of noise.

[0005]

According to a first aspect of the present invention, there is provided an apparatus for preventing vibration of a microscope, comprising: a microscope for observing a high-resolution sample image; A circuit for generating a signal having an opposite phase to the acoustic signal, and a speaker to which the signal having the opposite phase is supplied from the circuit, wherein a sound wave from the speaker cancels a sound at a predetermined position of the microscope main body. It is characterized by having comprised.

According to the first aspect of the present invention, a microphone is arranged close to a position where vibration is prevented, and a signal having an opposite phase to an acoustic signal from the microphone is supplied to a speaker. Cancels the sound at the predetermined position.

The vibration preventing device according to the second aspect of the present invention
The invention according to claim 1 is characterized in that a plurality of combinations of microphones and speakers are provided. According to a third aspect of the present invention, in the first and second aspects, an acoustic signal of a specific frequency band is supplied to a speaker.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a scanning electron microscope to which the present invention is applied. In the figure, reference numeral 1 denotes a support for a scanning electron microscope. A sample chamber 2 is provided on the support 1, and further thereon, an electron gun, a focusing lens and an objective lens for focusing an electron beam generated from the electron gun, and an electron beam two-dimensionally on the sample. A lens barrel 3 including a scanning coil and the like for scanning is provided.

A microphone 4 is provided on the support 1. The microphone 4 detects sound, and the detected signal is supplied to the filter circuit 6 after being amplified by the amplifier 5. The filter circuit 6 passes a signal in a specific frequency band and supplies the signal to the control circuit 7.

The control circuit 7 creates a signal having a phase opposite to that of the supplied signal. The signal of the opposite phase from the control circuit 7 is amplified by the amplifier 8 and then supplied to a speaker 9 arranged at a predetermined distance from the main body of the scanning electron microscope. The operation of such a configuration will now be described.

A sample is placed in a sample chamber 2 of the main body of the scanning electron microscope, an electron beam is narrowly focused from a lens barrel 3 and irradiated onto the sample, and the electron beam is scanned in a desired two-dimensional area of the sample. Generated by irradiation of the sample with an electron beam,
For example, secondary electrons are detected, and a scanning image of the sample can be observed by supplying a detection signal to a cathode ray tube (not shown).

Here, various noises enter the room where the main body of the scanning electron microscope is installed. This noise is detected by the microphone 4. The detected sound signal is amplified by an amplifier 5 and then filtered by a filter circuit 6.
As a result, only a signal of a specific frequency is supplied to the control circuit 7. The control circuit 7 generates a signal having the opposite phase to the supplied signal, and the signal having the opposite phase is supplied to the speaker 9 via the amplifier 8.
Supplied to

The speaker 9 generates a sound based on the supplied sound signal. This sound wave is directed to the sample chamber 2 or the lens barrel 3 of the main body of the scanning electron microscope which approaches the microphone 4. As a result, the noise is transmitted to the sample chamber 2 and the lens barrel 3 to vibrate, but a sound wave having a phase opposite to that of the noise is supplied.
The seed sounds cancel each other, and the vibration caused by the sounds of the sample chamber 2 and the lens barrel 3 is significantly reduced. In addition, even if there is an excess or deficiency in the volume from the speaker, the control circuit 7 operates to cancel the sound when the sound is detected by the microphone, so that the sound can be eliminated very effectively. Therefore, the image on the cathode ray tube is maintained at a high resolution.

It is desirable that the position where the sound is canceled be not the position of the microphone 4 but the position of the sample chamber 2 or the lens barrel 3 slightly away from the microphone 4. Therefore, when generating a signal having an opposite phase in the control circuit 7 so that the sound is canceled at the positions of the sample chamber 2 and the lens barrel 3, the signal is not completely in opposite phase but slightly shifted in phase, It is necessary to adjust the volume of the sound by the amplifier 8.

With respect to this point, for example, 30
For a sound of 0 Hz, the wavelength becomes a little over 1 m, and at a place about 50 cm away from the position of the microphone 4, the sound pressure increases, which has the opposite effect. As a result, 20
Within cm, the sound canceling effect is sufficient. Of course, the lower the frequency of the sound, the wider the effective range of silencing.

Further, in another type of scanning electron microscope, 2
It is assumed that the sound is particularly easily vibrated by sound in a frequency band of 00 to 300 Hz. In that case, it is desirable that the filter circuit 6 selects an acoustic signal in a band of 200 to 300 Hz. It is desirable that the filter circuit 6 be capable of passing an acoustic signal in an arbitrary band or a plurality of bands.

FIG. 2 shows another embodiment of the present invention. In the configuration of FIG. 2, the same parts as those of the configuration of FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. 2, a plurality of microphones 4a to 4c are provided at different positions around the sample chamber 2 and the lens barrel 3. The acoustic signals detected by the microphones 4a to 4c are amplified by amplifiers 5a to 5c, respectively, and
Through the control devices 7a to 7c.

The audio signals whose phases are reversed by the controllers 7a to 7c are amplified by the amplifiers 8a to 8c and supplied to the speakers 9a to 9c. Each speaker 9a
9c generate sound waves in order to remove vibrations caused by sounds at different positions in the sample chamber 2 and the lens barrel 3, respectively.

An embodiment of the present invention has been described above.
The present invention is not limited to this mode. For example,
Although the scanning electron microscope has been described as an example, the present invention can be applied to an apparatus for observing a high-resolution image such as a transmission electron microscope or a tunnel microscope. Further, the operation of canceling the sound may not be performed continuously, and for example, the effect of the sound may be removed by a microphone and a speaker only at the time of capturing an image.

[0020]

According to the first aspect of the present invention, a microphone is arranged close to a position where vibration is prevented, and a signal having an opposite phase to an acoustic signal from the microphone is supplied to a speaker.
The sound at the predetermined position of the microscope main body is canceled by the sound wave from the speaker. As a result, the microscope is prevented from vibrating due to noise, and high-resolution image observation becomes possible.

According to the second aspect of the invention, since a plurality of combinations of the microphone and the speaker are provided in the first aspect of the invention, it is possible to more precisely eliminate the influence of sound.
According to the third aspect of the present invention, in the first and second aspects of the present invention, the audio signal in the specific frequency band is configured to be supplied to the speaker. No discomfort to the operator of the microscope.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a scanning electron microscope using an apparatus according to the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support body 2 Sample chamber 3 Lens tube 4 Microphone 5 Amplifier 6 Filter circuit 7 Control circuit 8 Amplifier 9 Speaker

Claims (3)

[Claims] In a microscope for observing a high-resolution sample image, a microphone is arranged at a position close to a microscope main body, a circuit for generating a signal having an opposite phase of an acoustic signal from the microphone, and an inverse signal from the circuit. A vibration prevention device for a microscope, comprising: a speaker to which a signal of a phase is supplied; and a sound wave from the speaker cancels a sound at a predetermined position of the microscope main body. 2. The apparatus according to claim 1, wherein a plurality of combinations of microphones and speakers are provided. 3. The apparatus according to claim 1, wherein an acoustic signal in a specific frequency band is supplied to a speaker.