JP3217514B2 - Micro vibration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly sensitive microvibration detecting device using a superconductor.

[0002]

2. Description of the Related Art In a conventional micro-vibration detecting apparatus, as shown in FIG. 13, a cantilever is formed using a silicon substrate 131, and a weight 132 is provided at the tip of the cantilever and an electrode ( A typical example is an acceleration sensor to which an unillustrated sensor is attached. When the acceleration sensor receives the acceleration α in the z direction, a force of F = mα is applied to the weight 132 (the mass is m) at the tip of the cantilever, and the bending portion 133 is bent.

As a result, the flexure 133 is formed by the piezoresistive effect of the stress T generated in the flexure 133.
The micro vibration is detected by measuring the resistance change with an electrode (not shown) attached to the flexure. The amount of change in the resistance is proportional to the stress T as represented by the following equation.

| Δρ | = ρ | π || T | ρ: resistivity in the absence of strain Δρ: change in resistivity due to stress π: piezoresistive coefficient Since semiconductor processing technology can be used, the sensitivity can be improved by improving the processing accuracy of the sensor, reducing the size of the sensor, or devising the shape of the bent portion.

[0005]

The above-mentioned conventional microvibration detecting apparatus has the following problems since it utilizes the deflection of a cantilever. For example, the sensitivity of micro vibration detection,
To increase accuracy, reduce the thickness of the flexure,
The mass of the weight may be increased, but in this case, the mechanical strength of the bent portion is reduced. In addition, there is a possibility that the bent portion may be deformed even if the body is moved not only in the z direction, which is the measurement direction of the acceleration, but also in the y direction or the torsion direction.

For this reason, the resistance generated by deflection other than in the z direction is also measured, and the resolution of acceleration in the z direction is reduced. In the case of an accelerometer using a cantilever beam, it is possible to measure the speed in one-dimensional direction, but when measuring in two-dimensional and three-dimensional directions, two or three sensors must be used. Needs to be corrected. In addition, there are non-linear and temporal changes in the piezoresistive effect.

An object of the present invention is to provide a microvibration detecting device which has high mechanical reliability, can distinguish between torsion and bending, that is, can detect three-dimensional behavior, has excellent linearity, and has little change over time. It is in.

[0008]

A first minute vibration detecting device according to the present invention comprises a superconductor, a magnetic circuit for generating a magnetic field for levitating the superconductor by the Meissner effect, and an electromagnetic wave irradiation source. A detector for detecting a change in the position of the superconductor which floats using the electromagnetic waves of the electromagnetic wave irradiation source, wherein the detector for detecting the change in the position is a superconducting device using a Josephson junction. A sensor for cooling the superconductor and the superconducting sensor together, wherein the position detection of the levitated superconductor reflects the electromagnetic wave of the electromagnetic wave irradiation source from the superconductor. Alternatively, the detection is performed by detecting the projected electromagnetic wave with the superconducting sensor.

[0009] The superconducting sensor may be one in which superconducting line sensors having different normal resistance values of the respective Josephson junctions of the Josephson junction series array are arranged one-dimensionally or two-dimensionally. .

The detection of the position of the levitated superconductor is based on the fact that the superconductor is irradiated with electromagnetic waves in one, two or three directions.
Two or three dimensional detection can be performed.

The superconductor may be, for example, a sphere, a plate, a rod, a processed material thereof, a structure in which the superconductor is dispersed, or a material obtained by processing the superconductor into a sphere, plate, rod, or the like. A structure with a superconductor attached to the surface or inside.

A second microvibration detecting apparatus according to the present invention comprises a superconductor, a magnet levitated by the Meissner effect of the superconductor, an electromagnetic wave irradiation source, and a change in position of the levitated magnet, which is detected by the electromagnetic wave irradiation source. In a microvibration detection device having a detector that detects using electromagnetic waves, the detector that detects the position change is a superconducting sensor using a Josephson junction, and both the superconductor and the superconducting sensor are used. A cooling device for cooling is provided, and the position detection of the magnet that has floated is performed by detecting the electromagnetic wave reflected or projected from the magnet of the electromagnetic wave of the electromagnetic wave irradiation source by the superconducting sensor. Features.

[0013] The superconducting sensor may be a one-dimensional or two-dimensional superconducting line sensor in which the normal resistance of each Josephson junction in the Josephson junction series array has a different value. .

The detection of the position of the levitated magnet is performed by irradiating the magnet with electromagnetic waves in one, two, or three directions, so that one-, two-, or three-dimensional detection is performed. be able to.

A first microvibration detecting apparatus according to a related invention has a superconductor and a magnetic circuit for generating a magnetic field for levitating the superconductor by the Meissner effect. A micro-vibration detection device that detects an optical position of a light source that emits coherent and uniform-wavelength light; a reflector provided on the superconductor; a reference reflector provided on the magnetic circuit; An optical system that irradiates the plate and the reference reflector with light from the light source, and an optical system that effectively modulates one of the frequencies of the reflected light from the reflector and the reference reflector in the spatial direction, Imaging means for imaging an interference pattern between modulated light and unmodulated light, and processing means for processing an output of the imaging means and converting the output into a signal indicating an optical position of the superconductor. I do.

A second microvibration detecting apparatus according to a related invention has a superconductor and a magnet levitated by the Meissner effect of the superconductor, and detects a micro-vibration of the levitated magnet. In the device, a light source that emits coherent and uniform-wavelength light, a reflector provided on the magnet, a reference reflector provided on the superconductor, and the reflector and the reference reflector are each provided from the light source. An optical system that irradiates the light, an optical system that effectively modulates one of the frequencies of the reflected light from the reflection plate and the reference reflection plate in the spatial direction, and the modulated light and the unmodulated light. An image pickup means for picking up an image of the interference pattern, and a processing means for processing the output of the image pickup means and converting it into a signal indicating the optical position of the magnet.

A third microvibration detecting apparatus according to the related invention has a superconductor and a magnetic circuit for generating a magnetic field for levitating the superconductor by the Meissner effect. A micro-vibration detection device that detects the optical position of a light source that emits coherent and uniform-wavelength light, a reflector provided on the superconductor, a reference reflector provided on the magnetic circuit, and the light source An optical system for modulating the frequency of light from the optical system, an optical system for irradiating the modulated light and the unmodulated light to the reflector and the reference reflector, respectively, and a first and a second for detecting the intensity of the incident light. A light intensity sensing means, an optical system for causing the modulated light and the unmodulated light to enter the first light intensity sensing means and cause the light to interfere with the first light intensity sensing means, and the reflected light from the reflection plate and the reference reflection plate. Second light intensity An optical system which enters the sensing means and interferes with these lights, and outputs of the first and second light intensity sensing means are changed to a light intensity distribution and converted into a signal indicating a change in the position of the superconductor. And processing means.

According to a fourth aspect of the present invention, there is provided a microvibration detecting apparatus having a superconductor and a magnet floating by the Meissner effect of the superconductor, and detecting an optical position of the floating magnet. In the device, a light source that emits coherent and uniform-wavelength light, a reflector provided on the magnet, a reference reflector provided on the superconductor, and an optical system that modulates the frequency of light from the light source An optical system for irradiating the modulated light and the unmodulated light to the reflector and the reference reflector, first and second light intensity sensing means for detecting the intensity of the incident light, An optical system for causing light and non-modulated light to enter the first light intensity sensing means and causing the light to interfere with each other; and reflecting light from the reflection plate and the reference reflection plate to the second light intensity sensing means. Dry these lights An optical system for the output of the first and second light intensity sensing means to change the intensity distribution of the light, and having a processing means for converting a signal indicating the position change of the superconductor.

A first microvibration control apparatus according to the related invention has a superconductor and a magnetic circuit capable of controlling the magnetic force for generating a magnetic field for levitating the superconductor by the Meissner effect. And a micro-vibration control device that controls micro-vibration of the superconductor that floats, a light source that emits coherent, uniform-wavelength light, a reflector provided on the superconductor, and a magnetic circuit provided on the magnetic circuit. A reference reflector, an optical system for irradiating the reflector and the reference reflector with light from the light source, respectively, and effectively changing one frequency of the reflected light from the reflector and the reference reflector in the spatial direction. An optical system for modulating, an imaging unit for imaging an interference pattern between the modulated light and the unmodulated light, a processing unit for processing an output of the imaging unit, and converting the output to a signal indicating a position of the superconductor; , The processing Based on the output of the stage, and having a control means for controlling the magnetic force of the magnetic circuit.

A second microvibration control apparatus according to the related invention has a superconductor and a magnetic circuit capable of controlling the magnetic force for generating a magnetic field for levitating the superconductor by the Meissner effect. Then, in the micro-vibration control device for detecting the optical position of the floating superconductor, a light source that emits coherent and uniform-wavelength light, a reflector provided on the superconductor, and the magnetic circuit are provided. A reference reflector, an optical system that modulates the frequency of light from the light source, an optical system that irradiates the reflector and the reference reflector with modulated and unmodulated light, and detects the intensity of incident light. First and second light intensity sensing means, an optical system for causing the modulated light and the unmodulated light to enter the first light intensity sensing means and causing the light to interfere with the first and second light intensity sensing means, A reflector An optical system for causing interference of these light and the reflected light is incident on the second light intensity sensitive means, change the output of the first and second light intensity perceived means to the intensity distribution of the light,
It is characterized by comprising processing means for converting a signal indicating a change in the position of the superconductor, and control means for controlling a magnetic force of the magnetic circuit based on an output of the processing means.

[0021]

In the first and second minute vibration detecting devices of the present invention, when a relative vibration is generated between the magnetic circuit (or the superconductor) and the superconductor (or the magnet) which is a floating body, the Meissner effect is generated. Accordingly, the relative position between the magnetic circuit (or the superconductor) floating on the center line of the magnetic circuit or the superconductor changes due to the minute vibration. This relative position change is detected by a superconducting sensor as a detector.

By disposing the electromagnetic wave source and the detector in a two-dimensional or three-dimensional direction, it is possible to detect a two-dimensional or three-dimensional displacement. further,
In the first and second minute vibration detecting devices of the present invention, not only the electromagnetic wave from the electromagnetic wave generation source is irradiated to the floating body floating by the Meissner effect, and the position change is detected by the projected wave, but also the electromagnetic wave is detected. Change the position of the detector to detect,
The position change can also be detected by the reflected wave.

As described above, the first and second minute vibration detecting devices of the present invention do not use the conventional mechanical strain of a semiconductor, but use a superconductor and its Meissner effect to perform one-dimensional detection. This is such that minute vibrations in three-dimensional directions can be accurately detected.

Further, in the present invention and related inventions, in order to utilize the Meissner effect of the superconductor, it is necessary to cool a part or the whole of the device to a temperature lower than the critical temperature of the superconductor. The critical temperature of superconductors is about
It is 130K, and even if this material is used, the part of the detector for electromagnetic waves (for example, visible light) is often lower than about 80K. If a normal optical sensor is used in this temperature range, problems such as reduced sensitivity and reduced operation speed may occur depending on the sensor, so the detector section and the superconductor part that floated are thermally separated. There is a need.

In the first and second minute vibration detecting devices of the present invention, in order to detect the minute vibration with high accuracy without performing such thermal separation, the detector also uses a superconductor sensor. Things. One such superconducting sensor
The moving direction and the size of the levitation body can be known by arranging them in two or two dimensions and measuring the output from each superconducting sensor.

On the other hand, in the first to fourth minute vibration detecting devices according to the related invention, the optical position of the superconductor (or magnetic circuit) as a floating body is accurately controlled to the wavelength of light or less by utilizing the interference of light. Can be detected. The first and second minute vibration control devices of the related invention control the minute vibration of the floating body by controlling the magnetic force of the magnetic circuit based on the detected optical position.

[0027]

Next, an embodiment of the present invention and a reference example of a related invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the microvibration detecting device of the present invention, and FIG. 2 is a schematic explanatory view showing a superconducting sensor of the present embodiment.

In FIG. 1, the magnetic circuit 11 is composed of Sm-Co
The magnet is formed into a ring shape having an outer diameter of 2 cm and an inner diameter of 0.6 cm, and is fixedly installed on a table (not shown).
The superconductor 12 is an oxide superconductor (Y ₁ Ba ₂ Cu ₃ O _7-x superconductor) processed into a spherical shape having a diameter of 0.4 cm, and has a critical temperature of about 90K. The superconductor 12 floats in the air where the magnetic field of the magnetic circuit 11 is formed in a non-contact manner due to the Meissner effect, and blocks irradiated light.

The light source 13 used as a source of electromagnetic waves (light) is composed of a laser diode. The cylindrical lens 14 corrects the shape of the light from the light source 13 from a circle to a linear shape, and irradiates the superconductor 12 floating by the Meissner effect. The superconducting sensor 15 is a detector for detecting light not blocked by the superconductor 12, and has Josephson junctions arranged at intervals of 10 μm.

The magnetic circuit 11, the superconductor 12, and the superconductor sensor 15 are cooled as a cooling portion 16 to a temperature not higher than the critical temperature of the superconductor 12 by a cooling device (not shown). The magnetic circuit 11, the light source 13, the cylindrical lens, and the superconducting sensor 15 are fixed by the same structure so that their relative positions do not change.

The superconducting sensor 15 used in this embodiment is shown below. That is, this superconducting sensor 15 is a superconducting line sensor in which Josephson junctions are connected in series and one-dimensionally or two-dimensionally arranged (in this embodiment, the x direction in FIG. 1). The normal resistance values of the sections have different values.

In FIG. 2, the superconducting sensor 15 includes Josephson junctions 21 to 25, a load resistor R, and a DC voltage source E.
(For simplicity, five Josephson junctions are shown here). At this time, the normal resistance of each of the Josephson junctions 21 to 25 is r, 2r,
Set to 4r, 8r, 16r (Ω).

When no electromagnetic wave is incident, there is no resistance in each of the Josephson junctions 21 to 25. However, when an electromagnetic wave is incident, for example, if it is incident on the portion of the Josephson junction 21, rΩ, Josephson junction If the light is incident on two places of the parts 23 and 24, a resistance of 4r + 8r = 12r (Ω) is generated.
By utilizing this fact, it is possible to uniquely determine which of the Josephson junctions in the array the electromagnetic wave has entered by measuring the voltage across the Josephson junction array.

That is, when electromagnetic waves are incident on the Josephson junctions 21 and 24, V = E (r + 8r) / (R + (r + 8R)) = (E · 9r) / (R + 9r), and R >> r If set, V = 9rE / R.
Since there is no coefficient "9" other than the combination of the Josephson junctions 21, 24, the Josephson junctions 21, 24
It can be seen that the electromagnetic wave has entered.

In general, a superconducting sensor can obtain high sensitivity at a short wavelength. Also, as means for setting the normal resistance value of the Josephson junction to a different value, for example, when employing a weak coupling type Josephson junction, a method of changing the width of the weak coupling portion, providing a gate at the weak coupling portion There are a method of applying a voltage to the gate and a method of injecting quasiparticles into the gate. In any case, this can be realized by accurately forming the shape of the weakly coupled portion, but this may be performed by a normal patterning technique such as photolithography. Further, in the normal case, the process of the sensor according to the present embodiment is simpler when a weakly coupled Josephson junction is used to fabricate the sensor, but a point contact or a tunnel junction may be used.

Next, the operation of this embodiment will be described with reference to FIG.

When the cooling part 16 is cooled to about 77 K or less, the superconductor 12 floats as shown in FIG. 1 due to the Meissner effect. The light from the light source 13 is applied to the superconductor 12.
7 is linearly deformed by a cylindrical lens 14 to irradiate the light downward.

In the absence of vibration, a portion of the light 17 is reflected by the superconductor 12 and does not reach the superconducting sensor 15, but the unreflected light 17 is detected by the superconducting sensor 15. In the superconducting sensor 15, an optical sensor including a plurality of Josephson junctions is arranged in the x direction.
When the superconductor 12 moves in the direction, the movement can be detected by the light 17 not reflected by the superconductor 12.

When a vibration is generated, the magnetic circuit 11 is displaced by the vibration, but the position of the superconductor 12 is not changed immediately after the vibration is generated due to inertia. This means that the relative position between the superconductor 12 and the magnetic circuit 11 changes due to vibration.
Vibration can be detected by the position change of 7. The amplitude of the vibration that can be detected is determined by the interval between the Josephson junctions arranged in the superconducting sensor 15. In the present embodiment, a line sensor having the Josephson junctions arranged at an interval of 10 μm was used. Can be detected.

Next, a second embodiment of the present invention will be described.

In FIG. 1, a light source 13 is a halogen lamp, and light from the halogen lamp is converted into parallel rays by an optical system using a glass lens instead of the cylindrical lens 4. Furthermore, the superconducting sensor 15 is two-dimensional (x, y directions)
Array. With such a configuration, a minute vibration in the two-dimensional direction, that is, the xy direction can be detected. Also,
Instead of the halogen lamp and the optical system, a gun oscillator that can emit parallel millimeter waves having a wavelength of about 0.5 mm may be used.

Next, a first reference example of the related invention will be described.

FIG. 3 shows a first embodiment of a micro-vibration detecting apparatus according to the present invention.
It is a block diagram of a reference example. In this embodiment, the superconductor 32 is fixedly installed on a table (not shown) or the like, and the magnet 31 floats. The magnet 31 is formed by processing an Sm-Co magnet having an outer diameter of 10 mm and a thickness of 1 mm into a ring shape having a cylindrical hole of 0.5 mm at the center thereof. The superconductor 32 is an oxide superconductor of the same material as the superconductor 12 of the first embodiment, and has an outer diameter of 15 m.
m, the inner diameter was 5 mm, and the thickness was 1 mm.

The superconductor 32 and the superconductor sensor 35 are cooled by a cooling device (not shown). The cooling temperature may be lower than the critical temperature of the superconductor 32 and the superconducting sensor 35 of about 90K, but is preferably lowered to about 70K.

The superconducting sensor 35 has a 2 × 2 mm Josephson junction array two-dimensionally arranged. The interval between the Josephson junctions is about 1 μm. Irradiated from light source 133 through lens 34,
By moving the light 37 passing through the center hole of the magnet 31 on the superconducting sensor 35, a minute change can be detected as in the second embodiment.

Next, a second reference example of the related invention will be described.

FIG. 4 shows a second embodiment of the micro-vibration detecting device of the related invention.
It is a block diagram of a reference example.

In FIG. 4, the magnetic circuit 41 is equivalent to the magnetic circuit 11 of FIG. Superconductor 42 is 3m in diameter
m, 1 mm thick disk-shaped, the same material as the superconductor 12 of the first embodiment, but a 0.1 mm thick Al thin plate is attached on the upper surface as a light reflecting plate. .

The superconducting sensor 45 is a two-dimensional optical sensor. Light source 43, cylindrical lens 44
A light source 43a, a cylindrical lens 44a, and a superconducting sensor 45a, which are equivalent optical systems, are provided on the upper side (z direction side) of the superconducting sensor 45 and the superconducting sensor 45a.
2 are arranged so as to face one point on the upper surface.

Further, although omitted in FIG. 4, the light source 43, the cylindrical lens 44 and the superconducting sensor
The same optical system as in 45 is also arranged perpendicular to the plane of the paper. By cooling the superconductor 42 and the superconductor sensors 45 and 45a in the same manner as in the first embodiment, the superconductor 42 is cooled.
Emerges due to the Meissner effect.

Light source 43, cylindrical lens 44
And the superconducting sensor 45 detects the displacement in the z and y directions, the z and x directions are detected by the optical system arranged perpendicular to the plane of the drawing, and the light source 43a, the cylindrical lens 44a and the superconducting sensor 45a Conductor 4
2 is detected from the horizontal direction (xy plane). By comprehensively analyzing the detection data from each optical system, 3
Micro vibrations in the dimensional direction can be detected simultaneously.

Next, a third reference example of the related invention will be described.

FIG. 5 shows a third embodiment of the micro-vibration detecting device according to the present invention.
It is a block diagram of a reference example.

In this embodiment, the superconductor 52 levitated by the magnetic circuit 51 is a rectangular parallelepiped of 1.2 × 1.2 × 1.0 mm.
A pore of 100 μm is opened at the center of each surface. The pores may be processed by any method. For example, the pores can be formed by a method such as ion milling in which an argon ion laser beam is incident from an opposite surface to perform processing.

Each of the three light sources 53 and the cylindrical lens 54 (only two of them are shown in FIG. 5) has x, y, z
The superconductor 53 is irradiated with light 57 from three directions, and three corresponding superconducting sensors 55 (only two are shown in FIG. 5)
As a result, as in the second reference example, a minute vibration in a three-dimensional direction can be measured. In FIG. 5, the optical system in the direction perpendicular to the paper is omitted.

In the present embodiment, the light-passing pores are not perfectly cylindrical but conical, so that the stray light reflected by the conical surface blurs the light image on the superconducting sensor 55. there is a possibility. Therefore, the transmitted light is corrected into a parallel light by the optical system 54b. Further, since the beam can be enlarged by 100 times by the optical system 54b, the resolution of the vibration amplitude is improved from 2 μm which is the resolution of the superconducting sensor 55, and a minute vibration of 0.02 μm can be detected.

In the first and second embodiments of the present invention and the first to third reference examples of the related invention, Y ₁ Ba ₂ Cu ₃ O _7-x is used as the superconductor. However, the present invention is not limited to this. Metals such as Nb, alloy superconductors such as Nb ₃ Ti, Bi-Sr-Ca-Cu-O, and Tl-Sr-Ca-
Any material that exhibits superconductivity, such as a Cu—O-based oxide superconductor, may be used. The shape and number of superconductors can be varied as needed. That is, these are determined by the relative relationship with the magnet (magnetic circuit), and the superconductor or the magnet may be arranged so as to float most easily by the Meissner effect.

In each of the embodiments and the reference examples, the shape of the magnetic circuit is a ring. However, the shape and the number are not particularly limited, and may be determined in consideration of the magnetic field gradient. The magnetic circuit is not particularly limited as long as the superconductor floats, such as a permanent magnet, an electromagnet, and a superconducting magnet. Further, the magnet is not limited to a permanent magnet such as Sm-Co, and it goes without saying that an electromagnet or a superconducting magnet can be used.

Any kind of light (electromagnetic wave) generation source may be used as long as it has straightness. Since a superconducting sensor using a Josephson junction is used, a source in the millimeter wave region such as a gun diode is also used. Available. That is, the wavelength of the electromagnetic wave is not particularly limited as long as it is shorter than the long wavelength limit determined by the critical temperature of the superconductor line sensor. For example, microwaves and X-rays can be used. Also,
The electromagnetic wave need not be a coherent wave, but is preferably as parallel as possible. Furthermore, the size of the superconducting sensor can be reduced by applying semiconductor processing technology, and its limits are the same as those of semiconductor microfabrication (note that magnetic circuits, superconductors, and light generation sources are notably limited). See Japanese Unexamined Patent Publication No. Hei 4-317716).

Next, a fourth reference example of the related invention will be described.

FIG. 6 shows a fourth embodiment of the minute vibration detecting apparatus according to the present invention.
FIG. 7 is a perspective view showing a superconductor 61 and a magnetic circuit 62 shown in FIG. 6, FIG. 8 is a perspective view showing a magnetic circuit 82 which is another embodiment of the magnetic circuit, and FIG. 4 (a), (b) are explanatory diagrams relating to optical signals obtained by the fourth reference example.
FIG. 9 is an explanatory diagram relating to an electric signal obtained by the fourth reference example.

As shown in FIGS. 6 and 7, the superconductor 6
1 has a plurality of sufficiently polished reflectors 63 at predetermined positions on its upper surface, and floats in the air without contact by the Meissner effect. The magnetic circuit 62 is provided with a plurality of reference reflectors 64 polished sufficiently at predetermined positions on the upper surface thereof, and is an electrically controllable electromagnet that generates a magnetic force for floating the superconductor 61.

The magnetic circuit 62 may be a permanent magnet that generates a strong magnetic field. However, since the magnetic circuit 62 serves as a reference for a minute vibration, it is fixed to a stable ground or floor without sufficient vibration. It is necessary that there is no change over time. Control circuit 75
Controls the power of the magnetic circuit 62.

The laser light source 65 generates a light beam having a sufficiently coherent and uniform wavelength. In the present embodiment, a helium-neon laser horizontally installed is used. In front of the laser light source 65 (in the direction in which light rays are emitted), above the reference reflector 64, a half mirror 66 inclined downward by 45 ° is installed.

Further in front of the half mirror 66, a reflection plate
Above 63, a mirror also tilted 45 ° down
70 are installed. Between the half mirror 66 and the reference reflector 64, a half mirror 67 that is inclined downward by 45 ° is installed similarly to the half mirror 66. Between the mirror 70 and the reflection plate 63, there is provided a half mirror 71 which is tilted downward at an angle different from the angle of 45 ° by a small angle α. The half mirrors 67 and 71 are installed at almost the same height.

An imaging lens 68 and an image pickup device 69 are provided on the right side of the half mirror 67 in the drawing (in the traveling direction of light reflected by the half mirror 67 from below). The imaging device 69 is connected to a signal processing device 73 via a preprocessing device 72, and the signal processing device 73 is connected to an arithmetic device 74. The arithmetic unit 74 is connected to the control unit 75.

The preprocessing device 72 performs image integration of the signal output from the imaging device 69, controls the level so that the average value becomes a set value, and removes unnecessary portions (edges) of the image. Perform pre-processing such as cutting and removing noise. The signal processing device 73 has a phase difference φ of the signal preprocessed by the preprocessing device 72 (see FIGS. 10A and 10B).
Is calculated, and a signal indicating a change in the position of the reflector 63, that is, the superconductor 61 is output to the arithmetic unit 74. Arithmetic unit 74
Converts the signal input from the signal processing device 73 into an appropriate physical quantity, for example, the amplitude and frequency of vibration.

The superconductor 61 has already undergone rough alignment with an accuracy of approximately one half of the wavelength of the light from the laser light source 65, and the relative position between the superconductor 61 and the magnetic circuit 62 has the above accuracy. The laser light source
Assume that no vibration has an amplitude greater than half the wavelength of the 65 light. For vibrations having an amplitude greater than half the wavelength of the light of the laser light source 65, such a situation is sufficiently common by using other means.

Next, vibration detection according to the fourth reference example will be described.

The light beam emitted from the laser light source 65 is
The light is split by the half mirror 66 into two lights. The light ray 66a whose direction has been changed by the half mirror 66 is reflected after being incident on a reference reflector 64 mounted on the magnetic circuit 62. The direction of the reflected light is changed by a half mirror 67, and after passing through an imaging lens 68, an imaging device 69 is formed.
Image. On the other hand, the light transmitted through the half mirror 66
70a is a superconductor 61
The light is reflected by the reflecting plate 63 of FIG.

The half mirror 71 is 45 °, that is, 2
The light beams 66a and 70a are inclined by a small angle α from the angle at which the wavefronts of the light beams become parallel. Therefore, the wavefronts of the light beams 66a and 70a intersect at a small angle α. Half mirror in this way
The light beam reflected by 71 passes through the imaging lens 68 and enters the imaging device 69.

Two light beams are generated due to the inclination of the small angle α.
When the spatial frequencies of 66a and 70a are effectively different, an interference pattern (striped pattern) is formed on the surface of the imaging device 69 as shown in FIG. When the optical position of the superconductor 61 changes, the stripe pattern moves in the direction of the arrow in FIG. 9 or in the opposite direction.

The optical signal obtained by the image pickup device 69 is transmitted to the signal processing device 73 as an electric signal via the preprocessing device 72. The obtained electric signal has a spatial distribution as shown in FIG. The wavelength λ of this spatial distribution is determined by the minute angle α. The phase difference φ in FIG. 10 (a) corresponds to the reference reflector 64 provided on the magnetic circuit 62 and the superconductor.
This is the difference in optical position between the reflector 61 and the reflector 63 provided on the surface of the lens 61 when viewed by the 2π method.

The signal processor 73 calculates the phase difference φ as a time series as needed. That is, as shown in FIG. 10 (b), the time change of the phase difference φ is observed as a time change of the superconductor 61, that is, a minute vibration. Signal processing device
The information of the minute vibration obtained in 73 is transmitted to the arithmetic unit 74, and the time series of the phase difference φ is converted into an appropriate physical quantity.

As shown in FIGS. 7 and 8, the superconductor 61,
By setting similar devices at four points of the magnetic circuit 62 and performing similar measurements, it is possible to know a change in the inclination of the superconductor 61 and the like. For the sake of simplicity, FIG. 6 does not show such redundant devices, but their settings and the like can be easily guessed. In this case, the arithmetic unit 74
Monitors the position information of each of the four points comprehensively and calculates information such as inclination.

Instead of the magnetic circuit 62 shown in FIG. 7, as shown in FIG. 8, a coil (not shown) is divided in the spatial direction to some extent, and is configured so that each can be controlled independently.
If 82 is used, the superconductor 61
Can be fed back to keep the super level. That is, as shown in FIG. 8, the magnetic circuit 82 is divided and controlled, and based on the information on the detected minute vibration, the magnetic intensity generated by each of the magnetic circuits 82 is controlled to generate or attenuate the vibration. Or can be controlled. In this case, the minute vibration can be freely controlled by giving feedback to the control device 75 based on the physical quantity obtained by the arithmetic device 74 and changing the current value of each of the magnetic circuits 82 by the control device 75.

The micro-vibration in this embodiment can be applied to a vibration having a very high frequency. That is,
The limit of the sufficiently high frequency of the minute vibration is substantially the same as the state without vibration, in other words, it corresponds to minute position detection or minute position alignment.

Next, a fifth reference example of the related invention will be described.

FIG. 11 is a schematic view of a main part of a fifth embodiment of the microvibration detecting apparatus of the related invention, and FIGS. 12 (a) and 12 (b) are explanatory diagrams relating to electric signals obtained by the fifth embodiment.

The fifth reference example is formed according to the heterodyne interferometry well known in the field of interferometric optical measurement (Mitsuo Takeda, Optics, Vol. 13, No. 1, pp. 55-65, Japan Optical Society (Applied Physics) Society), published February 1984). As shown in FIG. 11, the superconductor 111 has a plurality of sufficiently polished reflectors 113 at predetermined positions on the upper surface thereof, and floats in the air without contact by the Meissner effect.

The magnetic circuit 112 has a plurality of reference reflectors 114 which are polished sufficiently flat at predetermined positions on the upper surface thereof.
An electromagnet that can be electrically controlled to generate a magnetic force that causes the superconductor 111 to float. The magnetic circuit 111 may be a permanent magnet that generates a strong magnetic field.However, since the magnetic circuit 112 serves as a reference for minute vibration, it is necessary that the magnetic circuit 112 is fixed to a stable ground or floor that does not vibrate sufficiently. It is necessary that the change with time be sufficiently small. The superconductor 111 and the magnetic circuit 112 are the same as the superconductor 61 and the magnetic circuit 62 in FIG. The control circuit 131 controls the power of the magnetic circuit 112.

The laser light source 115 generates a light beam having a sufficiently coherent and uniform wavelength. In this embodiment, a horizontally installed helium neon laser is used. In front of laser light source 115 (light emission direction)
Above the reference reflector 114, a half mirror 116 tilted downward by 45 ° is provided.

Further in front of the half mirror 116 and above the reflection plate 113, a mirror 126 which is similarly inclined downward by 45 ° is provided. Between the half mirror 116 and the reference reflector 114, 4
A half mirror 119 tilted 5 ° downward is installed. Between the half mirror 116 and the half mirror 119, a half mirror 117 inclined upward by 45 ° opposite to the half mirror 119 is provided.

Between the mirror 126 and the reflecting plate 113,
As with the mirror 126, a half mirror 124 which is inclined downward by 45 ° is provided. Between the mirror 126 and the half mirror 124, a half mirror 123 inclined upward by 45 ° opposite to the half mirror 124 is provided.

Further, the mirror 126 and the half mirror 123
Between them, a minute frequency changing device 122 is provided.
As the minute frequency changing device 122, a device based on an ultrasonic Bragg cell method, a Zeeman effect method, or the like can be used (Mitsuo Takeda, Optics, Vol. 13, No. 1, pp. 55-65,
Optical Society of Japan (Japan Society of Applied Physics), published February 1984).

The half mirror 117 is installed at a slightly higher height than the half mirror 123. Half mirror 119
Is installed at a slightly lower height than the half mirror 124. Right side of the half mirrors 117 and 123 shown in the figure (the traveling direction of light reflected from the half mirrors 117 and 123 from above)
Is provided with a lens 125 and a light intensity sensing element 118. A lens 120 and a light intensity sensing element 121 are provided on the right side of the half mirrors 119 and 124 (in the direction in which the light reflected from the lower mirrors 119 and 124 travels from below).

The light intensity sensing elements 118 and 121 do not need to be image pickup elements, but may be any element such as a photodiode which can detect the light intensity on the light receiving surface. The light intensity sensing elements 118 and 121 are connected to a signal processing device 129 via preprocessing devices 127 and 128, respectively, and the signal processing device 129 is connected to an arithmetic device 130.

The arithmetic unit 130 is connected to the control unit 131. The pre-processing devices 127 and 128
Level control is performed so that the average value of the signals output from 8, 121 becomes a set value, and preprocessing such as noise removal is performed. The signal processing device 129 is used for the preprocessing device 12.
The phase difference φ of the signal preprocessed by
2 (a), (b)) and calculate the reflector 113, that is, the superconductor
A signal indicating the position change of 111 is output to the arithmetic unit 130. The arithmetic unit 130 converts the signal input from the signal processing unit 129 into an appropriate physical quantity, for example, the amplitude and frequency of vibration.

The superconductor 111 has already been roughly aligned with an accuracy of approximately one half of the wavelength of the light from the laser light source 115, and the relative positions of the superconductor 111 and the magnetic circuit 112 have the above accuracy. It is assumed that the vibration is defined by the range, and that there is no vibration having an amplitude of half or more of the wavelength of the light of the laser light source 115. For vibrations having an amplitude greater than half the wavelength of the light of laser light source 115, such a situation is sufficiently common by using other means.

Next, the vibration detection according to the fifth reference example will be described.

The light beam emitted from the laser light source 115 is split by the half mirror 116 into two light beams. The light beam whose direction has been changed by the half mirror 116 is further split into two by the half mirror 117, and one of the light beams passes through the half mirror 117 and is directly passed through the magnetic circuit 112.
The light enters the reference reflector 114 mounted on the upper side, and the other passes through the lens 125 as reference light and passes through the light intensity sensing element 118.
Incident on.

The light incident on the reference reflector 114 mounted on the magnetic circuit 112 is vertically reflected by the reference reflector 114, the direction is changed by the half mirror 119, and the direction is minutely changed again by the lens 120. Later, it enters the light intensity sensing element 121.

On the other hand, the light beam transmitted through the half mirror 116 is changed in direction by the mirror 126 and then the frequency is minutely changed by the minute frequency changing device 112.
The light beam whose frequency is minutely changed by the minute frequency changing device 112 is split into two by the half mirror 123, and the light beam whose direction is changed by the half mirror 123 is incident on the light intensity sensing element 118 through the lens 125 as reference light. I do.

On the surface of the light-intensity sensing element 118, the half-mirror 117 interferes with the light beam whose direction has been changed, and the interference fringes change with time (brighter or darker). The phase of this change is defined as a reference phase. The light intensity sensing element 118 outputs a beat signal having a period T.

On the other hand, the light beam that has passed through the half mirror 123 enters the reflector 113 attached to the superconductor 111, is reflected there, changes its direction by the half mirror 124, and changes its direction again by the lens 120. After being changed to a very small value, the light enters the light intensity sensing element 121. On the surface of the light intensity sensing element 101, the light from the half mirror 119 and the light from the half mirror 124 interfere with each other and change with time (becomes brighter or darker). The phase component of this temporal change incorporates information on the optical position between the reference reflector 114 provided on the magnetic circuit 112 and the reflector 113 provided on the surface of the superconductor 111.

The optical signals obtained by the light intensity sensing elements 118 and 121 are transmitted to the signal processing device 129 as electric signals through the preprocessing devices 127 and 128. In the obtained electric signal, as shown in FIG. 12A, the phase difference φ changes with time. This phase difference φ is the difference in the optical position between the reference reflector 114 provided on the magnetic circuit 112 and the reflector 113 provided on the surface of the superconductor 111 as seen by the 2π method.

The signal processor 129 calculates the phase difference φ as a time series as needed. That is, as shown in FIG. 12 (b), the superconductor 111
Is observed as a time change, that is, a minute vibration. The information of the minute vibration obtained in the signal processing device 129 is
130, and the time series of the phase difference φ is converted into an appropriate physical quantity.

In this embodiment, the resolution of the vibration is defined by the period T of the beat signal of the light intensity sensing element 118, which serves as a reference. Therefore, in this embodiment, signals with a resolution lower than this resolution cannot be detected. However, due to the high spatial resolution, which is a feature of the heterodyne method, highly sensitive measurement can be performed for a vibration component that is sufficiently slow with respect to the period T.

In the present embodiment, similar to the fourth embodiment, the same device is set at the four points of the superconductor 111 and the magnetic circuit 112, and the same measurement is performed to obtain the same.
Changes in the slope of the object. Also, if a magnetic circuit configured so that the coil is divided somewhat in the spatial direction and can be controlled independently of each other is used, feedback is applied to keep the superconductor 111 super-horizontal by controlling its power. This is also the same as in the fourth reference example.

[0101]

As described above, according to the present invention, by utilizing the Meissner effect of the superconductor, 1 to 3 can be obtained.
It has become possible to detect dimensional minute vibrations at the same time.
Further, in the present invention, since the superconductor or the magnet levitated by the Meissner effect does not come into contact with other parts constituting the detector, there is no performance deterioration due to mechanical fatigue.

Further, in order to optically detect vibration, x,
The detection resolution in the y and z directions is also extremely excellent. For example, a minute relative change can be easily detected by inserting a light expansion mechanism between the superconductor and the detector. In addition, the present invention does not require a non-linear element such as a piezo element, and thus has excellent linearity.

Further, according to the present invention, a minute vibration can be detected with an accuracy smaller than the wavelength of light. The direction of minute vibration can be sensed. For this reason, it is possible to control minute vibrations, which is impossible with the conventional technology.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of a microvibration detection device of the present invention.

FIG. 2 is a schematic explanatory view showing a superconducting sensor of the present embodiment.

FIG. 3 is a configuration diagram of a first reference example of a minute vibration detection device of a related invention.

FIG. 4 is a configuration diagram of a second reference example of the minute vibration detection device of the related invention.

FIG. 5 is a configuration diagram of a third reference example of the minute vibration detection device of the related invention.

FIG. 6 is a schematic diagram of a main part of a fourth reference example of the microvibration detection device of the related invention.

FIG. 7 is a perspective view showing a superconductor 61 and a magnetic circuit 62 of FIG. 6;

FIG. 8 is a perspective view showing a magnetic circuit 82 which is another embodiment of the magnetic circuit.

FIG. 9 is an explanatory diagram regarding an optical signal obtained by a fourth reference example of the related invention.

FIGS. 10 (a) and (b) are explanatory diagrams relating to electric signals obtained by a fourth embodiment of the related invention.

FIG. 11 is a schematic diagram of a main part of a fifth reference example of the microvibration detection device of the related invention.

FIGS. 12 (a) and 12 (b) are explanatory diagrams relating to electric signals obtained by a fifth embodiment of the related invention.

FIG. 13 is a perspective view showing a conventional example of a minute vibration detecting device.

[Explanation of symbols]

 11, 41, 51, 62, 112: Magnetic circuit 12, 32, 42, 52, 61, 111: Superconductor 13, 33, 43, 53: Light source 14, 44: Cylindrical lense 15, 35, 45, 55: Superconducting sensor 31: Magnet 34: Lens 65, 115: Laser light source 66, 67, 71, 116, 117, 119, 123, 124: Half mirror 70, 126: Mirror 68: Imaging lens 69: Imaging device 72 , 127, 128: Preprocessor 73, 129: Signal processor 74, 130: Arithmetic unit 75, 131: Controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01H 9/00 G01H 11/02 G01H 17/00 ZAA

Claims (7)

(57) [Claims] 1. A superconductor, a magnetic circuit for generating a magnetic field for levitating the superconductor by the Meissner effect,
An electromagnetic wave irradiation source, and a micro-vibration detection device having a detector that detects a change in the position of the superconductor that floats using the electromagnetic waves of the electromagnetic wave irradiation source, wherein the detector that detects the change in position uses a Josephson junction. A superconducting sensor using a cooling device for cooling both the superconductor and the superconducting sensor, and detecting the position of the superconductor that has floated, A micro-vibration detecting device, which is performed by detecting electromagnetic waves reflected or projected from a conductor with the superconducting sensor. 2. The superconducting sensor according to claim 1, wherein the superconducting line sensor is a one-dimensional or two-dimensional superconducting line sensor having a normal resistance value of each of the Josephson junctions in the Josephson junction series array.
2. The arrangement according to claim 1, wherein the arrangement is in a dimension.
The microvibration detection device according to the above. 3. The method according to claim 1, wherein the detecting of the position of the levitated superconductor is performed by irradiating the superconductor with an electromagnetic wave irradiated in one, two, or three directions. 3. The minute vibration detecting device according to 1 or 2. 4. The superconductor may be a sphere, a plate, a rod, a processed body thereof, a structure in which the superconductor is dispersed, or a substance obtained by processing the superconductor into a sphere, a plate, a rod, or the like. 4. The micro-vibration detecting device according to claim 1, wherein the micro-vibration detecting device is a structure having a superconductor attached to a surface or inside thereof. 5. A superconductor, a magnet levitated by the Meissner effect of the superconductor, an electromagnetic wave irradiation source, and a detector for detecting a change in position of the levitated magnet using the electromagnetic wave of the electromagnetic wave irradiation source. In the micro-vibration detection device having: a detector for detecting the position change is a superconducting sensor using a Josephson junction; and a cooling device for cooling both the superconductor and the superconducting sensor. The position detection of the floating magnet is performed by detecting the electromagnetic wave reflected or projected from the magnet by the electromagnetic wave of the electromagnetic wave irradiation source by the superconducting sensor. 6. The superconducting line sensor may be a one-dimensional or two-dimensional superconducting line sensor having a normal resistance value of each Josephson junction of the Josephson junction series array having a different value.
6. An array arranged in a dimension.
The microvibration detection device according to the above. 7. The method according to claim 5, wherein the detection of the position of the levitating magnet is based on the fact that the electromagnetic wave applied to the magnet is irradiated in one, two or three directions. Micro vibration detector.