JPH06233568A - Optical actuator - Google Patents

Abstract

PURPOSE:To provide an optical actuator wherein a very small object can be freely moved three-diemnsionally. CONSTITUTION:This actuator is composed of a body 7, to be driven, to which a magnetic body whose magnetization becomes large by a rise in a temperature is attached, a magnet which is arranged in a position capable of applying a magnetic field to the body 7, to be driven, floating in a liquid, a driving part which can move the magnet to an arbitrary position, a light source 17 which is used to heat the body 7 to be driven and an optical system 8 which guides light from the light source 17 to the body, to be driven, by the mechanism of a phase conjugate mirror 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field where it is necessary to remotely drive a minute object in a fluid, such as a medical device,
The present invention relates to an optical actuator applied to the fields of medication, therapy, robots, and electronic and optical devices that use electrical and optical switches that dislike wiring.

[0002]

2. Description of the Related Art Conventionally, various actuators have been proposed. First, an actuator that moves gas or liquid using thermal expansion or photoacoustic effect.Next, a magnetic body whose magnetization direction changes with temperature is used as a rotor, and a fixed magnet is used as a stator by changing the magnetization direction by light irradiation. It is a rotating optical actuator or the like.

[0003]

However, first, it is impossible for the actuator according to the first method to freely drive a solid driving body three-dimensionally. Also, with the optical actuator according to the second method, although a single operation of rotation by light irradiation is possible, it is impossible to operate in any direction by light.

Further, in the medical field, as a method of concentrating medication only on the affected area, magnetic ferrite is put in a capsule together with a drug to concentrate the magnetic field on the affected area. In this case, since the magnetic field is applied from the outside of the human body, it is impossible to apply the magnetic field only to a specific place inside the human body.

Further, a method of moving a micro object in a gas or a liquid in an arbitrary direction by the pressure of light (= light pressure) is already known. However, since the light pressure is very small, only trapping of minute polystyrene latex spheres of about 10 μm, which balances the buoyancy, has been successful.

[0006] As described above, a technique for freely moving an object on the order of mm in three dimensions has not existed in the past. In view of the above-mentioned problems of the conventional technique, the present invention provides an optical actuator that enables a minute object to freely move three-dimensionally.

[0007]

The solution of the above-mentioned problems can be achieved by adopting the novel characteristic constitutional means listed below in the present invention. That is, the first feature of the present invention is that the driven body is provided with a magnetic body whose magnetization increases as the temperature rises, and a magnet arranged at a position where a magnetic field can be applied to the driven body floating in a fluid. , A power unit that can move the magnet to an arbitrary position, a light source that emits light for irradiating the driven body, and an optical that guides the light from the light source to the driven body by a phase conjugate mirror mechanism. It is an optical actuator consisting of a system.

A second feature of the present invention is that the magnetic material according to the first feature is RhFe containing 48 to 54 at% of Rh.
The optical actuator is an alloy.

A third feature of the present invention is that the first or second
The magnet in the above feature is a permanent magnet or an electromagnet,
It is an optical actuator that can move back and forth in parallel with the driving direction of a driven body and can rotate about the driving direction of the driven body as an axis.

A fourth feature of the present invention is that the magnetic field in the first, second or third feature shows a uniaxial anisotropic distribution in a plane perpendicular to the driving direction of the driven body. It is an optical actuator.

A fifth feature of the present invention is that the first, second, and
The magnetic body according to the third or fourth feature is an optical actuator having a plate shape, a spheroid shape close to a plate shape, or an outer shape of a surface portion of the spheroid shape.

A sixth feature of the present invention is that the first, second, and
The magnetic body according to the third, fourth, or fifth characteristics is an optical actuator in which uniaxial magnetic anisotropy is imparted in which a direction parallel to the driving direction of the driven body is an easy axis of magnetization.

A seventh feature of the present invention is that the first, second, and
The fluid according to the third, fourth, fifth, or sixth characteristics is an optical actuator having a specific gravity equal to or higher than the specific gravity of the main material forming the driven body.

An eighth feature of the present invention is that the first, second, and
The light source in the third, fourth, fifth, sixth, or seventh feature is an optical actuator that is a pair of laser light sources that respectively emit heating light and position detection light having different wavelengths.

The ninth feature of the present invention is that the first, second, and
The optical system according to the third, seventh, or eighth characteristic is a phase conjugate mirror which emits phase conjugate light when position detection light is incident from both directions and straight reflected light of a driven body is incident, and the phase conjugate light. A half mirror that transmits and goes straight and reflects light into two of the straight reflected light and the refracted reflected light of the phase conjugate mirror and refracts and refracts the heating light, and only the phase conjugate light component wavelength of the refracted reflected light It is an optical actuator comprising a filter for filtering and a detector array for detecting an irradiation position of the refracted / reflected light transmitted through the filter and controlling rotation of the half mirror to follow the driven body.

[0016]

Since the present invention takes such means, the magnetization of the magnetic body is controlled by the heat of the light, and the phase conjugate mirror mechanism is used so that the light can be automatically tracked according to the movement of the magnetic body. Further, since the magnetic field and the light are moved in association with each other, it is possible to freely move the driven body on the order of mm in three dimensions.

That is, specifically, the magnetic material on the driven body is antiferromagnetic or has a small magnetization at room temperature, and in this state, there is almost no force attracted by the magnetic field. The magnetic material on the driven body is irradiated with light, and when the light is absorbed by the magnetic material, the temperature of the magnetic material rises and a magnetic phase transition occurs, so that the magnetization becomes ferromagnetic. As a result, the driven body is driven according to the magnetic field gradient. In this case, the driven body is basically in the liquid. However, it may be in a state of floating in the air like dust in the air.

Further, the optical system is controlled so that the light always strikes the driven body in the direction of the light along with the movement of the driven body. In this case, it is possible to monitor the reflected light from the driven body three-dimensionally and control the irradiation direction of the light so that the light is constantly irradiated to the object, but the optical system becomes complicated.

By using a phase conjugate mirror as a part of this optical system, the light automatically tracks the driven body, so that it is not necessary to use a complicated optical system. Rh as a magnetic material is 48
Since an RhFe alloy containing ~ 54 at% is used, this material exhibits a phase transition from antiferromagnetism to ferromagnetism at around 70 ° C.
Since the transition temperature is relatively low, it is easy to control.

By using a permanent magnet or an electromagnet as the magnet and having a mechanism for moving the magnet parallel to the driving direction of the driven body and a mechanism for rotating the magnet around the driving direction as an axis, it is possible to drive the fixed permanent magnet with light. Is possible, but this is to increase the degree of freedom of driving.

That is, since the moving direction is the direction of the maximum magnetic field gradient, the position of the magnet is controlled so as to form the maximum magnetic field gradient in the desired direction. Further, in order to stop at a specific place, it is necessary to oscillate the magnetic field in an alternating current, and for that purpose an electromagnet is required. If the natural vibration amplitude of the driven body in a system is sufficiently smaller than the size of the driven body, the driven body will appear to be stationary.

The distribution of the magnetic field has a uniaxial anisotropic distribution in the plane perpendicular to the driving direction, and the shape of the magnetic body is plate-like.
Alternatively, it is a spheroid close to a plate. Unless the plate-shaped magnetic body has perpendicular magnetic anisotropy, the diamagnetic field coefficient in the direction perpendicular to the plate is large, so that the magnetization cannot stand up in the plane of the plate. In addition, when the magnetic body is placed in a magnetic field, the magnetization is aligned along the lines of magnetic force in order to reduce the magnetic energy.

As a result, since the plate surface of the plate-shaped magnetic body is parallel to the uniform magnetic flux surface, the positional relationship between the magnetic body surface and the magnetic field is determined.
Therefore, by fixing the positional relationship between the magnet and the optical system and moving them together, the light receiving surface of the driven body can be always directed toward the optical system.

Further, the driven body may be formed into a spheroid, and the periphery thereof may be covered with a plate-shaped (or thin-film) magnetic body in a skin form. As a result, even if the driven body freely rotates in the liquid, the reflection of light is almost in the incident direction.

Uniaxial magnetic anisotropy is given to the magnetic body attached to the driven body, with the easy axis of magnetization being parallel to the driving direction of the driven body. Normally, if the uniaxial magnetic anisotropy is not given, the magnetic substance is magnetic. A large magnetic field is required to align the magnetization of the body. By giving anisotropy, the directions of magnetization can be aligned in advance, so that a large driving force can be obtained with a small magnetic field. By putting the driven body in a liquid having a specific gravity equal to or higher than that, the buoyancy of the driven body is increased and it becomes easier to drive.

[0026]

(Embodiment 1) A first embodiment of the present invention will be described with reference to the drawings. 1 is a perspective view showing the overall structure of the optical actuator of the present embodiment, FIG. 2 is a view taken in the direction of arrow II in FIG. 1, and FIG. 3 is a view showing the structure of a driven body of the optical actuator of the present embodiment.
(A) is a diagram showing a configuration of a portion including a magnetic body, (b) is a perspective view showing a configuration of a driven body by laminating two portions including a magnetic substance shown in (a), and FIGS. It is a figure which shows the structure and operation state of the light source part used for the optical actuator of a present Example.

In the figure, A is the optical actuator of this embodiment,
1a, 1a are ring-shaped guide frames attached to the circular ends of the upper and lower parallel guide rod frames 1b, 1b, 2 is a slide magnet frame wound around the upper and lower parallel guide rod frames 1b, 1b so as to be rectilinearly movable and rotatable, and 3 is Drive rod, 4 is a power unit, 5 is a magnet, 6 is a water inlet / outlet 6a filled with water α
Is a cylindrical transparent water tank having a horizontal axis, 7 is a driven body, 8 is an optical system, and L is a light beam emitted from the optical system 8 for driving the driven body 7.

9 is a glass substrate having a thickness of 0.1 mm, and 10a
Is a SiN film having a thickness of 0.15 μm formed on the glass substrate 9 by sputtering, 10b is a SiN film having a thickness of 0.2 μm formed by sputtering, and 11 is a SiN film 1
50at% Rh prepared by sputtering on 0a
Is a RhFe magnetic alloy thin film that is a magnetic substance having a thickness of 0.1 μm, and 12 is a polycarbonate substrate having a thickness of 0.5 mm.

Reference numeral 13 denotes a phase conjugate mirror made of a single crystal of BaTiO ₃ having its surface optically polished and further provided with an antireflection film on each surface. Reference numeral 14 denotes a laser beam L0 for position detection having a wavelength of 523 nm.
Generating SHG-YLF laser device, 15a, 15
Reference numerals b and 15c are half mirrors, 16a, 16b and 16c are mirrors, 17 is a semiconductor laser device for generating a laser beam having a wavelength of 830 nm, and 18 is a two-dimensionally arranged detector array.

Numeral 19 does not transmit light of 830 nm wavelength and 523
A filter that passes light of wavelength nm, L1 is 4 of BaTiO ₃
Phase conjugate light generated by light wave mixing, L2 is reflected light as probe light from the driven body 7, L2 'is straight reflected light, L2 "is refracted reflected light, and L3 is heating laser light from the semiconductor laser device 17. is there.

The optical actuator A of the specification of the present embodiment exhibits such a concrete embodiment, and its operation will be described below. First, the magnet 5 is configured to be rotatable and linearly moved along the vertical parallel guide rod frames 1b, 1b by the power unit 4 and the drive rod 3 integrally with the ring-shaped slide frame 2.

The thickness of the SiN films 10a and 10b of the driven body 7 shown in FIGS. 3 (a) and 3 (b) is such that the reflectance for light of 830 nm when viewed from the direction of the glass substrate 9 is minimum. Decided. The size of the driven body 7 is, for example, 0.
The height is 8 mm, the height is 0.3 mm, and the thickness is 0.7 mm.

RhFe magnetic alloy film 11 on the driven body 7
Is non-magnetic at room temperature and is not subject to magnetic field forces.
However, once the light ray L is applied to the RhFe magnetic alloy thin film 11 and reaches a high temperature of 80 ° C. or higher, the RhFe magnetic alloy thin film 11 undergoes a magnetic phase transition, transitions from antiferromagnetism to ferromagnetism, and spontaneous magnetization occurs. As a result, the driven body 7 is attracted in the direction of the larger magnetic field according to the magnetic field gradient. The driven body 7 floats in water almost in balance with buoyancy.
It slowly moves in the direction of the strong magnetic field.

In this case, the driven body 7 can be arbitrarily moved three-dimensionally by arbitrarily rotating and linearly moving the magnet 5 of the optical actuator A.
By the way, along with the movement of the driven body 7, it is necessary to move the light beam L so that the driven body 7 can always be irradiated with the light beam L. For this purpose, the phase conjugate mirror 13 is attached to the optical system 8 as shown in FIG.

The position detection light L1 automatically tracks the driven body 7, the principle of which will be described below with reference to FIGS. First, when the position detection lights L0 are made to face each other and the pump lights La and Lb from both directions are made incident on the phase conjugate mirror 13 of the BaTiO ₃ crystal, the scattered light is scattered from the phase conjugate mirror 13 by fanning in all directions. . If the driven body 7 exists as a reflection point at one of the points, the reflected light L
2 becomes probe light, 4 light wave mixing occurs, and reflected light L
Phase conjugate light L1 is generated in the direction in which the probe light of 2, which is 2.

Even if the driven body 7 which is the reflection point moves in this state, four-wave mixing occurs in the phase conjugate mirror 13 one after another within the range β where the scattered light due to fanning reaches. Four-wave mixing is generated between the reflected light L2 and the phase conjugate light L1. As a result, the phase conjugate light L1
Is automatically tracked as the driven body 7 moves (see FIG. 5).

On the other hand, since the laser light L3 for heating the driven body 7 is weak only by the phase conjugate light L1, it is separately added. It is a semiconductor laser device 17 that emits a laser beam having a wavelength of 830 nm, and has an output of 1000 mW. However, the total output from the optical system 8 was set to 100 mW by an attenuator (not shown). Further, by a diaphragm device such as a lens (not shown)
The spot was made to have a diameter of μm.

A part of the reflected light L2 from the driven body 7 is guided as reflected and refracted light L2 ″ to the detector array 18 by the half mirrors 15b and 15c. The reflected light L2 always changes its direction as the driven body 7 moves, The detector array 18 at which the phase conjugate light L1 component wavelength of the catadioptric light L2 ″ reaches
The light reaching position above also changes. Therefore, by detecting the light arrival position on the detector array 18, the driven body 7
I know the position of.

In front of the detector array 18, 830n
Place a filter 19 to block m wavelength light, 830nm
It prevented the light of the wavelength from becoming noise. By moving the electrically driven half mirror 15b two-dimensionally by computer control based on this position information, it becomes possible to constantly irradiate the driven body 7 with light from the semiconductor laser device 17 that serves as a heat energy source.

Here, there is another device for keeping the driven body 7 always following the light. That is, the magnetic field distribution by the magnet 5 is a uniaxial anisotropic distribution when viewed in a cross section orthogonal to the magnetic force lines, and the shape of the magnetic body is a plate. This will be described below with reference to FIG.

FIG. 6 is a cross-sectional view showing the relationship between the equi-magnetic surface of the magnetic pole and the driven body 7. In the figure, 20 indicates a magnetic pole,
Reference numerals 21a, 21b, 21c, and 21d are cross sections of equi-magnetic surface. The RhFe magnetic alloy thin film 11 which is a magnetic body in the driven body 7 magnetized in the magnetic field direction by heating is aligned with its N pole and S pole parallel to the magnetic field lines.

That is, as shown in FIG. 5, the RhFe magnetic alloy thin film 11 which is a flat magnetic material in the driven body 7 has its shape magnetic anisotropy, so that the magnetization can rise from the film surface. Since it does not exist, the film surface is parallel to the equi-magnetic surface.

Therefore, by making the distribution of the magnetic field elliptical, it is possible to make the trap position of the RhFe magnetic alloy thin film 11 as the magnetic substance in the driven body 7 parallel to the plane parallel to the major axis of the ellipse. Becomes As a result, the light irradiation direction,
It is possible to make the surface of the magnetic body in the driven body 7 substantially perpendicular.

(Experimental Example 1) Here, experimental results using this embodiment will be shown. First, the magnetic field is applied by the electromagnet 5 having a magnetic pole. In this case, a DC magnetic field with a maximum of 5 koe was generated at the center of the magnetic pole. In the case of an alternating current of 1 kHz, a maximum of 1 ko
It was e. The laser beam L3 from the semiconductor laser device 17 for heating has a pulse width of 100 msec and an interval of 50 ms.
The driven body 7 was irradiated with the modulated ec.

As a result of the above preparations, the driven body 7 could be driven in any direction at a speed of about 5 cm / sec in water by light irradiation and movement of the magnetic field. It was also possible to bend the direction on the way or to stand still in water. When making a stationary state, the current to the electromagnet is 1k
An alternating magnetic field is generated as an alternating current of Hz.

(Experimental Example 2) Next, an experimental example of the present embodiment will be shown, assuming that the optical actuator is used in a living body. A pig meat with a thickness of 3 cm was inserted between the optical system 8 and the water tank 6 in FIG. 1, and light was irradiated through the meat. The optical power after passing through the meat with 3 cm of skin is 830
It was 5% of the incident light in the wavelength of nm. 523 nm
Since it hardly transmitted light of a wavelength, automatic tracking was impossible.

However, it is possible to heat with the laser beam L3 having a wavelength of 830 nm for heating, the total power of the light emitted from the optical system 8 is 300 mW, and the surface of the driven body 7 is 30 μm.
The driven body 7 was irradiated with CW after squeezing to m diameter. DC magnetic field 5
By applying koe, it was confirmed that the light was driven through the skin of pig for a moment.

Phase conjugate wave L1 having a wavelength that can pass through a living body
Although confirmation of automatic tracking using is not performed here, the phase conjugate wave L at a wavelength of 1060 nm, which has a large biological transmittance, is used.
Generation of 1 has already been performed using GaAs, and N
The same driving as in the first experimental example can be performed by using the d: YAG laser and GaAs.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to the drawings. FIGS. 7A and 7B are front views showing a state of a magnetic body of a driven body of the optical actuator of the present example and a state before a SiN film is sputtered on a RhFe magnetic alloy thin film produced by sputtering. FIG. 8 is a perspective view of a driven body provided inside the optical actuator of this embodiment.

In the figure, 7'is a driven body, 9'is a glass substrate, 10a 'and 10b' are SiN films formed by sputtering, and 11 'is a 50at% film formed by sputtering and processed into stripes. The RhFe magnetic alloy thin film, which is a magnetic substance containing Rh, is a polycarbonate substrate 12 '. The overall structure of the optical actuator of the present embodiment is substantially the same as that of the first embodiment, and will be omitted.

The feature of this embodiment lies in the structure of the driven body 7 ', and a method of manufacturing the driven body 7'will be described below. First,
RhFe on the glass substrate 9'with the SiN film 10a 'interposed therebetween.
Magnetic alloy thin film 11 'is sputtered to 0.1 μm
After being formed to a thickness, it was processed by etching into a thin stripe shape along the direction in which it is attached to the driven body 7 and operated. RhFe magnetic alloy thin film 11 '
The stripes had a width of 30 μm and an interval of 10 μm.

As a result, the RhFe magnetic alloy thin film 11 '
In addition, uniaxial magnetic anisotropy was generated with the easy axis of magnetization in the stripe direction. On the striped RhFe magnetic alloy thin film 11 ', a SiN film 10b' is further formed by sputtering. As in the case of the first embodiment, this was attached to a polycarbonate substrate 12 'and a drive experiment was conducted. As a result, it was driven with a magnetic field having a magnitude of 1/10 as compared with the case where uniaxial magnetic anisotropy was not applied. It was possible to

[0053]

As described above, according to the present invention, it is possible to freely and three-dimensionally move an object of mm order floating in a liquid or in the air by using light and a magnetic field. It will be possible. Therefore, in the field where it is necessary to remotely drive a minute object in a liquid, for example, in the field of medical equipment, medication, treatment, robots, or in the field of electronic or optical equipment that uses electrical or optical switches that dislike wiring. Demonstrate excellent usefulness.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of an optical actuator that is a first embodiment of the present invention.

FIG. 2 is a view taken along the line II in FIG.

FIG. 3 (a) is a partial view of a magnetic body, and FIG. 3 (b) is a diagram showing a structure of a driven body.

FIG. 4 is a diagram showing a configuration of an optical system of the above.

FIG. 5 is a diagram showing an operating state of the optical system of the above.

FIG. 6 is a cross-sectional view showing the relationship between the equi-potential surface of the magnetic pole and the driven body in the above.

7A and 7B are a front view and a side view of a magnetic body forming a driven body according to a second embodiment of the present invention.

FIG. 8 is a perspective view of a driven body of the above.

[Explanation of symbols]

 α ... Liquid β ... Range A ... Optical actuator L ... Ray L0 ... Position detection light L1 ... Phase conjugate light L2 ... Reflected wave L2 '... Straight reflected light L2 ″ ... Refracted reflected light L3 ... Heating laser light 1a ... Ring guide frame 1b ... Vertical parallel guide rod frame 2 ... Slide magnet frame 3 ... Driving rod 4 ... Power unit 5 ... Magnet 6 ... Water tank 6a ... Door / port 7,7 '... Driven body 8 ... Optical system 9, 9' ... Glass substrate 10a, 10b, 10a ', 10b' ... SiN film 11, 11 '... RhFe magnetic alloy thin film 12, 12' ... Polycarbonate substrate 13 ... Phase conjugate mirror 14 ... SHG-YLF laser device 15a, 15b, 15c ... Half mirror 16a, 16b, 16c ... Mirror 17 ... Semiconductor laser device 18 ... Detector array 19 ... Filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Sugiyama 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (9)

[Claims] 1. A driven body to which a magnetic body whose magnetization increases as temperature rises is attached, a magnet disposed at a position where a magnetic field can be applied to the driven body floating in a fluid, and the magnet can be any magnet. A power unit that can be moved to a position, a light source that emits light for irradiating the driven body, and an optical system that guides the light from the light source to the driven body by a phase conjugate mirror mechanism. An optical actuator characterized by. 2. The magnetic material comprises R containing 48 to 54 at% of Rh.
The optical actuator according to claim 1, wherein the optical actuator is an hFe alloy. 3. The magnet is a permanent magnet or an electromagnet, and is characterized in that it can move back and forth in parallel with the driving direction of the driven body and can rotate around the driving direction of the driven body as an axis. The optical actuator according to claim 1 or 2. 4. The optical actuator according to claim 1, wherein the magnetic field exhibits a uniaxial anisotropic distribution in a plane perpendicular to the driving direction of the driven body. 5. The light according to claim 1, wherein the magnetic body has a plate-like shape, a spheroid close to a plate-like shape, or an outer shape of a surface of the spheroid. Actuator. 6. The magnetic body is provided with uniaxial magnetic anisotropy in which a direction parallel to the driving direction of the driven body is an easy axis of magnetization. The optical actuator described. 7. The fluid has a specific gravity equal to or higher than the specific gravity of the main material forming the driven body.
The optical actuator according to 2, 3, 4, 5 or 6. 8. The light according to claim 1, wherein the light sources are a pair of laser light sources which respectively emit heating light and position detection light having different wavelengths. Actuator. 9. An optical system comprising: a phase conjugate mirror that emits phase conjugate light when position detection light is incident from both directions and straight reflection light of a driven body is incident; A half mirror that bifurcates the light into the straight reflected light and the refracted reflected light of the phase conjugate mirror and refracts and refracts the heating light, and a filter that filters only the phase conjugate light component wavelength of the refracted reflected light, 8. A detector array for detecting an irradiation position of the refracted / reflected light transmitted through the filter and controlling rotation of the half mirror so as to follow the driven body. Alternatively, the optical actuator according to item 8.