JPH072034B2 - Optical motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical motor for rotating a minute object forming a rotor by using two linearly polarized or circularly polarized laser beams facing each other, and more specifically, to an optical motor. For example, the present invention relates to an optical motor suitable for use in a microdevice requiring a driving force for a rotating mechanism such as a motor in the field of micromachines and a rotary pump.

[0002]

2. Description of the Related Art As a micromotor used in the field of micromachines, an electrode for applying an electric field by rotating a watermill-shaped object by the flow of an object or forming a microelectrode having many poles like a multipolar motor. Shift one by one,
Means such as generating driving force are considered, but these are based on the method of making a normal size motor as it is, and not only technically cause many difficulties, but also regarding the rotating shaft. It is necessary to consider a simple shaft support that minimizes mechanical resistance.

[0003]

The technical problem of the present invention is to focus on the fact that a minute object can be captured and fixed by using a laser beam, and the minute object can be rotated by the rotation of an electric field. The purpose is to obtain an optical motor that can rotate an object at high speed without mechanical resistance.

[0004]

In order to solve the above-mentioned problems, the optical motor of the present invention constitutes a minute object which serves as a rotor by a substance which induces or holds an electric dipole, and holds this minute object in a floating state. For projecting the two linearly polarized or circularly polarized laser beams facing each other, the direction of the linearly polarized light of the laser beam or the direction of rotation of the circularly polarized light in these projecting means is required at the place where the minute object is held. It is characterized by being set so that a rotating electric field is generated.

[0005]

When two linearly polarized or circularly polarized laser beams facing each other are projected onto a minute object, the minute object is captured at an intermediate position between them and a rotating electric field is generated at that position, so that the minute object is It is held and rotated without contact,
The resistance during rotation is extremely low.

[0006]

Embodiments of the present invention will be described in detail with reference to the drawings. The optical motor according to the present invention requires a driving force for a rotary mechanism such as a motor or a rotary pump used in the field of micromachines. It is suitable for use in a micro device.

In this optical motor, the minute object to which the rotary motion is given as a rotor is a fine particle-like object made of a substance which induces an electric dipole by an electric field or a substance having a permanent electric dipole. The size thereof usually has a diameter of several tens nm to several tens μm, and the shape is not particularly limited. For example, making a water wheel-shaped object from the above substances and rotating it to make a micro pump, or making something like a rotor of a motor and rotating it to take out rotational force from the shaft. Can be considered.

FIG. 1 shows a first embodiment of an optical motor according to the present invention. In this embodiment, a basic structure when two linearly polarized opposed laser beams are used is shown. There is. In this optical motor, two opposing linearly polarized laser beams B1 for floating and holding the above-mentioned minute object are held.
Lasers 1 and 2 are arranged to face each other as B2 projection means. These lasers 1 and 2 project linearly polarized laser beams B1 and B2, and these beams capture and fix a minute object at an intermediate position P1 based on the principle described later. As a result, the minute object is held in a non-contact manner, and the resistance during rotation is extremely reduced.

Further, since the minute object is rotated at the position P1 where it is captured and fixed, in the lasers 1 and 2, the laser beams of the respective laser beams are generated so as to generate a rotating electric field at the position of the minute object. The direction of linearly polarized light is set. That is, since circularly polarized light is the sum of two orthogonal linearly polarized light, if the linearly polarized light of the opposing laser beam is orthogonal in the region where the minute object is captured, circularly polarized light is obtained there. You can

The micro object rotates by receiving a force from the rotating electric field, but the electric field rotates very quickly. Therefore, the micro object has a rotational speed in which the torque produced by the electric field and the resistance against the rotation of the micro object are balanced. Rotate. To increase the number of rotations, the electric field should be strengthened.

FIG. 2 shows a second embodiment of the optical motor according to the present invention. In this embodiment, 2
A circularly polarized opposed laser beam of a book is used. In this optical motor, in order to float and hold a minute object, the laser 3,
4 are arranged to face each other, but they project two circularly polarized laser beams B3 and B4 which face each other, and these beams capture and fix a minute object at an intermediate position P2 based on the principle described later. To be done. Further, since the minute objects are captured and rotated at a fixed place, in the lasers 3 and 4, the rotation directions of the circularly polarized lights of the respective laser beams are adjusted so that the electric fields rotate in the same direction at the positions of the minute objects. Is set.

The capture and fixation of a minute object by a laser beam is based on the following principle. The force that the laser beam exerts on the fine particles is. A force generated by the movement of momentum by refraction when light passes through a particle ,. The force created by the interaction of the electric dipole with the electric field,
． The force of light pushing particles can be considered. The above acts as a force to pull the minute object on the axis of the laser beam, and the term acts as a force to push the minute object in the axial direction of the laser beam.

Therefore, the former force can confine the particles on the axis of the laser beam. Further, the latter force can push the particles confined on the axis of the laser beam in the traveling direction of the laser beam. Further, when the two beams are coaxially irradiated in opposite directions, the particles can be three-dimensionally captured and fixed by pushing the particles from the front and back. At this time, when the two laser beams facing each other are focused at an acute angle by using long-focus lenses, particles are captured between the focal points,
Fixed.

More specifically, referring to FIG. 3, as shown in FIG. 3, when the laser beam 10 bends on the surface of the spherical particle 11, a momentum transfer occurs and the force FDi1 , FDi2, FDo1, and FDo2 are generated. F1 and F2 in the figure represent integrals of forces generated in the respective hemispheres of the particle 2.

Now, assuming that the center of the particle 11 is deviated from the axis of the beam 10, the electric field is stronger at a position closer to the axis of the beam, and the force acting on the portion closer to the axis of the particle 11 is stronger. In addition, the sum of the forces of F1 and F2 in the direction perpendicular to the beam axis is directed toward the center of the beam. Therefore, the particles 11
A force to be drawn toward the center of the beam 10 acts on the beam.

The forces of F1 and F2 also generate a force FF in the axial direction of the beam. If the laser beam 10 is a parallel beam or a beam focused at an acute angle, F1, F
The resultant force FF of 2 pushes the particles 11 in the traveling direction of the beam. Therefore, particles are trapped at the point where the FF of the beam from the right and the FF of the beam from the left balance. In the case of a sharply focused beam, this balancing point is usually located between the respective focal points of the two beams. The principle of capturing and fixing by the laser is common when two opposing linearly polarized and circularly polarized laser beams are used.

Since the minute object is formed of a substance that induces or holds an electric dipole, it can be rotated according to the following principle. That is, the electric dipole is
The electric field receives a force that tries to turn in the direction of the electric field, but when the electric field rotates, the dipole also tries to follow it and rotate. When the dipole rotates inside the object, if the cross section of the object in this plane of rotation is not circular, the dipole will stress the object and generate a rotational torque. The term "not circular" as used herein does not necessarily mean that the outer shape is not a circle, and it is sufficient if the outer shape is circular and the distribution of the dielectric constant is not circularly symmetric. If the micro object has such an electric dipole, it can give rotation to the micro object.

Whether to use linearly polarized light or circularly polarized light depends on how light is guided to that point.
Judgment is made based on whether linear polarized light is more efficient or circular polarized light is more efficient. This is a consideration when actually assembling the device.

[0019]

According to the optical motor of the present invention as described above, since the minute object forming the rotor is held by the optical trap, mechanical resistance can be eliminated, and torque can be generated by rotating the light. Since it is performed by an electric field, it is possible to perform ultra-high rotation.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a basic configuration of a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a basic configuration of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining a principle for holding a minute object based on the present invention.

[Explanation of symbols]

1,2,3,4 laser, B1, B2 linearly polarized laser beam, B3, B4 circularly polarized laser beam.

Claims (2)

[Claims] 1. A micro object as a rotor is constituted by a substance that induces or holds an electric dipole, and two opposing linearly polarized laser beam projection means for floating and holding the micro object are provided. An optical motor characterized in that the direction of linear polarization of the laser beam in these projection means is set so that a rotating electric field is generated at a place where a minute object is held. 2. A micro object as a rotor is formed by a substance that induces or holds an electric dipole, and two opposing circularly polarized laser beam projection means for floating and holding the micro object are provided. An optical motor, characterized in that the rotation direction of circularly polarized light of the laser beam in those projection means is set so that the electric field rotates in the same direction where a minute object is held.