JP2014174041A - Optical antenna and optical wave rader system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To instantly switch a laser beam to a desired direction without increases in size and cost.SOLUTION: An optical antenna is provided with varifocal lenses 13A, 13B, 13C, 13D including a focal distance variable mechanism for changing a focal distance and a focus adjustment mechanism for adjusting a focus; and an optical fiber switch 15 selecting one of any optical fibers 12 from optical fibers 12A, 12B, 12C, 12D and connecting the other terminal end of the optical fiber 12 to an optical fiber 11.

Description

  The present invention relates to an optical antenna that transmits and receives laser light toward a space, and a light wave radar device that includes a transmission and reception device that observes a target from laser light received by the optical antenna.

In a light wave radar device that oscillates laser light toward a target existing in space and estimates the target speed from the Doppler shift of the return light scattered or reflected by the target, the laser light is directed to a desired direction or distance. An optical antenna that collects the laser beam scattered and returned by the target on the optical receiver is used.
As a means for the optical antenna to change the transmission / reception direction of the laser beam, a wedge prism that transmits the laser beam radiated from the optical antenna (or the laser beam that returns to the optical antenna) is arranged and transmitted through the wedge prism. A method of changing the refraction direction of laser light by rotating a wedge prism is known (for example, see Patent Document 1).

However, since it takes a finite time to rotate the wedge prism, it is not suitable for, for example, an application for measuring instantaneous wind speed.
Therefore, multiple optical fibers that transmit laser light are placed near the focal plane of the collimator lens, and the transmission / reception direction can be changed instantaneously by switching the optical fiber connected to the optical receiver among the multiple optical fibers. An optical fiber scanning system that can be used has been developed (see, for example, Patent Document 2).

Further, in the light wave radar device that measures the wind speed, it is necessary to move the optical fiber from the focal plane of the optical antenna so that the laser light is condensed at a desired measurement distance.
At that time, in order to obtain the maximum SN (Signal to Noise ratio) ratio, it is desirable to vary the diameter of the laser beam according to the measurement distance.
In order to realize this, a method has been developed in which focal length variable means having the same principle as that of a zoom lens of a photographic lens is provided inside an optical antenna (see, for example, Patent Document 3).

US2012 / 0105923 EP1589678 JP 2010-127918 (paragraph number [0024], FIG. 1)

Since the conventional optical antenna is configured as described above, when adopting a system in which a plurality of optical fibers are arranged near the focal plane of the collimating lens and the optical fiber connected to the optical receiver is switched. (In the case of Patent Document 2), a collimating lens having a wide field of view is required. However, since such a collimating lens is not common, the manufacturing cost increases. In addition, in order to secure a wide field of view, the collimating lens has a large diameter, and a plurality of optical fibers according to the transmission / reception direction must be arranged on the focal plane of the collimating lens. There was a problem that would increase.
Further, in the method in which the focal length changing means is provided inside the optical antenna (in the case of Patent Document 3), the focal length of the collimating lens changes as the diameter of the laser light changes, so that the laser is directed in an unintended direction. There was a problem that light changed.

  The present invention has been made to solve the above-described problems, and provides an optical antenna and a light wave radar device capable of instantaneously switching laser light in a desired direction without incurring an increase in size and cost. With the goal.

  An optical antenna according to the present invention is connected to a plurality of optical fibers that transmit laser light, and one end of the optical fiber, and a focal length variable mechanism that varies a focal distance and a focus adjustment mechanism that adjusts the focus A plurality of varifocal lenses provided with optical fiber selecting means, and an optical fiber selecting means selects one arbitrary optical fiber from the plurality of optical fibers and connects the other end of the optical fiber to the transmitting / receiving device It is what you do.

  According to the present invention, there is provided a plurality of varifocal lenses that are connected to one end portion of an optical fiber and are provided with a focal length variable mechanism that varies a focal distance and a focus adjustment mechanism that adjusts the focus. Since the means is configured to select one optical fiber from a plurality of optical fibers and connect the other end of the optical fiber to the transmission / reception device, the size and cost are increased. There is an effect that laser light can be instantaneously switched in a desired direction.

It is a block diagram which shows the light wave radar apparatus which mounts the optical antenna by Embodiment 1 of this invention. It is sectional drawing which shows the varifocal lens 13A of the optical antenna 10 by Embodiment 1 of this invention. It is a block diagram which shows the optical antenna by Embodiment 2 of this invention. It is a block diagram which shows the optical antenna by Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a light wave radar apparatus equipped with an optical antenna according to Embodiment 1 of the present invention.
In FIG. 1, a transmission / reception device 1 is a device for observing a target from laser light incident on the optical antenna 10 while outputting laser light radiated from the optical antenna 10 to the space.
The transmission light generation unit 2 of the transmission / reception device 1 is a laser light source that oscillates laser light (transmission light).
The circulator 3 outputs the laser light oscillated by the transmission light generation unit 2 to the optical antenna 10 and outputs the laser light as local oscillation light to the optical heterodyne reception unit 4, while the laser light incident by the optical antenna 10. This is an optical branching unit that outputs (received light) to the optical heterodyne receiver 4.

The optical heterodyne receiver 4 performs a process of generating an electrical signal corresponding to the light intensity of the difference frequency component between the local oscillation light output from the circulator 3 and the laser light (received light).
The signal processing unit 5 performs processing for observing the target based on the electrical signal generated by the optical heterodyne receiving unit 4. The processing for observing the target corresponds to, for example, processing for measuring wind speed, etc., but since these processing are assumed to be a known technique, detailed description thereof is omitted.

The optical antenna 10 radiates laser light (transmitted light) output from the transceiver 1 to the space, and enters laser light (received light) that has been scattered and returned to the target existing in the space. It is a device that outputs laser light (received light) to the transceiver 1.
The optical antenna 10 is connected to the transmission / reception device 1 via an optical fiber 11, and a plurality of optical fibers 12 are wired inside the optical antenna 10.
In the example of FIG. 1, four optical fibers 12 are wired, but this is only an example, and it is sufficient that two or more optical fibers 12 are wired.

The varifocal lenses 13A, 13B, 13C, and 13D are connected to one end of the optical fibers 12A, 12B, 12C, and 12D, and include a focal length variable mechanism that varies the focal distance and a focus adjustment mechanism that adjusts the focus. It is an optical component.
In the first embodiment, as will be described later, since the wedge prisms 14A, 14B, 14C, and 14D are arranged, the optical axes of the varifocal lenses 13A, 13B, 13C, and 13D are arranged in parallel to each other. When the wedge prisms 14A, 14B, 14C, and 14D are not arranged, the optical axes of the varifocal lenses 13A, 13B, 13C, and 13D are tilted at different angles so that the laser beam transmission / reception direction matches the desired direction. Placed.

The wedge prisms 14A, 14B, 14C, and 14D are arranged on the surfaces of the varifocal lenses 13A, 13B, 13C, and 13D that are not connected to one end of the optical fibers 12A, 12B, 12C, and 12D. The laser beams emitted from the varifocal lenses 13A, 13B, 13C, and 13D are refracted in different directions and emitted to the space, while the laser beams returned from the different directions are varifocal lenses 13A, 13B, This is an optical component that enters 13C and 13D.
The optical fiber switch 15 selects one arbitrary optical fiber 12 from the optical fibers 12A, 12B, 12C, and 12D, and performs a process of connecting the other end of the optical fiber 12 to the optical fiber 11. . The optical fiber switch 15 constitutes an optical fiber selection means.

Here, a focal length changing gear 16 is fixed to the outer periphery of the lens barrel of the varifocal lenses 13A, 13B, 13C, and 13D, and the focal length changing gears 16 mesh with each other.
The focal length changing gear 16 is engaged with a pinion gear 17a of a stepping motor 17 which is a geared electric motor. The focal length of the varifocal lenses 13A, 13B, 13C, and 13D is varied by rotating the lens barrel around the optical axis. The focal length changing gear 16 and the stepping motor 17 constitute a focal length varying mechanism.

A focus adjustment gear 18 is fixed to the outer periphery of the lens barrel of the varifocal lenses 13A, 13B, 13C, and 13D, and the focus adjustment gears 18 mesh with each other.
The focus adjustment gear 18 is meshed with a pinion gear 19a of a stepping motor 19 which is an electric motor with a gear. The barrel is rotated around the optical axis to adjust the focus of the varifocal lenses 13A, 13B, 13C, and 13D. A focus adjustment mechanism is configured by the focus adjustment gear 18 and the stepping motor 19.

FIG. 2 is a sectional view showing the varifocal lens 13A of the optical antenna 10 according to the first embodiment of the present invention.
The varifocal lenses 13A, 13B, 13C, and 13D have substantially the same configuration (parts of which are different will be described later), and FIG. 2 typically shows the configuration of the varifocal lens 13A.
In FIG. 2, a focusing lens 21 is a convex lens having a positive refractive power.
The variator lens 22 is a concave lens having negative refractive power.
The optical fiber receptacle 23 is a holder that holds one end of the optical fiber 12A.

The lens barrel 24, which is the first lens barrel, is a cylindrical part that fixes the focusing lens 21 therein.
The lens barrel 25 as the second lens barrel is a cylindrical part that fixes the variator lens 22 therein.
The lens barrel 24 has an inner screw on the inner surface of the cylinder, and the lens barrel 25 has an outer screw on the outer surface of the cylinder, and the inner screw and the outer screw mesh with each other.
The lens barrel 26, which is the third lens barrel, is a part that moves together with the lens barrel 25, with the optical fiber receptacle 23 fixed inside.

The adjustment ring 27 is a cylindrical part that rotates integrally with the focus adjustment gear 18, and has an inner screw that meshes with an outer screw of the lens barrel 25 on the inner surface of the cylinder.
The bearing 28 is a member that absorbs the rotational force of the adjusting ring 27 and transmits only the force in the expansion / contraction direction by the screw to the lens barrel 26.

Next, the operation will be described.
Four optical fibers 12 are wired to the optical antenna 10.
The optical fiber switch 15 selects one optical fiber 12 to which a varifocal lens 13 corresponding to a desired transmission / reception direction of the laser light is connected from the optical fibers 12A, 12B, 12C, and 12D. It operates so as to connect the terminal end of the fiber 12 to the optical fiber 11.
Such an optical fiber switch 15 is configured such that, for example, a laser beam emitted from any one of the optical fibers 12A, 12B, 12C, and 12D is connected to a terminal portion of another optical fiber 11 with a lens. Yes. Further, a mirror or the like whose angle is movable by an electric motor is installed in the space between the optical fibers 12A, 12B, 12C, and 12D and the optical fiber 11, and the angle of the mirror or the like is moved, so that the space propagates. This can be realized by dynamically reflecting and bending so that the laser light is coupled to the desired optical fiber 12.

One terminal portion of the four optical fibers 12 is connected to the varifocal lenses 13A, 13B, 13C, and 13D as described above.
The varifocal lenses 13A, 13B, 13C, and 13D have the same dimensions, functions, and performances except for slight differences that will be described later. The emitted laser light is converted into substantially parallel light and emitted to space.
The varifocal lenses 13A, 13B, 13C, and 13D move when the focal length changing gear 16 fixed to the outer periphery of the lens barrel 24 is rotated by the stepping motor 17, so that the internal lens group moves. The focal length can be arbitrarily changed (details will be described later).
The varifocal lenses 13A, 13B, 13C, and 13D have an internal lens group (lens system) when the focus adjustment gear 18 fixed to the outer periphery of the adjustment ring 27 that is a lens barrel is rotated by the stepping motor 19. The focal point of the optical fiber 12A, 12B, 12C, 12D increases or decreases, the distance at which the laser light (transmitted light) emitted into the space is collected (the distance to be measured by the light wave radar device) ) Can be arbitrarily changed (details will be described later).

As described above, the varifocal lenses 13A, 13B, 13C, and 13D are arranged so that their optical axes are parallel to each other.
Therefore, the transmission / reception directions of the laser beams of the varifocal lenses 13A, 13B, 13C, and 13D are parallel.
Laser light (transmitted light) emitted from the varifocal lenses 13A, 13B, 13C, and 13D and laser light (received light) incident on the varifocal lenses 13A, 13B, 13C, and 13D are wedge prisms 14A, 14B, 14C and 14D are transmitted.

The wedge prisms 14A, 14B, 14C, and 14D are made of glass or other optical material whose both surfaces are polished and are configured so that both surfaces are not parallel but have a predetermined angle.
Therefore, the transmission / reception light transmitted through the wedge prisms 14A, 14B, 14C, 14D is refracted by an angle corresponding to the refractive index difference between air and glass and the angle difference between both surfaces, and the transmission / reception direction of the laser light changes. To do.
For example, when the wedge prisms 14A, 14B, 14C, and 14D having the same shape and the same refraction angle are used, the wedge prisms 14A, 14B, 14C, and 14D are arranged so that the inclination directions thereof are different.
In the example of FIG. 1, when the wedge prism 14A is used as a reference, the wedge prisms 14B, 14C, and 14D are arranged so that the inclination directions are 90 degrees, 180 degrees, and 270 degrees.

Therefore, when the optical fiber 12 selected by the optical fiber switch 15 is switched, the varifocal lens 13 that transmits and receives laser light is switched.
When the varifocal lens 13 is switched, the laser beam transmission / reception direction is switched instantaneously.
Therefore, the optical fiber switch 15 can instantly switch the laser light transmission / reception direction to the desired direction by selecting the optical fiber 12 to which the varifocal lens 13 corresponding to the desired transmission / reception direction is connected.

The focal length changing gear 16 and the focus adjusting gear 18 of the varifocal lenses 13A, 13B, 13C, and 13D are rotated by stepping motors 17 and 19, respectively.
The stepping motors 17 and 19 are constituted by general stepping motors. By inputting a control signal to a driver circuit (not shown), the stepping motors 17 and 19 are rotated by a predetermined angle and then stopped. The holding operation can be arbitrarily performed.
The stepping motors 17 and 19 have pinion gears 17 a and 19 a attached to the rotation shaft, and the pinion gear 17 a of the stepping motor 17 meshes with the focal length changing gear 16. Further, the pinion gear 19 a of the stepping motor 19 is engaged with the focus adjustment gear 18.
Therefore, the varifocal lenses 13A, 13B, 13C, and 13D can change the focal length and adjust the focus by the stepping motors 17 and 19.

The focal length changing gear 16 of the varifocal lens 13A meshes with the focal length changing gear 16 of the varifocal lenses 13B and 13C, and the focal length changing gear 16 of the varifocal lens 13D is also the varifocal lens 13B. , 13C is engaged with the focal length changing gear 16.
Accordingly, the rotational movement of the stepping motor 17 is transmitted from the focal length changing gear 16 of the varifocal lens 13A to the focal length changing gear 16 of the varifocal lenses 13B and 13C, and the focal length changing gear of the varifocal lens 13D. 16 is transmitted.
Here, the focal length changing gear 16 of the varifocal lenses 13A, 13D and the focal length changing gear 16 of the varifocal lenses 13B, 13C are opposite in the direction of movement of the focal length with respect to the rotation direction. The absolute values of the quantities are configured equally.

For example, the focal lengths of the varifocal lenses 13A and 13D move in the positive direction when rotated from the right when viewed from above, whereas the focal lengths of the varifocal lenses 13B and 13C move in the positive direction when rotated from the left when viewed from above. .
That is, with respect to the rotation of the stepping motor 17, the varifocal lenses 13A and 13D are reversed and the varifocal lenses 13B and 13C are rotated forward.
By adopting the above configuration, the focal length is changed by the same moving direction and moving amount by changing the focal length by the rotation of the focal length changing gear 16.

Further, the focus adjustment gear 18 of the varifocal lens 13A is engaged with the focus adjustment gear 18 of the varifocal lenses 13B and 13C, and the focus adjustment gear 18 of the varifocal lens 13D is also connected to the varifocal lenses 13B and 13C. The focus adjustment gear 18 is engaged.
Therefore, the rotational motion of the stepping motor 19 is transmitted from the focus adjustment gear 18 of the varifocal lens 13A to the focus adjustment gear 18 of the varifocal lenses 13B and 13C, and is transmitted to the focus adjustment gear 18 of the varifocal lens 13D. Is done.
Here, the focus adjustment gear 18 of the varifocal lenses 13A and 13D and the focus adjustment gear 18 of the varifocal lenses 13B and 13C are in the focus movement direction with respect to the rotation direction (the end portion of the optical fiber 12 and the lens group). The distance increase / decrease direction) is in the opposite direction, and the absolute values of the movement amounts are configured to be equal.

For example, the varifocal lenses 13A and 13D move the focus in the positive direction when rotated from the right when viewed from above, while the varifocal lenses 13B and 13C move the focus in the positive direction when rotated from the left when viewed from above.
That is, with respect to the rotation of the stepping motor 19, the varifocal lenses 13A and 13D are reversed and the varifocal lenses 13B and 13C are rotated forward.
By adopting the above configuration, the focus position is changed by the same movement direction and movement amount by performing the focus adjustment by the rotation of the focus adjustment gear 18.

Next, the internal operation (variable focal length, focus adjustment) of the varifocal lenses 13A, 13B, 13C, 13D will be described.
The lens barrels 24 and 25 are cylindrical parts as described above. The lens barrel 24 has an inner screw on the inner surface of the cylinder, and the lens barrel 25 has an outer screw on the outer surface of the cylinder. The inner and outer screws mesh with each other.
Further, the lens barrel 25 is fixed to a holder (not shown), and the lens barrel 24 rotates integrally with the focal length changing gear 16, so that a screw screw is provided between the lens barrel 24 and the lens barrel 25. The lens barrel 24 and the lens barrel 25 expand and contract telescopically by the rotating action.
By this expansion and contraction, the distance between the focusing lens 21 in the lens barrel 24 and the variator lens 22 in the lens barrel 25 changes, and the combined focal length of the focusing lens 21 and the variator lens 22 can be changed.

As described above, the adjustment ring 27 is a cylindrical part, and has an inner screw that meshes with an outer screw of the lens barrel 25 on the inner surface of the cylinder.
Since the adjustment ring 27 rotates integrally with the focus adjustment gear 18, the adjustment ring 27 and the lens barrel 25 are telescopically expanded and contracted by the rotational action of the screw between the adjustment ring 27 and the lens barrel 25.
The bearing 28 is an angular bearing constituted by an outer race, an inner race, and a ball bearing. The outer race is fixed to the adjustment ring 27, and the inner race is fixed to the lens barrel 26.
Therefore, the bearing 28 acts to absorb the rotational force of the adjusting ring 27 and transmit only the force in the expansion / contraction direction by the screw to the lens barrel 26.
Thereby, the stepping motor 19 rotates the focus adjustment gear 18 so that the adjustment ring 27 and the lens barrel 25 are telescopically expanded and contracted, and by this expansion and contraction, the optical fiber receptacle 23 and the optical fiber 12 in the lens barrel 26 are expanded and contracted. The end part moves at the same time.
Therefore, the distance between the combined focal length formed by the focusing lens 21 and the variator lens 22 and the end portion of the optical fiber 12 can be changed.

The varifocal lens 13A and the varifocal lens 13D have exactly the same configuration.
The varifocal lenses 13B and 13C have almost the same configuration as the varifocal lenses 13A and 13D, but differ in the following two configurations.
The first difference is that in the screws of the lens barrels 24 and 25, the pitch is equal to that of the varifocal lenses 13A and 13D, but the spiral direction is opposite to that of the varifocal lenses 13A and 13D.
The second difference is that in the screw of the lens barrel 24 and the adjusting ring 27, the pitch is equal to that of the varifocal lenses 13A and 13D, but the spiral direction is opposite to that of the varifocal lenses 13A and 13D.
Therefore, the varifocal lenses 13A and 13D and the varifocal lenses 13B and 13C operate equally when the rotation directions of the focal length changing gear 16 and the focus adjusting gear 18 are opposite (the focal length variation amount with respect to the rotation angle and The amount of focus movement matches.)

  As apparent from the above, according to the first embodiment, the varifocal lenses 13A, 13B, 13C, and 13D including the focal length variable mechanism that varies the focal distance and the focus adjustment mechanism that adjusts the focus are provided. The fiber switch 15 is configured to select one arbitrary optical fiber 12 from the optical fibers 12A, 12B, 12C, and 12D and to connect the other end of the optical fiber 12 to the optical fiber 11. Therefore, there is an effect that the laser beam can be instantaneously switched in a desired direction without increasing the size and cost.

That is, according to the first embodiment, the following effects can be obtained as compared with the conventional optical fiber scanning optical antenna.
(1) With the varifocal lenses 13A, 13B, 13C, and 13D, focus adjustment and focal length can be controlled independently.
(2) A wide field of view is not required as a requirement of the varifocal lenses 13A, 13B, 13C, and 13D. For this reason, a general-purpose lens having a small lens diameter can be used, and cost reduction can be realized.
(3) By disposing the varifocal lenses 13A, 13B, 13C, and 13D in parallel, the drive of the variable focal length mechanism and the focus adjustment mechanism can be simply configured by two motors by interlocking with the spur gears. . Further, the varifocal lenses 13A, 13B, 13C, and 13D can be disposed close to each other. For this reason, the volume occupied by the optical antenna is reduced and the number of motors is two, so that the cost and size can be reduced.

  In the first embodiment, four optical fibers 12 are wired to the optical antenna 10 and four varifocal lenses 13 are installed. However, this is only an example, and two or more optical fibers 12 are provided. The optical fiber 12 may be wired and two or more varifocal lenses 13 may be installed.

In the first embodiment, an example in which one wedge prism 14 is disposed for one varifocal lens 13 is shown, but two or more are provided for one varifocal lens 13. Alternatively, the wedge prism 14 may be arranged.
When two or more wedge prisms 14 are arranged, the combined refraction angle is changed by adjusting the azimuth angle of each wedge prism 14, so that the transmission / reception direction can be easily adjusted, and the refraction angle is increased. There is a merit that becomes possible.

In the first embodiment, an example in which the varifocal lenses 13A, 13B, 13C, and 13D are mounted with two lenses is shown, but three or more lenses may be mounted.
When three or more lenses are mounted, the focus adjustment mechanism may be configured to move the lens or lens group instead of moving the optical fiber receptacle 23.
Further, in one varifocal lens 13, instead of using a screw between the lens barrels as a focal length variable mechanism and a focus adjustment mechanism, for example, another method known as a zoom lens technique such as a cam ring is used. It may be.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing an optical antenna according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
The optical antenna of FIG. 3 is built in a housing (not shown) that shields and protects from the external environment such as rain and dust, and this housing is provided with an optical window 31 through which laser light is transmitted. Yes.
The optical window 31 is a flat or curved glass or a plate made of a transparent material.
The varifocal lenses 13A, 13B, 13C, and 13D and the wedge prisms 14A, 14B, 14C, and 14D are arranged so that their optical axes coincide with each other on the circumference of one concentric circle.
Further, the wedge prisms 14A, 14B, 14C, and 14D have the same refraction angle, and are arranged so that all of the transmission / reception directions 32 intersect at substantially one point.

With this configuration, the optical window 31 can be configured to have a diameter that substantially matches the maximum effective diameter of the varifocal lenses 13A, 13B, 13C, and 13D. Therefore, the manufacturing cost of the optical window 31 is low. As a result, the cost can be reduced.
Here, the varifocal lenses 13A, 13B, 13C, and 13D and the wedge prisms 14A, 14B, 14C, and 14D are each arranged so that their optical axes coincide with each other on the circumference of one concentric circle. The optical axis may be arranged on the circumference of a plurality of concentric circles.

Embodiment 3 FIG.
FIG. 4 is a block diagram showing an optical antenna according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG.
The gear belt 41 is a power transmission band made of rubber or the like and provided with gear teeth on the inner side, and the inner gear teeth are the focal length changing gears 16 in the varifocal lenses 13A, 13B, 13C, and 13D. Are engaged.
The gear belt 42 is a power transmission band made of rubber or the like and provided with gear teeth on the inner side, and the inner gear teeth are connected to the focus adjusting gear 18 in the varifocal lenses 13A, 13B, 13C, and 13D. I'm engaged.

In the first embodiment, the focal length variable mechanism and the focus adjustment mechanism of the varifocal lenses 13A and 13D and the focal length variable mechanism and the focus adjustment mechanism of the varifocal lenses 13B and 13C are partially different. However, in the third embodiment, the configurations of the focal length variable mechanism and the focus adjustment mechanism in the varifocal lenses 13A, 13B, 13C, and 13D are all the same.
That is, in the third embodiment, the focal length changing gear 16 and the focus adjusting gear 18 in the varifocal lenses 13A, 13B, 13C, and 13D are not directly meshed with each other but interlocked as shown in FIG. Since the gear belts 41 and 42 are linked to each other, the focal length variation amount and the focus movement amount with respect to the rotation angle of the focal length variable mechanism and the focus adjustment mechanism in the varifocal lenses 13A, 13B, 13C, and 13D are made uniform. be able to. Therefore, the varifocal lenses 13A, 13B, 13C, and 13D can have the same configuration.
Thereby, further cost reduction can be realized.

In the third embodiment, the gear belts 41 and 42 are used to transmit power. However, the present invention is not limited to this, and power may be transmitted using a separately provided gear.
Further, instead of the focal length changing gear 16 and the focus adjusting gear 18, a power may be transmitted by a chain using a sprocket.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Transmission / reception apparatus, 2 Transmission light generation part, 3 Circulator, 4 Optical heterodyne reception part, 5 Signal processing part, 10 Optical antenna, 11 Optical fiber, 12A, 12B, 12C, 12D Optical fiber, 13A, 13B, 13C, 13D Focal lens, 14A, 14B, 14C, 14D wedge prism, 15 optical fiber switch (optical fiber selection means), 16 focal length changing gear (focal length variable mechanism), 17 stepping motor (focal length variable mechanism), 17a pinion gear , 18 Focus adjustment gear (focus adjustment mechanism), 19 Stepping motor (focus adjustment mechanism), 19a Pinion gear, 21 Focusing lens, 22 Variator lens, 23 Optical fiber receptacle, 24 Lens barrel (first lens barrel), 2 Barrel (second lens barrel) 26 barrel (third lens barrel) 27 adjusting ring, 28 bearing, 31 optical window 32 receiving direction, 41 Giyaberuto.

Claims (7)

In an optical antenna that radiates laser light output from a transmission / reception device to a space, and enters the laser light that has been scattered and returned to a target existing in space, and outputs the laser light to the transmission / reception device ,
A plurality of optical fibers for transmitting the laser light;
A plurality of varifocal lenses that are connected to one end of the optical fiber and include a focal length variable mechanism that varies a focal length and a focus adjustment mechanism that adjusts the focus;
An optical fiber comprising: an optical fiber selecting means for selecting an arbitrary optical fiber from the plurality of optical fibers and connecting the other end of the optical fiber to the transmitting / receiving device. antenna. A plurality of wedge prisms are arranged on the surface of the varifocal lens that is not connected to one end of the optical fiber,
The plurality of wedge prisms refract the laser light emitted from the varifocal lens in different directions and radiate it into the space, while allowing the laser light returned from different directions to enter the varifocal lens. The optical antenna according to claim 1. Vari-focal lens
A focusing lens having positive refractive power;
A variator lens having negative refractive power;
An optical fiber receptacle holding one end of the optical fiber;
A first lens barrel for fixing the focusing lens therein;
A second lens barrel for fixing the variator lens therein;
The optical fiber receptacle is fixed inside, and includes a third lens barrel that moves integrally with the second lens barrel,
The focal length variable mechanism is configured to telescopically expand and contract the lengths of the first lens barrel and the second lens barrel by rotating the first lens barrel around the optical axis. It is a mechanism that changes the interval between variator lenses,
The focus adjustment mechanism rotates the second lens barrel around the optical axis, thereby moving the second and third lens barrels together to form a synthetic lens formed by the focusing lens and the variator lens. The optical antenna according to claim 1, wherein the optical antenna is a mechanism that changes a distance between a focal point and one end portion of the optical fiber. The plurality of varifocal lenses have optical axes arranged in parallel to each other,
The variable focal length mechanism is fixed to the outer periphery of the first lens barrel of the plurality of varifocal lenses and rotates the plurality of gears and the plurality of gears, thereby rotating the plurality of varifocal lenses. It consists of a geared electric motor that rotates the first lens barrel around the optical axis,
The focus adjustment mechanism is fixed to the outer periphery of the second lens barrel of the plurality of varifocal lenses and rotates the plurality of gears and the plurality of gears, thereby rotating the first varifocal lens. The optical antenna according to claim 3, wherein the optical antenna includes a geared electric motor that rotates the lens barrel of 2 around the optical axis. The plurality of varifocal lenses have optical axes arranged in parallel to each other,
The variable focal length mechanism includes a plurality of gears fixed to the outer periphery of the first lens barrel of the plurality of varifocal lenses, a gear belt meshing with the plurality of gears, and the gears rotating to rotate the plurality of the plurality of gears. And a geared electric motor that rotates the first lens barrel of the varifocal lens around the optical axis.
The focus adjustment mechanism includes: a plurality of gears fixed to the outer periphery of the second lens barrel of the plurality of varifocal lenses; a gear belt engaged with the plurality of gears; The optical antenna according to claim 3, wherein the optical antenna includes a geared electric motor that rotates the second lens barrel of the varifocal lens around the optical axis. The plurality of varifocal lenses are built in a housing having an optical window through which laser light is transmitted, and are arranged such that the optical axes coincide with each other on one or more concentric circles,
The optical antenna according to claim 2, wherein the plurality of wedge prisms are arranged such that transmission / reception directions of the plurality of varifocal lenses are bent toward a center direction of the optical window. An optical antenna that radiates laser light into space and that is incident on the laser light that has been scattered and returned to a target that exists in space;
In the light wave radar device comprising: a laser beam emitted from the optical antenna to the space; and a transmitter / receiver for observing the target from the laser beam incident on the optical antenna.
The optical antenna is
A plurality of optical fibers for transmitting the laser light;
A plurality of varifocal lenses that are connected to one end of the optical fiber and include a focal length variable mechanism that varies a focal length and a focus adjustment mechanism that adjusts the focus;
An optical wave comprising: an optical fiber selecting means for selecting an arbitrary optical fiber from the plurality of optical fibers and connecting the other end of the optical fiber to the transmitting / receiving device. Radar device.

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