JP3191671B2 - Speed measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed measuring device, and more particularly to a speed measuring device using laser light.

[0002]

2. Description of the Related Art FIG. 9 shows a velocity measuring apparatus using a laser as a light source disclosed in Japanese Patent Application Laid-Open No. 5-312952. 1
01 is a laser oscillating at a single wavelength, 102 is a transmission laser beam, 103 is a target, 104 is a first beam splitter,
105 is a frequency shifter, 106 is a second beam splitter, 107 is a transmission / reception optical system, 108 is scattered light from a target,
Reference numeral 109 denotes received light, 110 denotes a reflecting mirror, 111 denotes a third beam splitter, 112 denotes local light, and 113 denotes a photodetector that performs heterodyne detection. Note that R is the distance from the device to the target 103.

The operation will be described with reference to FIG. The laser light from the laser 101 oscillating at a single wavelength is the transmission laser light 1
02, via the first beam splitter 104, the frequency shifter 105, and the second beam splitter 106,
The target 103 is irradiated by the transmission / reception optical system 107. The frequency of the transmission laser light 102 is shifted by the intermediate frequency f _IF by the frequency shifter 105. The laser beam 108 reflected and scattered from the target 103 is received by the transmission / reception optical system 107, and the second beam splitter 106, the reflection mirror 110,
Through the third beam splitter 111, the light reaches the photodetector 113 as the received light 109. On the other hand, a part of the laser beam from the laser 101 is branched by the first beam splitter 104 and reaches the photodetector 113 via the third beam splitter 111 as the local light 112. The photodetector 113 performs coherent detection and outputs beat signals of the received light 109 and the local light 112.

The frequency of the beat signal and the intermediate frequency f _IF
, That is, the Doppler frequency Δf is proportional to the speed V of the target 103. Thus, the speed of the target 103 can be measured. The following equation holds between the speed V and the Doppler frequency Δf. Δf = 2 · V · cos θ / λ (1) where θ: the angle between the optical axis of the transmission / reception optical system and the target velocity vector, λ: the wavelength of the transmission laser light

In the speed measuring apparatus using a laser light source as described above, if the angle θ between the optical axis of the transmitting and receiving optical system and the target speed vector is not known, as shown in equation (1), the accurate speed of the target cannot be obtained. There are disadvantages that are not required. Further, the speed measuring device as described above can measure the speed when the moving direction of the target is limited, but cannot measure the speed of the target moving in an arbitrary direction.

As a method of measuring the speed of a target moving in an arbitrary direction, there is a method of receiving scattered light from the target by a plurality of optical receivers at different positions. That is, a bi (multi) static radar configuration, which is one of the radar systems using electromagnetic waves, is to be adopted. FIG.
1 shows a bistatic radar device disclosed in Japanese Patent Publication No. 29080. Reference numeral 200 denotes a target, 201 denotes a monostatic radar station that transmits and receives electromagnetic waves, and 202 denotes a bistatic radar receiving station that receives a reflected wave of a transmission wave emitted from the monostatic radar station 201 from the target 200. 203 is a monostatic radar station 201
And 204, a reception beam formed by the antenna of the bistatic radar receiving station 202. Note that R is the distance from the laser device to the target 200, and A is the distance between the monostatic radar station 201 and the bistatic receiving station 202.

In this configuration, the monostatic radar station 2
The target 200 is irradiated with the transmission wave from the target 01, and the reflected wave is received by the monostatic radar station 201 and the bistatic receiving station 202 located at a distance A from each other. Since the angle between the received beam of the monostatic radar station 201 and the bistatic receiving station 202 and the target velocity vector are different, the Doppler frequency of the received wave obtained in each station is different. The target velocity can be obtained from the difference between the Doppler frequency obtained at each station and the angle formed by each reception beam with the target velocity vector.

FIG. 11 shows the configuration of the bi (multi) static radar composed of a laser transmitter and an optical receiver. Reference numeral 301 denotes a laser oscillating at a single wavelength, 302 denotes a transmission laser beam, 303 denotes a target, 304 denotes an optical transceiver,
05 is an optical receiver. 306 is a transmission / reception optical system, 307 is scattered light from the target 303, 308 is the first photodetector, 3
09 is a first local light generator, 310 is a signal processor as speed calculating means, 311 is laser light from the laser 301, 312 is received light received by the transmission / reception optical system 306, 31
3 is a transmission optical system, 314 is transmission light from the transmission optical system 313, 315 is a first reception optical system, 316 is a second local light generator, 317 is scattered light from the target 303, 318
Denotes a second receiving optical system, and 319 denotes a second photodetector.

The operation will be described with reference to FIG. A laser beam 311 from a laser 301 oscillating at a single wavelength is transmitted to a target 303 by a transmission / reception optical system 306 as a transmission laser beam 302.
Is irradiated. The laser light 307 reflected and scattered from the target 303 is received by the transmission / reception optical system 306 and reaches the first photodetector 308 as reception light 312. The first local light generator 309 outputs a laser beam 311 generated by the laser 301.
Supplying local light to the first optical detector 308 with a frequency difference of the intermediate frequency f _IF and. The first photodetector 308 performs coherent detection and outputs a beat signal of the received light 312 and the local light. The transmission optical system 313 transmits a part of the laser light emitted from the laser 301 to the optical receiver 305 as transmission light 314. This is for the optical receiver 305 at a long distance and the transmitted laser light 30
2 and a second local light generator 3
16 to provide a reference signal.

On the other hand, in the optical receiver 305, the direction of the reception beam formed by the first reception optical system 315 is adjusted, and the transmission light 3 from the optical transceiver 304 by the target 303 is adjusted.
02 scattered light 317 is received. The light received from the first receiving optical system 315 is guided to the second photodetector 319. The second receiving optical system 318 receives the transmitted light 314 from the second transmitting optical system 313. The second local light generator 316 generates local light based on the received light from the second receiving optical system 318, and generates a second light detector 319.
Supplied to The second light detector 319 is configured to receive light from the first receiving optical system 315 and a second local light generator 316.
The coherent detection is performed by the local light from the multiplexed light, and both beat signals are generated.

The signal processor 310 calculates the Doppler frequency from the beat signal of the first and second photodetectors 308 and 319 and the angle of the optical axis of the receiving beam of the transmitting / receiving optical system 306 and the receiving beam of the first receiving optical system 315. Calculate the target speed. Speed V
The following expression holds between the respective Doppler frequencies Δf ₁ and Δf ₂ obtained by the optical transceiver 304 and the optical receiver 305. (See FIG. 12) Δf ₁ = 2 · V · cos θ / λ (2) Δf ₂ = 2 · V · cos (θ + δ) / λ (3) δ = π− (α + β) (4) where α is the angle formed by the optical axis of the transmitting and receiving optical system, β is the angle formed by the optical axis of the receiving optical system. From equations (2) to (4), the target velocity V and its moving direction θ are It is represented by ^{_{V 2 = {Δf 1 2 +}} (Δf 1 · cosδ-Δf 2) 2 / sin 2 δ} · λ 2/4 ··· (5) θ = cos -1 {Δf 1 · λ / (2 · V)・ ・ ・ ... (6)

In this bi (multi) static radar configuration, the receiving beam of the optical receiver must be aligned with the target. However, when the position of the target is unknown, it is necessary to scan the reception beam of the optical receiver along the optical axis of the transmission / reception beam of the optical transceiver to search for the target, and it takes time to measure the speed of the target. It was hanging.

[0013]

As described above, the conventional speed measuring apparatus using a laser light source as shown in FIG. 9 cannot measure the speed of a target moving in an arbitrary direction. . A speed measuring device having a bi (multi) static radar configuration as shown in FIG. 10 can measure the speed of a target moving in an arbitrary direction. There was the disadvantage of taking time. In addition, in order to perform coherent detection in an optical receiver located at a position distant from the optical transmitter / receiver, it is necessary to send a laser beam as a local light frequency reference from the optical transmitter / receiver to the optical receiver, and However, a local light generator is required, and there is a disadvantage that the device becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to obtain a speed measuring apparatus having a bi (multi) static radar configuration which can be measured in a short time and has a simple configuration.

[0015]

In a speed measuring apparatus according to the present invention, a means for measuring a target distance to an optical transceiver and an optical axis direction of a receiving beam of the optical receiver are selected based on the distance information. An optical axis direction selecting means is provided.

Further, the optical transceiver is provided with means for connecting the optical transceiver to the optical receiver with an optical fiber and transmitting local light from the optical transceiver to the optical receiver with the optical fiber.

Further, the optical receiver has means for forming a multi-received beam arranged along the optical axis of the laser transmitter, and a signal from a specific receive beam of the multi-received beam is selected by the optical axis direction selecting means. It is something to choose.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows a speed measuring device according to a first embodiment of the present invention. In FIG. 1, 1 is a laser oscillating at a single wavelength, 2 is a transmission beam, 3 is a target,
Denotes an optical transceiver, which constitutes a laser transmitter and a first optical receiver. Reference numeral 5 denotes an optical receiver, which constitutes a second optical receiver. 6 transceiver optics, 7 scattered light from the target 3, 8 the first photodetector 9 is a frequency shifter for frequency shift of the laser oscillator or intermediate frequency f _IF marked with a function of controlling the oscillation frequency The configured local light generator, 10 is a signal processor as speed calculation means, 11 is laser light from the laser 1, 12 is reception light received by the transmission / reception optical system 6, 13
Is the receiving optical system, 14 is the scattered light from the target 3, and 15 is the second
A photodetector 16; a modulating means for modulating the laser 1;
Is a distance measuring means for measuring the distance of the target 3, 18 is an optical axis direction selecting means for selecting the optical axis direction of the receiving beam of the receiving optical system 13, and 19 is a local light from the local light generator 9 of the optical transceiver 4. Is supplied to the optical transceiver 5. Note that R is the distance from the apparatus to the target 3, and A is the distance between the transmission / reception optical system 6 and the reception optical system 13.

Next, a description will be given based on FIG. It is assumed that the target 3 moves in an arbitrary direction on a plane formed by the optical transceiver 4, the optical receiver 5, and the target 3. A laser beam 11 from a laser 1 oscillating at a single wavelength is radiated by a transmission / reception optical system 6 as a transmission beam 2 to a target 3 whose distance is unknown. The laser light 7 reflected and scattered from the target 3 is received by the transmission / reception optical system 6 and reaches the first photodetector 8 as reception light 12. At this time, the laser light 11 is modulated by the modulating means 16, and the distance measuring means 17 correlates the modulation by the modulating means 16 with the received signal obtained from the first photodetector 8, thereby setting the distance R to the target 3. Can be measured. Examples of the modulation method include pulse modulation, intensity modulation, and FM-
CW, pseudo-random modulation and the like.

Next, the distance from the optical transceiver 4 to the target 3 and the irradiation direction of the transmission beam 2 are sent to an optical axis direction selecting means 18 for selecting the optical axis direction of the reception beam of the reception optical system 13. The receiving optical system 13 is a scanning optical system that scans the optical axis of the transmission beam 2 of the optical transceiver 4. Optical axis direction selection means 1
At 8, the position of the target 3 is calculated from the positional relationship between the optical transceiver 4 and the optical receiver 5 and the above information, and the direction of the optical axis is determined so that the receiving optical system 13 allows the receiving beam to catch the target 3. Thereby, the scattered light (14 or 14 ') can be received by combining the receiving beam of the receiving optical system 13 with the target 3 at an arbitrary distance (for example, the point O or the point O') in a short time. . It is assumed that the field of view of the receiving beam of the receiving optical system 13 on the target is larger than the distance resolution of the distance measuring means 17.

The speed of the target 3 is determined by the Doppler frequency from the beat signal obtained by the first and second photodetectors 8 and 15 in the signal processor 10, the transmitting / receiving optical system 6 and the receiving optical system 13.
Is calculated from the angle of the optical axis of the received beam. The local light generator 9 converts the local light having a frequency difference of the intermediate frequency f _{IF from} the laser light 11 generated by the laser 1 to the first light detector 8.
To supply. The first photodetector 8 performs coherent detection, and outputs a beat signal of the received light 12 and the local light. A part of the local light from the local light generator 9 is supplied to the second photodetector 15 via the optical fiber 19. The second photodetector 15 performs coherent detection with the received light from the receiving optical system 13 and the local light from the optical fiber 19, and generates a beat signal of both. Since local light is supplied to the second photodetector 15 by the optical fiber 19, the optical receiver 5 does not need to have a local light generator, and the apparatus can be simplified.

With the above configuration, first, the distance to the target 3 is measured by the distance measuring means 17, and then the direction of the optical axis of the receiving beam of the optical receiver 5 performing the bistatic operation is determined. Thereby, the receiving beam of the optical receiver 5 can be instantaneously adjusted to the target 3, and the speed V of the target 3 can be measured in a short time. Also, since local light is supplied to the optical receiver 5 using the optical fiber 19, the optical receiver 5 does not need to have a local light generator,
The device can be simplified.

Embodiment 2 FIG. When performing coherent detection, it is known that the detection efficiency increases when the focal point of the received beam is placed on a target. Therefore, in the velocity measuring device having the configuration of the first embodiment, the optical axis direction selecting means 18 for selecting the optical axis direction of the reception beam of the reception optical system 13 always causes the focal point of the reception beam of the reception optical system 13 to transmit and receive the light. By adding a function of controlling the focus of the receiving optical system 13 so as to be near the optical axis of the receiving beam of the detector 5, a more efficient speed measuring device can be obtained.

Embodiment 3 FIG. FIG. 2 shows a speed measuring device according to a third embodiment of the present invention. In FIG. 2, reference numeral 20 denotes a multi-receiving beam of the optical receiver 5. Although not shown, the configuration is the same as that of FIG. Since the basic operation is the same as that of the first embodiment, a detailed description is omitted. However, in the second embodiment, the optical receiver 5 is not a scanning optical system, but along the optical axis of the transmission beam of the optical transceiver 4. It has a receiving optical system that forms the multiple receiving beams 20 arranged side by side.

The optical axis direction selecting means for selecting the optical axis direction of the reception beam of the optical receiver 5 calculates the position of the target 3 from the positional relationship between the optical transmitter / receiver 4 and the optical receiver 5 and the above information, and receives the light. The receiving beam including the target 3 is selected from the multiple receiving beams 20 of the device 5. Thus, even for a target at an arbitrary distance, the optical receiver 5 can instantaneously receive the scattered light from the target 3 and measure its Doppler frequency. Therefore, it is possible to measure the speed of the target 3 in a short time.

Embodiment 4 FIG. 3 shows a configuration example of an optical receiver of a speed measuring apparatus according to Embodiment 4 of the present invention.
In FIG. 3, reference numerals 21a, 21b and 21c denote receiving optical system groups for forming a multi-received beam, and 22a, 22b and 22c.
Is a receiving beam forming a multi-receiving beam, 23a, 2
Reference numerals 3b and 23c denote a group of photodetectors paired with the receiving optical systems 21a to 21c, and 24 denotes a receiving beam selection circuit.

A description will be given with reference to FIG. The basic operation is the same as in the first and third embodiments. Multi receiving beam 22a ~
Reference numeral 22c denotes a receiving optical system group including a plurality of receiving optical systems 21a to 21c. Each receiving optical system 21a-
The light received by 21c is guided to photodetector groups 23a to 23c. The local light supplied by the optical fiber 19 is also guided to the photodetector groups 23a to 23c, and performs coherent detection with the received light. The reception beam selection circuit 24 selects a reception beam including the target from the target distance information and the like, obtains a beat signal from the corresponding photodetector, and outputs a Doppler frequency. Thus, even for a target at an arbitrary distance, the optical receiver 5 can instantly receive the scattered light from the target, and measure the Doppler frequency. Therefore, it is possible to measure the target speed in a short time.

Embodiment 5 FIG. 4 shows a configuration example of an optical receiver of a speed measuring apparatus according to Embodiment 5 of the present invention.
In FIG. 4, 25 is an optical switch, 26 is a receiving beam selection means, and 27 is a second photodetector. Other than this, FIG.
This is the same configuration as.

A description will be given with reference to FIG. The basic operation is the same as in the first and third embodiments. Multi receiving beam 22a ~
Reference numeral 22c denotes a receiving optical system group including a plurality of receiving optical systems 21a to 21c. Each receiving optical system 21a-
The light received by 21c is guided to the 1: n optical switch 25. The receiving beam selecting means 26 selects a receiving beam including the target from the target distance information and the like, and controls the optical path by the optical switch 25 so that the receiving light from the receiving optical system corresponding to the target passes through the second photodetector 27. Do. The local light supplied by the optical fiber 19 is also guided to the second photodetector 27, performs coherent detection with the received light, and outputs a Doppler frequency. Thus, even for a target at an arbitrary distance, the optical receiver 5 can instantly receive the scattered light from the target, and measure the Doppler frequency. Therefore, it is possible to measure the target speed in a short time.

Embodiment 6 FIG. FIG. 5 shows a configuration example of an optical receiver of a speed measuring apparatus according to Embodiment 6 of the present invention.
In FIG. 5, 28 is a receiving optical system, 29 is a photodetector array, and a plurality of photodetectors are arranged on one straight line. Reference numeral 30 denotes an optical axis of a multi-received beam formed by the receiving optical system 28 and the photodetector array 29, 31 denotes a lens, 32 denotes a beam splitter, and 33 denotes a signal selection circuit.

A description will be given based on FIG. The basic operation is the same as in the first and third embodiments. The photodetectors on the photodetector array 29 form reception beams having different angles in combination with the reception optical system 28. Since the photodetectors are arranged in a straight line on the photodetector array 29,
A continuous multi-reception beam 30 along the optical axis of the transmission beam of the optical transceiver 4 can be formed. In order to perform coherent detection in the photodetector array 29, the optical fiber 19
Is collimated by a lens 31 and irradiates the entire photodetector array 29 by a beam splitter 32. The signal selection circuit 33 selects a photodetector having a reception beam including the target from the target distance information and the like,
The Doppler frequency is output from the beat signal of the received light and the local light in the photodetector. This makes it possible to select a reception beam of the optical receiver in a short time with respect to a target at an arbitrary distance, receive the scattered light, and measure the Doppler frequency. Therefore, it is possible to measure the target speed in a short time.

Embodiment 7 FIG. 6 shows a configuration example of an optical receiver of a speed measuring apparatus according to Embodiment 7 of the present invention.
In FIG. 6, 34 is a holographic reflection plate, and 35 is an optical axis of local light. Otherwise, the configuration is the same as that of FIG.

A description will be given with reference to FIG. The operation is the same as in the sixth embodiment. In the seventh embodiment, a photodetector array 29 is used.
In this case, the efficiency of coherent detection is improved. The holographic reflector 34 divides the local light into a plurality of beams, matches the optical axis 35 of the local light on each photodetector with the optical axis of the receiving beam 30 of the detector, and matches the wavefront of the local light with the wavefront of the local light. Make the wavefronts of the light coincide. Thereby, the efficiency of coherent detection in the photodetector array 29 is improved. Since the operation is the same as that of the sixth embodiment, the receiving beam of the optical receiver can be selected in a short time for a target located at an arbitrary distance, the scattered light can be received, and the Doppler frequency can be measured. Therefore, it is possible to measure the target speed in a short time.

Embodiment 8 FIG. FIG. 7 shows a configuration example of an optical receiver of a speed measuring apparatus according to an eighth embodiment of the present invention.
In FIG. 7, 36 is an optical deflector, and 37 is an optical axis of deflected local light. Otherwise, the configuration is the same as that of FIG.

A description will be given with reference to FIG. The basic operation is the same as in the first, third, and sixth embodiments. The local light from the optical fiber 19 is condensed by the lens 31 onto the photodetector array 29 via the optical deflector 36 and the beam splitter 32. The optical deflector 36 selects a photodetector having a reception beam including the target from the target distance information and the like, and places the optical axis 37 of the local light and the reception beam 3 of the photodetector on the photodetector.
The optical axes of 0 are matched so that the wavefront of the local light matches the wavefront of the received light. Since the local light can be concentrated on a specific photodetector, the efficiency of coherent detection can be improved.
The signal selection circuit 33 outputs the Doppler frequency from the beat signal of the received light and the local light in the photodetector. This makes it possible to select a reception beam of the optical receiver in a short time with respect to a target at an arbitrary distance, receive the scattered light, and measure the Doppler frequency. Therefore, it is possible to measure the target speed in a short time.

Embodiment 9 FIG. 8 shows a configuration example of an optical receiver of a speed measuring apparatus according to Embodiment 9 of the present invention.
In FIG. 8, reference numeral 38 denotes an optical fiber bundle in which optical fibers are arranged on one straight line, 39 denotes an optical fiber distributor, 40 denotes a photodetector, and 41 denotes a signal selection circuit. Otherwise, the configuration is the same as that of FIG.

A description will be given with reference to FIG. The basic operation is the same as in the first and third embodiments. Since the end faces of the optical fiber bundle 38 are arranged in a straight line, the end faces of the optical fibers are aligned.
Each of the optical fibers on the optical fiber bundle 38 forms a receiving beam having a different angle in combination with the receiving optical system 28. Since the optical fibers are arranged in a straight line on the optical fiber bundle 38, it is possible to form a continuous multi-reception beam 30 along the optical axis of the transmission beam of the optical transceiver 4. The other end of the optical fiber bundle 38 is connected to a photodetector 40. On the other hand, the local light transmitted through the optical fiber 19 is distributed by the optical distributor 39 and multiplexed with the received light transmitted through the optical fiber of each optical fiber bundle 38 by the photodetector 40. The local light and the received light are coherently detected by the photodetector 40. The signal selection circuit 41 selects an optical fiber on the optical fiber bundle 38 having a reception beam including the target from target distance information and the like, and outputs a Doppler frequency from the beat signal of the reception light and the local light. This makes it possible to select a reception beam of the optical receiver in a short time with respect to a target at an arbitrary distance, receive the scattered light, and measure the Doppler frequency. Therefore, it is possible to measure the target speed in a short time.

Embodiment 10 FIG. Further, the optical distributor 39 in the ninth embodiment is provided with the function of an optical switch, and receives the optical fiber on the optical fiber bundle 38 having the reception beam including the target based on the target distance information and the like as in the signal selection circuit 41. Alternatively, only light and local light may be combined. Thus, local light can be concentrated on one optical fiber, so that high coherent detection efficiency can be obtained.

In Embodiments 4 and 5, for convenience, the number of multi-received beams is 3, and Embodiments 6 to 9 are used.
In this example, the number of beams is not particularly limited, and it goes without saying that the same or better effect can be obtained even if the number of beams is increased.

In each of the above embodiments, the transmitting and receiving optical system of the optical transceiver may be coaxial, or may be an optical system in which the optical axes of the transmitting beam and the receiving beam are substantially parallel to each other.

In each of the above embodiments, the moving direction of the target is limited to the plane formed by the optical transmitter / receiver, the optical receiver, and the target. However, the speed of the target moving in any direction (three-dimensional). In order to measure, another optical receiver that performs exactly the same operation may be prepared. That is, the configuration includes an optical transceiver that performs a monostatic operation and two optical receivers that perform a bistatic operation. Further, if necessary, more accurate measurement is possible by using a larger number of optical receivers that perform a bistatic operation.

[0042]

Since the present invention is configured as described above, it has the following effects.

In the speed measuring apparatus according to the present invention, the target distance is measured by means for measuring the target distance from the optical transceiver. The target position is calculated from the optical axis direction of the transmission beam from the optical transceiver and the target distance, and the optical axis direction of the reception beam of the optical receiver performing the bistatic operation is selected. Thus, the target speed can be measured in a short time without unnecessary scanning of the receiving beam of the optical receiver.

Further, since the focus adjusting means for adjusting the focal point of the reception beam of the second optical transceiver so as to be near the optical axis of the reception beam of the first optical receiver is provided, higher efficiency can be achieved. A speed measuring device can be obtained.

Further, the optical transceiver is connected to the optical receiver by an optical fiber, and the local light is transmitted from the optical transceiver to the optical receiver through the optical fiber, whereby the local light is transmitted to the optical receiver performing the bistatic operation. There is no need to provide a generator, and the device can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of a speed measuring device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a speed measuring device according to a third embodiment of the present invention.

FIG. 3 is a block diagram of an optical receiver performing a bistatic operation according to a fourth embodiment of the present invention.

FIG. 4 is a block diagram of an optical receiver performing a bistatic operation according to a fifth embodiment of the present invention.

FIG. 5 is a block diagram of an optical receiver performing a bistatic operation according to a sixth embodiment of the present invention.

FIG. 6 is a block diagram of an optical receiver performing a bistatic operation according to a seventh embodiment of the present invention.

FIG. 7 is a block diagram of an optical receiver performing a bistatic operation according to an eighth embodiment of the present invention.

FIG. 8 is a block diagram of an optical receiver performing a bistatic operation according to a ninth embodiment of the present invention.

FIG. 9 is a block diagram showing a conventional speed measuring device using a laser.

FIG. 10 is a block diagram showing a conventional bi (multi) static radar device.

FIG. 11 is a block diagram showing a conventional speed measuring apparatus using a laser having a bi (multi) static radar configuration.

FIG. 12 is a diagram illustrating a relationship between an optical axis of a reception beam of a conventional optical transceiver and an optical receiver and a target velocity vector.

[Explanation of symbols]

1 laser oscillating at a single wavelength, 2 transmit beam, 3
Target, 4 optical transceivers (laser transmitter and first optical receiver), 5 optical receivers (second optical receiver), 6 transmitting / receiving optical system, 7 scattered light from target, 8 first light detection Bowl, 9
Local light generator, 10 signal processor, 11 laser 1
, Laser light received from the transmitting and receiving optical system 6, 13 receiving optical system, 14 scattered light from the target 3, 1
5 second optical receiver, 16 modulating means for modulating laser 1, 17 distance measuring means for measuring distance of target 3, 18
Optical axis direction selecting means for selecting the optical axis direction of the receiving beam of the receiving optical system 13, 19 an optical fiber for supplying local light to the optical receiver 5, 20 multi-receiving beams of the optical receiver 5, 21a, 21b, 21c Receiving optical system group for forming multiple receiving beams, 22a, 22b, 22c Receiving beams for forming multiple receiving beams, 23a, 23b, 2
3c photodetector group paired with receiving optical system group 21, 24
Reception beam selection circuit, 25 optical switch, 26 reception beam selection means, 27 second photodetector, 28 reception optical system, 29 photodetector array, 30 optical axes of multiple reception beams, 31 lens, 32 beam splitter, 33
Signal selection circuit, 34 holographic reflector, 35 optical axis of local light, 36 optical deflector, 37 optical axis of deflected local light, 38 optical fiber bundle in which optical fibers are arranged on one straight line, 39 optical fiber distributor , 40 photodetector, 41 signal selection circuit.

Continuation of front page (56) References JP-A-4-29080 (JP, A) JP-A-58-79271 (JP, A) JP-A-5-34447 (JP, A) JP-A-57-136174 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/51 G01S 17/00-17/95 G01S 13/00-13/95

Claims (13)

(57) [Claims] 1. A laser transmitter for irradiating a target with laser light, a local light generating means for generating local light, and a first optical axis of a received beam being coaxial or substantially parallel to the optical axis of the laser transmitter. An optical receiver, a second optical receiver positioned at a distance from the first optical receiver such that an angle with respect to a target is different from that of the first optical receiver, and the first and second optical receivers. Speed calculating means for calculating a target speed from a target speed component in the optical axis direction of each reception beam obtained from the optical receiver; a modulation means for modulating laser light from the laser transmitter; and the modulation means. And a distance measuring means for measuring a target distance from a signal received from the first optical receiver; distance information from the distance measuring means;
Optical axis direction selecting means for selecting the optical axis direction of the reception beam of the second optical receiver based on the distance between the optical receivers and the irradiation direction of the laser beam of the laser transmitter. Speed measuring device. 2. An optical axis direction selecting means for selecting an optical axis direction of a reception beam of a second optical receiver is constituted by a scanning optical system for scanning on an optical axis of a laser transmitter. The speed measuring device according to claim 1, wherein 3. A focus adjusting means for adjusting a focal point of a reception beam of the second optical receiver so as to be near an optical axis of the reception beam of the first optical receiver. 2. The speed measuring device according to 2. 4. A laser transmitter for irradiating a target with laser light, local light generating means for generating local light, and a first optical axis of a received beam being coaxial or substantially parallel to the optical axis of the laser transmitter. An optical receiver, a second optical receiver positioned at a distance from the first optical receiver such that an angle with respect to a target is different from that of the first optical receiver, and the first and second optical receivers. A speed calculating means for calculating a target speed from a target speed component in the optical axis direction of each of the reception beams obtained from the optical receivers, wherein the local light generating means A speed measuring device for supplying local light from the optical receiver to the first and second optical receivers via an optical fiber. 5. The second optical receiver has means for forming multiple reception beams aligned along the optical axis of the laser transmitter, and the direction of the optical axis of the reception beam of the second optical receiver is changed. 2. The speed measuring apparatus according to claim 1, wherein a signal from a specific receiving beam of the multi-receiving beam is selected by an optical axis direction selecting means. 6. A speed measuring apparatus according to claim 5, wherein said means for forming a multi-received beam comprises a plurality of pairs of receiving optical systems and photodetectors. 7. A plurality of receiving optical systems, wherein the means for forming a multi-receiving beam comprises a plurality of receiving optical systems, and the optical axis direction selecting means for selecting an optical axis direction of the receiving beam of the second optical receiver comprises the plurality of receiving optical systems. 6. The speed measuring device according to claim 5, further comprising an optical switch for controlling an optical path of a signal from the system. 8. A speed measuring apparatus according to claim 5, wherein said means for forming a multi-received beam comprises one receiving optical system and a photodetector array. 9. Each photodetector of the photodetector array forms a reception beam having a different angle in combination with a reception optical system, and furthermore, local light is transmitted to all photodetectors of the photodetector array. 9. The velocity measuring device according to claim 8, further comprising a beam splitter for irradiating the beam. 10. The local light is split into a plurality of beams,
10. The velocity measuring device according to claim 9, further comprising a holographic reflector for making the optical axis of the local light coincide with the optical axis of the reception beam of the photodetector on each photodetector. 11. The speed measuring device according to claim 8, further comprising a local light deflecting means for supplying local light to any photodetector of the photodetector array. 12. The speed measuring apparatus according to claim 5, wherein the means for forming a multi-received beam comprises one receiving optical system and an optical fiber bundle in which a plurality of optical fibers are bundled. 13. One or more third optical receivers having the same configuration and function as the second optical receiver, wherein the third optical receiver has an angle with respect to the target of the first and second optical receivers. 2. The speed measuring device according to claim 1, wherein the speed measuring device is located apart from the first and second optical receivers differently from the receiver.