JP2002156452A - Laser radar system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser radar system which can be made inexpensive and constituted to small size and can measure light intensity characteristics with high precision. SOLUTION: This laser radar system 1 equipped with a transmission device 2 which sends laser light B1 and a reception device 3 which receives a scattered light of the laser light scattered by a scattering body; and the transmission device 2 is so constituted as to send laser lights B1 with mutually different wavelengths λ1 to λN in synchronism with a synchronizing signal TP generated having a specific time difference in order and the reception device 3 is equipped with a photodetection part 10 which photoelectrically converts the scattered light B11 and outputs an electric signal S11 in order and a measurement part 11 which measures light intensity characteristics for reception times by the wavelengths with the λ1 to λN included in the scattered light B11 in synchronism with the synchronizing signal TP according to the electric signal S11 outputted by the photodetection part 19 in sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmitting laser light having different wavelengths, receiving scattered light of laser light scattered by a scatterer, and receiving time for each wavelength contained in the scattered light. The present invention relates to a laser radar system for measuring a light intensity characteristic of a laser radar.

[0002]

2. Description of the Related Art As a laser radar system of this kind,
A laser radar system 91 shown in FIG. 11 is conventionally known. This laser radar system 91 has N kinds of wavelengths different from each other (λ1 to λN: N is a natural number of 2 or more).
Are transmitted simultaneously from the transmitter 92 to the scatterer, and the scattered light scattered by the scatterer is received by the receiver 93.
At the wavelengths λ1 to λN contained in the scattered light.
It is configured to be able to measure a light intensity characteristic (hereinafter, also simply referred to as “light intensity characteristic”) representing the light intensity for each reception time. Therefore, this laser radar system 91
For example, the distribution state of atmospheric molecules and aerosol (suspended particulate matter) in the atmosphere can be observed based on the light intensity characteristics measured by the method. Specifically, the intensity of the scattered light due to the aerosol or the like depends on the particle size and the wavelength of the transmission laser. Therefore, by measuring the wavelength of the scattered light and the amount of scattered light at the wavelength, the particle size of the scatterer and its concentration distribution can be measured. Further, by measuring the reception time until receiving the scattered light of the wavelength, the distance from the transmitting device 92 to the aerosol or the like can be measured. Therefore, the laser radar system 91 can measure the concentration distribution (hereinafter, also referred to as “particle size distribution”) for each particle size of the aerosol or the like in the atmosphere by measuring the light intensity characteristics for each wavelength. Has become.

The transmitting device 92 includes a trigger generator 5, a laser generator 6, and a wavelength converter 33. In this case, the trigger generator 5 generates a synchronization signal (trigger) TP and outputs the signal to the laser generator 6. The laser generator 6 generates a pulsed laser beam B1 in synchronization with the input synchronization signal TP, and outputs the pulsed laser beam B1 to the wavelength converter 33. On the other hand, the wavelength conversion unit 33 is configured to be capable of performing wavelength conversion using, for example, Raman scattering of methane, and converts the input laser light B1 as the excitation laser light into multiple wavelengths λ1 to λN.
And the converted laser lights of multiple wavelengths λ1 to λN are simultaneously transmitted on the same optical axis.

On the other hand, the receiving device 93 includes a telescope 9, a spectroscopic unit 43, N light detecting units 10, and N measuring units 11. In this case, the telescope 9 condenses the light scattered on the scatterer out of the laser light transmitted by the transmission device 92 and outputs the collected light as scattered light B11. Also,
The spectroscopy unit 43 transmits the input scattered light B11 to the transmitting device 92.
Are dispersed into scattered lights B12 (λ1 to λN) respectively corresponding to the respective wavelengths λ1 to λN of the laser light transmitted by the above.
Each photodetector 10 is composed of a weak photodetector such as a photomultiplier tube or an APD (avalanche photodiode). The photodetector 10 is provided for each dispersed scattered light B12 of each wavelength and scattered light B12 of each wavelength. And outputs an electric signal S11 generated by photoelectric conversion. In addition, each measurement unit 11
Is configured to include a digital oscilloscope when measuring by the analog measurement method, and is configured to include a pulse counter when measuring by the photon counting method, and is provided corresponding to each light detection unit 10. Further, each measuring unit 11 measures the light intensity characteristics for each of the wavelengths λ1 to λN based on the input electric signal S11.

In the laser radar system 91, first, the trigger generator 5 of the transmitter 92 generates a synchronization signal TP and outputs it to the laser generator 6 and each of the measuring units 11. Next, the laser generation unit 6 outputs the input synchronization signal T
The laser beam B <b> 1 is generated in synchronization with P and output to the wavelength conversion unit 33. Next, the wavelength conversion unit 33 converts the input laser light B1 into multi-wavelength laser light and transmits it to the atmosphere.
On the other hand, in the receiving device 93, the telescope 9 receives and condenses the multi-wavelength laser light scattered by the scatterer. Subsequently, the spectroscopic unit 43 converts the scattered light B11 output by the telescope 9 into scattered light B corresponding to each of the wavelengths λ1 to λN.
The light is split into two and output almost simultaneously. Next, each photodetector 10 photoelectrically converts the dispersed scattered light B12 of each wavelength into a corresponding electric signal S11. Next, based on the electric signal S11 corresponding to each wavelength output by the corresponding light detection unit 10, each measurement unit 11 synchronizes the light intensity characteristics of the scattered light of each wavelength with the synchronization signal TP. It measures and outputs it as observation data DM.

[0006]

However, the conventional laser radar system 91 has the following problems. That is, in the conventional laser radar system 91, the light detection unit 10 requiring an expensive weak light detection element such as a photomultiplier tube or an APD, and the measurement unit 11 including an expensive digital oscilloscope or a pulse counter are included. It is necessary to provide as many as the number of wavelengths (N sets) of laser light to be received. For this reason, there is a problem that the system cost of the laser radar system 91 has risen extremely. Further, the laser radar system 91 has a problem that it becomes a large-scale system due to the provision of a large number of the light detection units 10 and the measurement units 11. Furthermore, since many weak light detecting elements are used, there is a problem that the measurement accuracy is reduced due to variations in characteristics among the weak light detecting elements. In this case, it is possible to correct the variation, but
It is difficult to accurately correct due to a change over time or the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its main object to provide a laser radar system which can be configured inexpensively and compactly and can measure light intensity characteristics with high accuracy.

[0008]

According to a first aspect of the present invention, there is provided a laser radar system for transmitting a laser beam, and a receiving device for receiving a scattered beam of the laser beam scattered by a scatterer. A laser radar system including a device, wherein the transmitting device is configured to sequentially transmit laser beams having different wavelengths in synchronization with a synchronization signal generated at a predetermined time difference, and the receiving device includes: A photodetector for sequentially photoelectrically converting the scattered light to output an electric signal; and a light corresponding to the reception time for each wavelength included in the scattered light based on the electric signal sequentially output by the photodetector. And a measuring unit for measuring an intensity characteristic in synchronization with the synchronization signal.

According to a second aspect of the present invention, there is provided a laser radar system.
2. The laser radar system according to claim 1, wherein the transmitting device is provided with a laser generating unit that generates a laser beam, and a laser of each wavelength that is provided for each of the wavelengths and transmits the wavelength of the input laser beam. A plurality of wavelength converters for respectively converting the light into light; and an optical switching unit for sequentially outputting the laser light generated by the laser generation unit to the wavelength converters in synchronization with the synchronization signal. It is characterized by.

The laser radar system according to claim 3 is
2. The laser radar system according to claim 1, wherein the transmitting device includes: a laser generating unit that generates a laser beam; a wavelength converting unit that converts the wavelength of the laser beam to simultaneously generate the laser beams of the respective wavelengths; A light selector for sequentially selecting laser light of each wavelength generated by the converter in synchronization with the synchronization signal, and sequentially outputting the selected laser light of each wavelength as the laser light of each transmitted wavelength; And characterized in that:

A laser radar system according to claim 4 is
2. The laser radar system according to claim 1, wherein the transmitting device includes: a laser generating unit that generates a laser beam; a wavelength converting unit that converts the wavelength of the laser beam to simultaneously generate the laser beams of the respective wavelengths; A spectroscopic unit that splits the laser light generated by the converting unit for each of the wavelengths, and sequentially sets the laser light split by the spectroscopic unit as a laser beam of each wavelength to be transmitted with a time difference between the wavelengths. And an optical delay unit for outputting.

According to a fifth aspect of the present invention, there is provided a laser radar system.
A transmitting device that transmits laser light, and a receiving device that receives the scattered light of the laser light scattered by the scatterer, the transmitting device transmits a laser light obtained by multiplexing a plurality of laser lights having different wavelengths. At least as many times as the number of types of the wavelengths, it is configured to be able to transmit sequentially in synchronization with the synchronization signal, and the receiving device is configured to separate the scattered light into the wavelengths by the spectral unit and the spectral unit. A light detection unit that sequentially performs photoelectric conversion of the scattered light in synchronization with the synchronization signal, and light that outputs the scattered light of each wavelength separated by the spectroscopy unit to the light detection unit in synchronization with the synchronization signal. The switching unit, the light intensity characteristics for the reception time for each wavelength included in the scattered light based on the electrical signal corresponding to each wavelength sequentially output by the light detection unit to the synchronization signal same Characterized in that it is constituted by a measuring unit for measuring and.

A laser radar system according to claim 6 is
A transmitting device that transmits laser light, and a receiving device that receives the scattered light of the laser light scattered by the scatterer, the transmitting device transmits a laser light obtained by multiplexing a plurality of laser lights having different wavelengths. At least as many times as the number of types of the wavelengths are configured so as to be sequentially transmitted in synchronization with the synchronization signal, and the receiving device sequentially selects the scattered light of each wavelength from the scattered light in synchronization with the synchronization signal. A light selection unit for outputting the light, a light detection unit for sequentially photoelectrically converting the scattered light of each wavelength sequentially output by the light selection unit, and a light detection unit corresponding to each of the wavelengths sequentially output by the light detection unit. A measuring unit that measures a light intensity characteristic with respect to a reception time for each wavelength included in the scattered light based on an electric signal in synchronization with the synchronization signal. .

According to a seventh aspect of the present invention, there is provided a laser radar system.
A transmitting device that transmits laser light, and a receiving device that receives the scattered light of the laser light scattered by the scatterer, the transmitting device transmits a laser light obtained by multiplexing a plurality of laser lights having different wavelengths. The receiving device is configured to be able to transmit at the same time, the receiving device includes a spectroscopic unit that disperses the scattered light for each wavelength, and an optical delay unit that sequentially outputs the scattered light separated by the spectroscopic unit with a time difference for each wavelength. A multiplexing unit that multiplexes the scattered lights of the respective wavelengths sequentially output by the optical delay unit and sequentially outputs the scattered lights of the respective wavelengths, and sequentially photoelectrically converts the scattered light of the respective wavelengths sequentially output by the multiplexing unit. A light detection unit, and a light intensity characteristic with respect to a reception time for each wavelength included in the scattered light based on an electric signal corresponding to each wavelength sequentially output by the light detection unit; Sync to Characterized in that it is constituted by a measuring unit for measuring.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a laser radar system according to the present invention will be described with reference to the accompanying drawings. Note that the same components as those of the conventional laser radar system 91 are denoted by the same reference numerals, and redundant description will be omitted.

First, the configuration of the laser radar system 1 will be described with reference to the drawings.

As shown in FIG. 1, a laser radar system 1 includes a transmitter 2 for transmitting laser light of multiple wavelengths (λ1 to λN) and a receiver for receiving scattered light of laser light scattered by a scatterer. 3 is provided. The transmitting device 2
A trigger generation unit 5, a laser generation unit 6, a wavelength conversion unit 7 including a plurality of (N-1) wavelength converters 7A2 to 7AN (hereinafter, also referred to as a "wavelength converter 7A" when not distinguished), and light A switching unit 8 is provided.

In this case, the trigger generation section 5 generates a synchronization signal TP (hereinafter, also referred to as “TP1 to TPN” when distinguished) at a predetermined cycle (a predetermined time difference). The laser generator 6 generates a laser beam B1 (wavelength λ1) in synchronization with the synchronization signal TP. Also, the light switching unit 8
Are N mirrors 8A1 to 8A8 respectively arranged on the optical axis X of the laser beam B1 generated by the laser generator 6.
AN (hereinafter, also referred to as “mirror 8A” when not distinguished) and N shutters 8B1 to 8BN (hereinafter, not distinguished) arranged on each optical axis of the laser beam B1 reflected by each of the mirrors 8A1 to 8AN. The laser beam B1 generated by the laser generator 6 is sequentially output to the wavelength converter 7A in synchronization with the synchronizing signal TP. In this case, the mirror 8A1 is constituted by a total reflection type mirror through which light does not pass, and the other mirrors 8A2 to 8AN have their reflectivity so that the intensity of the laser beam B1 toward each of the shutters 8B1 to 8BN is substantially uniform. And a half mirror whose transmittance is adjusted in advance. Note that the synchronization signal T
The cycle of P is set to a time longer than the control time of the shutter 8B. In addition, each shutter 8B1-8B
N opens the laser beam B1 reflected by the mirror 8A by opening for a predetermined time when the corresponding synchronization signals TP1 to TPN are input. Further, each of the wavelength converters 7A2 to 7AN has a shutter 8 respectively.
The laser light B1 is arranged on the optical axis of the laser light B1 passing through B2 to 8BN and passes through a crystal for wavelength conversion so that the wavelength of the laser light B1 is λ2, λ3,.
The light is converted into a laser light of λN and transmitted.

On the other hand, the receiving device 3 is provided with one telescope 9, one light detecting unit 10, and one measuring unit 11. In this case, the telescope 9 has a predetermined viewing angle, receives scattered light from the scatterer included in the viewing angle, collects the scattered light, and outputs the scattered light as scattered light B11. Further, the light detection unit 10 photoelectrically converts the scattered light B11 output by the telescope 9 and sequentially outputs the scattered light B11 as an electric signal S11. Also,
The measuring unit 11 includes a pulse counter, and is configured to be able to count the light intensity characteristics for each of the wavelengths λ1 to λN according to the photon counting method.
Based on 11, the light intensity characteristics for each of the wavelengths λ1 to λN included in the scattered light from the scatterer are measured in synchronization with the synchronization signal TP. Note that the measuring unit 11 may be provided with a digital oscilloscope so as to enable analog measurement.

Next, the operation of the laser radar system 1 will be described with reference to an example of observation of aerosol in the atmosphere.

In this laser radar system 1, FIG.
As shown in (a), the trigger generation unit 5 sequentially generates the synchronization signals TP1 to TPN at a predetermined cycle, and sends the synchronization signals TP1 to TPN to the laser generation unit 6, the shutter 8B, and the measurement unit 11, respectively.
P is sequentially output. At this time, the laser generator 6 outputs a laser beam B1 (wavelength λ1) for a predetermined time in synchronization with each synchronization signal TP, as shown in FIG. on the other hand,
Each of the shutters 8B1 to 8BN opens for a predetermined time in synchronization with the corresponding synchronization signal TP each time the corresponding synchronization signal TP is input, as shown in FIGS. Thereby, the laser beam B1 reflected by each of the mirrors 8A1 to 8AN passes through the shutter 8B1, the shutter 8B2,... In this case, the laser beam B1 that has passed through the shutter 8B1 is transmitted from the transmitting device 2 as a laser beam having the wavelength λ1 without being subjected to wavelength conversion. Subsequently, the laser light B1 that has passed through the shutters 8B2 to 8BN, respectively.
Are sequentially input to the wavelength converters 7A2 to 7AN, are wavelength-converted, and are sequentially transmitted by the transmission device 2 as laser beams having wavelengths λ2 to λN. In this way, the transmitting device 2 sequentially transmits the laser beams having the wavelengths λ1 to λN into the atmosphere at a predetermined cycle, as shown in FIG.

On the other hand, in the receiving device 3, each time the transmitting device 2 transmits the laser light having the wavelength λ1 to the wavelength λN, the telescope 9 sequentially receives the laser light having the wavelength λ1 to the wavelength λN scattered by the aerosol in the atmosphere. And focus. Next, the light detection unit 10 sequentially photoelectrically converts the scattered light B11 collected by the telescope 9 into a pulse-like electric signal S11 and outputs the signal to the measurement unit 11. Subsequently, the measurement unit 11 measures the number of pulses exceeding a predetermined level in the electric signal S11 output by the light detection unit 10 in synchronization with each of the synchronization signals TP1 to TPN. ~ TP
The light intensity of the scattered light B11 with respect to the elapsed time (reception time) after N is input is measured. Next, the measuring unit 11
As shown in FIG. 2 (g), observation data D representing the light intensity characteristics of each wavelength λ1 to λN by converting the light intensity into data.
It is output as M (light intensity characteristic).

Here, the observation data DM shown in FIG.
Indicates that the light intensity corresponds to the aerosol concentration and that each synchronization signal T
The elapsed time from the rising edge of P corresponds to the distance from the laser radar system 1 (ground) to the aerosol. Therefore, each observation data DM for each wavelength λ1 to λN corresponds to the concentration distribution of the aerosol in the atmosphere from the ground. In addition, the transmitting device 2 repeatedly transmits the laser beams of the wavelengths λ1 to λN to the atmosphere, and the receiving device 3 generates the observation data DM each time and performs each observation. Data DM
Can be averaged to obtain the final observation data DM. According to such a configuration, a more reliable aerosol particle size distribution can be measured.

As described above, the laser radar system 1
According to the above, the receiving device 3 is provided with a set of the photodetecting unit 10 and the measuring unit 11, so that regardless of the number of wavelengths of the laser light to be transmitted, expensive and weak light sources such as a photomultiplier tube and an APD are used. Since it can be configured using one photodetector, the cost can be significantly reduced as compared with the conventional laser radar system 91. In addition, since the receiving device 3 can be configured to include one set of the light detecting unit 10 and the measuring unit 11, the size of the receiving device 3 can be reduced, and the size of the entire laser radar system 1 can be reduced. Furthermore, since one weak light detecting element is used, the measurement accuracy does not decrease due to the variation in the characteristics of the weak light detecting element. As a result, the light intensity characteristics can be measured with high accuracy.

It should be noted that the present invention is not limited to the configuration shown in the above embodiment of the present invention. For example, each wavelength λ1
Each of the configurations shown in FIGS. 3 to 6 can be adopted as the configuration of the transmission device that sequentially transmits the laser beams of up to λN at a predetermined cycle. In the following description, the same components as those of the laser radar system 1 are denoted by the same reference numerals,
Duplicate description will be omitted.

The laser radar system 21 shown in FIG.
It comprises a transmitting device 22 and a receiving device 3. The transmission device 22 includes an optical switching unit 23 instead of the optical switching unit 8 in the transmission device 2. In this case, the light switching unit 2
3 is a laser beam B1 generated by the laser generator 6
One variable angle mirror (scanning mirror) 23A and N fixed mirrors 23B arranged on the optical axis X
1 to 23BN (hereinafter, also referred to as “fixed mirror 23B” when not distinguished). In this case, the angle-variable mirror 23A changes the optical axis X of the laser beam B1 output by the laser generator 6 to the fixed mirrors 23B1-2.
Selectively switch to any of the 3BN installation directions. Note that the cycle of the synchronization signal TP is determined by the angle variable mirror 23A.
Is set to a time longer than the control time. Also,
Each of the fixed mirrors 23B1 to 23BN has a function of changing the optical axis of each laser beam B1 reflected by the variable angle mirror 23A, and outputs the laser beam B1 reflected by the variable angle mirror 23A to the wavelength converter 7A. Make it incident. Each of the wavelength converters 7A2 to 7AN is connected to each of the fixed mirrors 2.
It is arranged on the optical axis of each laser beam reflected by 3B2 to 23BN.

In the laser radar system 21, the angle variable mirror 23A changes the angle in a stepwise manner in synchronization with the synchronization signals TP1 to TPN, thereby converting the laser beam B1 output by the laser generator 6 into each of the laser beams B1. The fixed mirror 23B1, the fixed mirror 23B2,..., And the fixed mirror 23BN are sequentially reflected toward the fixed mirror 23B. At this time, the fixed mirror 23B
1 is reflected by the laser beam B1 as it is at the wavelength λ.
Transmitted from the transmission device 22 as one laser beam. The laser beams B1 reflected by the fixed mirrors 23B2 to 23BN are sequentially input to the wavelength converters 7A2 to 7AN, the wavelengths are respectively converted, and are sequentially transmitted from the transmission device 22 as laser beams having wavelengths λ2 to λN. . In this way, the transmission device 22 transmits the wavelengths λ1 to λ
N laser beams are transmitted to the atmosphere in that order. On the other hand, the receiving device 3 receives the sequentially input scattered lights of the wavelengths λ1 to λN and measures the light intensity characteristics for each of the wavelengths λ1 to λN in the same manner as the receiving device 3 in the laser radar system 1, The aerosol concentration distribution in the atmosphere from the ground and the particle size distribution of the aerosol are measured.

According to the laser radar system 21,
Since the laser radar system 1 has the effect of the laser radar system 1 and can avoid the attenuation of the laser beam B1 due to the passage of the half mirror as compared with the laser radar system 1 in which the optical switching unit 8 is configured using the half mirror, the laser generation is performed. Part 6
Can be reduced accordingly. As a result, it is possible to reduce the cost of the transmission device 22 and the cost of the laser radar system 21.

Next, the laser radar system 31 will be described with reference to FIG. Note that the same components as those of the above-described laser radar systems are denoted by the same reference numerals, and redundant description will be omitted.

The laser radar system 31 includes a transmitting device 32 and a receiving device 3. Transmission device 32
Are the optical switching unit 8 and the wavelength conversion unit 7 in the transmission device 2.
, A wavelength conversion unit 33 and a light selection unit 34 are provided. In this case, for example, the wavelength conversion unit 33
The laser beam B1 generated by the laser generation unit 6 is converted into a multi-wavelength (wavelength λ1) by using Raman scattering of methane with respect to an excitation laser beam (for example, a YAG fundamental wave of 1064 nm).
~ ΛN, for example, primary Stokes 1542 nm, anti-Stokes 812 nm, secondary Stokes 2800 n
m, anti-Stokes 656 nm)
Generate The light selector 34 sequentially selects the laser beams B2 of the respective wavelengths λ1 to λN generated by the wavelength converter 33 in synchronization with the synchronization signal TP output by the trigger generator 5, and sequentially selects the selected laser beams B2. A laser beam having a wavelength of λ1 to λN is transmitted. As an example, as shown in FIG. 5, the light selecting unit 34 includes a rotating disk body 34 b in which N holes are provided concentrically, and N filters 34 A 1 to 34 AN (hereinafter, referred to as “N”) attached to each hole. If not distinguished, it is also referred to as “filter 34A”).

In the laser radar system 31, the wavelength converter 33 generates a multi-wavelength laser beam B2 from the laser beam B1 generated by the laser generator 6. In this case, the rotating disk 34b rotates the filters 34A1 to 34AN in a stepwise manner in synchronization with the synchronization signal TP. At this time, each of the filters 34A rotates to a predetermined position P1 on the optical axis of the laser beam B1, thereby causing the laser beam B2 to rotate.
The laser light of the wavelength corresponding to each pass frequency band of each filter 34A is transmitted through the filter 34A. As a result, the rotating disk 34b outputs the synchronization signal T
By sequentially rotating stepwise in synchronization with P, laser lights of wavelengths λ1 to λN respectively corresponding to the pass frequency bands of the filters 34A1 to 34AN are selected in synchronization with the synchronization signal TP, and sequentially. Sent.

According to the laser radar system 31,
In addition to the effect of the laser radar system 1, the configuration can be made without using a half mirror or a mirror that is easily damaged.
The handleability can be improved, and the cost can be reduced by reducing the number of parts. In addition, as a result of omitting steps such as a mirror angle adjustment operation that requires time for adjustment, it is possible to reduce the system manufacturing time and the system cost. further,
The size of the optical system can be reduced by not using a mirror.

Next, the laser radar system 41 will be described with reference to FIG. Note that the same components as those of the above-described laser radar systems are denoted by the same reference numerals, and redundant description will be omitted.

The laser radar system 41 includes the transmitting device 4
2 and a receiving device 3. The transmitting device 42 includes a spectroscopic unit 43 and an optical delay unit 44 instead of the optical selecting unit 34 in the laser radar system 31. In this case, the light splitting unit 43 is configured by, for example, a prism or the like, and splits the laser light B2 of multiple wavelengths (wavelengths λ1 to λN) generated by the wavelength conversion unit 33 for each wavelength. Further, the optical delay unit 44 includes the same number of optical fibers 44A1 to 44A4 as the number of types of wavelengths split by the splitter 43.
4AN. In this case, each optical fiber 44
A1 to 44AN have mutually different lengths, and laser beams of wavelengths λ1 to λN are sequentially transmitted at regular intervals. On the other hand, the receiving device 3 is a laser radar system 31
The observation data DM is generated in synchronization with the synchronization signal TP in the same manner as in the receiving device 3 in.

According to the laser radar system 41,
In addition to the effects of the laser radar system 1, the laser radar system 31 can be configured without using a breakable half mirror or mirror in the same manner as the laser radar system 31, so that the handleability can be improved and the number of parts can be reduced to reduce costs. Can be reduced. In addition, as a result of omitting steps such as a mirror angle adjustment operation that requires time for adjustment, it is possible to reduce the system manufacturing time and the system cost. Further, the size of the optical system can be reduced as much as the mirror is not used.

Each of the above-described laser radar systems 1
In such a case, the transmitting device transmits the laser lights of the respective wavelengths λ1 to λN in that order in synchronization with the synchronization signal TP, and the receiving device sequentially photoelectrically converts the scattered lights of the respective wavelengths λ1 to λN that are sequentially input. At the same time, the light intensity characteristic of each wavelength is measured in synchronization with the synchronization signal TP. However, the transmitting device performs multi-wavelength (wavelength λ1 to λ1) combining a plurality of laser beams having different wavelengths.
[lambda] N) can be employed in which laser light is sequentially transmitted at least as many times (N times) as the number of wavelength types in synchronization with the synchronization signal TP. In this case, the receiving device can adopt a configuration in which light of each wavelength is separated or selected from the received scattered light of multiple wavelengths, and the light intensity characteristics of each of the wavelengths λ1 to λN are measured. Hereinafter, a laser radar system having this configuration will be described with reference to FIGS. The same components as those of the above-described laser radar systems 1, 21, 31, and 41 are denoted by the same reference numerals, and redundant description will be omitted.

The laser radar system 51 shown in FIG.
The transmission device 52 and the reception device 53 are provided, and the configuration of the transmission devices 2 and 42 described above is applied to the reception device 53. In this case, the transmission device 52 includes the trigger generation unit 5,
It comprises a laser generator 6 and a wavelength converter 33. On the other hand, the receiving device 53 includes the telescope 9 and the spectral unit 4.
3. It comprises a light switching unit 55, a light detection unit 10, and a measurement unit 11. In this case, the light splitting unit 43 splits the scattered light B11 condensed by the telescope 9 into each of the wavelengths λ1 to λN of the transmitted laser light. Also, the light switching unit 5
Reference numeral 5 denotes each of the wavelengths λ1 to λN output by the spectral unit 43.
Of the scattered light B12 in synchronization with the synchronization signal TP
Output to 0. As an example, the light switching unit 55 includes the spectroscopic unit 4
3 scattered light B1 of each wavelength λ1 to λN output by
2 for each of the corresponding synchronization signals TP1 to TP1.
N that opens when TPN is input and transmits scattered light
Shutters 8B1 to 8BN and each shutter 8B1
And a multiplexing unit 55a that multiplexes and outputs the scattered light B12 of each of the wavelengths λ1 to λN that have passed through BN.

In the laser radar system 51, the trigger generation section 5 generates a synchronization signal TP at a predetermined cycle, and outputs the generated synchronization signal TP to the laser generation section 6, each shutter 8B, and the measurement section 11. At this time, the laser generator 6 outputs the laser beam B1 to the wavelength converter 33 for a predetermined time in synchronization with each synchronization signal TP. Next, the wavelength conversion unit 33 uses the laser beam B1 generated by the laser generation unit 6 as an excitation laser beam and has multiple wavelengths (wavelengths λ1 to λ).
N) Generate and transmit laser light. Thus, the multi-wavelength laser light is output N times in synchronization with the synchronization signal TP. On the other hand, in the receiving device 53, the telescope 9 constantly receives and collects the scattered light from the aerosol included in the viewing angle,
The collected scattered light B11 is output to the spectroscopy unit 43. Next, each time the scattered light B11 is output by the telescope 9, the spectroscopic unit 43 simultaneously outputs the scattered light B12 (λ1 to λN) including the laser light of the wavelengths λ1 to λN. Subsequently, the shutters 8B1 to 8BN of the light switching unit 55 are opened one by one in that order in synchronization with the sequentially input synchronization signals TP1 to TPN. Thereby, each shutter 8B1-8
The scattered lights B12 of the respective wavelengths λ1 to λN that have passed through the BN are sequentially output to the multiplexing unit 55a. Next, the multiplexing unit 55a
The scattered lights B12 of the respective wavelengths λ1 to λN are multiplexed and sequentially output on one optical axis. Thereby, the scattered lights B12 of the respective wavelengths λ1 to λN are sequentially output to the light detection unit 10 in that order. Thereafter, similarly to the receiving device 3, the measuring unit 11
The light intensity characteristics of each of the wavelengths λ1 to λN are measured in synchronization with the synchronization signal TP and output as observation data DM. As a result, the light intensity characteristics for each of the wavelengths λ1 to λN included in the received scattered light are measured.

According to the laser radar system 51,
As in the case of the laser radar system 1, the receiving device 53 includes one set of the photodetecting unit 10 and the measuring unit 11, so that the photomultiplier tube and the APD can be used regardless of the number of wavelengths of the laser light to be transmitted. , Etc., it is possible to reduce the cost as compared with the conventional laser radar system 91. In addition, since the receiving device 53 can be configured by including one set of the light detecting unit 10 and the measuring unit 11, the size of the receiving device 53 can be reduced, and the size of the entire laser radar system 51 can be reduced. Furthermore, since one weak light detection element is used, the measurement accuracy does not decrease due to the variation in the characteristics of the weak light detection element.
Light intensity characteristics can be measured with high accuracy.

Next, the laser radar system 61 will be described with reference to FIG.

The laser radar system 61 includes the transmitting device 5
2 and a receiving device 63. The transmitting device 22 described above is applied to the receiving device 53. In this case, the receiving device 63 includes the optical switching unit 23 instead of the optical switching unit 55 of the receiving device 53. Optical switching unit 2
Reference numeral 3 includes N fixed mirrors 23B1 to 23BN and one variable angle mirror 23A. Here, the fixed mirror 23B is provided corresponding to each of the scattered lights B12 of the wavelengths λ1 to λN output by the spectroscopic unit 43, and the scattered light B12 is directed toward the angle variable mirror 23A.
(Λ1 to λN) are reflected. The angle-variable mirror 23A rotates in a stepwise manner in synchronization with the synchronization signal TP, and sequentially reflects the scattered light B12 reflected by the fixed mirrors 23B1 to 23BN toward the light detection unit 10.

In the laser radar system 61, the light switching unit 23 of the receiving device 63 basically performs the reverse operation of the light switching unit 23 in the laser radar system 21. That is, in the optical switching unit 23 of the receiving device 63, the telescope 9
Each time receives the scattered light of each wavelength λ1 to λN from the scatterer, the fixed mirrors 23B1 to 23BN
Of the scattered light B12 split by the
Reflect 3A. Next, the angle variable mirror 23A
Is synchronized with each of the synchronization signals TP1 to TPN to generate the scattered light B
The scattered light B <b> 12 having one wavelength among the wavelengths λ <b> 1 to λN included in the scattered light 12 is sequentially selected and output to the light detection unit 10. According to the laser radar system 61, similarly to the laser radar system 51, the receiving device 63 can be configured by including one set of the light detecting unit 10 and the measuring unit 11. As a result, the cost of the receiving device 63 can be reduced, and the size of the receiving device 63 can be reduced, and further, the overall size of the laser radar system 61 can be reduced. In addition, since one weak light detection element is used, a decrease in measurement accuracy due to variations in the characteristics of the weak light detection element does not occur, so that the light intensity characteristics can be measured with high accuracy.

Next, the laser radar system 71 will be described with reference to FIG.

The laser radar system 71 includes the transmitting device 5
2 and a receiving device 73. The transmitting device 32 described above is applied to the receiving device 53. In this case, the receiving device 73 includes the light selecting unit 34 instead of the light splitting unit 43 and the light switching unit 55 of the receiving device 53. The light selecting unit 34 sequentially synchronizes the scattered light B12 of one of the wavelengths λ1 to λN included in the multi-wavelength scattered light B11 collected by the telescope 9 in synchronization with the synchronization signal TP. Select and output to the light detection unit 10. According to the laser radar system 71, similarly to the laser radar system 51, the receiving device 63 can be configured by including one set of the light detecting unit 10 and the measuring unit 11, so that the cost of the receiving device 73 can be reduced. The size of the receiving device 73 can be reduced, and the size of the entire laser radar system 71 can be reduced. In addition, since one weak light detection element is used, a decrease in measurement accuracy due to variations in the characteristics of the weak light detection element does not occur, so that the light intensity characteristics can be measured with high accuracy.

Next, the laser radar system 81 will be described with reference to FIG.

The laser radar system 81 includes the transmitting device 5
2 and a receiving device 83. The transmitting device 42 described above is applied to the receiving device 53. In this case, the transmission device 52 is the same as the transmission device 52 in the laser radar system 51 in terms of configuration, but is different from the transmission device 52 in the laser radar system 51 in that each wavelength λ1 to λN is measured once. The difference is that multi-wavelength laser light B1 including .about..lambda.N needs to be transmitted only once at the same time. Further, the receiving device 83 includes shutters 8B1 to 8B of the receiving device 53.
An optical delay unit 44 is provided instead of N. In this case, the optical delay unit 44 converts the scattered light B12 of each of the wavelengths λ1 to λN split by the splitter 43 into wavelengths λ1, λ2,.
.., And output to the multiplexing unit 55a in the order of λN. According to the laser radar system 81, similarly to the laser radar system 51, one set of the light detection unit 10 and the measurement unit 1
As a result, the receiving device 83 can be configured with
The cost of the receiving device 83 can be reduced, and the size of the receiving device 83 can be reduced, and the overall size of the laser radar system 81 can be reduced. Also, 1
Since the two weak light detecting elements are used, the measurement accuracy does not decrease due to the variation in the characteristics of the weak light detecting elements. As a result, the light intensity characteristics can be measured with high accuracy.

It should be noted that the present invention is not limited to the configurations shown in the above embodiments of the present invention, but can be appropriately modified.
For example, the measurement target of the laser radar system according to the present invention is not limited to the concentration distribution of the aerosol in the atmosphere and the particle size distribution of the aerosol, and various measurements based on the light intensity of the laser light scattered by the scatterer are possible. . Also, laser light of various wavelengths can be used for the laser,
It goes without saying that various known circuits can be employed for the configuration of each unit.

[0048]

As described above, according to the laser radar system according to any one of the first to seventh aspects, the multi-wavelength scattered by the scatterer can be obtained only by providing one set of the light detection unit and the measurement unit. Light intensity characteristics for each wavelength included in the laser light can be measured. Therefore, the cost of the receiving device can be reduced, so that the cost of the entire system can be reduced. Further, as a result of the downsizing of the receiving apparatus, the downsizing of the entire laser radar system can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser radar system 1 according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the laser radar system 1.

FIG. 3 is a configuration diagram of a laser radar system 21 according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of a laser radar system 31 according to the embodiment of the present invention.

FIG. 5 shows a light selector 3 in the laser radar system 31.
4 is a configuration diagram of FIG.

FIG. 6 is a configuration diagram of a laser radar system 41 according to an embodiment of the present invention.

FIG. 7 is a configuration diagram of a laser radar system 51 according to an embodiment of the present invention.

FIG. 8 is a configuration diagram of a laser radar system 61 according to the embodiment of the present invention.

FIG. 9 is a configuration diagram of a laser radar system 71 according to the embodiment of the present invention.

FIG. 10 is a configuration diagram of a laser radar system 81 according to an embodiment of the present invention.

FIG. 11 is a configuration diagram of a conventional laser radar system 91.

[Explanation of symbols]

1, 21, 31, 41, 51, 61, 71, 81 Laser radar system 2, 22, 32, 42, 52 Transmitting device 3, 53, 63, 73, 83 Receiving device 5 Trigger generation unit 6 Laser generation unit 7, Reference Signs List 33 wavelength conversion unit 7A2-7AN wavelength converter 8,23,55 light switching unit 8B1-8BN shutter 9 telescope 10 light detection unit 11 measurement unit 23A variable angle mirror 23B1-23BN fixed mirror 34 light selection unit 43 spectral unit 44 Optical delay unit 44A1 to 44AN Optical fiber 55a Coupling unit B1 Laser light B11, B12 Scattered light λ1 to λN Wavelength

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Kudo 81, Sakuramachi, Koizumi, Ueda-shi, Nagano Prefecture Inside of Hioki Electric Co., Ltd. (72) Inventor Miki Tanaka 81, Sakuramachi, Koizumi, Oaza, Ueda-shi, Nagano Hioki Electric Co., Ltd. F term (reference) 2G059 AA01 BB01 CC19 EE02 EE11 FF04 GG01 GG08 HH01 HH02 HH06 JJ02 JJ13 JJ17 JJ22 JJ23 KK01 MM03 MM08 5J084 AA01 AA14 AB08 AD03 BA22 BA35 BA36 CA31 BB02 DA35 BB01

Claims (7)

[Claims] 1. A laser radar system comprising: a transmitting device for transmitting laser light; and a receiving device for receiving scattered light of the laser light scattered by a scatterer, wherein the transmitting device has a predetermined configuration. In synchronization with the synchronization signal generated by the time difference, it is configured to be able to sequentially transmit laser beams of different wavelengths, the receiving device, a photodetector that sequentially photoelectrically converts the scattered light and outputs an electric signal, A measuring unit that measures a light intensity characteristic with respect to a reception time for each wavelength included in the scattered light based on the electric signal sequentially output by the light detection unit in synchronization with the synchronization signal. A laser radar system comprising: 2. The transmitting device according to claim 1, further comprising: a laser generating unit configured to generate a laser beam; and a laser generating unit that is provided for each of the wavelengths and converts a wavelength of the input laser beam into a laser beam of each of the transmitted wavelengths. A plurality of wavelength converters, and an optical switching unit that sequentially outputs the laser light generated by the laser generation unit to each of the wavelength converters in synchronization with the synchronization signal. Item 4. The laser radar system according to Item 1. 3. The transmission device according to claim 1, wherein the transmitting device includes a laser generating unit configured to generate the laser light, a wavelength converting unit configured to convert the wavelength of the laser light to generate the laser light of each of the wavelengths at the same time, and generated by the wavelength converting unit. And a light selector for sequentially selecting the laser light of each wavelength in synchronization with the synchronization signal and sequentially outputting the selected laser light of each wavelength as the laser light of each transmitted wavelength. The laser radar system according to claim 1, wherein: 4. The transmission device according to claim 1, wherein the transmitting device is configured to generate a laser beam, a wavelength converting unit that converts the wavelength of the laser beam to simultaneously generate the laser beams of the respective wavelengths, and a laser beam generated by the wavelength converting unit. A light splitting unit for splitting the laser light for each of the wavelengths, and an optical delay unit for sequentially outputting the laser light split by the light splitting unit as the laser light of each wavelength with a time difference for each wavelength. The laser radar system according to claim 1, further comprising: 5. A transmitting device for transmitting laser light, and a receiving device for receiving scattered light of the laser light scattered by a scatterer, wherein the transmitting device combines a plurality of laser lights having different wavelengths from each other. The receiving device is configured to be capable of sequentially transmitting the waved laser light at least as many times as the number of types of the wavelength in synchronization with the synchronization signal, and the receiving device further includes a spectral unit configured to spectrally separate the scattered light for each wavelength. A light detection unit that sequentially performs photoelectric conversion of the scattered light dispersed by the unit in synchronization with the synchronization signal,
A light switching section that outputs the scattered light of each wavelength separated by the light splitting section to the light detection section in synchronization with the synchronization signal, and corresponds to each of the wavelengths sequentially output by the light detection section. A measuring unit that measures a light intensity characteristic with respect to a reception time for each wavelength included in the scattered light based on an electric signal in synchronization with the synchronization signal. Laser radar system. 6. A transmitting device for transmitting laser light, and a receiving device for receiving scattered light of the laser light scattered by a scatterer, wherein the transmitting device combines a plurality of laser lights having different wavelengths from each other. The waved laser light is configured to be sequentially transmitted in synchronization with the synchronization signal at least as many times as the number of types of the wavelength, and the receiving device is configured to synchronize the scattered light of each wavelength with the synchronization signal. A light selection unit for sequentially selecting and outputting the scattered light, a light detection unit for sequentially photoelectrically converting the scattered light of each wavelength sequentially output by the light selection unit, and each of the light detection units sequentially output by the light detection unit A measuring unit configured to measure a light intensity characteristic with respect to a reception time for each wavelength included in the scattered light based on an electric signal corresponding to each wavelength in synchronization with the synchronization signal. That Laser radar system that butterflies. 7. A transmitting apparatus for transmitting laser light, and a receiving apparatus for receiving scattered light of the laser light scattered by a scatterer, wherein the transmitting apparatus combines a plurality of laser lights having different wavelengths from each other. The receiving device is configured to be capable of simultaneously transmitting the waved laser light, and the receiving device sequentially disperses the scattered light by the wavelength by providing a spectral unit that disperses the scattered light for each wavelength and a scattered light that is dispersed by the spectral unit. An optical delay section for outputting, a multiplexing section for multiplexing and sequentially outputting the scattered lights of the respective wavelengths sequentially output by the optical delay section, and a scattered light of the respective wavelengths sequentially output by the multiplexing section And a light intensity characteristic with respect to a reception time for each wavelength included in the scattered light based on an electrical signal corresponding to each wavelength sequentially output by the light detection unit. The said synchronization Laser radar system characterized in that it is configured by a measuring unit for measuring in synchronism with the signal.