CN113671524A - False color laser radar system - Google Patents
False color laser radar system Download PDFInfo
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- CN113671524A CN113671524A CN202110789796.3A CN202110789796A CN113671524A CN 113671524 A CN113671524 A CN 113671524A CN 202110789796 A CN202110789796 A CN 202110789796A CN 113671524 A CN113671524 A CN 113671524A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/46—Indirect determination of position data
- G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
- G01S7/484—Transmitters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
- G01S7/486—Receivers
- G01S7/4865—Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak
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- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention provides a false color laser radar system, which comprises a wide spectrum light receiving and transmitting device, a color separation prism combination, a data acquisition system and a control system which are connected in sequence; the control unit is used for controlling the broad spectrum light receiving and transmitting device to illuminate the radar beam emitted by the target object; the broad spectrum light receiving and transmitting device transmits the echo light signal reflected by the target object to the dichroic prism combination; the color separation prism combination divides the echo optical signal into a plurality of spectral channels according to the wavelength; the control unit is also used for processing and synthesizing the light beams of the plurality of spectral channels acquired by the data acquisition unit to obtain pseudo-color point cloud data. The invention divides the echo light signal into a plurality of spectrum channels according to the wavelength by utilizing the combination of the dichroic prism, has simple structure, and simultaneously has the advantages that compared with a hyperspectral light splitting mode with the channel width of 10nm, the dichroic filter selects the channel width not less than 100nm, can receive higher light pulse energy in the channel and has the technical advantage of remote detection.
Description
Technical Field
The invention relates to the technical field of laser radars, in particular to a false color laser radar system.
Background
The laser radar is used as an active photoelectric device for acquiring space direction information of a target and an observer, has the advantages of narrow beam, good directivity, high spatial resolution, interference resistance, full-time work and the like, and is widely applied to the fields of topographic mapping, agriculture, forestry, three-dimensional modeling, unmanned driving and the like at present. The ranging type laser radar transmits a single-wavelength laser pulse to a target, measures flight time information of the pulse between the radar and the target to obtain a target distance, provides scanning angle information according to a field of view of a radar light emitting and receiving system, calculates three-dimensional space point cloud data distribution of the target in a spherical coordinate system, and is used for analyzing target object characteristics by combining a gray value provided by echo signal intensity. However, the traditional ranging type laser radar has the close correlation between the target feature extraction capability and the density of the three-dimensional space point cloud data, and brings too much point cloud data to a large object, so that redundancy is removed by a post-processing algorithm, and an incomplete detection problem exists for a sheltered object or a small object, so that the target cannot be effectively identified.
In order to improve the detection and identification capability of the laser radar on the target, an effective solution is to fuse the spatial point cloud data and the target color or spectrum information, and improve the classification judgment capability of the target category by using the target color information or spectrum information. The patent with the application number of CN201310214136.8 discloses an integrated three-dimensional color laser radar data point cloud generating method and a device thereof, but a monocular color camera of the method belongs to passive photoelectric equipment, depends on the sunlight in the daytime, and has the problem that the method cannot work all day long. Patent with application number CN201911165990.3 discloses an unmanned aerial vehicle transmission line geological disaster early warning system with laser radar and hyperspectral imager combination application, but its hyperspectral imager belongs to passive imaging device, has the problem of unable full-time work equally. The high-energy supercontinuum laser is selected as a coherent illumination light source, wide-spectrum long-distance illumination with spectrum covering from visible light to near-infrared wave band can be provided, the single-wavelength laser pulse of the traditional laser radar is replaced by the high-energy supercontinuum laser, and the target azimuth information and the spectrum information can be actively acquired simultaneously by combining a spectrum detection device. The patent with the application number of CN201810034753.2 discloses a hyperspectral lidar system with high spectral resolution and distance resolution, adopts optical fiber dispersion to separate the frequency of a supercontinuum laser pulse spectrum in time, utilizes a spectrum measuring unit to respectively acquire target visible light and near-infrared waveband spectrum characteristic data, but the continuous light splitting process of the hyperspectral lidar system leads to low energy in a single spectrum channel, and the radar spectrum detection working distance cannot be guaranteed. Patent application No. CN201811598297.0 discloses a hyperspectral three-dimensional structure radar system based on near-infrared full-waveform ranging, spectral data are obtained by splitting a supercontinuum laser pulse into a plurality of visible light to near-infrared spectrum channels, but the problem that energy in a single spectrum channel is low is also existed. The patent with the application number of CN202010570326.3 discloses an airborne supercontinuum laser hyperspectral lidar system, the width of a single spectrum channel is only 10nm, the problems of low energy in the single spectrum channel and limitation of radar spectrum detection working distance exist, and the problem of strong interference of visible light wave band solar radiation exists. The patent with the application number of CN201811598297.0 discloses a hyperspectral three-dimensional laser radar system based on near-infrared full-waveform ranging, the ranging and spectrum detection contents of the patent are separated, the utilization mode of spectrum information is different from that of the hyperspectral three-dimensional laser radar system, the related calculation method is complex, and the identification effect is poor.
It can be seen that because the working distance of the laser radar is closely related to the energy of the supercontinuum laser pulse, the existing invention combining the spectrum detection technology and the ranging type laser radar technology still has obvious technical defects, although the high resolution (the spectral bandwidth is 10nm) of the spectrum channel can provide a fine spectrum, the energy of the light pulse in a single channel is too low, so that the working distance of the radar is greatly reduced, and the practical application is difficult.
Disclosure of Invention
In order to solve the technical problem that technical defects still exist when a spectrum detection technology and a ranging type laser radar technology are combined in the prior art, the invention provides a false color laser radar system, which comprises the following components: the wide-spectrum light receiving and transmitting device, the color separation prism combination, the data acquisition system and the control system are sequentially connected, and the control unit is also connected with the wide-spectrum light receiving and transmitting device;
the control unit is used for controlling the wide-spectrum light receiving and transmitting device to illuminate a laser radar beam emitted by a target object;
the wide-spectrum light transceiver transmits the received echo light signal reflected by the target object to the dichroic prism combination;
the color separation prism combination divides the echo optical signals into a plurality of spectral channels according to the wavelength;
the control unit is also used for processing and synthesizing the light beams of the plurality of spectral channels acquired by the data acquisition unit to obtain pseudo-color point cloud data.
Preferably, the broad spectrum optical transceiver device includes: a wide-spectrum light emitting and receiving system, a beam collimator and a high-energy supercontinuum laser;
the broad spectrum light emitting and receiving system comprises: a broad spectrum light emitting system and a broad spectrum light receiving system which are arranged in a quasi-coaxial way.
Preferably, the broad spectrum light emission system comprises: the beam expander comprises a beam expander, a first plane reflector arranged at an angle of 45 degrees with the beam expander and a second plane reflector arranged in parallel with the first plane reflector.
Preferably, the high-energy supercontinuum laser is directly generated by a fiber amplifier, and transmits fundamental mode supercontinuum laser pulses with the repetition frequency of 100kHz, the pulse width of 10ns, the pulse energy of 10 mu J, the spectral range of 1000-2000nm and the beam waist radius of 5 mu m, and the fundamental mode supercontinuum laser pulses are concentrated in the near infrared range of 1-2 mu m or 2-2.5 mu m.
Preferably, when the spectrum emitted by the high-energy supercontinuum laser is in the range of 1-2 μm, the optical fiber amplifier is a trivalent ytterbium-doped ion-doped quartz optical fiber amplifier with a double-cladding structure;
when the spectral range is 2-2.5 μm, the optical fiber amplifier is a trivalent thulium ion doped quartz optical fiber amplifier with a double-cladding structure.
Preferably, the wide-spectrum light receiving system comprises a reflector, a main reflector, a small aperture diaphragm and a short focal length collimating lens which are arranged in sequence;
the reflector is a convex mirror, and the convex surface of the reflector faces the main reflector;
the mirror surface of the main reflector has a certain radian, and the concave surface of the main reflector faces the reflector;
the main reflecting mirror is provided with a light hole;
the middle point of the reflector, the light hole of the main reflector, the light hole of the small aperture diaphragm and the middle point of the short-focus collimating lens are positioned on the same straight line.
Preferably, the color separation prism assembly includes: an even number of identically configured triangular prisms.
Preferably, the triangular prism is a right-angled triangular prism;
the bevel edges of every two right-angle triangular prisms are adhered to form a square, and the adhered position is a bevel edge interface; the squares are adhered pairwise to form a nonlinear structure.
Preferably, different optical films are further plated on the light-emitting surface and the bevel edge interface of the triangular prism.
Preferably, the number of the triangular prisms is 6; three squares are formed;
when the first square and the second square are adhered, the bevel edge interfaces of the first square and the second square are arranged in parallel;
the third square is adhered to the second square, and the vertexes of the bevel edge interfaces of the third square and the second square are intersected to form a right angle; the surface (14) of the second square is arranged perpendicular to the echo optical signal transmitted by the broad spectrum light emitting and receiving system.
Preferably, the optical film includes: a long-wave pass filter film, a bicolor light splitting film and a short-wave pass filter film;
the surface (13) of the third square is plated with a long-wave pass filter film under the incident condition of 0 degree;
the bevel edge interface (9) of the second square, the bevel edge interface (10) of the first square and the surface (11) of the first square are respectively plated with two-color light splitting films with different color splitting wavelengths under the incident condition of 45 degrees;
and a short-wave-pass filter film under the incident condition of 0 DEG is plated at the hypotenuse interface (12) of the third square.
Preferably, the number of the light emergent surfaces is 4.
Preferably, the data acquisition system comprises: a four-channel data acquisition card and 4 channel units;
each channel unit comprises a photoelectric detector, a signal amplifier and an analog-to-digital converter which are connected in sequence;
the four-channel data acquisition card is used for receiving light intensity information of each channel.
Preferably, the control system includes: the device comprises a control computer, a time interval measuring unit, a scanning mechanism, a data processing unit and a data storage unit;
the time interval measurement unit is configured to: comparing the time delay amount of the trigger signal and the echo light signal provided by the control computer;
the scanning mechanism is used for: recording azimuth angle information of a single laser radar beam;
the data processing unit is configured to: calculating based on the time delay amount of the trigger signal and the echo light signal obtained by the time interval measuring unit, the azimuth angle information determined by the scanning mechanism and the four-channel light intensity information obtained by the four-channel data acquisition card to obtain single-point radar data;
the data storage unit is used for: and storing the single-point radar data obtained by calculation of the data processing unit.
Preferably, the data processing unit is further configured to integrate a set of a large amount of single-point radar data stored in the data storage unit to form multi-channel radar point cloud data; and obtaining a false color radar point cloud picture with multiple colors corresponding to the target object according to the multi-channel radar point cloud data and a false color synthesis method.
Preferably, the radar point data includes: and radar point space coordinates and multi-channel light intensity information corresponding to the target object.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention provides a false color laser radar system, which comprises a wide-spectrum light transceiver, a dichroic prism combination, a data acquisition system and a control system which are connected in sequence, wherein the control unit is also connected with the wide-spectrum light transceiver; the control unit is used for controlling the wide-spectrum light receiving and transmitting device to illuminate a laser radar beam emitted by a target object; the wide-spectrum light transceiver transmits the received echo light signal reflected by the target object to the dichroic prism combination; the color separation prism combination divides the echo optical signals into a plurality of spectral channels according to the wavelength; the control unit is also used for processing and synthesizing the light beams of the plurality of spectral channels acquired by the data acquisition unit to obtain pseudo-color point cloud data. The invention utilizes the combination of the dichroic prism to divide the echo light signal into a plurality of spectrum channels according to the wavelength, has the characteristic of simple structure, and simultaneously compared with a hyperspectral light splitting mode with the channel width of 10nm, the dichroic filter selects the channel width of not less than 100nm, can provide higher light pulse energy in the channel, and has the technical advantage of long-distance detection distance;
2. meanwhile, compared with point cloud data of a monochromatic laser radar, the technical means provided by the invention forms false color laser radar data based on a plurality of spectral channels, embodies the color information of a target object and enriches the information quantity;
3. the technical means provided by the invention can provide false colors of double-color synthesis, three-color synthesis and four-color synthesis of the target in a near infrared band, and supports the identification of the target category by using the color difference between channels; the calculation method is simple and flexible;
4. the invention adopts a high-energy supercontinuum laser as a lighting source, which is directly generated by a scheme of a near-infrared optical fiber amplifier, and the pulse energy of the obtained supercontinuum laser reaches more than 10 muJ; the spectral energy is more concentrated in the characteristic spectral band of the target, and the energy utilization rate is higher;
5, the spectral range of the high-energy supercontinuum laser is larger than the sum of four spectral channel ranges finally filtered by the dichroic prism combination, the utilization rate of the total energy of the supercontinuum laser is maximized by selecting the width of a single channel, and the detection efficiency is higher;
6. the false color radar point cloud data provided by the invention can be used for identifying the target by utilizing the target color characteristics, and particularly can be used for identifying the target category according to the rich color information of the target under the condition of single-point detection or sparse detection.
Drawings
FIG. 1 is a schematic diagram of a pseudo color lidar system according to the present invention;
FIG. 2 is a general functional block diagram of the present invention;
FIG. 3 is a graph of average solar flux versus supercontinuum laser light used in an embodiment of the invention;
FIG. 4 is a schematic diagram of a broad spectrum light emitting and receiving system in an embodiment of the invention;
FIG. 5 is a schematic diagram of a color separation prism assembly according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a reflection spectrum of a dichroic beam splitting film at an interface of a dichroic prism assembly according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a transmission spectrum of a surface filter of a color separation prism set according to an embodiment of the present invention;
FIG. 8 is a diagram of a four-channel spectral channel shape in an embodiment of the present invention.
Detailed Description
For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.
Example 1:
the invention aims to provide a false color laser radar system, which adopts high-energy supercontinuum laser with spectral energy positioned in a near infrared band as a lighting source, and divides an echo light signal into four ultra wide band (the channel width is 100 plus 200nm) light channels through a color separation prism combination.
The technical scheme adopted by the invention is shown in figure 1. The system specifically comprises a control system, a wide-spectrum light transceiver, a color separation prism combination and a data acquisition system;
furthermore, the wide-spectrum light transceiver comprises a wide-spectrum light emitting and receiving system, a beam collimator and a high-energy supercontinuum laser; the broad spectrum light emitting and receiving system includes: a wide-spectrum light emitting system and a wide-spectrum light receiving system which are arranged in a quasi-coaxial manner; the broad spectrum light emission system includes: a beam expander and two plane mirrors;
further, the data acquisition system comprises: a four-channel data acquisition card and a channel unit;
further, the channel unit includes: the photoelectric detector comprises a first photoelectric detector, a first electric signal amplifier, a first analog-to-digital converter, a second photoelectric detector, a second electric signal amplifier, a second analog-to-digital converter, a third photoelectric detector, a third electric signal amplifier, a third analog-to-digital converter, a fourth photoelectric detector, a fourth electric signal amplifier and a fourth analog-to-digital converter;
further, the control system includes: a control computer, a time interval measuring unit, a data processing unit, a data storage unit and a scanning mechanism.
The control computer is composed of a field programmable gate array or a digital signal processor and is used for generating a trigger signal to start the high-energy supercontinuum laser to work.
The high-energy supercontinuum laser is directly generated by an optical fiber amplifier, and the spectral energy output of the high-energy supercontinuum laser is continuously distributed on the optical frequency and is concentrated on the near infrared 1-2 mu m or 2-2.5 mu m. When the spectrum is in the range of 1-2 mu m, the optical fiber amplifier is a trivalent ytterbium-doped ion-doped quartz optical fiber amplifier with a double-cladding structure. When the spectral range is 2-2.5 μm, the optical fiber amplifier is a trivalent thulium ion doped quartz optical fiber amplifier with a double-cladding structure.
Further, the pulse width of the high-energy supercontinuum laser is more than 1ns and less than 20ns, the repetition frequency is more than 10kHz, and the pulse energy is more than 10 muJ.
Further, the output beam of the high-energy supercontinuum laser is a fundamental mode, and the beam quality M2 factor is smaller than 1.3.
The high-energy supercontinuum laser outputs pulse laser, the pulse laser is collimated and output through the beam collimator, and the pulse laser illuminates a long-distance target through the wide-spectrum light emitting and receiving system.
The wide-spectrum transmitting and receiving system adopts a telescope structure design, can efficiently collect echo light signals reflected by the surface of a target, and transmits the echo light signals to the dichroic prism combination.
The color separation prism combination adopts the structural design of a plurality of isosceles right-angle triple prism combinations, and the dual-color light splitting film, the long-wave-pass filter film, the short-wave-pass filter film and the like are plated on the prism interface or the light emitting surface to realize the division of spectral channels.
Furthermore, the color separation prism combination filters the echo super-continuum spectrum signal into four spectrum component signals with spectrum separation, and the width of a single spectrum channel is not less than 100 nm.
Further, the spectral component signals are subjected to photoelectric conversion by a photoelectric detector, signal enhancement by an electric signal amplifier, analog-to-digital conversion by an analog-to-digital converter, and light intensity values of four channels are obtained by a four-channel data acquisition card.
The time interval measuring unit is used for comparing the time delay quantity of the trigger signal and the echo light signal provided by the control computer to obtain the flight time of the supercontinuum laser pulse.
The scanning mechanism is composed of a high-speed two-dimensional scanning galvanometer or a swing mirror, can realize rapid surface scanning or line scanning of a target area, and provides azimuth angle information of radar beams to the data processing unit.
The data processing unit obtains four-channel radar data of a target in a near-infrared band by processing original information such as time delay, four-channel light intensity information, azimuth angle information provided by the scanning structure and the like, and then sends the four-channel radar data to the data storage unit for storage. Therefore, the four spectrum channels of the distance detection realized by the invention can provide distance measurement information, and the distance measurement precision can be improved through simple average processing.
Further, after the four-channel light intensity information is obtained, a method for synthesizing double-color, three-color and four-color false colors can be realized by randomly selecting two channels, three channels or all four channels in the four-channel light, and false color point cloud data with vivid colors and outstanding features can be obtained.
The invention directly utilizes the near-infrared supercontinuum laser and filters the supercontinuum signals into four spectrum component signals (the spectrum channels are only 4) separated by the spectrum through the color separation prism combination, and the width of a single spectrum channel is not less than 100nm (the channel range is extremely large, and the spectrum is not a hyperspectral spectrum). The spectrum detection wave band, the channel number and the spectrum width are different, so the obtained information is completely different. Particularly, the light pulse energy in a single channel is higher, so that the spectrum detection distance of the radar is remarkably increased, and the method is closer to practical application.
Example 2:
as shown in FIG. 2, the pseudo-color lidar system of the present invention has a control computer comprising a programmable gate array to generate a clock signal, and controls a high-energy supercontinuum laser comprising an ytterbium-doped fiber amplifier to emit fundamental mode supercontinuum laser pulses with repetition frequency of 100kHz, pulse width of 10ns, pulse energy of 200 μ J, spectral range of 1000-2000nm, and beam waist radius of 5 μm. The emitted laser pulse is changed into parallel light after passing through a beam collimator formed by a parabolic reflector with the focal length of 25mm, and the parallel light is injected into an emitting reflector of a wide-spectrum light emitting and receiving system, so that the target object within the distance of 200m can be effectively illuminated. The backward echo signals loaded with the target spectrum are collected by a telescope receiving system of a wide-spectrum light emitting and receiving system, then injected into a color separation prism combination formed by pasting six right-angle triple prisms, filtered out four channels with spectrum separation and bandwidth not less than 200nm, and converged on photosensitive surfaces of four indium gallium arsenic photoelectric detectors through focusing lenses respectively to complete the conversion from optical signals to electric signals. The electric signal passes through the electric signalAfter the signal is amplified by the amplifier, the amplified signal is transmitted to the analog-to-digital converter to be converted into a quantized digital signal, and then the quantized digital signal is recorded by a four-channel data acquisition card to obtain the intensity information { I) of four channels1、I2、I3、I4}. The time interval measuring unit is used for comparing the time delay quantity of the trigger signal and the echo light signal provided by the control computer, and the flight time t of the supercontinuum laser pulse can be obtained after calibration. Therefore, the target distance information L — c × t/2 can be calculated in combination with the light speed value.
In the embodiment, the scanning mechanism is composed of a high-speed two-dimensional scanning galvanometer and can record an included angle theta between a single laser radar beam and the x-axis direction and an included angle phi between the single laser radar beam and the z-axis direction. Therefore, the radar is used as the origin 0 of the three-dimensional space coordinate, and the space coordinate of the target point cloud is { L multiplied by sin phi multiplied by cos theta, L multiplied by sin phi multiplied by sin theta, L multiplied by cos phi }.
The processing unit in this embodiment calculates the processing time delay amount, the four-channel light intensity information, and the azimuth angle information provided by the scanning structure to obtain the single-point radar data { L × sin Φ × cos θ, L × sin Φ × sin θ, L × cos Φ, I |)1、I2、I3、I4And sending the data to a data storage unit for storage.
And then, the control computer controls the scanning mechanism to move to the next detection position, controls the high-energy supercontinuum laser to emit the next laser pulse and records the single-point radar data of the radar to other spatial positions. And finally, a large number of single-point radar data are collected to form four-channel radar point cloud data. The colorful false color radar point cloud picture can be obtained by selecting two colors, three colors or four colors in the four-channel radar point cloud data and combining a false color synthesis method, and high-precision resolution and target category identification can be supported.
FIG. 3 is a schematic diagram showing the average radiant flux value formed when the 1000-2000nm supercontinuum beam reaches the target surface in this embodiment, and the average irradiation energy is 3W/m2The/nm is still about 10 times higher than the average radiant flux of sunlight in the near infrared band. FIG. 3 shows another embodiment of an amplifier comprising a thulium doped fiber2000-2500nm high-energy supercontinuum laser.
Fig. 4 is a schematic diagram of a broad-spectrum light emitting and receiving system in this embodiment, where the broad-spectrum light emitting system specifically includes a beam expander 1, a first plane mirror 2, and a second plane mirror 3, and the two plane mirrors and the beam expander are arranged at an angle of 45 °. The wide-spectrum light receiving system adopts a Cassegrain telescope structure and specifically comprises a secondary reflector 4, a primary reflector 5, a small-hole diaphragm 6 and a short-focus collimating lens 7. The optical structure of the transmitting system and the receiving system is characterized in that the super-continuum spectrum laser beam is quasi-coaxial with the optical axis of the receiving telescope, and the blind zone distance is short.
FIG. 5 is a schematic diagram of a color separation prism assembly of the present embodiment, which is formed by sequentially bonding six right-angle triple prisms, wherein a long-wave-pass filter film is plated on the surface 13 under an incident condition of 0 degree, and the corresponding filtering wavelength is λ1Plating two-color light splitting films under 45-degree incidence condition at a bevel edge interface 9, a bevel edge interface 10 and a surface 11 respectively, wherein the corresponding color separation wavelength is lambda3、λ4And λ2The hypotenuse interface 12 is coated with a short wave pass filter film under the condition of 0 degree incidence, and the corresponding filtering wavelength is lambda5. Where lambda is1、λ2、λ3、λ4And λ5According to the channel position requirement.
FIG. 6 is a schematic diagram showing the reflection spectra of three dichroic beam splitting films under an incident angle of 45 ° in this embodiment.
Fig. 7 is a schematic diagram of the transmission spectra of the long-wavelength-pass and short-wavelength-pass filter films under the 0 ° incident condition in this embodiment.
According to the combination of the prism group, the long-wave-pass filter film, the bicolor light splitting film and the short-wave-pass filter film, the filtered return light signal output of the four channels can be finally obtained.
Fig. 8 is a schematic diagram showing the shapes of four spectral channels in this embodiment. Wherein the first channel has a selective spectral range of λ1-λ2The second channel has a selected spectral range of λ2-λ3The third channel selects a spectral range of λ3-λ4The fourth channel selects the spectral rangeIs enclosed as lambda4-λ5. The channel position and the bandwidth size can be adjusted by adjusting the size of the wavelength values. In this embodiment, the four channel selection spectral ranges are 1000-.
It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.
Claims (10)
1. A false color lidar system, comprising: the wide-spectrum light receiving and transmitting device, the color separation prism combination, the data acquisition system and the control system are sequentially connected, and the control unit is also connected with the wide-spectrum light emitting and receiving system;
the control unit is used for controlling the wide-spectrum light receiving and transmitting device to illuminate a laser radar beam emitted by a target object;
the wide-spectrum light transceiver transmits the received echo light signal reflected by the target object to the dichroic prism combination;
the color separation prism combination divides the echo optical signals into a plurality of spectral channels according to the wavelength;
the control unit is also used for processing and synthesizing the light beams of the plurality of spectral channels acquired by the data acquisition unit to obtain pseudo-color point cloud data.
2. The system of claim 1, wherein the broad spectrum light transceiving means comprises: a wide-spectrum light emitting and receiving system, a beam collimator and a high-energy supercontinuum laser;
the broad spectrum light emitting and receiving system comprises: a broad spectrum light emitting system and a broad spectrum light receiving system which are arranged in a quasi-coaxial way.
3. The system of claim 2, wherein the broad spectrum light emission system comprises: the beam expander comprises a beam expander, a first plane reflector arranged at an angle of 45 degrees with the beam expander and a second plane reflector arranged in parallel with the first plane reflector.
Preferably, the high-energy supercontinuum laser is directly generated by a fiber amplifier, and transmits fundamental mode supercontinuum laser pulses with the repetition frequency of 100kHz, the pulse width of 10ns, the pulse energy of 10 mu J, the spectral range of 1000-2000nm and the beam waist radius of 5 mu m, and the fundamental mode supercontinuum laser pulses are concentrated in the near infrared range of 1-2 mu m or 2-2.5 mu m.
Preferably, when the spectrum emitted by the high-energy supercontinuum laser is in the range of 1-2 μm, the optical fiber amplifier is a trivalent ytterbium-doped ion-doped quartz optical fiber amplifier with a double-cladding structure;
when the spectral range is 2-2.5 μm, the optical fiber amplifier is a trivalent thulium ion doped quartz optical fiber amplifier with a double-cladding structure.
4. The system of claim 2, wherein the wide spectrum light receiving system comprises, in order, a mirror, a primary mirror, an aperture stop, and a short focal length collimating lens;
the reflector is a convex mirror, and the convex surface of the reflector faces the main reflector;
the mirror surface of the main reflector has a certain radian, and the concave surface of the main reflector faces the reflector;
the main reflecting mirror is provided with a light hole;
the middle point of the reflector, the light hole of the main reflector, the light hole of the small aperture diaphragm and the middle point of the short-focus collimating lens are positioned on the same straight line.
5. The system of claim 1, wherein the dichroic prism combination comprises: an even number of identically configured triangular prisms.
Preferably, the triangular prism is a right-angled triangular prism;
the bevel edges of every two right-angle triangular prisms are adhered to form a square, and the adhered position is a bevel edge interface; the squares are adhered pairwise to form a nonlinear structure.
6. The system of claim 5, wherein different optical films are further coated on the light exit surface and the hypotenuse interface of the triangular prism.
7. The system of claim 6, wherein the triangular prisms are 6; three squares are formed;
when the first square and the second square are adhered, the bevel edge interfaces of the first square and the second square are arranged in parallel;
the third square is adhered to the second square, and the vertexes of the bevel edge interfaces of the third square and the second square are intersected to form a right angle; the surface (14) of the second square is arranged perpendicular to the echo optical signal transmitted by the broad spectrum light emitting and receiving system.
8. The system of claim 7, wherein the optical film comprises: a long-wave pass filter film, a bicolor light splitting film and a short-wave pass filter film;
the surface (13) of the third square is plated with a long-wave pass filter film under the incident condition of 0 degree;
the bevel edge interface (9) of the second square, the bevel edge interface (10) of the first square and the surface (11) of the first square are respectively plated with two-color light splitting films with different color splitting wavelengths under the incident condition of 45 degrees;
and a short-wave-pass filter film under the incident condition of 0 DEG is plated at the hypotenuse interface (12) of the third square.
Preferably, the number of the light emergent surfaces is 4.
Preferably, the data acquisition system comprises: a four-channel data acquisition card and 4 channel units;
each channel unit comprises a photoelectric detector, a signal amplifier and an analog-to-digital converter which are connected in sequence;
the four-channel data acquisition card is used for receiving light intensity information of each channel.
9. The system of claim 8, wherein the control system comprises: the device comprises a control computer, a time interval measuring unit, a scanning mechanism, a data processing unit and a data storage unit;
the time interval measurement unit is configured to: comparing the time delay amount of the trigger signal and the echo light signal provided by the control computer;
the scanning mechanism is used for: recording azimuth angle information of a single laser radar beam;
the data processing unit is configured to: calculating based on the time delay amount of the trigger signal and the echo light signal obtained by the time interval measuring unit, the azimuth angle information determined by the scanning mechanism and the four-channel light intensity information obtained by the four-channel data acquisition card to obtain single-point radar data;
the data storage unit is used for: and storing the single-point radar data obtained by calculation of the data processing unit.
10. The system of claim 9, wherein the data processing unit is further configured to integrate the collection of the plurality of single-point radar data stored by the data storage unit to form multi-channel radar point cloud data; and obtaining a false color radar point cloud picture with multiple colors corresponding to the target object according to the multi-channel radar point cloud data and a false color synthesis method.
Preferably, the radar point data includes: and radar point space coordinates and multi-channel light intensity information corresponding to the target object.
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