CN113748358B - Laser receiving device, laser receiving method and laser radar - Google Patents
Laser receiving device, laser receiving method and laser radar Download PDFInfo
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- CN113748358B CN113748358B CN202080031652.5A CN202080031652A CN113748358B CN 113748358 B CN113748358 B CN 113748358B CN 202080031652 A CN202080031652 A CN 202080031652A CN 113748358 B CN113748358 B CN 113748358B
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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
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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
- G01S17/88—Lidar systems specially adapted for specific applications
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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
- G01S7/486—Receivers
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- 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)
- Optical Couplings Of Light Guides (AREA)
Abstract
A laser receiving device, a laser receiving method and a laser radar belong to the field of photoelectric detection. The receiving device includes: the device comprises a receiving objective lens (10), a spatial filter (11), an optical waveguide light homogenizing device (13), a spectrum filter (12) and a photoelectric detector (14), wherein the spatial filter (11) carries out spatial filtering on echo light signals from the receiving objective lens (10), and the echo light signals in a preset view field are reserved, so that the signal to noise ratio of a laser receiving device can be increased; the optical waveguide light homogenizing device (13) performs light homogenizing treatment on the echo light signals subjected to the spatial filtering treatment, so that the echo light signals are uniformly irradiated on the photoelectric detector (14), and the energy of light spots is uniformly distributed on each pixel of the photoelectric detector (14), so that the photoelectric detector (14) has lower false alarm rate; the spectral filter (12) carries out band-pass filtering on the echo optical signals, reserves the echo optical signals in a preset frequency band, can further improve the signal-to-noise ratio of the laser receiving device, improves the accuracy of the photoelectric detector (14), and reduces the interference of the noise optical signals on the photoelectric detector (14).
Description
Technical Field
The present invention relates to the field of photoelectric detection, and in particular, to a laser receiving device, a laser receiving method, and a laser radar.
Background
The laser radar is a radar system for detecting the position and speed of a target by emitting laser echo light signals, and the working principle is that the laser echo light signals are emitted to the target in a field of view, then the received reflected laser echo light signals reflected from the target are subjected to photoelectric conversion by a photoelectric detector to obtain electric signals, and the electric signals are properly processed to obtain relevant information of the target, such as: target distance, reflectivity, azimuth, speed, attitude, and even shape. Because the reflected laser echo light signal is generally weak, the background light noise outside the field of view has larger interference on the reflected laser echo light signal, thereby affecting the detection performance of the photoelectric detector, and how to reduce the interference of the background light noise on the reflected laser is a problem to be solved at present.
Disclosure of Invention
The embodiment of the invention provides a laser receiving device, a laser receiving method and a laser radar, which solve the problem that background light noise has larger interference on echo light signals in the related technology.
In order to solve the technical problems, the embodiment of the invention discloses the following technical scheme:
In a first aspect, the present application provides a laser light receiving apparatus comprising: receiving objective lens, spatial filter, spectral filter and photoelectric detector;
the receiving objective lens is used for receiving the echo optical signals and transmitting the echo optical signals to the spatial filter;
The spatial filter is used for spatially filtering the echo optical signals from the receiving objective lens so as to filter noise optical signals outside a preset view field, and transmitting the spatially filtered echo optical signals to the spectral filter;
the spectral filter is used for carrying out band-pass filtering on the echo optical signals from the spatial filter so as to filter noise optical signals outside a preset frequency band, and transmitting the echo optical signals after the band-pass filtering to the photoelectric detector;
the photoelectric detector is used for carrying out photoelectric conversion on the echo optical signals from the spectrum filter to obtain electric signals.
In one possible design, the method further comprises:
The optical waveguide light homogenizer is used for carrying out band-pass filtering on the echo light signals from the spatial filter so as to filter noise light signals outside a preset frequency band, and transmitting the echo light signals after band-pass filtering to the photoelectric detector.
In one possible design, the spatial filter includes a stop that is an aperture stop, a field stop, a vignetting stop, or an anti-stray light stop.
In one possible design, the aperture size=θ×f, θ of the diaphragm represents the divergence angle of the emitted light signal, and f is the focal length of the receiving objective lens.
In one possible design, the receiving objective adopts a telecentric light path, and the optical waveguide homogenizer is arranged in parallel with the optical axis of the receiving objective; or when the receiving objective lens adopts a non-telecentric light path, the optical waveguide light homogenizer and the optical axis of the receiving objective lens are arranged at a preset angle.
In one possible design, the number of the optical waveguide light uniformizers is a plurality, the plurality of the optical waveguide light uniformizers are arranged into N rows and M columns, and M and N are integers greater than or equal to 1; the number of the photoelectric detectors is multiple, the number of the photoelectric detectors is M multiplied by N, the number of the photoelectric detectors is equal to the number of the optical waveguide light homogenizing devices, and the number of the photoelectric detectors is equal to the number of the optical waveguide light homogenizing devices.
In one possible design, the optical waveguide light homogenizer has the shape of a cylinder, a truncated cone, a cuboid or a prismatic table.
In one possible design, the photodetector is an APD detector or an SiPM detector.
In one possible design, the method further comprises: a collimating lens, an angle filter, and a focusing lens;
the collimating lens is used for carrying out collimation processing on the echo optical signals from the spatial filter and transmitting the echo optical signals after the collimation processing to the angle filter;
The angle filter is used for performing angle filtering on the echo optical signals from the collimating lens and transmitting the echo optical signals subjected to angle filtering to the focusing lens;
And the focusing lens is used for focusing the echo optical signals from the angle filter and transmitting the focused echo optical signals to the optical waveguide homogenizer.
In one possible design, the angle filter is a dove mirror.
In a second aspect, the present application provides a laser light receiving method, including:
receiving an echo optical signal received by an objective lens, and transmitting the echo optical signal to a spatial filter;
The spatial filter performs spatial filtering on the echo optical signals from the receiving objective lens to filter noise optical signals outside a preset view field, and transmits the echo optical signals after spatial filtering to the spectral filter;
the spectral filter carries out band-pass filtering on the echo optical signals from the spectral filter so as to filter noise optical signals outside a preset frequency band, and the echo optical signals after the band-pass filtering are transmitted to the photoelectric detector;
and the photoelectric detector is used for carrying out photoelectric conversion on the echo optical signal from the spectrum filter to obtain an electric signal.
In one design, the optical waveguide homogenizer performs a light homogenizing process on the echo light signal from the spatial filter, and transmits the light-homogenized echo light signal to the spectral filter.
In a third aspect, an embodiment of the present application provides a laser radar, including the laser receiving device described above.
In this embodiment, the spatial filter performs spatial filtering on the echo optical signal from the receiving objective lens to filter out the noise optical signal outside the preset field of view, and retains the echo optical signal in the preset field of view, so that the signal-to-noise ratio of the laser receiving device can be increased, and the greater interference of the optical noise signal on the echo optical signal is avoided; the spectral filter carries out band-pass filtering on the echo optical signals so as to filter noise optical signals outside a preset frequency band, and the echo optical signals in the preset frequency band are reserved, so that the signal-to-noise ratio of the laser receiving device can be further increased, the accuracy of the photoelectric detector is improved, and the interference of the noise optical signals to the photoelectric detector is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram showing a structure of a laser light receiving device according to an embodiment of the present invention;
FIG. 2 is a schematic view of an optical path of a laser receiving device according to an embodiment of the present invention;
Fig. 3 is a block diagram showing the structure of a laser light receiving device according to an embodiment of the present invention;
Fig. 4 is a schematic view of an optical path of a laser receiving device according to an embodiment of the invention;
fig. 5 is a schematic flow chart of a laser receiving method according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.
Referring to fig. 1 and 2, fig. 1 is a schematic structural diagram of a laser receiving device according to an embodiment of the present invention, and as shown in fig. 1, the laser receiving device includes: a receiving objective lens 10, a spatial filter 11, a spectral filter 12 and a photodetector 14.
Wherein the receiving objective lens 10 may be composed of one or more lenses, and the receiving objective lens may adopt a telecentric optical path or a non-telecentric optical path. The receiving objective lens can be provided with a plurality of receiving light channels, and an emergent light signal is obtained after an echo light signal from an object is incident on the receiving light channels; the receiving objective may consist of a plurality of groups of lenses. In the telecentric optical path, the outgoing optical signal of the receiving objective lens 10 is parallel to the optical axis of the receiving objective lens 10; in the non-telecentric optical path, a preset angle is formed between an emergent light signal of the receiving objective lens 10 and an optical axis; correspondingly, the included angle between the optical device (such as a diaphragm or an optical waveguide homogenizer, etc.) arranged behind the receiving objective lens 10 and the optical axis is also equal to the preset angle, so that the emergent optical signal of the receiving objective lens 10 is perpendicular to the input port of the optical device; the preset angle is related to an included angle between the emitted light signal corresponding to the echo light signal and the optical axis, for example: the included angle between the optical axis of the transmitting optical signal and the optical axis of the receiving objective lens 10 is 45 degrees, so that the transmitting optical signal forms an echo optical signal after encountering an object, and the included angle between the outgoing optical signal obtained after the echo optical signal is incident on the receiving objective lens 10 and the optical axis is also 45 degrees.
For example: as shown in fig. 2, the receiving objective lens 10 is provided with a plurality of light receiving channels, each of which includes a spatial filter 11, a spectral filter 12, an optical waveguide homogenizer 13, and a photodetector 14.
The spatial filter 11 is configured to filter out noise optical signals outside an effective field, where the noise optical signals may be a sunlight background noise optical signal and an ineffective echo optical signal scattered back by the atmosphere, the effective field includes a vertical field of view and a horizontal field of view, one spatial filter 11 is disposed in each receiving optical channel, a sum of the horizontal fields of view of the respective spatial filters 11, and a sum of the vertical fields of view of the respective spatial filters 11 form a total effective field of view of the laser receiving device. For example: the laser receiving device is provided with 100 receiving optical channels, and correspondingly, the 100 receiving optical channels comprise 100 spatial filters 11, the vertical view field of each spatial filter 11 is 1 degree, the horizontal view field is 2 degrees, and each spatial filter 11 filters noise optical signals of which the vertical view field is outside 1 degree and the horizontal view field is outside 2 degrees. Then the laser receiving device may filter out noise light signals outside the vertical field of view of 1 degree x 100=100 degrees and outside the horizontal field of view of 2 degrees x 100=200 degrees.
Further, the spatial filter 11 includes a diaphragm, which is an aperture in the optical system that limits the light beam, and the size of the aperture may be fixed or adjustable. The aperture may be an aperture stop, a field stop, a vignetting stop or an anti-parasitic stop depending on the type. Wherein the aperture stop can limit the beam solid angle (cone angle). The field stop may limit the maximum range over which the object plane or object space can be imaged by the optical system. The vignetting diaphragm aims to reduce the off-axis aberration of light and allows the light beam part emitted by the off-axis point of the object space to pass through. The flare reducing diaphragm is used for limiting light signals emitted from a non-imaging object, light signals reflected by each refraction surface of the optical system, light signals reflected by the inner wall of the instrument and the like.
Further, the diaphragm may be arranged in the focal plane of the receiving objective 10, i.e. the distance between the diaphragm and the receiving objective 10 is equal to the focal length of the receiving objective 10. When the number of the diaphragms is multiple, the diaphragms are arranged in the focal plane, and the intervals between any two adjacent diaphragms are equal. Wherein the aperture size=θ×f of the diaphragm, θ represents a divergence angle of the emitted light signal, and the divergence angle represents a speed at which the light beam diverges from the beam waist; f represents the focal length of the receiving objective 10, the diaphragm corresponds to a receiving optical channel, and the transmitted optical signal encounters the object to form an echo optical signal, and the echo optical signal is incident into the receiving optical channel.
The spectral filter 12 is a band-pass filter, which is used to filter out optical noise outside a preset frequency band, and may be a narrowband filter. The main parameters of the narrow-band filter comprise a center wavelength, a bandwidth, a peak transmittance, a cut-off range and a cut-off depth; wherein the center wavelength represents an operating wavelength of the optical system; bandwidth represents the distance between two positions in the passband where the transmittance is generally the peak transmittance, also referred to as half-width height; the peak transmittance represents the highest transmittance level in the passband; the cut-off range means a wavelength range requiring cut-off except for the passband; for a narrow-band filter, one section is a front cut-off, i.e., one section with a cut-off wavelength smaller than the center wavelength, and the other section is a long cut-off, i.e., one end with a cut-off wavelength higher than the center wavelength; the cutoff depth represents the maximum transmittance of the light that can pass through the cutoff band.
The optical waveguide light homogenizer 13 is used for homogenizing the echo optical signal, the optical waveguide light homogenizer 13 can comprise a light guide component and a light homogenizing component, and the light guide component and the light homogenizing component can be integrally formed; the light guide component is used for transmitting echo light signals, the light homogenizing component is used for converting echo light signals with concentrated energy distribution into echo light signals with even energy distribution, and the light homogenizing component can be a light homogenizing lens system consisting of a plurality of lenses; for example: and realizing the output of the uniform echo optical signals by utilizing the front and back double fly-eye lens arrays. The shape of the light guide component can be a cylinder, a cuboid, a round table, a prismatic table and the like, and the shape of the light spot subjected to light homogenizing treatment can be a round shape or a rectangular shape; the light guide member may be a solid waveguide or a hollow waveguide. The main parameters of the optical waveguide homogenizer 13 include: the output spot size, operating wavelength, incident spot size, and transmittance, the output spot size representing the size of the spot formed on the photodetector 14 by the output return light signal, the photodetector 14 comprising a plurality of pixels (pixels), one pixel being made up of a plurality of cells, each cell corresponding to an avalanche diode for detecting single photons, the spot covering one or more pixels on the photodetector 14. For example: the size of the light spot output by the optical waveguide light homogenizer 13 is represented by a diameter or a side length; the operating wavelength represents the wavelength of the echo optical signal that the optical waveguide homogenizer 13 can perform the homogenization processing; the incident light spot size represents the size of a light spot formed on the optical waveguide homogenizer 13 by the input echo light signal, and can be represented by a diameter or a side length; the transmittance represents the ratio of the intensity of the output echo optical signal to the intensity of the input echo optical signal, and the ratio is generally less than 1.
Optionally, the light guide member in the optical waveguide homogenizer 13 includes an input port and an output port, the input port representing a cross section of an incident light signal of the light guide member, and the output port representing a cross section of an output light signal of the light guide member. The shape and size of the input port and the output port may be the same or different. For example: the shape of the input port and the output port of the optical waveguide homogenizer 12 is circular, and the areas of the two circular shapes are the same; or the shape of the input port and the output port of the optical waveguide light homogenizer 12 is circular, and the area of the input port is smaller than that of the output port, so as to increase the area of the light spot; or the shape of the input port and the output port is rectangular, and the areas of the two rectangles are equal; or the shape of the input port and the output port is rectangular, and the area of the input port is smaller than that of the output port. The shape and size of the output port determines the shape and size of the spot impinging on the photodetector 14.
In one possible embodiment, when one optical waveguide homogenizer 13 is located in one light receiving channel and the number of optical waveguide homogenizers 13 is plural, the optical waveguide homogenizers 13 may be arranged in a one-dimensional manner or in a two-dimensional manner, that is, a plurality of optical waveguide homogenizers 13 are aligned in a one-dimensional manner, or a plurality of optical waveguide homogenizers 13 are aligned in a line. The optical waveguide homogenizers 13 are arranged in a two-dimensional manner, i.e., in M rows and N columns, where M and N are integers greater than 1. For example: m=4, n=4, and the plurality of optical waveguide homogenizers 13 are arranged in 4 rows and 4 columns.
The principle of the photodetector 14 is a photoelectric effect, which converts an echo optical signal into an electrical signal, the photodetector may be an APD (AVALANCHE PHOTO DIODE ), a PN junction of the APD is made of silicon or germanium, and after a reverse bias voltage is applied to the PN junction, the incident echo optical signal is absorbed by the PN junction to form a photocurrent, and the photocurrent is multiplied after the reverse bias voltage is increased. The photodetector 14 may also be a single photon photodetector, such as: siPM (Silicon photomultiplier ) or SPAD (Single Photon Avalanche Diode, single photon avalanche diode), single photon photodetectors have extremely high sensitivity, and can detect and count single photons with minimum energy quantum-photons of light. The number of the photodetectors 14 may be one or more, and when the number of the photodetectors 14 is plural, the number of the spatial filters 11, the spectral filters 12, the optical waveguide homogenizers 13 and the number of the photodetectors 14 are equal, and the spatial filters, the spectral filters 12, the optical waveguide homogenizers and the photodetectors 14 are arranged in a one-to-one manner. The photodetector 14 includes a plurality of pixels (pixels), each of which includes a plurality of cells, and the light spot output from the optical waveguide homogenizer 13 covers one or more pixels on the photodetector 14. The size and shape of the light spot output from the optical waveguide homogenizer 13 are related to the size and shape of the output port of the optical waveguide homogenizer 13. The size and number of the pixels included in the photodetector 14 may be determined according to actual requirements, and the embodiment of the present application may increase the dynamic range of the photodetector 14 by increasing the number of pixels, and decrease the dynamic range of the photodetector 14 by decreasing the number of pixels, so that the photodetector 14 can detect the optical signal in a larger detection range, thereby increasing the detection probability of the photodetector 14. In addition, when the area of the input port of the optical waveguide device 13 is larger than the area of the output port, that is, the output optical signal is larger than the light spot of the input optical signal, the output light spot can cover more pixels on the photodetector 14, so that the detection probability of the photodetector can be further improved.
Referring to fig. 1 and 2, the spectral filter 12 is located in front of the optical waveguide homogenizer 13, and the echo optical signal is transmitted to the photodetector 14 through the receiving objective lens 10, the spatial filter 11, the spectral filter 12, and the optical waveguide homogenizer 13 in this order.
The following describes in detail the operation principle of the laser receiving device of fig. 1 and 2:
The receiving objective lens 10 is used for receiving the echo optical signal and transmitting the echo optical signal to the spatial filter.
The spatial filter 11 is configured to spatially filter the echo optical signal from the receiving objective lens 10 to filter out noise optical signals outside the preset field of view, and transmit the spatially filtered echo optical signal to the spectral filter 12. The spatial filter 11 filters out noise optical signals outside the preset view field, retains echo optical signals within the preset view field, reduces interference of the noise optical signals with normal echo optical signals, and improves the signal-to-noise ratio of the laser receiving device.
The spectral filter 12 is configured to bandpass filter the echo optical signal from the spatial filter 11 to filter out noise optical signals outside a preset frequency band, and transmit the bandpass filtered echo optical signal to the photodetector 14. The spectral filter 12 filters out noise optical signals outside the operating frequency band, retains echo optical signals within the operating frequency band, and reduces interference of the noise optical signals on normal echo optical signals.
The photodetector 14 is configured to photoelectrically convert the echo optical signal from the spectral filter 12 to an electrical signal.
Wherein, in a possible implementation manner, the laser receiving device further comprises: the optical waveguide homogenizer 13 is configured to perform homogenization processing on the echo optical signal from the spectral filter 12, and to transmit the echo optical signal after the homogenization processing to the photodetector 14. The optical waveguide light evening device 13 can evenly irradiate light spots with evenly distributed energy to the photoelectric detector after carrying out light evening treatment on the echo light signals, so that each cell on the photoelectric detector detects the same illumination intensity, and false alarm is prevented from being triggered by the fact that the illumination intensity of a certain cell exceeds an alarm threshold, and the false alarm rate of the photoelectric detector is reduced.
In another possible embodiment, the spectral filter 12 may also be located behind the optical waveguide homogenizer 12, and the echo optical signal is transmitted to the photodetector through the receiving objective lens 10, the spatial filter 11, the optical waveguide homogenizer 13 and the spectral filter 12 in order. The working principle of the laser receiving device is as follows: the receiving objective lens 10 is used for receiving the echo optical signal and transmitting the echo optical signal to the spatial filter 11. The spatial filter 11 is configured to spatially filter the echo optical signal from the receiving objective lens 10, and transmit the spatially filtered echo optical signal to the optical waveguide homogenizer 13. The optical waveguide homogenizer 13 performs homogenization processing on the echo optical signal from the spatial filter, and transmits the echo optical signal after the homogenization processing to the spectral filter 12. The spectral filter is configured to bandpass filter the echo optical signal from the optical waveguide homogenizer 13 to filter out noise optical signals outside the preset frequency band, and transmit the bandpass filtered echo optical signal to the photodetector 14. The photodetector 14 receives the echo optical signal from the spectral filter 12 and converts the echo optical signal into an electrical signal.
In the embodiment of the invention, the spatial filter performs spatial filtering on the echo optical signals from the receiving objective lens to filter noise optical signals outside a preset view field, reserves the echo optical signals in the preset view field, can increase the signal-to-noise ratio of the laser receiving device, the angle filter 16 filters the noise optical signals outside the preset angle, reserves the echo optical signals within the preset angle, reduces the interference of the noise optical signals on normal echo optical signals, and further improves the signal-to-noise ratio of the laser receiving device; the spectral filter carries out band-pass filtering on the echo optical signals so as to filter noise optical signals outside a preset frequency band, keep the echo optical signals in the preset frequency band, improve the accuracy of detecting the optical signals by the photoelectric detector and reduce the interference of the noise optical signals to the photoelectric detector.
Referring to fig. 3 and fig. 4, another schematic structural diagram of a laser receiving device according to an embodiment of the present application is provided, where the laser receiving device includes: a receiving lens 10, a spatial filter 11, a collimating lens 15, an angle filter 16, a focusing lens 17, a spectral filter 12, an optical waveguide homogenizer 13 and a photodetector 14.
The difference between this embodiment and the embodiment in fig. 1 is that this embodiment includes, in addition to: the receiving lens 10, the spatial filter 11, the spectral filter 12, the optical waveguide homogenizer 13 and the photodetector 14, and also comprises a collimating lens 15, an angle filter 16 and a focusing lens 17.
The description of the receiving lens 10, the spatial filter 11, the spectral filter 12, the optical waveguide homogenizer 13 and the photodetector 14 in this embodiment may refer to the description of the embodiment of fig. 1 and 2, and will not be repeated here.
Wherein the collimator lens 15 is used for converting an incident echo light signal into an echo light signal parallel to the optical axis, the collimator lens 15 may be composed of a single lens, for example: a plano-convex lens or a biconvex lens; it may also consist of a plurality of lenses, for example: a doublet lens.
The angle filter 16 is configured to filter the echo light signals outside the preset incident angle, and the magnitude of the preset incident angle may be determined according to the actual requirement, which is not limited in the embodiment of the present application. The angle filter 16 may be a dove reflector, wherein two layers of films are respectively arranged on the upper and lower non-working surfaces of the dove reflector, a dielectric film is arranged on the inner surface of the dove reflector, the dielectric film totally reflects the echo light signals meeting the incident angle condition, and transmits the echo light signals not meeting the incident angle condition; the outer surface of the dove reflector is provided with an absorption film which is used for absorbing the echo light signals projected by the dielectric film and preventing the echo light signals transmitted by the dielectric film from generating crosstalk again.
The focusing LENS 17 is also called a gradient-index LENS (G-LENS), and the refractive index of the focusing LENS 17 gradually decreases along the radial direction, so that an echo optical signal which is incident parallel to the optical axis is smoothly and continuously converged to a point. The focusing lens 17 may be a spherical lens or a planar lens according to the shape classification. The type of focusing lens 17 may be a plano-convex lens, a positive meniscus lens, an aspherical lens, a diffractive lens, or a reflective lens.
The working principle of the laser receiving device according to the embodiment of the present application is described below with reference to fig. 3:
and a receiving lens 10 for receiving the echo optical signal and transmitting the echo optical signal to the spatial filter 11.
The spatial filter 11 is configured to spatially filter the echo optical signal from the receiving lens 10 to filter out noise optical signals outside the preset field of view, and transmit the spatially filtered echo optical signal to the collimating lens 15. The spatial filter 11 filters out noise optical signals outside the preset view field, retains echo optical signals within the preset view field, reduces interference of the noise optical signals with normal echo optical signals, and improves signal-to-noise ratio of echo optical signal transmission.
And a collimator lens 15 for collimating the echo optical signal from the spatial filter 11 and transmitting the collimated echo optical signal to an angle filter 16.
The angle filter 16 is configured to perform angle filtering on the echo optical signal from the collimating lens 16 to filter out noise optical signals outside the preset angle, and transmit the angle-filtered echo optical signal to the focusing lens 17. The angle filter 16 filters out noise optical signals outside the preset angle, retains echo optical signals within the preset angle, reduces interference of the noise optical signals on normal echo optical signals, and improves signal-to-noise ratio of the laser receiving device.
And a focusing lens 17 for focusing the echo optical signal from the angle filter 16 and transmitting the focused echo optical signal to the spectrum filter 12.
The spectral filter 12 is configured to bandpass filter the echo optical signal from the focusing lens 17 to filter out noise optical signals outside a preset frequency band, and transmit the bandpass filtered echo optical signal to the photodetector 14. The spectral filter 12 filters out noise optical signals outside the operating frequency band, retains echo optical signals within the operating frequency band, and reduces interference of the noise optical signals on normal echo optical signals.
The photodetector 14 is configured to photoelectrically convert the echo optical signal from the spectral filter 12 to an electrical signal.
In one possible embodiment, referring to fig. 3, the laser receiving device further includes: the optical waveguide homogenizer 13 is configured to perform homogenization processing on the echo optical signal from the spectral filter 12, and to transmit the echo optical signal after the homogenization processing to the photodetector 14. The optical waveguide light homogenizer 13 can uniformly irradiate the echo optical signals to the photoelectric detector after carrying out light homogenizing treatment on the echo optical signals, thereby improving and reducing the false alarm rate of the photoelectric detector.
In another possible embodiment, referring to fig. 4, the spectral filter 12 may also be located behind the optical waveguide homogenizer 12, and the echo optical signal is transmitted to the photodetector through the receiving objective lens 10, the spatial filter 11, the optical waveguide homogenizer 13, and the spectral filter 12 in sequence. The working principle of the laser receiving device is as follows: and a receiving lens 10 for receiving the echo optical signal and transmitting the echo optical signal to the spatial filter 11. The spatial filter 11 spatially filters the echo optical signal from the receiving lens 10 to filter out noise optical signals outside the preset field of view, and transmits the spatially filtered echo optical signal to the collimator lens 15. The collimator lens 15 performs collimation processing on the echo light signal from the spatial filter 11, and transmits the echo light signal after the collimation processing to the angle filter 16. An angle filter 16 for angle-filtering the echo optical signal from the collimator lens 15 and transmitting the angle-filtered echo optical signal to a focusing lens 17. And a focusing lens 17 for focusing the echo light signal from the angle filter 16 and transmitting the focused echo light signal to the optical waveguide homogenizer 13. The optical waveguide homogenizer 13 performs homogenization processing on the echo optical signal from the focusing lens 17, and transmits the echo optical signal after the homogenization processing to the spectral filter 12. The spectral filter 12 is configured to bandpass filter the echo optical signal from the optical waveguide homogenizer 13 to filter out noise optical signals outside the preset frequency band, and transmit the echo optical signal after the bandpass filtering to the photodetector 14. The photodetector 14 is configured to photoelectrically convert the echo optical signal from the spectral filter 12 to an electrical signal.
In the embodiment of the invention, the spatial filter performs spatial filtering on the echo optical signals from the receiving objective lens to filter noise optical signals outside a preset view field, and retains the echo optical signals in the preset view field, so that the signal to noise ratio of the laser receiving device can be improved; the spectral filter carries out band-pass filtering on the echo optical signals subjected to the dodging treatment so as to filter noise optical signals outside a preset frequency band, and the echo optical signals in the preset frequency band are reserved, so that the signal-to-noise ratio of the echo optical signals can be further increased, the accuracy of the photoelectric detector is improved, and the interference of the noise optical signals to the photoelectric detector is reduced.
Referring to fig. 5, a flow chart of a laser receiving method according to an embodiment of the present application is shown, where the laser receiving method includes:
s501, the receiving objective receives the echo optical signal and transmits the echo optical signal to the spatial filter.
S502, the spatial filter performs spatial filtering on the echo optical signals from the receiving objective lens to filter noise optical signals outside a preset view field, and transmits the echo optical signals after spatial filtering to the spectral filter.
S503, the spectral filter carries out band-pass filtering on the echo optical signals from the spatial filter so as to filter noise optical signals outside a preset frequency band, and the echo optical signals after band-pass filtering are transmitted to the photoelectric detector.
S504, the photoelectric detector performs photoelectric conversion on the echo optical signal from the spectrum filter to obtain an electric signal.
In one possible embodiment, the laser receiving method further includes:
The optical waveguide homogenizer performs light homogenizing processing on the echo optical signal from the spatial filter, and transmits the echo optical signal after the light homogenizing processing to the spectral filter.
In one possible embodiment, the spatial filter includes a diaphragm, which is an aperture diaphragm, a field diaphragm, a vignetting diaphragm, or an anti-stray light diaphragm.
In one possible embodiment, the diaphragm is arranged in the focal plane of the receiving objective.
In one possible embodiment, the aperture size=θ×f, θ of the diaphragm represents the divergence angle of the emitted light signal, and f represents the focal length of the receiving objective lens.
In one possible implementation, the receiving objective adopts a telecentric light path, and the optical waveguide homogenizer is arranged parallel to the optical axis of the receiving objective; or the receiving objective adopts a non-telecentric light path, and the optical waveguide light homogenizer and the optical axis of the receiving objective are arranged at a preset angle.
In one possible implementation manner, the number of the optical waveguide light homogenizers is a plurality, the optical waveguide light homogenizers are arranged into M rows and N columns, and M and N are integers greater than or equal to 1; the number of the photodetectors is a plurality, and the number of the photodetectors is equal to the number of the spectral filters.
In one possible embodiment, the optical waveguide homogenizer includes a light guide member and a light homogenizing member;
The light guide component is used for transmitting the echo light signals from the spectrum filter and transmitting the echo light signals to the light homogenizing component; the shape of the light guide component is a cylinder, a truncated cone, a cuboid or a prismatic table;
and the light homogenizing component is used for homogenizing the echo light signals from the light guide component.
In one possible embodiment, the photodetector is an avalanche diode APD detector or a silicon photomultiplier SiPM detector.
In one possible embodiment, the method further comprises:
The collimating lens performs collimation processing on the echo optical signals from the spatial filter and transmits the echo optical signals after the collimation processing to the angle filter;
the angle filter performs angle filtering on the echo light signals from the collimating lens and transmits the echo light signals subjected to angle filtering to the focusing lens;
the focusing lens focuses the echo light signals from the angle filter and transmits the focused echo light signals to the spectrum filter.
In one possible embodiment, the angle filter is a dove mirror.
In one possible embodiment, the focusing lens is in the shape of a spherical lens or a planar lens.
The embodiments of the present application and the embodiments of fig. 1 to 4 are based on the same concept, and the technical effects brought by the embodiments of the present application are the same as those of fig. 1 to 4, and the specific implementation process may refer to the descriptions of the embodiments of fig. 1 to 4, which are not repeated here.
It will be apparent to those skilled in the art that the techniques in the embodiments of the present invention may be implemented by software plus necessary general purpose hardware, including general purpose integrated circuits, general purpose CPUs, general purpose memories, general purpose components, etc., but of course may be implemented by special purpose hardware, including application specific integrated circuits, special purpose CPUs, special purpose memories, special purpose components, etc., although in many cases the former is a preferred embodiment. Based on such understanding, the technical solution in the embodiments of the present invention may be embodied essentially or what contributes to the prior art in the form of a software product, which may be stored in a storage medium, such as a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the embodiments or some parts of the embodiments of the present invention.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.
The embodiments of the present invention described above do not limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (14)
1. A laser light receiving device, comprising: receiving objective lens, spatial filter, collimating lens, angle filter, focusing lens, spectrum filter and photoelectric detector;
the receiving objective lens is used for receiving the echo optical signals and transmitting the echo optical signals to the spatial filter;
The spatial filter is used for spatially filtering the echo optical signals from the receiving objective lens so as to filter noise optical signals outside a preset view field and transmitting the spatially filtered echo optical signals to the collimating lens;
the collimating lens is used for carrying out collimation processing on the echo optical signals from the spatial filter so as to convert the incident echo optical signals into echo optical signals parallel to an optical axis, and transmitting the echo optical signals after the collimation processing to the angle filter;
The angle filter is used for carrying out angle filtering on the echo optical signals from the collimating lens so as to filter noise optical signals outside a preset angle and transmitting the echo optical signals after angle filtering to the focusing lens;
the focusing lens is used for focusing the echo optical signals from the angle filter and transmitting the echo optical signals after focusing to the spectrum filter;
The spectral filter is used for carrying out band-pass filtering on the echo optical signals from the focusing lens so as to filter noise optical signals outside a preset frequency band, and transmitting the echo optical signals after the band-pass filtering to the photoelectric detector;
the photoelectric detector is used for carrying out photoelectric conversion on the echo optical signals from the spectrum filter to obtain electric signals.
2. The laser light receiving device according to claim 1, further comprising:
and the optical waveguide light homogenizing device is used for carrying out light homogenizing treatment on the echo light signals from the spectrum filter and transmitting the echo light signals subjected to the light homogenizing treatment to the photoelectric detector.
3. The laser receiver according to claim 2, wherein the receiving objective lens adopts a telecentric optical path, and the optical waveguide homogenizer is disposed parallel to an optical axis of the receiving objective lens; or (b)
The receiving objective adopts a non-telecentric light path, and the optical waveguide light homogenizer and the optical axis of the receiving objective are arranged at a preset angle.
4. The laser light receiving device according to claim 1, wherein the spatial filter includes a diaphragm, the diaphragm being an aperture diaphragm, a field diaphragm, a vignetting diaphragm, or an stray light eliminating diaphragm.
5. The laser light receiving device according to claim 4, wherein the diaphragm is disposed on a focal plane of the receiving objective lens.
6. The laser light receiving device according to claim 4, wherein the aperture size = θ x f of the diaphragm, θ represents a divergence angle of the emitted light signal, and f represents a focal length of the receiving objective lens.
7. A laser receiving device as claimed in claim 2 or 3, wherein the number of the optical waveguide homogenizers is plural, the plural optical waveguide homogenizers are arranged in M rows and N columns, M and N being integers greater than or equal to 1; the number of the photoelectric detectors is M multiplied by N, and the number of the spectrum filters and the number of the optical waveguide light uniformizers are equal.
8. A laser light receiving device as claimed in claim 2 or 3, wherein the optical waveguide homogenizer comprises: a light guide member and a light homogenizing member;
The light guide component is used for transmitting the echo light signals from the spectrum filter and transmitting the echo light signals to the light homogenizing component; the shape of the light guide component is a cylinder, a truncated cone, a cuboid or a prismatic table;
and the light homogenizing component is used for homogenizing the echo light signals from the light guide component.
9. The laser light receiving device according to claim 1, wherein the photodetector is an avalanche diode APD detector or a silicon photomultiplier detector.
10. The laser light receiving device according to claim 1, wherein the angle filter is a dove mirror.
11. The laser light receiving device according to claim 1, wherein the focusing lens comprises a plano-convex lens, a positive meniscus lens, an aspherical lens, a diffraction lens, or a reflection lens.
12. A laser receiving method, comprising:
receiving an echo optical signal received by an objective lens, and transmitting the echo optical signal to a spatial filter;
the spatial filter performs spatial filtering on the echo optical signals from the receiving objective lens to filter noise optical signals outside a preset view field, and transmits the echo optical signals after spatial filtering to the collimating lens;
The collimating lens performs collimation processing on the echo optical signals from the spatial filter so as to convert the incident echo optical signals into echo optical signals parallel to an optical axis, and transmits the echo optical signals after the collimation processing to the angle filter;
The angle filter performs angle filtering on the echo light signals from the collimating lens to filter noise light signals outside a preset angle, and transmits the echo light signals after angle filtering to the focusing lens;
The focusing lens focuses the echo light signals from the angle filter and transmits the focused echo light signals to the spectrum filter;
The spectrum filter carries out band-pass filtering on the echo optical signals from the focusing lens so as to filter noise optical signals outside a preset frequency band, and the echo optical signals after band-pass filtering are transmitted to the photoelectric detector;
and the photoelectric detector is used for carrying out photoelectric conversion on the echo optical signal from the spectrum filter to obtain an electric signal.
13. The method as recited in claim 12, further comprising:
The optical waveguide light homogenizing device performs light homogenizing processing on the echo light signals from the spatial filter and transmits the echo light signals subjected to the light homogenizing processing to the spectrum filter.
14. A lidar, comprising: the laser light receiving device according to any one of claims 1 to 11.
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| PCT/CN2020/078560 WO2021179158A1 (en) | 2020-03-10 | 2020-03-10 | Laser receiving device, laser receiving method and lidar |
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| CN113917242A (en) * | 2021-09-28 | 2022-01-11 | 华中科技大学 | Conductor corona discharge electric field non-intervention measurement system and application thereof |
| CN114325640B (en) * | 2021-11-18 | 2022-11-04 | 杭州宏景智驾科技有限公司 | Laser radar receiving device and laser radar |
| CN114659624A (en) * | 2022-02-24 | 2022-06-24 | 北京科益虹源光电技术有限公司 | A laser energy measuring device |
| CN114942449A (en) * | 2022-05-06 | 2022-08-26 | 洛伦兹(宁波)科技有限公司 | Lidar receiving system, lidar and method for improving ranging intensity |
| CN116184436B (en) * | 2023-03-07 | 2023-11-17 | 哈尔滨工业大学 | Array orbital angular momentum cloud and fog penetration quantum detection imaging system |
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