Subsequent light path architecture adaptive to different wavelength laser combinations and laser radar

Abstract

The invention relates to the technical field of laser radars, in particular to a subsequent light path architecture adaptive to different wavelength laser combinations and a laser radar. The invention discloses a subsequent light path structure adaptive to different wavelength laser combinations. The subsequent light path structure is sequentially provided with a shading cylinder and a main light cavity in the transmission direction of a main optical axis of an echo signal; the detection mode compatible structure and the reconfigurable light splitting module are integrated on the main optical cavity; the reconfigurable light splitting module is installed in the main light cavity and is composed of a plurality of adjustable and switchable optical elements. The side part of the main optical cavity is provided with three detection channel interfaces which are respectively connected with corresponding detectors; the detection mode compatible structure is composed of a two-dimensional fine tuning structure which penetrates through the first detection channel interface and is used for being compatible with two types of detectors of spatial light and optical fiber; the two-dimensional fine tuning structure carries the coupling mirror. Combination can be carried out according to specification requirements of different wavelengths, secondary design and processing of the main optical cavity are not needed, and only different optical standard component combinations need to be adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser radar, in particular to a follow-up optical path architecture and laser radar suitable for combination of different wavelengths of laser. BACKGROUND

[0002] The existing aerosol radar is composed of a laser emission unit, a return signal receiving unit and a follow-up optical path, and is used for optical remote sensing of the atmosphere.

[0003] Since the wavelength or wavelength combination form of the laser emitted by the laser emission unit changes, the wavelength of the return signal also changes accordingly, so the conventional aerosol radar will design different follow-up optical paths for the above different wavelength combinations. A set of parts and a set of process flows are often used for one specification, which leads to low part reuse rate, low interchangeability of parts, and complex material and BOM management in the production and manufacturing process of different specifications of radar.

[0004] To this end, the common solution in the existing laser radar technology is: 1) one is to use modular and standardized optical devices to build a unified back-end optical path, such as the technical document published by Cesar Observatory of Ruisdael Observatory in the Netherlands, titled "Optimization-Through Optical Design-Of AMulti-Wavelength Fiber-Based Raman Lidar System In The Near-Field ForVertical Aerosol Measurements In The Troposphere"; 2) the other is to design an integrated receiving unit that can process multiple wavelengths of return signals at the same time, such as the Chinese patent with publication number CN201910337146.8, titled "A High-Spectral Laser Radar System for Aerosol Size Spectrum Measurement". Both solutions belong to the concept of a set of optical paths and wavelength detection, but the design based on this concept often only focuses on how to use specific optical principles to solve a specific atmospheric science detection problem, so it improves the special design of the optical system, which often ignores the generality of mechanical design.

[0005] That is, the person skilled in the art does not focus on how to more economically and flexibly construct various optical receiving systems, and based on this, the person skilled in the art urgently needs to design a new and general follow-up optical path architecture that can improve the above defects from the perspective of production and utilization. SUMMARY

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a follow-up optical path architecture and lidar that are adapted to different wavelength laser combinations.

[0007] A follow-up optical path architecture adapted to different wavelength laser combinations is adapted to a laser emitting unit that emits n lasers of different wavelengths, where n is an integer, 3≥n≥2. The follow-up optical path structure is provided with a light shielding tube and a main optical cavity in sequence along the transmission direction of the main optical axis of the echo signal. The follow-up optical path structure also includes: a detection mode compatible structure and a reconfigurable beam splitting module integrated on the main optical cavity. The reconfigurable beam splitter is installed inside the main optical cavity. The reconfigurable beam splitter consists of multiple adjustable and switchable optical elements. Specifically, the reconfigurable beam splitter consists of a two-phase beam splitter, a first dual filter assembly, and a dual prism assembly arranged sequentially along the echo signal transmission direction, as well as a second dual filter assembly arranged on the beam splitting path of the two-phase beam splitter. The main optical cavity has three detection channel interfaces on its side, which are used to connect to the corresponding detectors respectively; among them, the first detection channel interface is connected to the beam splitting path of the two-phase beam splitting component; the dual prism assembly is adapted to the detection channel interfaces other than the first detection channel interface; The detection mode compatible structure consists of a two-dimensional fine-tuning structure that runs through the first detection channel interface and is compatible with both space light and fiber optic detectors. A two-dimensional fine-tuning structure carries a coupling mirror.

[0008] Preferably, the main optical cavity is provided with: The first chamber is used to install the two-phase beam splitter; The second chamber is used to install the first dual-filter assembly; The third chamber is used to install the dual prism assembly; The fourth chamber is used to install the second dual-filter assembly; The first and second chambers share a circular optical path channel on their common cavity wall.

[0009] Preferably, the two-dimensional fine-tuning structure consists of an adjustment base, an adjustable base, a coupling mirror, and a disc spring; The adjustment base is installed on the outer wall of the side of the main optical cavity, and the central optical path channel of the adjustment base is connected to the interface of the first detection channel. The fixed seat and the adjustable seat are connected by a first screw, and a disc spring is fitted on the first screw. The adjustable seat has an internal thread that matches the external thread of the coupling mirror, so that the adjustable seat and the coupling mirror are locked together by a set screw.

[0010] Preferably, the second dual filter assembly includes a pressure ring; The two filters in the second dual filter assembly are pressed and assembled in the third filter seat by a pressing ring.

[0011] Preferably, the reflection cavity is provided, and an outlet end of the reflection cavity constitutes a fourth detection channel interface; an inlet end of the reflection cavity and the main light cavity are connected in a light path channel.

[0012] Preferably, the reflection cavity is right-angled. An opening is formed at the right-angled part of the reflection cavity. A step groove gradually expanding from inside to outside is formed at the opening. A mirror is further arranged in the reflection cavity, and the mirror is arranged on the innermost step of the step groove. A sealing cover plate is further arranged outside the reflection cavity, and the sealing cover plate seals the opening of the right-angled part of the reflection cavity by screws.

[0013] A laser radar suitable for combination of lasers of different wavelengths, and a subsequent light path structure suitable for combination of lasers of different wavelengths.

[0014] The technical scheme has the following advantages: The whole structure is simple, and the laser radar has versatility suitable for combination of lasers of different wavelengths. DETAILED DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the present application or the technical scheme in the prior art, the drawings needed in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0016] Figure 1 It is a schematic diagram of the whole structure of the subsequent light path structure of the embodiment 1. Figure 2 It is a schematic diagram of the internal structure of the subsequent light path structure of the embodiment 1. Figure 3 It is a schematic diagram of the cross section of the subsequent light path structure of the embodiment 1. Figure 4 It is a schematic diagram of the longitudinal section of the reflection cavity of the embodiment 1. Figure 5 It is a schematic diagram of the light path of the embodiment 2. Figure 6 It is a schematic diagram of the light path of the embodiment 3.

[0017] Explanation of reference signs: 1 - main light cavity, 2 - dichroic mirror seat, 3 - dichroic beam splitter, 4 - light shielding cylinder, 5 - adjusting seat, 6 - adjustable seat, 7 - coupling mirror, 8 - first filter seat, 9 - second filter seat, 10 - first prism, 11 - second prism, 12 - first detector, 13 - reflecting cavity, 14 - second detector, 15 - third detector, 16 - cover plate, 17 - compression ring, 18 - first filter, 19 - second filter, 20 - disc spring, 21 - third filter, 22 - fourth filter, 23 - first prism seat, 24 - second prism seat, 25 - reflecting mirror, 26 - first spare groove, 27 - second spare groove, 28 - optical fiber joint, 29 - sealing cover plate, 30 - third filter seat. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0019] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 As Figures 1-6As shown, a kind of subsequent optical path architecture suitable for the combination of different wavelength lasers is adapted to the laser emission unit emitting n different wavelength lasers, n is integer, 3≥n≥2, subsequent optical path structure is provided with light blocking cylinder 4 and main optical cavity 1 in turn along the transmission direction of echo signal main optical axis, in the embodiment, subsequent optical path structure further includes: integrated detection mode compatible structure and reconfigurable optical splitting module on main optical cavity 1; Specifically: Reconfigurable optical splitting module is installed in main optical cavity 1, and reconfigurable optical splitting module is composed of multiple adjustable and switchable optical elements, specifically: Figure 3 After removing the cover plate 16 of main optical cavity 1, reconfigurable optical splitting module in main optical cavity 1 is specifically composed of two binomial optical splitting components, first double filter component and double prism component arranged in turn along the transmission direction of echo signal, and second double filter component arranged on the optical splitting path of two binomial optical splitting components; Three detection channel interfaces are provided on the side of main optical cavity 1, for being connected with corresponding detectors respectively;Wherein, the first detection channel interface is connected with the optical splitting path of two binomial optical splitting components;Double prism component is adapted to the detection channel interface except the first detection channel interface; Detection mode compatible structure is composed of two-dimensional fine adjustment structure penetrating through the first detection channel interface and being used for compatible spatial light and optical fiber two types of detectors;Two-dimensional fine adjustment structure carries coupling mirror 7.

[0023] Further, in main optical cavity 1 is provided with: First chamber, for installing two binomial optical splitting components;Two binomial optical splitting components include: two binomial color mirror seat 2 installed in first chamber and two binomial color splitting sheet 3 installed on two binomial color mirror seat 2;Main optical cavity 1 is connected with two binomial color mirror seat 2 by screw, two binomial color splitting sheet 3 is pasted on two binomial color mirror seat 2 by glue, and arc mounting hole is provided on the flange surface of two binomial color mirror seat 2, so that the angle of two binomial color mirror seat 2 can be appropriately adjusted during installation and adjustment; Second chamber, for installing first double filter component;First double filter component includes: first filter seat 8 and third filter 21 installed on first filter seat 8;Second filter seat 9 and fourth filter 22 installed on second filter seat 9;Third filter 21 and fourth filter 22 are pasted in first filter seat 8 and second filter seat 9 respectively by glue; Third chamber, for installing double prism component;Double prism component includes: first prism seat 23, first prism 10 installed on first prism seat 23, second prism seat 24 and second prism 11 installed on second prism seat 24; The fourth chamber is used for mounting the second double filter assembly; the second double filter assembly comprises a third filter seat 30, a pressing ring 17, a first filter 18 and a second filter 19; wherein the two filters in the second double filter assembly are pressed into the third filter seat 30 through the pressing ring 17.

[0024] The first filter seat 8, the second filter seat 9 and the third filter seat 30 are respectively mounted in the grooves of the corresponding chambers of the main light cavity 1 through screws.

[0025] The first chamber and the second chamber share the circular light path channel on the chamber wall; The specific parameters of the rectangular light path channel and the circular light path channel depend on the size of the final overall device, so they are not specifically limited in this embodiment.

[0026] In this embodiment, the two-dimensional fine adjustment structure is composed of an adjusting base 5, an adjustable movable base 6, a coupling mirror 7 and a disc spring 20; The adjusting base 5 is mounted on the outer wall of the side of the main light cavity 1, and the central light path channel of the adjusting base 5 is in interface conduction connection with the first detection channel; The adjusting base 5 and the adjustable movable base 6 are connected through a first screw, and the disc spring 20 is sleeved on the first screw; The adjustable movable base 6 is internally provided with an internal thread which is matched with an external thread of the coupling mirror 7, so that the adjustable movable base 6 and the coupling mirror 7 are locked through a jackscrew, and are coated with glue to prevent the coupling mirror 7 from loosening.

[0027] In this embodiment, the main light cavity 1 is also provided with a reflection cavity 13 at the end away from the light shielding cylinder 4, and the outlet end of the reflection cavity 13 constitutes a fourth detection channel interface; the inlet end of the reflection cavity 13 is in light path conduction connection with the light path channel of the end of the main light cavity 1 away from the light shielding cylinder 4.

[0028] The reflection cavity 13 is bent at a right angle; An opening is formed at the bent part of the reflection cavity 13; And a stepped groove which gradually expands from inside to outside is formed at the opening; A reflecting mirror 25 is also arranged in the reflection cavity 13; the reflecting mirror 25 is mounted on the innermost step of the stepped groove; A sealing cover plate 29 is also arranged outside the reflection cavity 13; the sealing cover plate 29 seals the opening at the bent part of the reflection cavity 13 through a screw.

[0029] Embodiment 2 Based on embodiment 1, specific wavelength combinations are now given as examples for explanation.

[0030] This embodiment is for the combination of two different wavelength channels of 532-P laser and 532-S laser; For example, Figure 5The detector at the exit of the reflection cavity 13 does not need to be installed; The first prism 10 is a polarization prism, which transmits 532-P laser and reflects 532-S laser; The second prism 11 is a reflection prism, and the second detector 14 installed at the interface of the second detection channel receives 532-P laser signals; The third detector 15 installed at the interface of the third detection channel receives 532-S laser signals; During adjustment, in order to make the echo light signals fall on the center of the target surface of each detector, the first prism seat 23 and the second prism seat 24 can be appropriately fine-tuned during actual application.

[0031] In this embodiment, the third filter 21 is selected to be a filter with a pass wavelength of 532nm±0.5nm and an optical density value of OD7, and the fourth filter 22 is selected to be a filter with a pass wavelength of 532nm±10nm and an optical density value of OD5. The use of the two filters can not only limit the sky background noise by using a relatively narrow pass bandwidth with an optical density value of OD5, but also can superimpose a relatively deep blocking band with an optical density value of OD12, thereby ensuring the signal-to-noise ratio of the received signals.

[0032] Embodiment 3 Based on embodiment 2, the number of wavelength combinations is increased to three in this embodiment, and further examples are shown: In this embodiment, the implementation of the wavelength combination of 532-P laser, 532-S laser and 1064 laser is shown as follows: Figure 6 At this time, the third filter 21 is selected to be a filter with a pass wavelength of 532nm±0.5nm and an optical density value of OD7; The fourth filter 22 is selected to be a filter with a pass wavelength of 532nm±10nm and an optical density value of OD5; The dichroic beam splitter 3 is selected to be a dichroic lens that reflects 1064nm laser and transmits 532nm laser; The first filter 18 is selected to be a filter with a pass wavelength of 1064nm±0.7nm and an optical density value of OD6; The second filter 19 is selected to be a filter with a pass wavelength of 1064nm±2nm and an optical density value of OD5, and the purpose of superimposing the two filters is also to ensure the blocking depth of the 1064 laser channel.

[0033] The first prism 10 is a polarization prism, which transmits 532-P laser and reflects 532-S laser; The second prism 11 is a half-reflecting half-transmitting prism, and in the embodiment, a spare groove is arranged at each of the two detection channel interfaces corresponding to the two prisms, i.e., a first spare groove 26 and a second spare groove 27; in the embodiment, a neutral density attenuation sheet is also pasted at the position of the first spare groove 26 arranged at the detection channel interface corresponding to the first prism 10, so as to ensure that 1% of the laser beam can pass through.

[0034] At this time, the light entering the subsequent optical path includes 532-P laser, 532-S laser and 1064 nm laser; After the light passes through the dichroic beam splitter 3, the 1064 nm wavelength is reflected, and the 532-P laser and the 532-S laser pass through; The 1064 nm laser enters the coupling mirror 7 after passing through the two filters in the fourth chamber, and the coupling mirror 7 is provided with a fiber joint 28. The 1064 nm light can be guided into the 1064 nm fiber detector through the fiber joint 28. Since the field angle of the coupling mirror 7 is extremely small, the angle of the coupling mirror 7 relative to the light entering the subsequent optical path is extremely sensitive. The angle of the coupling mirror 7 can be adjusted by adjusting the screw between the adjusting base 5 and the adjustable base 6. After the optical path is aligned, silicone is injected between the adjusting base 5 and the adjustable base 6 for reinforcement.

[0035] In the embodiment, the third detector 15 receives the 532-S laser; The second detector 14 receives a small part of the 532-P signal, and the first detector 12 receives most of the 532-P signal. This design is because when such a laser radar performs atmospheric aerosol detection in the vertical ground direction, the echo signal of the lower atmosphere and the echo signal of the upper atmosphere have a large difference in intensity. On the basis of ensuring that the radar has sufficient detection distance, the echo signal of the lower atmosphere is extremely easy to saturate the detector, resulting in signal distortion. Therefore, the 532-P signal is divided into two parts, the signal with relatively large energy is received by one detector, and the signal with relatively small energy is received by another detector. The signal collected by the large-energy detector takes the echo signal of the upper atmosphere, and the signal collected by the small-energy detector takes the echo signal of the lower atmosphere. Then, the signals of the two are spliced together. In this way, the detection distance of the 532-P of the radar can be ensured to be far enough, and the unsaturation of the lower atmosphere detection can also be ensured. Specifically, the signal size ratio between the second detector 14 and the first detector 12 is subject to actual conditions. In the embodiment, the 532-P signal received by the second detector 14 is smaller than the 532-P signal received by the first detector 12.

[0036] Embodiment 4 A laser radar suitable for different wavelength laser combinations, a subsequent optical path applying a subsequent optical path architecture suitable for different wavelength laser combinations.

[0037] Obviously, the above-mentioned embodiments are only examples for clearly illustrating the present application, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A follower optical path architecture adaptable to combinations of different wavelength lasers, adapted to a laser emitting unit that emits n laser beams of different wavelengths, where n is an integer, 3 ≥ n ≥ 2, characterized in that, The subsequent optical path structure is provided with a light shield (4) and a main optical cavity (1) in sequence along the transmission direction of the main optical axis of the echo signal. The subsequent optical path structure also includes a detection mode compatible structure and a reconfigurable beam splitter integrated on the main optical cavity (1). The reconfigurable beam splitter is installed inside the main optical cavity (1). The reconfigurable beam splitter is composed of multiple adjustable and switchable optical elements. Specifically, the reconfigurable beam splitter is composed of a two-phase beam splitter, a first dual filter component and a dual prism component arranged sequentially along the echo signal transmission direction, and a second dual filter component arranged on the beam splitting path of the two-phase beam splitter. The main optical cavity (1) has three detection channel interfaces on its side, which are used to connect to the corresponding detectors respectively; among them, the first detection channel interface is connected to the beam splitting path of the two-phase beam splitting component; the dual prism component is adapted to the detection channel interfaces other than the first detection channel interface; The detection mode compatible structure consists of a two-dimensional fine-tuning structure that runs through the first detection channel interface and is compatible with both space light and fiber optic detectors. The two-dimensional fine-tuning structure carries a coupling mirror (7).

2. The subsequent optical path architecture adaptable to different wavelength laser combinations according to claim 1, characterized in that, The main optical cavity (1) is equipped with: The first chamber is used to install the two-phase beam splitter; The second chamber is used to install the first dual-filter assembly; The third chamber is used to install the dual prism assembly; The fourth chamber is used to install the second dual-filter assembly; The first and second chambers share a circular optical path channel on their common cavity wall.

3. The subsequent optical path architecture adaptable to different wavelength laser combinations according to claim 1, characterized in that, The two-dimensional fine-tuning structure consists of an adjustment base (5), an adjustable base (6), a coupling mirror (7), and a disc spring (20); The adjusting base (5) is installed on the outer side wall of the main optical cavity (1), and the central optical path channel of the adjusting base (5) is connected to the interface of the first detection channel. The fixed seat (5) and the adjustable seat (6) are connected by a first screw, and a disc spring (20) is fitted on the first screw. The adjustable seat (6) has an internal thread that matches the external thread of the coupling mirror (7) so that the adjustable seat (6) and the coupling mirror (7) are locked together by a set screw.

4. The subsequent optical path architecture adaptable to different wavelength laser combinations according to claim 3, characterized in that, The second dual filter assembly is provided with a pressure ring (17); In the second dual-filter assembly, two filters are press-fitted into the third filter holder (30) by a pressure ring (17).

5. The subsequent optical path architecture adaptable to different wavelength laser combinations according to claim 1, characterized in that, It also includes a reflective cavity (13), the exit end of which forms the fourth detection channel interface; the entrance end of the reflective cavity (13) and the optical path channel of the main optical cavity (1) away from the light shield (4) are connected.

6. The subsequent optical path architecture adaptable to different wavelength laser combinations according to claim 5, characterized in that, The reflecting cavity (13) is rotated at a right angle; An opening is provided at the bend of the reflective cavity (13); Furthermore, a stepped groove that gradually widens from the inside out is created at the opening; A reflector (25) is also provided inside the reflective cavity (13); the reflector (25) is installed on the innermost step of the stepped groove; A sealing cover plate (29) is also provided outside the reflective cavity (13); the sealing cover plate (29) seals the opening at the fold of the reflective cavity (13) by screws.

7. A lidar adapted to different combinations of laser wavelengths, characterized in that, The subsequent optical path uses a subsequent optical path architecture adapted to different wavelength laser combinations as described in any one of claims 1-6.

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