A laser ranging optical system in dynamic scanning state

Abstract

The present invention discloses a laser ranging optical system in a dynamic scanning state, comprising a pulsed laser and a laser detector; a laser emitting system, a two-dimensional scanning mirror, a folding reflector, and a laser receiving system arranged in sequence along the optical axis; the normal directions of the two-dimensional scanning mirror and the folding reflector are arranged at a 45-degree angle to the optical axis; the laser receiving system comprises a pitch scanning reflector and an azimuth scanning reflector, the normal directions of the pitch scanning reflector and the azimuth scanning reflector being arranged at a 45-degree angle to the optical axis; the angles of the two-dimensional scanning mirror, the pitch scanning reflector, and the azimuth scanning reflector are adjustable. By adjusting the angles of the two-dimensional scanning mirror, the pitch scanning reflector, and the azimuth scanning reflector, the detection angle of the receiving system can be changed. The pitch and azimuth scanning reflectors in parallel light can reduce their own size, reduce their positioning accuracy and the required rotation adjustment time, and achieve the purpose of obtaining target distance information in a dynamic scanning state.

Description

Technical Field

[0001] The present invention relates to the field of laser optics with scanning and ranging capabilities, and in particular to a laser ranging optical system in a dynamic scanning state. Background Art

[0002] In recent years, optoelectronic technology has flourished, and there is a huge demand and broad development prospect for target detection and tracking at home and abroad. However, the recognition objects are becoming more and more diverse, and the recognition environment is becoming more complex and changeable, requiring the system to have good adaptability and survivability.

[0003] Photoelectric detection systems are generally equipped with a variety of active and passive detection methods such as infrared, television, and laser. In the application mode of laser ranging, infrared or television sensors are generally used to extract the target. The system enters a stable tracking state for the target and emits laser for laser ranging to obtain the target's distance information. This method can only achieve tracking and ranging of a single target or a maximum of two targets in a 90° range. It has gradually failed to meet the needs of rapid acquisition of photoelectric three-dimensional information. For laser ranging technology, there is little research on the stable adjustment of the laser optical axis and rapid backscanning. At present, there is a lack of laser ranging systems in a dynamic scanning state, which cannot achieve rapid acquisition of target distance information in a dynamic scanning state. Summary of the Invention

[0004] In view of the above-mentioned defects in the prior art, a laser ranging optical system in a dynamic scanning state is provided, which has the ability to obtain target distance information in the dynamic scanning state.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] A laser ranging optical system in a dynamic scanning state includes a pulsed laser and a laser detector; the system is characterized in that it includes a laser emitting system, a two-dimensional scanning mirror, a deflecting reflector, and a laser receiving system arranged in sequence along the optical axis, the pulsed laser is located at the starting end of the optical axis, and the laser detector is located at the ending end of the optical axis;

[0007] The laser emission system includes an emission eyepiece, an emission objective lens 1, and an emission objective lens 2;

[0008] The normal direction of the two-dimensional scanning mirror and the folding reflector is arranged at 45 degrees to the optical axis direction, and the two are parallel to each other. The angle of the two-dimensional scanning mirror can be adjusted, while the angle of the folding reflector is fixed.

[0009] The laser receiving system includes receiving objective lens 1, receiving objective lens 2, receiving objective lens 3, receiving objective lens 4, pitch scanning reflector, azimuth scanning reflector, long-wave pass filter, narrow-band filter, rear lens group 1, and rear lens group 2 along the optical axis direction. The normal direction of the pitch scanning reflector and the azimuth scanning reflector is arranged at 45° to the optical axis direction, and the two are parallel to each other. The angles of the pitch scanning reflector and the azimuth scanning reflector can be adjusted.

[0010] According to the above technical solution, the emitting eyepiece, the emitting objective lens 1, and the emitting objective lens 2 form a Galilean structure, the magnification is m times, and the value range of m is 5 to 10.

[0011] According to the above technical solution, the first receiving objective lens, the second receiving objective lens, the third receiving objective lens and the fourth receiving objective lens form a Kepler structure, the magnification is n times, and the value range of n is 5-10.

[0012] According to the above technical solution, the scanning angle range of the pitch scanning reflector and the azimuth scanning reflector is The adjustment angle is always the same for both.

[0013] According to the above technical solution, the value of m is 8 and the value of n is 7.

[0014] According to the above technical scheme, the transmitting eyepiece adopts a meniscus QK3 negative lens, the transmitting objective lens 1 adopts a meniscus ZF6 negative lens, the transmitting objective lens 2 adopts a meniscus ZF2 positive lens, the receiving objective lens 1 adopts a meniscus H-ZLAF90 positive lens, the receiving objective lens 2 adopts a double concave H-LAF3B negative lens, the receiving objective lens 3 adopts a meniscus H-ZF88 positive lens, the receiving objective lens 4 adopts a double convex H-ZK9B positive lens, the rear lens group 1 adopts a meniscus H-ZF52 positive lens, the rear lens group 2 adopts a meniscus H-ZF62 positive lens, the two-dimensional scanning mirror, the folding reflector, the pitch scanning reflector and the azimuth scanning reflector are all plane reflectors.

[0015] According to the above technical scheme, in the direction of the optical axis, the distance from the output end of the pulse laser to the vertex of the second surface of the transmitting objective lens 2 is 95mm, the distance between the vertex of the second surface of the transmitting objective lens 2 and the two-dimensional scanning mirror is 68mm, the distance between the two-dimensional scanning mirror and the folding reflector is 91mm, the distance between the folding reflector and the vertex of the first surface of the receiving objective lens 1 is 33.5mm, the distance from the vertex of the first surface of the receiving objective lens 1 to the vertex of the second surface of the receiving objective lens 4 is 190mm, the distance from the vertex of the second surface of the receiving objective lens 4 to the pitch scanning reflector is 25mm, the distance between the pitch scanning reflector 10 and the azimuth scanning reflector 11 is 30mm, the distance between the azimuth scanning reflector 11 and the vertex of the first surface of the long-wave pass filter is 23mm, and the distance between the vertex of the second surface of the long-wave pass filter and the laser receiving detector is 70mm.

[0016] According to the above technical solution, all reflectors are made of K9 glass, and all lenses have spherical surfaces.

[0017] According to the above technical solution, the aperture of the receiving objective lens 1 is the largest, and the entrance pupil diameter is 120mm.

[0018] According to the above technical solution, the narrowband filter is a 1064nm narrowband filter; the lens band is 1064nm±10nm.

[0019] Principle of the present invention:

[0020] The laser emission system composed of the emitting eyepiece, emitting objective lens 1, and emitting objective lens 2 further compresses the divergence angle of the laser emitted by the pulse laser; then, after being reflected by the two-dimensional scanning mirror and the folding reflector, it irradiates the object, and its diffusely reflected light returns along the original path and enters the laser receiving system; the laser receiving system parallel processes and reflects the diffusely reflected light of the target, and finally focuses it on the laser detector, using the flight time of the pulse laser in space to achieve the acquisition of the target distance.

[0021] The laser ranging optical system uses two sets of scanning galvanometer mirrors to adjust the optical axis. The pitch and azimuth scanning mirrors adjust the detection angle of the laser receiver system, while the two-dimensional scanning mirror corrects the optical axis. To reduce the size of the pitch and azimuth scanning mirrors, they are placed in the parallel optical path behind the laser receiver. This reduction in size reduces positioning accuracy and the required rotation adjustment time, making the system easier to implement.

[0022] The present invention has the following beneficial effects:

[0023] 1. A two-dimensional scanning mirror is installed at the front end of the laser receiving system, and a pitch scanning reflector and an azimuth scanning reflector are installed at the back end of the laser receiving system. By adjusting the angles of the two-dimensional scanning mirror, the pitch scanning reflector, and the azimuth scanning reflector, the detection angle of the receiving system can be changed. In addition, the light diffusely reflected by the target is converted into parallel light by the receiving lens group at the front end of the laser receiving system. The pitch scanning reflector and the azimuth scanning reflector in the parallel light can reduce their own size, reducing their positioning accuracy and the required rotation adjustment time, thereby achieving the purpose of obtaining target distance information in a dynamic scanning state.

[0024] 2. The entrance pupil diameter of the laser receiving system reaches 120mm, which can obtain signals with sufficient energy and improve the receiving efficiency.

[0025] 3. The laser receiving system uses narrowband filters and long-wave pass filters, which can effectively improve the transmittance of the system.

[0026] 4. All lens materials are commonly used materials in Chengdu Guangming Glass Warehouse. No aspherical surfaces are used. They are easy to process and can control costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention provides a schematic diagram of an optical system of an embodiment;

[0028] Figure 2 The present invention provides a two-dimensional diagram of the emission optical system of an embodiment;

[0029] Figure 3 The present invention provides a point diagram of a transmitting optical system according to an embodiment;

[0030] Figure 4 The present invention provides a two-dimensional diagram of a laser receiving system according to an embodiment;

[0031] Figure 5 The present invention provides a spot diagram of a laser receiving system when not scanning.

[0032] Figure 6 The present invention provides a spot diagram of a laser receiving system when scanning +1° according to an embodiment;

[0033] Figure 7 The present invention provides a spot diagram of a laser receiving system when scanning -1° according to an embodiment;

[0034] In the figure, 1-transmitting eyepiece, 2-transmitting objective lens 1, 3-transmitting objective lens 2, 4-two-dimensional scanning mirror, 5-folding reflector, 6-receiving objective lens 1, 7-receiving objective lens 2, 8-receiving objective lens 3, 9-receiving objective lens 4, 10-pitch scanning reflector, 11-azimuth scanning reflector, 12-long wave pass filter, 13-narrow band filter, 14-rear lens group 1, 15-rear lens group 2; 16-pulsed laser; 17-laser receiving detector; 18-target to be measured; among them, 1 to 3 constitute the laser transmitting system, and 6 to 15 constitute the laser receiving system. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0036] Reference Figures 1 to 7As shown, the present invention provides a laser ranging optical system in a dynamic scanning state, comprising a pulsed laser and a laser detector. It also includes laser emitting systems 1-3, a two-dimensional scanning mirror 4, a deflecting reflector 5, and laser receiving systems 6-15, arranged sequentially along the optical axis from emission to reception. The pulsed laser is located at the starting end of the optical axis, and the laser detector is located at the ending end. The laser emitting system includes an emitting eyepiece 1, an emitting objective lens 1 2, and an emitting objective lens 2 3. The normals of the two-dimensional scanning mirror and the deflecting reflector are arranged at 45° to the optical axis and are parallel to each other. The angle of the two-dimensional scanning mirror is adjustable, while the angle of the deflecting reflector is fixed. The laser receiving system includes, along the optical axis direction, a receiving objective lens 1 6, a receiving objective lens 2 7, a receiving objective lens 3 8, a receiving objective lens 4 9, a pitch scanning reflector 41, an azimuth scanning reflector 11, a long-wave pass filter 12, a narrow-band filter 13, a rear lens group 14, and a rear lens group 2 15. The normal directions of the pitch scanning reflector and the azimuth scanning reflector are arranged at 45° to the optical axis direction, and the two are parallel to each other; the angles of the pitch scanning reflector and the azimuth scanning reflector can be adjusted.

[0037] The lens includes a laser transmitter and a laser receiver. The transmitter and receiver do not share a beam expansion telescope system. The laser transmitter is placed at the center of the laser receiver through a reflector and is coaxially designed. The light from the pulsed laser passes through the laser transmitter system, is reflected by the two-dimensional scanning mirror and the folding reflector, and then irradiates the target 18 to be measured. Its diffusely reflected light enters the laser receiving system and is focused on the laser detector. The flight time of the pulsed laser in space is used to obtain the target distance information (the time interval between the laser traveling back and forth between the object to be measured and the ranging optical system is recorded, and the distance between the object to be measured and the ranging optical system can be obtained by combining it with the speed of light). The lens uses a two-dimensional scanning mirror, a pitch and azimuth scanning reflector to reversely scan. That is, the detection angle range of the receiving system is first adjusted by the pitch and azimuth scanning reflector, and then the position of the optical axis in the laser receiving system is corrected by the reflection of the laser by the two-dimensional scanning mirror, realizing the function of adjustable laser detection angle. The operating band of this optical system is 1064nm±10nm. The lens is well corrected for aberrations through reasonable initial structure, appropriate optical material selection, and reasonable optical power distribution, making the size of the focused spot smaller than the size of the laser detector target surface.

[0038] In some embodiments, the transmitting eyepiece, transmitting objective lens 1, and transmitting objective lens 2 of the laser transmitting system form a Galilean structure with a magnification of m times, where the value of m ranges from 5 to 10, and in this embodiment, the magnification is 8 times. The laser emitted by the pulsed laser is expanded and collimated by the transmitting eyepiece, transmitting objective lens 1, and transmitting objective lens 2 of the laser transmitting system, which can effectively compress the divergence angle of the laser emitted by the laser. After the detection angle of the laser receiving system needs to be adjusted, the optical axis needs to be corrected by a two-dimensional scanning mirror so that the optical axis falls within the preset range of the laser receiving system.

[0039] In some embodiments, the first, second, third, and fourth receiving objective lenses of the laser receiving system form a Kepler-type structure with a magnification of n, where n ranges from 5 to 10. In this embodiment, the magnification of the Kepler-type structure is 7. Diffusely reflected light from the object being measured forms a parallel optical path through the first, second, third, and fourth receiving objective lenses of the laser receiving system. The elevation scanning reflector and the azimuth scanning reflector of the laser receiving system are located within the parallel optical path, thereby reducing their aperture and compressing the lateral and longitudinal dimensions of the system.

[0040] In some embodiments, the scanning angles of the pitch scanning mirror and the azimuth scanning mirror are in the range of (The value of n is determined by the multiple n of the Kepler structure, and the value range of n is 5 to 10), and the adjustment angles of the two are always the same. In this embodiment, the magnification of the Kepler structure is 7 times, and the scanning angle range of the pitch scanning reflector and the azimuth scanning reflector is set to ±3.5°. The above measures enable the adjustment range of the laser detection angle to reach ±1°. When the scanning angle of the pitch scanning reflector and the azimuth scanning reflector is 3.5°, the detection angle of the laser receiver is 1°; then, the scanning angle of the pitch scanning reflector and the azimuth scanning reflector gradually decreases to -3.5°, and the detection angle of the laser receiver will also gradually decrease by 1° to -1°.

[0041] In some embodiments, the optical lens materials are all selected from materials commonly used in Chengdu Guangming Library; the transmitting eyepiece adopts a meniscus QK3 negative lens, the transmitting objective lens 1 adopts a meniscus ZF6 negative lens, the transmitting objective lens 2 adopts a meniscus ZF2 positive lens, the receiving objective lens 1 adopts a meniscus H-ZLAF90 positive lens, the receiving objective lens 2 adopts a double concave H-LAF3B negative lens, the receiving objective lens 3 adopts a meniscus H-ZF88 positive lens, the receiving objective lens 4 adopts a double convex H-ZK9B positive lens, the rear lens group 1 adopts a meniscus H-ZF52 positive lens, the rear lens group 2 adopts a meniscus H-ZF62 positive lens, the two-dimensional scanning mirror, the folding reflector, the pitch scanning reflector and the azimuth scanning reflector are all plane reflectors.

[0042] In some embodiments, along the optical axis, the distance from the output end of the pulse laser to the vertex of the second surface of the transmitting objective lens 2 is 95 mm, the distance between the vertex of the second surface of the transmitting objective lens 2 and the two-dimensional scanning mirror is 68 mm, the distance between the two-dimensional scanning mirror and the folding reflector is 91 mm, the distance between the folding reflector and the vertex of the first surface of the receiving objective lens 1 is 33.5 mm, the distance from the vertex of the first surface of the receiving objective lens 1 to the vertex of the second surface of the receiving objective lens 4 is 190 mm, the distance from the vertex of the second surface of the receiving objective lens 4 to the pitch scanning reflector is 25 mm, the distance between the pitch scanning reflector 10 and the azimuth scanning reflector 11 is 30 mm, the distance between the azimuth scanning reflector 11 and the vertex of the first surface of the long-wave pass filter is 23 mm, and the distance between the vertex of the second surface of the long-wave pass filter and the laser receiving detector is 70 mm.

[0043] In some embodiments, the aperture of the receiving objective lens 1 is the largest, with an entrance pupil diameter of 120 mm. The laser receiving system has an entrance pupil diameter of 120 mm, which can obtain signals with sufficient energy and improve reception efficiency.

[0044] In some embodiments, all reflectors are made of K9 glass and all lenses are spherical, avoiding the use of aspheric designs. This simplifies the processing, reduces costs, and ensures accuracy.

[0045] In some embodiments, a 1064nm narrowband filter is used as the narrowband filter; the lens wavelength is 1064nm±10nm. Laser ranging systems are used in atmospheric environments. Because external stray light can significantly impact the receiving lens, a longwavepass filter and a 1064nm narrowband filter are placed in the receiving system to eliminate stray light. Considering the size and incident angle limitations of the filter, the filter is placed before the rear lens of the receiving system. The filter acts as a parallel plate in the optical path, and its thinness negligible impact on imaging and light.

[0046] Working principle of the present invention:

[0047] The laser emission system composed of the emitting eyepiece, emitting objective lens 1, and emitting objective lens 2 further compresses the divergence angle of the laser emitted by the pulse laser; then, after being reflected by the two-dimensional scanning mirror and the folding reflector, it is irradiated on the object, and its diffusely reflected light returns along the original path and enters the laser receiving system; the laser receiving system processes and reflects the diffusely reflected light in parallel, and finally focuses it on the laser detector, using the flight time of the pulse laser in space to achieve the acquisition of the target distance.

[0048] The laser transmitter and receiver utilize an off-axis design and separate telescope systems. Two sets of scanning galvanometers are used to adjust the optical axis. The elevation and azimuth scanning mirrors adjust the detection angle of the laser receiver system, while the two-dimensional scanning mirror corrects the optical axis. To reduce their size, the elevation and azimuth scanning mirrors are placed in the parallel optical path behind the laser receiver. This reduced size reduces positioning accuracy and the required rotation adjustment time, making the system easier to implement.

[0049] Aiming at the demand for rapid acquisition of distance information in the warning alarm mode, the present invention has carried out research on laser ranging technology under dynamic scanning state. In order to ensure the field of view of the system's working detection, based on the application of high-precision scanning galvanometer, the difficulty of traditional photoelectric systems in entering the tracking state and the target must be in the center of the image is solved. Only then can the time for the pulse laser to fly in space be used to acquire the target distance information under the dynamic scanning state, so as to achieve the purpose of ranging and solve the problem of the photoelectric system measuring distance while scanning. The receiving system has a magnification of 7 times through the selection of appropriate optical materials, reasonable optical focal length distribution, and good correction of aberrations. The scanning angle range of the pitch scanning reflector and the azimuth scanning reflector is set to ±3.5°. The above measures make the adjustment range of the laser detection angle reach ±1°. The magnification of the transmitting system reaches 8 times, and the laser emitted by the laser is expanded and collimated so that its divergence angle meets the system requirements.

[0050] A suitable overall design scheme for laser emission and laser reception was selected, and the optical system design technology for off-axis, separate, and large-angle scanning of laser emission and laser reception was studied. The scanning galvanometers were placed in the parallel optical paths at the front end of the laser emission optical system and the back end of the receiving and beam expansion optical system, respectively. The optical axes can be adjusted separately. The reasonable magnification of the receiving system and the transmitting system was designed to reduce the size of the corresponding galvanometer, reduce its positioning accuracy and the required rotation adjustment time, and achieve the purpose of obtaining target distance information under dynamic scanning state.

[0051] The above are only preferred embodiments of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope of protection of the present invention.

Claims

1. A laser ranging optical system in a dynamic scanning state, comprising a pulsed laser and a laser detector; characterized in that: It includes a laser emission system, a two-dimensional scanning mirror, a folding reflector and a laser receiving system arranged in sequence along the optical axis, the pulse laser is located at the starting end of the optical axis, and the laser detector is located at the ending end of the optical axis; The laser emission system includes an emission eyepiece, an emission objective lens 1, and an emission objective lens 2; The normal direction of the two-dimensional scanning mirror and the folding reflector is arranged at 45 degrees to the optical axis direction, and the two are parallel to each other. The angle of the two-dimensional scanning mirror is adjustable, and the angle of the folding reflector is fixed; The laser receiving system includes receiving objective lens 1, receiving objective lens 2, receiving objective lens 3, receiving objective lens 4, a pitch scanning reflector, an azimuth scanning reflector, a long-wave pass filter, a narrow-band filter, a rear lens group 1, and a rear lens group 2 along the optical axis. The normal direction of the pitch scanning reflector and the azimuth scanning reflector is arranged at 45 degrees to the optical axis direction and the two are parallel to each other. The angles of the pitch scanning reflector and the azimuth scanning reflector are adjustable. The diffusely reflected light of the measured object forms a parallel optical path through the receiving objective lens 1, receiving objective lens 2, receiving objective lens 3 and receiving objective lens 4 of the laser receiving system. The pitch scanning reflector and azimuth scanning reflector of the laser receiving system are located in the parallel optical path.

2. The laser ranging optical system in a dynamic scanning state according to claim 1, characterized in that: The emitting eyepiece, the first emitting objective lens, and the second emitting objective lens form a Galilean structure, the magnification is m times, and the value range of m is 5 to 10.

3. The laser ranging optical system in a dynamic scanning state according to claim 2, characterized in that: The first receiving objective lens, the second receiving objective lens, the third receiving objective lens and the fourth receiving objective lens form a Kepler structure, the magnification is n times, and the value range of n is 5-10.

4. The laser ranging optical system in a dynamic scanning state according to claim 3, characterized in that: The scanning angle range of the pitch scanning reflector and the azimuth scanning reflector is , the adjustment angles of the two are always the same.

5. The laser ranging optical system in a dynamic scanning state according to claim 3, characterized in that: The value of m is 8 and the value of n is 7.

6. The laser ranging optical system in a dynamic scanning state according to claim 1, characterized in that: The transmitting eyepiece adopts a meniscus QK3 negative lens, the transmitting objective lens 1 adopts a meniscus ZF6 negative lens, the transmitting objective lens 2 adopts a meniscus ZF2 positive lens, the receiving objective lens 1 adopts a meniscus H-ZLAF90 positive lens, the receiving objective lens 2 adopts a double concave H-LAF3B negative lens, the receiving objective lens 3 adopts a meniscus H-ZF88 positive lens, the receiving objective lens 4 adopts a double convex H-ZK9B positive lens, the rear lens group 1 adopts a meniscus H-ZF52 positive lens, the rear lens group 2 adopts a meniscus H-ZF62 positive lens, the two-dimensional scanning mirror, the folding reflector, the pitch scanning reflector and the azimuth scanning reflector are all plane reflectors.

7. The laser ranging optical system in a dynamic scanning state according to claim 1, characterized in that: In the direction of the optical axis, the distance from the output end of the pulse laser to the vertex of the second surface of the transmitting objective lens 2 is 95 mm, the distance between the vertex of the second surface of the transmitting objective lens 2 and the two-dimensional scanning mirror is 68 mm, the distance between the two-dimensional scanning mirror and the folding reflector is 91 mm, the distance between the folding reflector and the vertex of the first surface of the receiving objective lens 1 is 33.5 mm, the distance from the vertex of the first surface of the receiving objective lens 1 to the vertex of the second surface of the receiving objective lens 4 is 190 mm, the distance from the vertex of the second surface of the receiving objective lens 4 to the pitch scanning reflector is 25 mm, the distance between the pitch scanning reflector 10 and the azimuth scanning reflector 11 is 30 mm, the distance between the azimuth scanning reflector 11 and the vertex of the first surface of the long-wave pass filter is 23 mm, and the distance between the vertex of the second surface of the long-wave pass filter and the laser receiving detector is 70 mm.

8. The laser ranging optical system in a dynamic scanning state according to claim 1, characterized in that: All reflectors are made of K9 glass and all lenses are spherical.

9. The laser ranging optical system in a dynamic scanning state according to claim 1, characterized in that: The receiving objective lens 1 has the largest aperture, with an entrance pupil diameter of 120mm.

10. The laser ranging optical system in a dynamic scanning state according to any one of claims 1 to 9, characterized in that: The narrowband filter uses a 1064nm narrowband filter; the lens band is 1064nm±10nm.

Images