CN110061446B - CO based on off-axis RC lens group2Laser ablation apparatus - Google Patents

Abstract

The invention provides a CO ₂ laser ablation device based on an off-axis RC lens group, which aims to solve the technical problems that the traditional high-voltage wire lap joint foreign matter removal mode is low in safety, high in maintenance cost and low in removal efficiency, and the existing CO ₂ laser ablation simple device is not suitable for removing long-distance or small foreign matters. The coaxial spectroscope group is adopted to realize three coaxial paths of a CO ₂ laser beam expansion focusing system, a visible light camera and a laser ranging system, and the CO ₂ laser beam expansion focusing system is based on the off-axis RC lens group, has no central shielding, is light and can meet the use requirement of a large caliber; the optical axis of the visible light camera is coaxial with the optical axis of the CO ₂ laser beam expanding and focusing system, so that the optimal ablation effect can be ensured; the optical axis of the ranging system is coaxial with the optical axis of the CO ₂ laser beam expanding focusing system, so that the remote focusing of CO ₂ laser can be realized when the focusing negative lens in the lens group is adjusted; the foreign object can be searched, captured and locked by combining the visible light camera with the two-dimensional rotating mechanism.

Description

A CO2 laser ablation device based on off-axis RC mirror group

Technical Field

The present invention relates to an optical non-contact _CO2 laser ablation device, in particular to a _CO2 laser ablation device based on an off-axis RC lens group, which can be used for removing foreign matter from high-voltage transmission lines, and is particularly suitable for removing foreign matter from long-distance high-voltage transmission lines.

Background technique

High-voltage and ultra-high-voltage power grids are important physical conduction networks for long-distance and large-scale electric energy transmission in power systems. The transmission grid uses multiple high-voltage and ultra-high-voltage physical cables, which are insulated and suspended between towers 20m to 100m high. Because the cables are exposed to the natural environment all year round, due to objective natural or human reasons, non-metallic foreign objects such as plastics are often attached to power grid facilities such as cables, towers, and insulators. This leads to poor insulation between high-voltage power cables, and the potential risk of causing short-circuit tripping of power lines is one of the major threats to the normal operation of the current power system.

Usually, in the design of transmission lines for high-voltage power grids, a fixed safety distance is left between the conductors. Under normal circumstances, as long as this air gap is maintained between the conductors, the overhead transmission lines can operate safely. If there are non-insulating objects other than air between the wires, such as kite lines, balloons, plastic sheets, etc., it is very easy to cause a short circuit between the wires, causing the substation switch to trip. Common foreign objects are non-metallic objects such as kites and balloons. Once they are connected between high-voltage power grids, the transmission line will immediately trip and cause a power grid failure. Even if the foreign object has high insulation, on rainy days or when the air humidity is high, the current may break through and discharge through the rain (or water vapor), causing a power grid failure.

There are two main traditional methods for removing foreign objects from high-voltage wires: one is for electricians or robots to go online and remove them after a power outage; the other is to remove them during equipotential live work. Both methods require a lot of manpower and material resources, and the operation procedures are complicated, time-consuming, and labor-intensive, and the safety is low. Even with the use of non-manual means such as robots, it still takes a long time to remove foreign objects from cables. Robots and other automated equipment pose a certain threat to the safe operation of the power grid when the power grid is energized, and the use and maintenance costs of robots are high, making it difficult to promote and apply them on a large scale.

The principle of laser cleaning foreign matter on cables is to emit laser on the ground, accurately control the laser direction so that it radiates the surface of the foreign matter, and the radiated part of the foreign matter absorbs the laser energy, thereby increasing the temperature and eventually burning off, achieving the purpose of cleaning the foreign matter. Foreign matter on cables is generally made of non-metallic materials, and _CO2 lasers can burn most of the foreign matter without damaging the metal cable. The existing _CO2 laser ablation simple device requires manual aiming at the foreign matter, which is not suitable for long-distance or small foreign matter removal.

Summary of the invention

Based on the above background, in order to solve the technical problems that the traditional method of removing foreign matter from high-voltage wire splices has low safety, high maintenance cost, low removal efficiency, and the existing simple _CO2 laser ablation device is not suitable for removal at a long distance or when the foreign matter is small, the present invention provides a _CO2 laser ablation device based on an off-axis RC lens group.

The technical solution of the present invention is:

A _CO2 laser ablation device based on an off-axis RC mirror group is special in that it includes a _CO2 laser beam expansion and focusing system, a coaxial beam splitter group, a visible light camera, a distance measurement system, a two-dimensional rotation mechanism and a display and control terminal; the _CO2 laser beam expansion and focusing system, the visible light camera, the distance measurement system and the coaxial beam splitter group are packaged in one body and arranged on the two-dimensional rotation mechanism;

The _CO2 laser beam expansion and focusing system includes a _CO2 laser and a _CO2 laser beam expansion and focusing refractive optical system;

The _CO2 laser beam expansion and focusing catadioptric optical system is a multi-group cascaded Galilean telescope type catadioptric infrared optical system, including a beam deflection group, a lens group and an off-axis RC mirror group, wherein the off-axis RC mirror group and the lens group constitute an afocal system;

The beam deflection group is used to deflect the _CO2 laser beam output by the _CO2 laser to the lens group, and at the same time make the optical axis of the output beam of the lens group meet the oblique incident angle requirement of the off-axis RC lens group to the incident beam;

The lens group includes a negative lens, a positive lens and a focusing negative lens which are arranged in sequence; the negative lens and the positive lens constitute a beam expansion system, the negative lens is arranged on the exit light path of the beam deflection group, and the focusing negative lens and the off-axis RC lens group constitute a beam expansion and focusing system; the position of the focusing negative lens is adjustable;

The coaxial beam splitter group is arranged on the outgoing light path of the off-axis RC mirror group;

The coaxial beam splitter group includes a main beam splitter and a dual-path beam splitter arranged in parallel, and both the main beam splitter and the dual-path beam splitter are coated with a two-color beam splitter film; the two-color beam splitter film on the main beam splitter transmits _CO2 laser and reflects visible light and ranging laser; the two-color beam splitter film on the dual-path beam splitter transmits ranging laser and reflects visible light;

The main beam splitter is arranged on the outgoing light path of the off-axis RC mirror group; the surface of the main beam splitter away from the off-axis RC mirror group is defined as the first mirror surface, and the dual-path beam splitter is arranged on the reflected light path of the first mirror surface;

The optical axis of the visible light camera is parallel to the optical axis of the outgoing light beam of the off-axis RC mirror group; the surface of the dual-path beam splitter facing the main-path beam splitter is defined as the second mirror surface, and the visible light camera is located on the reflection light path of the second mirror surface;

The distance measuring system is located on the transmission light path of the second mirror surface;

The display and control terminal includes a display terminal and a control manipulator;

The control manipulator is connected to the _CO2 laser beam expansion and focusing system, the visible light camera, the distance measurement system and the two-dimensional rotating mechanism, and is used to: adjust the azimuth and pitch of the two-dimensional rotating mechanism; transmit the image acquired by the visible light camera and the distance measurement data output by the distance measurement system to the display terminal; adjust the position of the focusing negative lens in the lens group according to the distance measurement data of the distance measurement system to control the _CO2 laser beam expansion and focusing system to lock the ablation target and laser ablate; and monitor the ablation process.

Furthermore, the F numbers of the off-axis RC mirror group and the lens group are both less than 4.

Furthermore, the off-axis RC mirror group includes a large-sized main off-axis reflector and a small-sized secondary off-axis reflector. The small-sized secondary off-axis reflector is arranged on the output light path of the lens group, and the large-sized main off-axis reflector is arranged on the output light path of the small-sized secondary off-axis reflector; the large-sized main off-axis reflector is a parabolic mirror or a hyperbolic mirror close to a parabola. When it is a parabolic mirror, its quadratic surface constant K is equal to -1, and when it is a hyperbolic mirror close to a parabola, its quadratic surface constant is less than -1; the small-sized secondary off-axis reflector is a hyperbolic mirror, and its quadratic surface constant K is less than -1.

Furthermore, the minimum value of the mirror diameter _D1 of the large-size main off-axis reflector is calculated according to the formula Determine; where Lm is the farthest working distance of laser ablation, and d′ is the diffraction-limited spot size of the entire _CO2 laser ablation device.

Furthermore, the _CO2 laser is a continuous or pulsed high-power _CO2 laser with a power not less than 100W.

Furthermore, the two-color beam splitter film on the main beam splitter has a transmittance of greater than 99% for _CO2 laser and a reflectivity of greater than 90% for visible light and ranging laser; the two-color beam splitter film on the dual-path beam splitter has a transmittance of greater than 90% for ranging laser and a reflectivity of greater than 90% for visible light.

Furthermore, the two-dimensional rotating mechanism is a precision rotating mechanism with both azimuth and elevation angle accuracy better than 5″.

Furthermore, the two-dimensional rotating mechanism has a manual adjustment function.

Furthermore, the lens group is made of Ge material that can transmit _CO2 laser.

Furthermore, the visible light camera has a zoom function, which can clearly image distant targets and can frame the currently locked target.

Beneficial effects of the present invention:

1. The present invention adopts a coaxial spectroscope group to realize the three-way coaxiality of the _CO2 laser beam expansion and focusing system, the visible light camera and the laser ranging system. The _CO2 laser beam expansion and focusing system is based on an off-axis RC lens group, has no center obstruction, is lightweight and can meet the use requirements of large apertures; the _CO2 laser beam expansion and focusing catadioptric optical system in the _CO2 laser beam expansion and focusing system adopts a Galilean telescope-type catadioptric infrared optical system without an intermediate image point, thereby avoiding the occurrence of high-energy laser points in the system; the optical axis of the visible light camera is kept coaxial with the optical axis of the _CO2 laser beam expansion and focusing system, which can ensure the best ablation effect; the optical axis of the ranging system is kept coaxial with the optical axis of the _CO2 laser beam expansion and focusing system, which can ensure that when the focusing negative lens in the lens group is adjusted, the long-distance focusing of the _CO2 laser is achieved; the visible light camera combined with a two-dimensional rotating mechanism can be used to search, capture and lock foreign targets. At around 50m, under clear weather conditions, this focusing solution and off-axis setting are used, and the high-energy laser energy utilization rate is high, and the foreign object can be ignited within 5S; under extreme weather conditions and at the extreme action distance, this focusing solution and off-axis setting are used, and the high-energy laser energy utilization rate is high, and the foreign object can be ignited within 30S.

2. The position of the off-axis RC lens group in the present invention is fixed, and the position of the focusing negative lens in the lens group is adjustable. In this way, when working at a long distance, only the position of the focusing negative lens is precisely adjusted, and the off-axis element is not adjusted, which can ensure the focusing stability and coaxiality and avoid the focusing jump of the distant target.

3. The F number of the off-axis RC lens group and the lens group in the present invention is less than 4, which can fully shorten the length of the optical system and reduce the volume of the ablation device.

4. The _CO2 laser in the present invention is a continuous or pulsed high-power _CO2 laser with a power of not less than 100W, which can meet the needs of long-distance ablation.

5. The two-dimensional rotating mechanism is a precision rotating mechanism with azimuth and elevation angle accuracy better than 5", which can ensure the adjustment accuracy.

6. The lens group is made of Ge material that can transmit _CO2 laser, which further reduces the cost of the equipment.

7. The present invention can complete long-distance, non-contact ablation tasks at a relatively low cost and avoid human-machine damage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the principle of the CO ₂ laser ablation device of the present invention.

FIG. 2 is a specific embodiment of the CO ₂ laser ablation device of the present invention.

FIG. 3 is a hardware block diagram of the CO ₂ laser ablation device of the present invention.

FIG. 4 is a software flow chart of the CO ₂ laser ablation device of the present invention.

FIG5 is an operational flow chart of long-distance high-voltage electric foreign body removal using the present invention.

Description of reference numerals:

1- _CO2 laser beam expansion and focusing system, 11- _CO2 laser, 12- _CO2 laser beam expansion and focusing refraction optical system, 121-off-axis RC lens group, 122-lens group, 123-beam deflection group, 1221-focusing negative lens, 1222-positive lens, 1223-negative lens, 2-visible light camera, 3-ranging system, 4-coaxial beam splitter group, 41-main beam splitter, 42-dual-path beam splitter, 5-two-dimensional rotation mechanism, 51-azimuth rotation mechanism, 52-pitch rotation mechanism, 6-power supply, 7-display and control terminal, 71-display terminal, 72-control manipulator.

Detailed ways

In order to enable those skilled in the art to fully understand the technical solution, feasibility and advantages of the present invention, the inventive concept and technical route of the present invention are first described as follows.

The main output wavelength range of _CO2 laser is about 10.6 microns. Since the laser absorption rate of metal and non-metal materials in this band is very different, and the transmittance of this band in the atmosphere is relatively high, it is suitable for long-distance, non-contact removal of non-metallic foreign objects hanging on high-voltage transmission lines (metal).

Since high-voltage transmission lines are installed at a certain height from the ground, and some of them are installed on mountain tops or other remote areas, they are generally far from the safe working distance for operators to actually remove foreign objects, and this is a long-distance removal operation. Where λ is the laser wavelength, θ is the far-field divergence half angle of the laser, and _ω0 is the beam waist radius of the laser spot. It can be seen that in order to achieve a smaller divergence angle, the beam radius needs to be very large, and because the laser wavelength is long, almost dozens of times longer than the wavelength of visible light, if the _CO2 laser is directly expanded, it is impossible to guarantee a smaller laser spot size at a long distance. Therefore, the _CO2 laser beam transmitted over a long distance needs to be focused to meet the energy requirements of the ablation spot.

In the _CO2 laser ablation system, the actual diffraction spot of the entire system is subject to the size of the beam expansion port. According to the diffraction theory, the diameter of the first dark ring of the circular aperture diffraction dr′ is:

Where: λ is the laser wavelength, D is the aperture of the laser ablation system’s beam expander, and f′ is the focal length of the laser ablation system; when the _CO2 laser’s output laser wave λ=10.6μm, the spot diameter needs to be less than Φ20mm at a distance of 200m from the laser ablation system. According to the above formula, the beam diameter at the exit of the beam expander needs to be about 258.64mm. By using a beam expander with a certain structure and adjusting the distance between the two beam expander groups, the long-distance spot focusing can be achieved. Before ablating a long-distance foreign body, the distance between the foreign body and the system needs to be measured by the distance measurement system, and then the focusing system needs to be precisely controlled to achieve the _CO2 laser spot focusing.

Since _CO2 laser is invisible and when working at a long distance, even visible light cannot be used to see the laser spot clearly, the present invention uses a visible light camera to search and lock the entire foreign object target and monitor the ablation effect.

In order to achieve the long-distance removal of foreign objects from high-voltage transmission lines, it is also necessary to organically connect the three subsystems of the _CO2 laser beam expansion and focusing system, the distance measurement system, and the visible light camera (monitoring system). The organic connection here is not simply stacked together. In addition, if the three subsystems are to work together to achieve the purpose of searching, locking, ablation, and effect detection of long-distance laser foreign objects, there are certain requirements for the angle accuracy of the two-dimensional rotation mechanism that carries the three subsystems.

In order to achieve the removal of foreign matter from long-distance high-voltage transmission lines, the _CO2 laser beam expansion and focusing system should be able to shorten the system length, without intermediate image points, and avoid the appearance of high-energy laser points in the system. When the action distance is far, the required objective lens aperture is large, and there are moving adjustment components. Large-aperture components and off-axis components in the adjustment system should be avoided. Center obstruction will cause loss of laser energy, and center obstruction should be avoided in the system; in order to ensure the stability and coaxiality of focusing, large-aperture components and off-axis components in the adjustment system should be avoided to focus on distant targets.

The _CO2 laser beam expansion and focusing system itself is a small field of view and large aperture optical system, while the visible light camera and ranging system are both systems with a large field of view and a small aperture. Since the _CO2 laser itself has a relatively large structural size, and the visible light camera and ranging system also need to be reasonably arranged in the corresponding optical path, a reasonable optical path layout is very critical.

Since there is high-energy laser in the laser ablation device, in order to avoid harm to the operator or surrounding organisms, the present invention preferably has a two-dimensional rotating mechanism with adjustment and locking functions, and the entire ablation device must meet certain operating procedures before the ablation operation can be performed.

Based on the above technical concept, the present invention is further described below in conjunction with the accompanying drawings.

As shown in Fig. 1 and Fig. 2, the _CO2 laser ablation device based on the off-axis RC mirror group provided by the present invention comprises a _CO2 laser beam expansion and focusing system 1, a coaxial beam splitter group 4, a visible light camera 2, a distance measurement system 3, a two-dimensional rotation mechanism 5, a power supply 6 and a display and control terminal 7. _{The CO2} laser beam expansion and focusing system 1, the coaxial beam splitter group 4, the visible light camera 2 and the distance measurement system 3 are packaged in one body and arranged on the two-dimensional rotation mechanism 5.

The _CO2 laser beam expansion and focusing system 1 includes a _CO2 laser 11 and a _CO2 laser beam expansion and focusing refractive optical system 12; the _CO2 laser 11 can adopt a continuous or pulsed high-power _CO2 laser; considering that the laser energy is too low and may not meet the needs of long-distance foreign body ablation, the power of the _CO2 laser 11 is not less than 100W. In order to ensure that there is no intermediate image point and avoid the appearance of high-energy laser points in the system, the _CO2 laser beam expansion and focusing refraction optical system 12 adopts a multi-group cascaded Galilean telescope type refraction infrared optical system, including a beam refraction group 123, a lens group 122 and an off-axis RC lens group 121, wherein the off-axis RC lens group 121 and the lens group 122 together constitute an _afocal system; the beam refraction group 123 is used to perform angle transformation on the _CO2 laser beam of the CO2 laser 11, and transform the output beam angle of the _CO2 laser 11 into an angle (10° to 30°) required to meet the oblique incidence requirement of the off-axis RC lens group 121; the purpose of setting the beam refraction group 123 is to ensure the normal operation of the off-axis RC lens group 121, and fully consider the large size and weight of the _CO2 laser 11, so that the output beam of the _CO2 laser 11 is transformed by using the beam refraction group 123, and converted into the angle required to meet the oblique incidence requirement of the off-axis RC lens group 121. The lens group 122 is used to focus the _CO2 spot, and includes a negative lens 1223, a positive lens 1222, and a focusing negative lens 1221, which are arranged in sequence; the negative lens 1223 and the positive lens 1222 constitute a beam expansion system, the negative lens 1223 is arranged on the exit light path of the beam deflection group 123, and the focusing negative lens 1221 and the off-axis RC lens group 121 constitute a beam expansion and focusing system; the position of the off-axis RC lens group 121 is fixed, and the position of the focusing negative lens 1221 is adjustable. By fine-tuning the position of the focusing negative lens 1221, the focusing stability and coaxiality during the focusing process of the _CO2 spot at a long distance can be guaranteed, and the focusing jump of the distant target can be avoided. In order to reduce costs, the negative lens 1223, the positive lens 1222, and the focusing negative lens 1221 are all made of Ge material that can transmit _CO2 lasers.

In order to shorten the length of the optical system and reduce the volume of the ablation device, the F numbers of the off-axis RC mirror group 121 and the lens group 122 are preferably less than 4. The off-axis RC mirror group 121 can adopt a standard off-axis RC mirror group or a quasi-off-axis RC mirror group, including a large-sized main off-axis reflector and a small-sized secondary off-axis reflector. The small-sized secondary off-axis reflector is arranged on the output light path of the lens group 122, and the large-sized main off-axis reflector is arranged on the output light path of the small-sized secondary off-axis reflector; wherein, the large-sized main off-axis reflector is a parabolic mirror or a hyperbolic mirror close to a parabola. When a parabolic mirror is adopted, its quadratic surface constant K is equal to -1, and when a hyperbolic mirror close to a parabola is adopted, its quadratic surface constant is less than -1; the small-sized secondary off-axis reflector adopts a hyperbolic mirror, and its quadratic surface constant K is less than -1. For the convenience of design and implementation, the minimum value of the mirror diameter _D1 of the large-sized main off-axis reflector is calculated according to the formula Determine; where Lm is the farthest working distance of laser ablation, and d′ is the diffraction-limited spot size of the entire _CO2 laser ablation device.

The coaxial beam splitter group 4 includes a main beam splitter 41 and a dual-path beam splitter 42 which are arranged in parallel; both the main beam splitter 41 and the dual-path beam splitter 42 are coated with a two-color beam splitter film; the two-color beam splitter film on the main beam splitter 41 transmits _CO2 laser and reflects visible light and ranging laser; the two-color beam splitter film on the dual-path beam splitter 42 transmits ranging laser and reflects visible light. The main beam splitter 41 is arranged on the outgoing light path of the off-axis RC mirror group 121; the surface of the main beam splitter 41 away from the off-axis RC mirror group 121 is defined as the first mirror surface, and the dual-path beam splitter 42 is arranged on the reflected light path of the first mirror surface; the relative angle relationship between the main beam splitter 41 and the dual-path beam splitter 42 makes the three-path light of the _CO2 laser beam expansion and focusing system 1, the visible light camera 2 and the ranging system 3 coaxial, so that the ablation target focused by the _CO2 laser beam expansion and focusing system 1, the monitoring target locked by the image center of the visible light camera 2 and the ranging target measured by the ranging system 3 remain consistent.

In order to improve the energy utilization rate of _CO2 laser, the main beam splitter 41 is coated with a two-color beam splitter film, so that the transmittance τ of the _CO2 laser near the wavelength λ ₁ = 10.6μm is greater than 99%, and the reflectivity ρ of the visible light camera λ ₂ = 450nm~750nm and the ranging laser λ ₃ = 1.06μm of the ranging system 3 is greater than 90%; the dual-path beam splitter 42 is coated with a two-color beam splitter film, so that the reflectivity ρ of the visible light camera 2 with an operating wavelength band of λ ₂ = 450nm~750nm is greater than 90%, and the transmittance τ of the ranging laser λ ₃ = 1.06μm of the ranging system 3 is greater than 90%.

The optical axis of the visible light camera 2 is parallel to the optical axis of the outgoing light beam of the off-axis RC mirror group 121; the surface of the dual-path beam splitter 42 facing the main-path beam splitter 41 is defined as the second mirror surface, and the visible light camera 2 is located on the reflection light path of the second mirror surface; the visible light camera 2 preferably has a large-magnification zoom function, and can clearly image a large range of long-distance and short-distance targets. The large range of long-distance clear imaging is used for ablation, and the close-range clear imaging is used for debugging, and is compared and calibrated with the long-distance focus calibration, and the currently locked target can be framed, that is, it has the function of electronically locking the target; the visible light camera 2 is also connected to the display and control terminal 7 to send the acquired image to the display and control terminal 7.

The two-dimensional rotating mechanism 5 includes an azimuth rotating mechanism 51 and a pitch rotating mechanism 52, and has manual adjustment, automatic adjustment and locking functions. The azimuth rotating mechanism 51 and the pitch rotating mechanism 52 can be adjusted automatically or manually to achieve aiming and locking of foreign objects.

The display and control terminal 7 includes a display terminal 71 and a control manipulator 72. The control manipulator 72 is connected to the _CO2 laser beam expansion and focusing system 1, the visible light camera 2, the distance measurement system 3 and the two-dimensional rotating mechanism 5, and is used to: adjust the azimuth and pitch of the two-dimensional rotating mechanism 5; transmit the image acquired by the visible light camera 2 and the distance measurement data output by the distance measurement system 3 to the display terminal 71; adjust the position of the focusing negative lens 1221 in the lens group 122 according to the distance measurement data of the distance measurement system 3 (the method of converting the distance measurement data into the position coordinates of the focusing negative lens 1221 refers to the document "Experimental Study on Laser Far-Field Focusing Characteristics") to control the _CO2 laser beam expansion and focusing system 1 to lock the ablation target and laser ablate; and monitor the ablation process.

The control manipulator 72 is provided with camera zoom and focus buttons, and the visible light camera 2 is adjusted through the serial port to make the video display clear; the visible light camera 2 is fixed on the two-dimensional rotating mechanism 5, and the two-dimensional rotating mechanism is manually adjusted to make the target within the display terminal 71, and the foreign body target is framed on the display terminal 71. The control manipulator calculates the two-dimensional miss amount, and sends the miss amount to the two-dimensional rotating mechanism 5 through the serial port, thereby controlling the azimuth and pitch of the two-dimensional rotating mechanism; after the target coincides with the center of the video, the ranging system 3 is started, and data is received through the serial port.

The present invention arranges the three independent sub-optical paths of the _CO2 laser beam expansion and focusing system 1, the visible light camera 2, and the distance measurement system 3 on the two-dimensional rotating mechanism 5. In combination with the initial position of the _CO2 laser ablation device and the foreign matter information provided by the visible light camera 2, the azimuth rotation mechanism 51 and the pitch rotation mechanism 52 of the two-dimensional rotating mechanism 5 are adjusted to lock the foreign matter target at the center of the video image displayed by the display terminal 71 of the display control terminal 7. After locking the foreign matter target, according to the distance measurement information provided by the distance measurement system 3, the corresponding position of the focusing negative lens 1221 in the lens group 122 in the _CO2 laser beam expansion and focusing refraction optical system 12 is precisely adjusted to complete the focusing and ablation of the ablation laser. In this process, the display control terminal 7 is used to monitor the ablation process. During the measurement process, the power supply 6 supplies power to all related systems to jointly complete the long-distance, non-contact high-voltage transmission line foreign matter removal.

As shown in Figure 3, the visible light camera 2 is connected to the display terminal 71 via a USB data cable, and the video is transmitted to the display terminal 71 in real time. In addition, the visible light camera 2 is connected to the control manipulator 72 via the RS485 serial port, and the control manipulator 72 sends instructions to control the zoom and focus of the visible light camera 2 through the serial port, thereby improving the video quality. The control manipulator 72 is connected to the distance measurement system 3 via the RS485 serial port, and controls the distance measurement system 3 to achieve the distance measurement function by sending instructions, and transmits the distance parameter to the display terminal 71 via the data line. The visible light camera 2 is fixed on the two-dimensional rotating mechanism 5, and the control manipulator 72 controls the pitch and rotation of the two-dimensional rotating mechanism 5 via RS485. By observing the real-time video on the display terminal 71, the two-dimensional rotating mechanism 5 can be manually adjusted to the ideal position. In addition, the position can also be adjusted by selecting a target in the video and automatically sending a position instruction to the two-dimensional rotating mechanism 5.

As shown in Figure 4, first determine whether the display terminal 71 can display the video in real time, then adjust the two-dimensional rotating mechanism 5 so that the target is located in the video, control the zoom and focus of the visible light camera 2 by controlling the manipulator 72 to make the picture clear, select the foreign body target in the video, control the manipulator to automatically calculate the miss distance and send instructions to the two-dimensional rotating mechanism 5 by controlling the manipulator 72, and finally start the distance measurement system 3 to obtain the real-time distance parameters and display them on the display terminal 71.

As shown in Figure 5, before the preparation work, the _CO2 laser ablation device is installed on a small transport vehicle. During the driving of the vehicle, a foreign object target is found on the high-voltage transmission line. The parking position is determined according to the distance (generally greater than 20m), and the light output position of the _CO2 laser ablation device is adjusted to roughly face the foreign object to be removed.

Then turn on the main power of the entire device, press the "visible light camera" button to power the visible light camera 2, observe the real-time video in the display terminal 71, manually adjust the two-dimensional rotating mechanism 5 so that the target is roughly in the middle area of the video, adjust the "zoom" button and the "focus" button on the control manipulator 72, frame the foreign body target in the real-time video in the display terminal 71, control the manipulator to calculate the off-target amount (the relative two-dimensional displacement between the frame selection center and the video center), and control the two-dimensional rotating mechanism 5 to automatically adjust so that the target image is located in the center of the video. Press the "distance measurement" button, the distance measurement system 3 starts distance measurement, and after the distance measurement is completed, the distance parameter is obtained and displayed after the "distance measurement is completed". Then press the "ablation light focus" to adjust the position of the focusing negative lens 1221. After the "focus is completed" is displayed, the energy parameter of the ablation laser is set according to the distance parameter. Press the "start ablation" button, the _CO2 laser 11 emits high-energy laser, observe the real-time video in the display terminal 71, fine-tune the two-dimensional rotating mechanism 5, and follow the ablation position. When the foreign matter is observed to burn and fall off, press the "Stop Ablation" button, turn off the main power of the equipment, and finally complete the removal of the foreign matter.

The present invention can be used for long-distance, non-contact removal of non-metallic foreign objects hanging on high-voltage transmission lines. It adopts a special optomechanical structure to realize the long-distance search, locking and removal of foreign objects, ensuring that the device is relatively low-priced, highly feasible, and ensuring human-machine safety.

Claims (10)

1. The utility model provides a CO ₂ laser ablation device based on off-axis RC mirror group which characterized in that: the system comprises a CO ₂ laser beam expansion focusing system (1), a coaxial spectroscope group (4), a visible light camera (2), a ranging system (3), a two-dimensional rotating mechanism (5) and a display control terminal (7); the CO ₂ laser beam expanding focusing system (1), the visible light camera (2), the ranging system (3) and the coaxial spectroscope group (4) are packaged into a whole and are arranged on the two-dimensional rotating mechanism (5);

The CO ₂ laser beam expansion focusing system (1) comprises a CO ₂ laser (11) and a CO ₂ laser beam expansion focusing refractive-reflective optical system (12);

The CO ₂ laser beam expanding focusing refractive-reflective optical system (12) is a multi-group cascade Galilean type refractive-reflective infrared optical system and comprises a beam refractive-reflective group (123), a lens group (122) and an off-axis RC lens group (121), wherein the off-axis RC lens group (121) and the lens group (122) form an afocal system;

the beam deflection group (123) is used for deflecting the CO ₂ laser beam output by the CO ₂ laser (11) to the lens group (122), and simultaneously enabling the optical axis of the outgoing beam of the lens group (122) to meet the requirement of the off-axis RC mirror group (121) on the oblique incidence angle of the incoming beam;

The lens group (122) comprises a negative lens (1223), a positive lens (1222) and a focusing negative lens (1221) which are sequentially arranged; the negative lens (1223) and the positive lens (1222) form a beam expanding system, the negative lens (1223) is arranged on an emergent light path of the beam deflection group (123), and the focusing negative lens (1221) and the off-axis RC lens group (121) form a beam expanding focusing system; the position of the focusing negative lens (1221) is adjustable;

The coaxial spectroscope group (4) is arranged on the emergent light path of the off-axis RC mirror group (121);

The coaxial spectroscope group (4) comprises a main spectroscope (41) and a double-path spectroscope (42) which are arranged in parallel, and two-color spectroscopes are plated on the main spectroscope (41) and the double-path spectroscope (42); the bicolor light-splitting film on the main path spectroscope (41) transmits CO ₂ laser and reflects visible light and ranging laser; the bicolor light-splitting film on the two-way spectroscope (42) transmits the ranging laser and reflects the visible light;

the main path spectroscope (41) is arranged on an emergent light path of the off-axis RC mirror group (121); defining the surface of the main path spectroscope (41) far away from the off-axis RC mirror group (121) as a first mirror surface, and arranging the two-path spectroscope (42) on the reflection light path of the first mirror surface;

The optical axis of the visible light camera (2) is parallel to the optical axis of the emergent light beam of the off-axis RC lens group (121); defining the surface of the two-way spectroscope (42) facing the main-way spectroscope (41) as a second mirror surface, wherein the visible light camera (2) is positioned on the reflection light path of the second mirror surface;

A distance measuring system (3) is positioned on the transmission light path of the second mirror;

the display control terminal (7) comprises a display terminal (71) and a control manipulator (72);

The control manipulator (72) is connected with the CO ₂ laser beam expansion focusing system (1), the visible light camera (2), the ranging system (3) and the two-dimensional rotating mechanism (5) and is used for: adjusting the azimuth and the pitch of the two-dimensional rotating mechanism (5); transmitting the image acquired by the visible light camera (2) and the ranging data output by the ranging system (3) to a display terminal (71); position adjustment is carried out on a focusing negative lens (1221) in the lens group (122) according to the ranging data of the ranging system (3) so as to control the locking and laser ablation of the CO ₂ laser beam expanding focusing system (1) on an ablation target; the ablation process is monitored.

2. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 1, wherein: the F numbers of the off-axis RC lens group (121) and the lens group (122) are smaller than 4.

3. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set according to claim 1 or 2, wherein: the off-axis RC mirror group (121) comprises a large-size main off-axis reflecting mirror and a small-size secondary off-axis reflecting mirror, the small-size secondary off-axis reflecting mirror is arranged on an output light path of the lens group (122), and the large-size main off-axis reflecting mirror is arranged on an output light path of the small-size secondary off-axis reflecting mirror; the large-size main off-axis reflector is a parabolic mirror or a hyperboloid mirror close to a paraboloid, the quadric constant K of the large-size main off-axis reflector is equal to-1 when the large-size main off-axis reflector is the parabolic mirror, and the quadric constant K of the large-size main off-axis reflector is smaller than-1 when the large-size main off-axis reflector is the hyperboloid mirror close to the paraboloid; the small-size secondary off-axis reflector is a hyperboloid reflector, and the quadric constant K is smaller than-1.

4. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 3, wherein: the minimum value of the mirror diameter D ₁ of the large-size main off-axis reflector is calculated according to the formulaDetermining; where Lm is the laser ablation furthest working distance and d' is the diffraction limited spot size of the overall CO ₂ laser ablation device.

5. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 3, wherein: the CO ₂ laser (11) is a continuous or pulse high-power CO ₂ laser, and the power is not lower than 100W.

6. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 3, wherein: the transmittance of the bicolor light-splitting film on the main path spectroscope (41) to CO ₂ laser is more than 99 percent, and the reflectivity to visible light and ranging laser is more than 90 percent; the dual-color light-splitting film on the two-way spectroscope (42) has the transmittance of more than 90% for distance measuring laser and the reflectivity of more than 90% for visible light.

7. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 3, wherein: the two-dimensional rotating mechanism (5) is a precise rotating mechanism with azimuth angle and pitch angle precision better than 5'.

8. The off-axis RC mirror based CO ₂ laser ablation apparatus of claim 7 wherein: the two-dimensional rotating mechanism (5) has a manual adjusting function.

9. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 3, wherein: the lens group (122) is made of Ge material which can transmit CO ₂ laser.

10. The CO ₂ laser ablation apparatus based on an off-axis RC mirror set of claim 3, wherein: the visible light camera (2) has a zooming function, can clearly image a long-distance target, and can frame the currently locked target.