Anti-interference laser scanning range finder

Abstract

An anti-interference laser scanning range finder comprises a finder shell, a laser emission module and a main optical window, the laser emission module and the main optical window are arranged in the finder shell, the range finder further comprises a variable aperture mechanism and a distance sensing assembly, and the distance sensing assembly comprises a sensor substrate, an auxiliary laser emission tube and a photosensitive element displacement mechanism. The auxiliary laser transmitting tube is fixedly mounted at the front end of the sensor substrate and is horizontally arranged with the laser transmitting module, and the distance sensing assembly is connected with the variable aperture mechanism through a transmission mechanism so as to drive the variable aperture mechanism to change the clear aperture, so that the purposes of strong light interference resistance and full-scale adaptive distance measurement can be achieved.

Description

Technical Field

[0001] This invention relates to an anti-interference laser scanning rangefinder, belonging to the technical field of laser scanning rangefinders. Background Technology

[0002] Lasers have a wide range of applications in the field of detection, are highly technical, and have a significant impact on social production and life. In particular, laser rangefinders are increasingly used due to the advantages of lasers, such as strong directionality, high brightness, and good monochromaticity. They are suitable for various measurement occasions and can measure both close-range and long-range targets.

[0003] In existing technologies, reflective single-line coaxial laser scanning rangefinders generally employ fixed-aperture optical systems. To suppress interference from stray light, they primarily rely on narrowband filters at the receiver for optical filtering. However, in practical applications, especially in strong outdoor light environments, this method has significant limitations in its anti-interference capabilities. When strong stray light of the same wavelength as the laser (such as sunlight) exists in the environment, the narrowband filter, due to its limited filtering bandwidth, cannot effectively filter out this specific wavelength of strong light. If this strong light enters the receiving optical system directly at a specific angle, it will form a strong interference signal on the receiver, which in severe cases can completely mask the weak effective laser echo signal, resulting in a large amount of noise in the measurement data, or even causing receiver saturation and temporary failure of the ranging function. Furthermore, fixed-aperture systems cannot simultaneously meet the different light transmission requirements for long and short ranging distances; when measuring extreme or very short distances, the signal-to-noise ratio and measurement accuracy will significantly decrease. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides an anti-interference laser scanning rangefinder that can achieve the purpose of resisting strong light interference and full-range adaptive ranging.

[0005] The technical solution of the present invention is as follows: An anti-interference laser scanning rangefinder includes an instrument housing, a laser emitting module and a main optical window disposed within the instrument housing, and further includes a variable aperture mechanism and a distance sensing component. The distance sensing component includes a sensor substrate, an auxiliary laser emitting tube, and a photosensitive element displacement mechanism. The auxiliary laser emitting tube is fixedly mounted at the front end of the sensor substrate and is horizontally positioned with the laser emitting module. The photosensitive element displacement mechanism includes a bimetallic photosensitive arm, a phototube, a first reset spring, and a focusing lens. The bimetallic photosensitive arm is formed by laminating a first metal layer and a second metal layer with different coefficients of thermal expansion. One end is a fixed end, fixed to the sensor substrate, and the other end is a free end; the free end of the bimetallic photosensitive arm faces the imaging surface of the focusing lens, and its light-receiving surface is coated with a high-absorption coating; the first reset spring acts on the free end of the bimetallic photosensitive arm to provide it with a reset force; the focusing lens is fixed to the sensor substrate and located in the optical path between the auxiliary laser emitting tube and the bimetallic photosensitive arm; the phototube is disposed below the bimetallic photosensitive arm; the distance sensing component is connected to the variable aperture mechanism through a transmission mechanism to drive the variable aperture mechanism to change the light transmission aperture.

[0006] The light-receiving surface of the bimetallic photosensitive arm is divided into a first photosensitive area and a second photosensitive area along its length; the surface of the first photosensitive area is covered with a first high absorptivity coating, and the surface of the second photosensitive area is covered with a second high absorptivity coating, wherein the thermal absorptivity of the first high absorptivity coating and the second high absorptivity coating are different.

[0007] The variable aperture mechanism includes an aperture base, a drive ring, and at least two aperture blades. The aperture base is fixedly disposed inside the main optical window. The drive ring is rotatably coaxially disposed on the aperture base. The first end of each aperture blade is hinged to the aperture base via a first rotating shaft, and a strip-shaped groove is formed in the middle of each aperture blade. A drive pin is fixedly disposed on the drive ring corresponding to each aperture blade, and the drive pin is slidably nested in the corresponding strip-shaped groove. The drive pin is connected to the transmission mechanism.

[0008] It also includes an anti-strong light interference component, which includes a switching unit and a strong light sensing structure; the transmission mechanism includes a connecting rod that rotates on one side of the bimetallic photosensitive arm, a rotating disk that is rotatably installed inside the instrument housing, the other end of the connecting rod being fixedly set at one end of the rotating disk, a drive rod being fixedly installed at the bottom of the rotating disk, and the drive rod being connected to the switching unit to change the driving mode of the variable aperture mechanism.

[0009] The strong light sensing structure includes a condenser lens and a photosensitive piston cylinder. The condenser lens is fixed to the outside of the instrument housing. The photosensitive piston cylinder is fixed to the inside of the instrument housing, with its axis coinciding with the optical axis of the condenser lens and its opening facing the focal point of the condenser lens. The photosensitive piston cylinder contains a piston that can slide along its axis and a second return spring. The surface of the piston facing the condenser lens is a dark light-absorbing surface, and the second return spring acts on the piston to make it tend to move towards the condenser lens.

[0010] The switching unit includes a linkage lever, which is parallel to the drive rod and hinged to the side wall of the drive rod via a hinge seat. The drive rod has two through holes. One end of the linkage lever is hinged with a pin, and the other end is provided with a collar. The drive pin has a vertical groove, and the pin matches the vertical groove. A sliding plate is slidably mounted on the piston, and a push spring is sleeved on the outside of the piston. One end of the push spring is fixed to the sliding plate, and the other end is fixed to a protruding ring on the piston. The end of the piston is connected to the drive pin via a pull rope.

[0011] A connecting elastic rope is provided between the pin and the vertical groove.

[0012] The present invention has the following beneficial effects: This invention effectively solves the shortcomings of existing technologies that rely on electronic filtering by using a purely mechanical strong light sensing and triggering mechanism. When strong interference sources such as sunlight shine directly on the system, it can quickly and automatically lock the optical aperture to the minimum safe state, physically limiting the light energy entering the receiver. This fundamentally avoids the problem of ranging signals being overwhelmed or receiver saturation causing blindness, and significantly improves the reliability of operation in harsh lighting environments.

[0013] This invention achieves adaptive adjustment of the aperture to the measurement distance by converting distance information into mechanical displacement to drive aperture changes. When measuring distant targets, the aperture automatically increases to improve laser energy emission and collection efficiency; when measuring nearby targets, the aperture automatically decreases to prevent signal overload and suppress background stray light. This dynamic optimization ensures that the instrument maintains a high signal-to-noise ratio and measurement accuracy throughout the entire measurement range, from near to far. Attached Figure Description

[0014] Figure 1 This is a half-sectional view of the laser scanning rangefinder of the present invention; Figure 2 This is a schematic diagram of the variable aperture mechanism of the present invention; Figure 3 This is a schematic diagram of the switching unit of the present invention; Figure 4 This is a schematic diagram of the pin and vertical groove of the present invention.

[0015] The reference numerals in the figure are as follows: 1. Instrument housing; 2. Laser emitting module; 3. Main optical window; 4. Sensor substrate; 41. Auxiliary laser emitting tube; 42. Bimetallic photosensitive arm; 43. Phototube; 45. Focusing lens; 51. Aperture base; 52. Drive ring; 521. Drive pin; 53. Aperture blades; 531. First rotating shaft; 532. Strip groove; 61. Connecting rod; 62. Rotating disk; 63. Drive rod; 71. Condensing lens; 72. Photosensitive piston cylinder; 73. Piston; 8. Linkage lever; 81. Through hole; 82. Pin; 83. Collar; 84. Vertical groove; 85. Connecting elastic rope; 86. Sliding plate; 87. Push spring. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0017] Please see Figures 1 to 4 The invention provides a technical solution: The anti-interference laser scanning rangefinder of this embodiment includes an instrument housing 1, a laser emitting module 2 disposed within the instrument housing 1, and a main optical window 3. It also includes a variable aperture mechanism and a distance sensing component. The distance sensing component includes a sensor substrate 4, an auxiliary laser emitting tube 41, and a photosensitive element displacement mechanism. The auxiliary laser emitting tube 41 is fixedly mounted on the front end of the sensor substrate 4 and is horizontally arranged with the laser emitting module 2. The photosensitive element displacement mechanism includes a bimetallic photosensitive arm 42, a phototube 43, a first reset spring, and a focusing lens 45. The bimetallic photosensitive arm 42 consists of a first metal layer and a second metal layer with different coefficients of thermal expansion. The bimetallic photosensitive arm 42 is laminated together, with one end being a fixed end fixed to the sensor substrate 4 and the other end being a free end. The free end of the bimetallic photosensitive arm 42 faces the imaging surface of the focusing lens 45, and its light-receiving surface is coated with a high-absorption coating. A first reset spring acts on the free end of the bimetallic photosensitive arm 42 to provide it with a reset force. The focusing lens 45 is fixed to the sensor substrate 4 and is located in the optical path between the auxiliary laser emitting tube 41 and the bimetallic photosensitive arm 42. The phototube 43 is disposed below the bimetallic photosensitive arm 42. The distance sensing component and the variable aperture mechanism are connected through a transmission mechanism to drive the variable aperture mechanism to change the light transmission aperture.

[0018] The light-receiving surface of the bimetallic photosensitive arm 42 is divided into a first photosensitive area and a second photosensitive area along its length; the surface of the first photosensitive area is covered with a first high absorptivity coating, and the surface of the second photosensitive area is covered with a second high absorptivity coating, and the thermal absorptivity of the first high absorptivity coating and the second high absorptivity coating are different.

[0019] It is worth mentioning that increasing the aperture can improve the beam collimation of the laser emission optical system and reduce the divergence angle of the laser beam. This makes the laser energy more concentrated during long-distance transmission, resulting in a higher energy density when it reaches the distant target, thus obtaining a stronger reflected signal. At the same time, at the receiving end, a larger aperture means a larger effective light-receiving area. The laser echo signal returning from a distant target is extremely weak; a large aperture can capture more photons, significantly improving the signal-to-noise ratio of the received signal and ensuring the stability and success rate of long-distance measurements.

[0020] When measuring at close range, the intensity of the laser signal reflected from the target is very high. An excessively large aperture would allow too much energy to enter the receiver, potentially saturating or even damaging the core photodetector. Reducing the aperture physically limits the incident light energy, maintaining the signal intensity within the detector's optimal linear operating range and ensuring measurement accuracy. Furthermore, a smaller aperture corresponds to a smaller receiving field of view, effectively eliminating stray ambient light from non-measurement targets (such as background objects or sidewall reflections), improving the signal-to-noise ratio, and avoiding data noise caused by background light interference during close-range measurements. Finally, a smaller aperture can moderately increase the diffraction and divergence of the laser beam, resulting in a slightly larger spot size and more uniform energy distribution at close range, which is beneficial for measuring diffuse or complex surfaces.

[0021] Specifically, the light-receiving surface of the bimetallic photosensitive arm 42 is covered with a high-absorption coating. When the light beam emitted by the auxiliary laser emitter 41 is reflected by the target and forms a light spot on the surface of the photosensitive arm by the focusing lens 45, the coating in the area irradiated by the light spot efficiently absorbs the light energy and converts it into heat energy.

[0022] The generated heat is rapidly conducted to the bimetallic material layer tightly adhering to the coating. The bimetallic photosensitive arm 42 is formed by laminating a first metal layer (such as Invar, a high-expansion layer) and a second metal layer (such as Invar, a low-expansion layer) with significantly different coefficients of thermal expansion. Localized heating causes the temperature in that area to rise. The first metal layer faces the light-receiving surface of the focusing lens 45, while the second metal layer faces away from the focusing lens 45.

[0023] Because the two metal layers have different coefficients of thermal expansion, when heated, the higher expansion layer attempts to expand longer than the lower expansion layer. This differential expansion is constrained by the internal bonding of the materials, and instead of free elongation, it forces the entire bimetallic sheet to bend and deform towards the lower expansion layer. The higher the temperature at the heating point, the greater the resulting bending curvature.

[0024] The ingenuity of this design lies in using the positional changes of the light spot to control the shape and magnitude of the bending deformation, thereby outputting different mechanical displacements.

[0025] According to the geometric relationship of triangulation, the distance to the target determines the incident angle of the reflected light, which in turn determines the specific coordinates of the light spot along the length of the bimetallic photosensitive arm 42.

[0026] When the light spot illuminates the photosensitive arm near the fixed end, the bending caused by heating mainly results in a large angular displacement of the photosensitive arm and a relatively large linear displacement at the free end. The contribution of the light spot to the overall bending shape varies depending on its position near the free end, and the linear displacement at the free end also changes accordingly. By considering the dimensions, material properties, and support method of the bimetallic photosensitive arm 42, a one-to-one, continuous, and monotonic mapping relationship can be established between the coordinates of the light spot position and the output displacement of the free end of the bimetallic photosensitive arm 42.

[0027] When measuring distant targets, the reflected laser signal is extremely weak, and the spot energy is very low. In this case, the system needs extremely high sensitivity, meaning that even slight heating can generate sufficiently large deformation to drive the aperture mechanism. This requires a high coating absorptivity and a sensitive bimetallic response. However, when measuring near targets, the reflected signal is extremely strong, and the spot energy is very high. If the system maintains high sensitivity, even a small change in distance will cause huge, drastic deformation of the photosensitive arm, making it difficult to control the aperture change smoothly and potentially even causing oscillations. In this case, it is necessary to reduce the system sensitivity to make the control smoother and more stable.

[0028] Therefore, it is preferable to set up a first photosensitive zone and a second photosensitive zone with different thermal absorptivity to further optimize the control characteristics. For example, when measuring at a long distance (the light spot falls on the first photosensitive zone), a coating with a higher absorptivity is used to make the system more sensitive to changes in distance; when measuring at a short distance (the light spot falls on the second photosensitive zone), a coating with a slightly lower absorptivity is used to prevent overheating and adjust the sensitivity, so that the displacement output curve throughout the measurement range better meets the ideal requirements of optical aperture adjustment.

[0029] In detail, the optical axis of the auxiliary laser emitter 41 is parallel to the optical axis of the main laser ranging module 2, maintaining a fixed baseline distance. Simultaneously, the optical axis of the focusing lens 45 is strictly coaxial with the optical axis of the auxiliary laser emitter 41. This constitutes a classic triangulation ranging system.

[0030] According to geometric optics, for a focal length of Lens, incident angle The distance X from the image point off the optical axis satisfies the formula .

[0031] When the target is very far away (D is large), the reflected light is incident almost parallel to the optical axis, and the incident angle θ is very small. Therefore, the image point position X is very close to the center of the optical axis.

[0032] When the target is very close (D is very small), the reflected light is incident at a large angle θ, so the image point position X is far away from the center of the optical axis.

[0033] Based on the aforementioned immutable geometric laws, we can accurately calculate the trajectory (a straight line) of the light spot on the image plane of the photosensitive arm within the entire effective measurement range during the design phase. The first and second photosensitive areas are then divided along this predetermined trajectory.

[0034] We define the segment of the light spot trajectory corresponding to the long-distance measurement range as the first photosensitive zone. We define the segment of the light spot trajectory corresponding to the short-distance measurement range as the second photosensitive zone.

[0035] The variable aperture mechanism includes an aperture base 51, a drive ring 52, and at least two aperture blades 53. The aperture base 51 is fixedly disposed inside the main optical window 3. The drive ring 52 is rotatably coaxially disposed on the aperture base 51. The first end of each aperture blade 53 is hinged to the aperture base 51 through a first rotating shaft 531, and a strip groove 532 is provided in the middle of each aperture blade 53. A drive pin 521 is fixedly disposed on the drive ring 52 corresponding to each aperture blade 53, and the drive pin 521 is slidably nested in the corresponding strip groove 532. The drive pin 521 is connected to the transmission mechanism.

[0036] The aperture base 21 is a ring structure, which is fixedly installed on the inner wall of the instrument housing by means of threads or snaps, and is precisely aligned with the inner side of the main optical window 3. The drive ring 52 is a rotatable ring component, which is rotatably coaxially fitted inside the aperture base 51 by means of miniature bearings or low-friction shaft hole fit. The circumferential end face of the drive ring 52 is usually provided with an interface for connection with the transmission mechanism, and at least two aperture blades 53 are evenly arranged circumferentially around the center of the optical axis. The shape of each aperture blade 53 is precisely designed so that its edge contour can form an approximately circular light-transmitting hole when opening and closing.

[0037] When an external driving force is applied to the drive ring 52 through the transmission mechanism, the drive ring 52 rotates around the center of the optical axis. The rotational motion of the drive ring 52 causes all the drive pins 521 on it to move in a circular motion.

[0038] Since the drive pin 521 is nested in the strip groove 532 of the aperture blade 53, its circumferential motion is constrained by the groove and decomposed into two component motions: one is the relative sliding along the direction of the strip groove 532, and the other is the force that pushes the aperture blade 53 to rotate around its first axis of rotation 531.

[0039] Ultimately, all aperture blades 53, driven by the drive pin 521, synchronously oscillate inward or outward around their respective first rotating shafts 531.

[0040] It also includes an anti-strong light interference component, which includes a switching unit and a strong light sensing structure; the transmission mechanism includes a connecting rod 61 that rotates on one side of the bimetallic photosensitive arm 42, a rotating disk 62 that is rotatably installed inside the instrument housing 1, the other end of the connecting rod 61 being fixedly set at one end of the rotating disk 62, and a drive rod 63 that is fixedly installed at the bottom of the rotating disk 62. The drive rod 63 is connected to the switching unit to change the driving mode of the variable aperture mechanism.

[0041] Specifically, as the target distance changes, the position of the reflected light spot on the surface of the bimetallic photosensitive arm 42 moves accordingly. This movement causes different parts of the bimetallic photosensitive arm 42 to heat up, resulting in varying degrees of bending deformation due to the bimetallic effect. Ultimately, this manifests as a lateral linear displacement at its free end that is strictly corresponding to the distance. Since one end of the connecting rod 61 is hinged to the free end of the bimetallic photosensitive arm 42, while the other end is fixed at an eccentric position on the rotating disk 62, the linear displacement of the bimetallic photosensitive arm 42 directly pulls the connecting rod 61.

[0042] The linear motion of link 61 forces rotating disk 62 to rotate around its central axis. A lever structure can also be provided; according to the lever principle, the displacement of bimetallic photosensitive arm 42 can be amplified into a significant rotation angle of rotating disk 62. The greater the distance, the smaller the corresponding rotation angle of rotating disk 62; the closer the distance, the larger the corresponding rotation angle of rotating disk 62. Thus, distance information is converted and amplified into rotation angle information.

[0043] The drive rod 63 is vertically fixed below the rotating disk 62. Specifically, the drive rod 63 is located on the side of the rotating disk 62, meaning it is not concentric with the rotating disk 62. Therefore, the rotation angle of the rotating disk 62 is transmitted to the drive rod 63, causing it to rotate, which in turn drives the aperture blades 53 to complete the opening and closing operation. As a preferred option, a gear mechanism can also be provided on the outer side of the rotating disk 62. By changing the transmission ratio through the cooperation of the gear mechanism, the rotation amplitude of the drive rod 63 can be further made more obvious, so that it can better drive the aperture blade 53 to open and close. The strong light sensing structure includes a condenser lens 71 and a photosensitive piston cylinder 72. The condenser lens 71 is fixed to the outside of the instrument housing 1. The photosensitive piston cylinder 72 is fixed inside the instrument housing 1, and its axis coincides with the optical axis of the condenser lens 71, with its opening end facing the focal point of the condenser lens 71. The photosensitive piston cylinder 72 is provided with a piston 73 that can slide along its axis and a second return spring. The surface of the piston 73 facing the condenser lens 71 is a dark light-absorbing surface, and the second return spring acts on the piston 73 to make it tend to move towards the condenser lens 71.

[0044] The condenser lens 71 is fixed to the outside of the instrument housing 1. Its function is to focus a large area of ​​parallel incident light (such as sunlight) onto a point on its focal plane, thereby increasing the light energy flux density several times and providing a high-intensity input for subsequent energy conversion.

[0045] The photosensitive piston cylinder 72 is fixed inside the instrument housing 1. Its open end faces the focal point of the condenser lens 71. The surface of the piston 73 facing the condenser lens 71 is a dark light-absorbing surface (such as coated with black paint or a special solar energy-absorbing coating), its function is to efficiently absorb the high-density light energy after convergence and convert it almost entirely into heat energy. A sealed air chamber is formed between the piston 73 and the cylinder of the photosensitive piston cylinder 72, which is filled with air or a specific gas. This is the key to realizing energy conversion and amplification. According to the ideal gas law (Charles' law), in a sealed container with constant volume, the pressure (P) of a gas is directly proportional to its thermodynamic temperature (T). That is, when the dark heat-absorbing surface of the piston is heated, the heat is rapidly conducted to the entire piston and heats the gas in the sealed air chamber. The gas temperature (T) rises sharply, causing its pressure (P) to increase significantly simultaneously. The increased gas pressure acts on the entire end face of the piston 73, generating a powerful thrust. This thrust is used to overcome the preload of the second return spring and the friction between the piston 73 and the cylinder wall of the photosensitive piston cylinder 72, driving the piston 73 to move into the photosensitive piston cylinder 72. When the strong light disappears and the heat source is removed, the gas in the sealed chamber gradually cools down, and the pressure drops. At this time, the compressed second return spring releases its elastic force, pushing the piston 73 back towards the condenser lens 71 until it returns to its initial state.

[0046] The specific process is as follows: When there is no direct strong light, piston 73, under the thrust of the second return spring, is in its initial position closest to the condenser lens 71. The system is in standby mode.

[0047] When a strong light source such as the sun shines directly on the instrument at a specific angle, the parallel light is focused by the condenser lens 71. The focused high-energy light spot precisely illuminates the dark heat-absorbing surface of the piston 73, where the light energy is efficiently absorbed and converted into heat energy. This heat energy then heats the piston 73 and the gas in the sealed chamber, causing the gas temperature to rise and the pressure to increase significantly. The thrust generated by the gas expansion overcomes the resistance of the second return spring, driving the piston 73 to move linearly into the instrument along the cylinder axis. This stroke is the mechanical trigger signal output by this structure.

[0048] The linear motion of piston 73 transmits the mechanical signal to the next-level priority switching mechanism 73, ultimately forcing the variable aperture mechanism to switch to the safe state of minimum aperture.

[0049] The switching unit includes a linkage lever 8, which is parallel to the drive rod 63 and the middle part of the linkage lever 8 is hinged to the side wall of the drive rod 63 through a hinge seat. The drive rod 63 has two through holes 81. One end of the linkage lever 8 is hinged with a pin 82 and the other end is provided with a collar 83. The drive pin 521 is provided with a vertical groove 84, and the pin 82 matches the vertical groove 84. A sliding plate 86 is slidably provided on the piston 73. A push spring 87 is sleeved on the outside of the piston 73. One end of the push spring 87 is fixed to the sliding plate 86 and the other end is fixed to the protruding ring on the piston 73. The end of the piston 73 is connected to the drive pin 521 by a pull rope.

[0050] Specifically, when the switching unit is not started, the drive rod 63 rotates around the center of the rotating disk 62. Due to the restriction of the strip groove 532 on the aperture blade 53, it will be dragged by the drive rod 63 to slide on the strip groove 532, thus completing the opening and closing of the variable aperture mechanism. When the switching unit is activated, i.e., when the strong light sensing structure detects strong light, piston 73 extends and enters one of the through holes 81. At this time, as piston 7 continues to extend until the sliding plate 86 is in contact with the collar 83 of the linkage lever 8, the force provided by the sliding plate 86 will cause the linkage lever 8 to tilt towards the sliding plate 86 until it tilts to the maximum angle. At this time, the pin 82, which is in another through hole 81, will be disengaged from the vertical groove 84 by the tilt of the linkage lever 8, thus disconnecting the connection between the drive rod 63 and the drive pin 521. That is, at this time, the variable aperture mechanism is no longer driven by the transmission mechanism. Then, since the sliding plate 86 and piston 73 are slidably connected, the position of the sliding plate 86 is restricted and cannot be moved when the linkage lever 8 cannot rotate, while piston 73 can continue to move forward. After piston 73 moves forward until the pull rope is straightened, it can drive the drive pin 521 to move, and the drive pin 521 will rotate, completing the change of driving mode. When the strong light weakens, the piston 73 retracts. Specifically, a return spring is also provided inside the strip groove 532. One end of the return spring is fixed inside the strip groove 532, and the other end is fixed to the drive pin 521. It can automatically reset when the piston 73 retracts, so that the drive rod 63 and the drive pin 521 are locked again. A connecting elastic rope 85 is provided between the pin 82 and the vertical groove 84.

[0051] Preferably, the switching unit achieves the best driving effect when the laser emission module 2 of the scanning rangefinder is not started.

[0052] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An anti-interference laser scanning rangefinder, comprising an instrument housing (1), a laser emitting module (2) disposed within the instrument housing (1), and a main optical window (3), characterized in that: It also includes a variable aperture mechanism and a distance sensing component. The distance sensing component includes a sensor substrate (4), an auxiliary laser emitting tube (41), and a photosensitive element displacement mechanism. The auxiliary laser emitting tube (41) is fixedly installed at the front end of the sensor substrate (4) and is horizontally arranged with the laser emitting module (2). The photosensitive element displacement mechanism includes a bimetallic photosensitive arm (42), a phototube (43), a first reset spring, and a focusing lens (45). The bimetallic photosensitive arm (42) is formed by pressing a first metal layer and a second metal layer with different coefficients of thermal expansion together. One end of the bimetallic photosensitive arm is a fixed end, which is fixed to the sensor substrate (4), and the other end is a fixed end. The free end of the bimetallic photosensitive arm (42) faces the imaging surface of the focusing lens (45), and its light-receiving surface is coated with a high-absorption coating. The first reset spring acts on the free end of the bimetallic photosensitive arm (42) to provide it with a reset force. The focusing lens (45) is fixed on the sensor substrate (4) and located in the optical path between the auxiliary laser emitting tube (41) and the bimetallic photosensitive arm (42). The phototube (43) is located below the bimetallic photosensitive arm (42). The distance sensing component is connected to the variable aperture mechanism through a transmission mechanism to drive the variable aperture mechanism to change the light transmission aperture.

2. The anti-interference laser scanning rangefinder as described in claim 1, characterized in that: The light-receiving surface of the bimetallic photosensitive arm (42) is divided into a first photosensitive area and a second photosensitive area along its length direction; the surface of the first photosensitive area is covered with a first high absorptivity coating, and the surface of the second photosensitive area is covered with a second high absorptivity coating, wherein the thermal absorptivity of the first high absorptivity coating and the second high absorptivity coating are different.

3. The anti-interference laser scanning rangefinder as described in claim 2, characterized in that: The variable aperture mechanism includes an aperture base (51), a drive ring (52), and at least two aperture blades (53); the aperture base (51) is fixedly disposed on the inner side of the main optical window (3); the drive ring (52) is rotatably coaxially disposed on the aperture base (51); the first end of each aperture blade (53) is hinged to the aperture base (51) through a first rotating shaft (531), and a strip groove (532) is provided in the middle of each aperture blade (53); a drive pin (521) is fixedly disposed on the drive ring (52) corresponding to each aperture blade (53), and the drive pin (521) is slidably nested in the corresponding strip groove (532); the drive pin (521) is connected to the transmission mechanism.

4. The anti-interference laser scanning rangefinder as described in claim 3, characterized in that: It also includes an anti-strong light interference component, which includes a switching unit and a strong light sensing structure; the transmission mechanism includes a connecting rod (61) rotating on one side of the bimetallic photosensitive arm (42), a rotating disk (62) is rotatably installed inside the instrument housing (1), the other end of the connecting rod (61) is fixedly set at one end of the rotating disk (62), a drive rod (63) is fixedly installed at the bottom of the rotating disk (62), and the drive rod (63) is connected to the switching unit to change the driving mode of the variable aperture mechanism.

5. The anti-interference laser scanning rangefinder as described in claim 4, characterized in that: The strong light sensing structure includes a condenser lens (71) and a photosensitive piston cylinder (72); the condenser lens (71) is fixed to the outside of the instrument housing (1); the photosensitive piston cylinder (72) is fixed inside the instrument housing (1), its axis coincides with the optical axis of the condenser lens (71), and its opening end is directly opposite the focal point of the condenser lens (71); the photosensitive piston cylinder (72) is provided with a piston (73) that can slide along its axis and a second return spring; the surface of the piston (73) facing the condenser lens (71) is a dark light-absorbing surface, and the second return spring acts on the piston (73) to make it tend to move towards the condenser lens (71).

6. The anti-interference laser scanning rangefinder as described in claim 5, characterized in that: The switching unit includes a linkage lever (8), which is parallel to the drive rod (63) and the middle part of the linkage lever (8) is hinged to the side wall of the drive rod (63) through a hinge seat. The drive rod (63) has two through holes (81). One end of the linkage lever (8) is hinged with a pin (82) and the other end is provided with a collar (83). The drive pin (521) is provided with a vertical groove (84) and the pin (82) matches the vertical groove (84). A sliding plate (86) is slidably provided on the piston (73). A push spring (87) is sleeved on the outside of the piston (73). One end of the push spring (87) is fixed to the sliding plate (86) and the other end is fixed to the protruding ring on the piston (73). The end of the piston (73) is connected to the drive pin (521) by a pull rope.

7. The anti-interference laser scanning rangefinder as described in claim 6, characterized in that: A connecting elastic rope (85) is provided between the pin (82) and the vertical groove (84).

Images