Aperture adjustable receiving system for laser ranging

Abstract

This invention provides an aperture-adjustable receiving system for laser ranging, comprising a receiver encapsulated in a tube housing. A light incident window is disposed on the tube housing facing the receiver. The system is characterized by a field-of-view aperture and a receiving optical structure sequentially disposed between the light incident window and the receiver. The field-of-view aperture is positioned near the light incident window and has an adjustable first central aperture to adjust the range of incident light. The receiving optical structure includes multiple optical lenses arranged sequentially, which sequentially change the angle of the incident light to focus it onto the receiver. An aperture stop is disposed between the optical lenses, and the aperture stop has an adjustable second central aperture. This invention utilizes a field-of-view aperture to reduce the influence of ambient light by adjusting its aperture size, and a receiving optical structure to focus the incident light onto the receiver, thereby improving measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of laser ranging technology, and in particular to an aperture-adjustable receiving system for laser ranging. Background Technology

[0002] The receiver 2 for laser ranging is typically encapsulated in a housing 1. For example... Figure 1 As shown, the housing 1 has a large flat bottom surface for mounting the receiver 2, and a light incident window 3 parallel to the flat bottom surface and facing the receiver 2. Ranging systems often require a large window to receive a large amount of light and allow the receiving system to have a small receiving field of view (e.g., 3 mrad). The large window causes more ambient light to enter the light incident window 3, interfering with the signal light and affecting the accuracy of the measurement results. At the same time, although there is a large window, it cannot be guaranteed that most of the incident light will hit the receiving target surface of the receiver 2, making the receiver 2 less sensitive to changes in incident light and affecting the measurement accuracy.

[0003] Therefore, it is necessary to provide an aperture-adjustable receiving system for laser ranging to effectively solve the above problems. Summary of the Invention

[0004] This invention provides an aperture-adjustable receiving system for laser ranging, which includes a field-of-view aperture to reduce the influence of ambient light by adjusting the aperture size of the field-of-view aperture; and a receiving optical structure to focus the incident light onto the receiver, thereby improving measurement accuracy.

[0005] This invention provides an aperture-adjustable receiving system for laser ranging, including a receiver encapsulated in a housing. A light incident window is disposed on the housing facing the receiver. A field stop and a receiving optical structure are sequentially disposed between the light incident window and the receiver. The field stop is located near the light incident window and has an adjustable first central aperture to adjust the range of incident light. The receiving optical structure includes a plurality of sequentially arranged optical lenses, which sequentially change the angle of the incident light to focus it onto the receiver. An aperture stop is disposed between the optical lenses, and the aperture stop has an adjustable second central aperture that allows incident light to pass through.

[0006] Preferably, the side of the optical lens closest to the field stop is a first surface, and the side closest to the receiver is a second surface. The receiving optical structure includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially and at intervals between the field stop and the receiver. The first lens is a concave-convex lens, with its first surface being convex and its second surface being concave. The second lens is a biconcave lens, with both its first and second surfaces being concave. The third lens is a biconvex lens, with both its first and second surfaces being convex. The fourth lens is a plano-convex lens, with its first surface being convex and its second surface being planar.

[0007] Preferably, the first lens, the second lens, the third lens, and the fourth lens respectively satisfy the following formula:

[0008]

[0009]

[0010]

[0011]

[0012] Where f1 is the focal length of the first lens, which is 47.51 mm; n1 is the refractive index of the first lens; R 11 R is the radius of curvature of the first surface of the first lens; 12 d1 is the radius of curvature of the second surface of the first lens; d1 is the center thickness of the first lens.

[0013] f2 is the focal length of the second lens, which is -26.44 mm; n2 is the refractive index of the second lens; R 21 R is the radius of curvature of the first surface of the second lens; 22 d1 is the radius of curvature of the second surface of the second lens; d2 is the center thickness of the second lens;

[0014] f3 is the focal length of the third lens, which is 59.42 mm; n3 is the refractive index of the third lens; R 31 R is the radius of curvature of the first surface of the third lens; 32 d3 is the radius of curvature of the second surface of the third lens; d3 is the center thickness of the third lens;

[0015] f4 is the focal length of the fourth lens, which is 14.19 mm; n4 is the refractive index of the fourth lens; R 41R is the radius of curvature of the first surface of the fourth lens; 42 d4 is the radius of curvature of the second surface of the fourth lens; d4 is the center thickness of the fourth lens.

[0016] Preferably, the aperture stop is disposed between the second lens and the third lens, and the diameter of the second central hole is 5mm-20mm.

[0017] Preferably, a filter is disposed between the third lens and the fourth lens, and the filter is disposed close to the fourth lens.

[0018] Preferably, the diameter of the first central hole of the field stop is 20mm-35mm.

[0019] Preferably, the system further includes an ambient light sensor and a controller. The ambient light sensor is disposed inside the field stop and is used to detect the intensity of ambient light entering the field stop. Both the ambient light sensor and the receiver are electrically connected to the controller. The controller receives a first current signal E1 fed back by the ambient light sensor, the magnitude of which is proportional to the intensity of the ambient light received by the ambient light sensor. The controller also receives a second current signal S1 fed back by the receiver, the magnitude of which is proportional to the intensity of the signal light received by the receiver.

[0020] Preferably, the field stop is electrically connected to the controller, and the controller adjusts the aperture of the first central hole according to the magnitude of the first current signal E1 and the second current signal S1;

[0021] When E1 > 0.001 * S1, the controller controls the diameter of the first central hole to decrease;

[0022] When E1≤0.001*S1, the controller controls the diameter of the first central hole to remain unchanged.

[0023] Preferably, the controller controls the diameter of the first central hole to gradually decrease, with each decrease being 2% of the maximum diameter of the first central hole.

[0024] Preferably, the aperture stop is electrically connected to the controller, and the second current signal fed back to the controller by the receiver when receiving saturated light is S. max The controller adjusts the diameter of the second central hole according to the magnitude of the second current signal S1 received in real time;

[0025] When S1 > 0.9*S max At that time, the controller controls the diameter of the second central hole to decrease;

[0026] When 0.9*S max ≥S1≥0.3*S max At that time, the controller controls the diameter of the second central hole to remain unchanged;

[0027] When S1 < 0.3*S max At that time, the controller controls the diameter of the second central hole to increase.

[0028] Preferably, the controller controls the diameter of the second central hole to gradually increase or decrease, with each increase or decrease being 2% of the maximum diameter of the second central hole.

[0029] Preferably, the receiver is a single-photon avalanche diode.

[0030] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:

[0031] This invention provides an aperture-adjustable receiving system for laser ranging. A field-view aperture and a receiving optical structure are set between the light incident window and the receiver. By adjusting the aperture size of the field-view aperture, the influence of ambient light is reduced. By using multiple optical lenses in the receiving optical structure, the angle of the incident light is changed, and the incident light is focused on the receiver, thereby improving sensitivity and measurement accuracy.

[0032] Furthermore, an aperture stop is set between the optical lenses. By adjusting the size of the aperture stop, the intensity of the signal light illuminating the receiver is adjusted to avoid signal light intensity saturation distortion or signal light intensity being too weak to be measured.

[0033] Furthermore, an ambient light sensor and controller are set up. The aperture size of the field stop is adjusted by comparing the feedback signal from the ambient light sensor with the feedback signal from the receiver, which is a more reasonable adjustment method. The aperture size of the aperture stop is adjusted by comparing the real-time feedback signal from the receiver with the signal value when the receiver is saturated, which is a reasonable and efficient adjustment method. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention, but not all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of an existing laser ranging and receiving system;

[0036] Figure 2A schematic diagram of an aperture-adjustable receiving system for laser ranging provided according to an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of a receiving optical structure provided for one embodiment of the present invention;

[0038] Figure 4 A flowchart of field-of-view aperture adjustment is provided for one embodiment of the present invention;

[0039] Figure 5 A flowchart for aperture stop adjustment is provided for one embodiment of the present invention.

[0040] In the picture:

[0041] 1. Tube shell; 2. Receiver; 3. Light entrance window; 4. Field stop; 5. Receiving optical structure; 6. Aperture stop; 7. Signal light; 8. Ambient light;

[0042] 41. First central aperture; 51. First lens; 52. Second lens; 53. Third lens; 54. Fourth lens; 55. Filter; 61. Second central aperture. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0045] To address the problems existing in the prior art, this invention provides an aperture-adjustable receiving system for laser ranging. It includes a field-of-view aperture diaphragm, which reduces the influence of ambient light by adjusting the aperture size; and a receiving optical structure that focuses incident light onto the receiver, improving measurement accuracy.

[0046] Figure 2 A schematic diagram of an aperture-adjustable receiving system for laser ranging provided according to an embodiment of the present invention; Figure 3 A schematic diagram of a receiving optical structure provided for one embodiment of the present invention; Figure 4 A flowchart of field-of-view aperture adjustment is provided for one embodiment of the present invention; Figure 5A flowchart for aperture stop adjustment is provided for one embodiment of the present invention.

[0047] Now see Figures 2 to 5 This invention provides an aperture-adjustable receiving system for laser ranging, comprising a receiver 2 encapsulated in a housing 1. A light incident window 3 is disposed on the housing 1 facing the receiver 2. A field of view aperture 4 and a receiving optical structure 5 are sequentially disposed between the light incident window 3 and the receiver 2. The field of view aperture 4 is disposed on the side close to the light incident window 3 and has an adjustable first central aperture 41 to adjust the range of incident light. The receiving optical structure 5 includes a plurality of optical lenses sequentially disposed, which sequentially change the angle of the incident light to focus the incident light onto the receiver 2. An aperture aperture 6 is disposed between the optical lenses and has an adjustable second central aperture 61 that allows incident light to pass through.

[0048] In some embodiments, the side of the optical lens near the field stop 4 is the first side, and the side near the receiver 2 is the second side. The receiving optical structure 5 includes a first lens 51, a second lens 52, a third lens 53, and a fourth lens 54 arranged sequentially between the field stop 4 and the receiver 2. The first lens 51 is a concave-convex lens, with its first side being convex and its second side being concave. The second lens 52 is a biconcave lens, with both its first and second sides being concave. The third lens 53 is a biconvex lens, with both its first and second sides being convex. The fourth lens 54 is a plano-convex lens, with its first side being convex and its second side being planar.

[0049] In some embodiments, the first lens 51, the second lens 52, the third lens 53, and the fourth lens 54 satisfy the following formula:

[0050]

[0051]

[0052]

[0053]

[0054] Where f1 is the focal length of the first lens 51; n1 is the refractive index of the first lens 51;

[0055] R 11 R is the radius of curvature of the first surface of the first lens 51; 12d1 is the radius of curvature of the second surface of the first lens 51; d1 is the center thickness of the first lens 51; f1 is 47.51mm, which is beneficial for the first lens 51 to effectively enlarge the light-transmitting aperture of the lens and improve the receiving efficiency.

[0056] f2 is the focal length of the second lens 52; n2 is the refractive index of the second lens 52; R 21 R is the radius of curvature of the first surface of the second lens 52. 22 d2 is the radius of curvature of the second surface of the second lens 52; d2 is the center thickness of the second lens 52; f2 has a value of -26.44mm, which is beneficial for the second lens 52 to correct the on-axis aberration of the receiving optical structure 5, so that the received beam is focused on the target surface as much as possible.

[0057] f3 is the focal length of the third lens 53; n3 is the refractive index of the third lens 53; R 31 R is the radius of curvature of the first surface of the third lens 53. 32 d3 is the radius of curvature of the second surface of the third lens 53; d3 is the center thickness of the third lens 53; f3 is 59.42 mm, which is beneficial for the third lens 53 to correct off-axis aberrations of the receiving optical structure 5 and improve the system receiving efficiency.

[0058] f4 is the focal length of the fourth lens 54; n4 is the refractive index of the fourth lens 54; R 51 R is the radius of curvature of the first surface of the fourth lens 54. 52 d4 is the radius of curvature of the second surface of the fourth lens 54; d4 is the center thickness of the fourth lens 54; f4 is 14.19 mm, which helps the fourth lens 54 reduce the image height generated by the receiving optical structure 5 in the case of a large field of view, so that the smaller receiver target surface can receive the signal light of the entire field of view.

[0059] In some embodiments, the aperture stop 6 is disposed between the second lens 52 and the third lens 53, and the diameter of the second central hole 61 is 5mm-20mm.

[0060] In some embodiments, a filter 55 is disposed between the third lens 53 and the fourth lens 54, and the filter 55 is disposed close to the fourth lens 54.

[0061] In some embodiments, the diameter of the first central hole 41 of the field stop 4 is 20mm-35mm.

[0062] In some embodiments, an ambient light sensor and a controller are also included. The ambient light sensor is disposed inside the field stop 4 and is used to detect the intensity of ambient light entering the field stop 4. Both the ambient light sensor and the receiver 2 are electrically connected to the controller. The controller receives a first current signal E1 fed back by the ambient light sensor. The magnitude of the first current signal E1 is proportional to the intensity of the ambient light 8 received by the ambient light sensor. The controller receives a second current signal S1 fed back by the receiver 2. The magnitude of the second current signal S1 is proportional to the intensity of the signal light 7 received by the receiver 2.

[0063] In some embodiments, the field stop 4 is electrically connected to the controller, and the controller adjusts the aperture of the first central hole 41 according to the magnitude of the first current signal E1 and the second current signal S1.

[0064] When E1>0.001*S1, the controller controls the diameter of the first center hole 41 to decrease;

[0065] When E1≤0.001*S1, the controller controls the diameter of the first central hole 41 to remain unchanged.

[0066] In the initial state, the diameter of the first central hole 41 is at its maximum. When E1>0.001*S1, the controller controls the diameter of the first central hole 41 to gradually decrease. The diameter of the first central hole 41 decreases by 2% of the maximum diameter of the first central hole 41 each time, until E1≤0.001*S1.

[0067] In some embodiments, the aperture stop 6 is electrically connected to the controller, and the second current signal S fed back to the controller when the receiver 2 receives saturated light is... max The controller adjusts the diameter of the second central hole 61 according to the magnitude of the second current signal S1 received in real time.

[0068] When S1 > 0.9*S max At that time, the controller controls the diameter of the second center hole 61 to decrease;

[0069] When 0.9*S max ≥S1≥0.3*S max At that time, the controller controls the diameter of the second center hole 61 to remain unchanged;

[0070] When S1 < 0.3*S max At that time, the controller controls the diameter of the second center hole 61 to increase.

[0071] In some embodiments, the controller controls the diameter of the second central hole 61 to gradually increase or decrease, with each increase or decrease being 2% of the maximum diameter of the second central hole 61.

[0072] In specific implementation, receiver 2 is an avalanche diode (APD), preferably a single-photon avalanche diode (SPAD). The tube shell 1 is made of ceramic, and the light incident window 3 is made of glass.

[0073] In summary, the aperture-adjustable receiving system for laser ranging provided by the embodiments of the present invention sets up a field stop 4 and a receiving optical structure 5 between the light incident window 3 and the receiver 2. By adjusting the aperture size of the field stop 4, the influence of ambient light 8 is reduced. By using multiple optical lenses of the receiving optical structure 5, the angle of the incident light is changed, and the incident light is focused on the receiver 2, thereby improving sensitivity and measurement accuracy.

[0074] Furthermore, an aperture stop 6 is set between the optical lenses. By adjusting the aperture size of the aperture stop 6, the intensity of the signal light 7 illuminating the receiver 2 is adjusted to avoid saturation distortion of the signal light 7 or the signal light 7 being too weak to be measured.

[0075] Furthermore, an ambient light sensor and controller are set up. The aperture size of the field stop 4 is adjusted by comparing the feedback signal from the ambient light sensor with the feedback signal from the receiver 2, which is a more reasonable adjustment method. The aperture size of the aperture stop 6 is adjusted by comparing the real-time feedback signal from the receiver 2 with the signal value when the receiver 2 is saturated, which is a reasonable and efficient adjustment method.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aperture-adjustable receiving system for laser ranging, comprising a receiver encapsulated in a housing, wherein a light entrance window is provided on the housing facing the receiver, characterized in that, A field stop and a receiving optical structure are sequentially arranged between the light incident window and the receiver. The field stop is located on the side close to the light incident window and has a first central aperture with an adjustable aperture to adjust the range of the incident light area. The receiving optical structure includes a plurality of optical lenses arranged sequentially. The plurality of optical lenses sequentially change the angle of the incident light to focus the incident light onto the receiver. An aperture stop is arranged between the optical lenses and has a second central aperture with an adjustable aperture, which allows the incident light to pass through. The optical lens has a first surface near the field stop and a second surface near the receiver. The receiving optical structure includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially and at intervals between the field stop and the receiver. The first lens is a concave-convex lens, with its first surface being convex and its second surface being concave. The second lens is a biconcave lens, with both its first and second surfaces being concave. The third lens is a biconvex lens, with both its first and second surfaces being convex. The fourth lens is a plano-convex lens, with its first surface being convex and its second surface being planar. The aperture stop is disposed between the second lens and the third lens, and the diameter of the second central hole is 5mm-20mm; It also includes an ambient light sensor and a controller. The ambient light sensor is disposed inside the field stop and is used to detect the intensity of ambient light entering the field stop. Both the ambient light sensor and the receiver are electrically connected to the controller. The controller receives a first current signal E1 fed back by the ambient light sensor, the magnitude of which is proportional to the intensity of the ambient light received by the ambient light sensor. The controller also receives a second current signal S1 fed back by the receiver, the magnitude of which is proportional to the intensity of the signal light received by the receiver. The aperture stop is electrically connected to the controller, and the second current signal S fed back to the controller when the receiver receives saturated light is... max The controller adjusts the diameter of the second central hole according to the magnitude of the second current signal S1 received in real time; when At that time, the controller controls the diameter of the second central hole to decrease; when At that time, the controller controls the diameter of the second central hole to remain unchanged; when At that time, the controller controls the diameter of the second central hole to increase.

2. The aperture-adjustable receiving system for laser ranging according to claim 1, characterized in that, The first lens, the second lens, the third lens, and the fourth lens each satisfy the following formula: ； ； ； ； in, The focal length of the first lens is 47.51 mm. Let be the refractive index of the first lens; Let be the radius of curvature of the first surface of the first lens; Let be the radius of curvature of the second surface of the first lens; The center thickness of the first lens; The focal length of the second lens is -26.44 mm. The refractive index of the second lens is denoted as . The radius of curvature of the first surface of the second lens; Let be the radius of curvature of the second surface of the second lens; The center thickness of the second lens; The focal length of the third lens is 59.42 mm. The refractive index of the third lens; The radius of curvature of the first surface of the third lens; The radius of curvature of the second surface of the third lens; The center thickness of the third lens; The focal length of the fourth lens is 14.19 mm. The refractive index of the fourth lens; The radius of curvature of the first surface of the fourth lens; The radius of curvature of the second surface of the fourth lens; The center thickness of the fourth lens is given.

3. The aperture-adjustable receiving system for laser ranging according to claim 1, characterized in that, A filter is disposed between the third lens and the fourth lens, and the filter is disposed close to the fourth lens.

4. The aperture-adjustable receiving system for laser ranging according to claim 1, characterized in that, The diameter of the first central hole of the field stop is 20mm-35mm.

5. The aperture-adjustable receiving system for laser ranging according to claim 1, characterized in that, The field stop is electrically connected to the controller, and the controller adjusts the aperture of the first central hole according to the magnitude of the first current signal E1 and the second current signal S1. when At that time, the controller controls the diameter of the first central hole to decrease; when At that time, the controller controls the diameter of the first central hole to remain unchanged.

6. The aperture-adjustable receiving system for laser ranging according to claim 5, characterized in that, The controller controls the diameter of the first central hole to gradually decrease, with each decrease being 2% of the maximum diameter of the first central hole.

7. The aperture-adjustable receiving system for laser ranging according to claim 1, characterized in that, The controller controls the diameter of the second central hole to gradually increase or decrease, with each increase or decrease being 2% of the maximum diameter of the second central hole.

8. The aperture-adjustable receiving system for laser ranging according to claim 1, characterized in that, The receiver is a single-photon avalanche diode.

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