Laser ranging receiving optical path assembly and optical axis debugging method

Abstract

The present invention discloses a laser ranging receiving optical path assembly and an optical axis debugging method. In the light propagation direction, the laser ranging receiving optical path assembly successively includes an object-side telecentric lens group, a collimating lens group, and a converging lens group that are arranged at intervals; the light is collimated by the collimating lens group and exits in the form of parallel light; the converging lens group is used to correct the aberration of the front-end lens group, and the light is focused on the image plane after passing through the converging lens group. By adopting the present invention, the image quality requirements can be met directly after the lenses are processed and combined, without processes such as grinding / padding, which is beneficial to mass production, and has universality, has good applicability to lasers of different bands, and has a large adjustable space. The optical axis is adjusted by translating some lens groups instead of traditional methods such as grinding and adding gaskets, and has the advantages of high reliability, high optical axis adjustment accuracy, and high debugging efficiency.

Description

Technical Field

[0001] The present invention relates to the field of optics, and particularly to a laser ranging receiving optical path assembly and an optical axis debugging method. Background Art

[0002] In recent years, with the continuous development of laser ranging technology, due to advantages such as high repetition frequency, fast measurement speed, high accuracy, long distance, and strong anti-interference ability, laser ranging technology has been widely applied in target detection, aerospace, and civilian ranging fields. Among them, the alignment accuracy of the optical axes of the laser emission optical path and the receiving optical path directly affects the laser ranging performance. However, in complex optoelectronic detection systems, especially in systems with multi-band common optical paths, the available optical axis debugging space for the laser receiving part is relatively narrow. In related technologies, when debugging the laser receiving optical axis, methods such as overall translation of the lens, adding gaskets at fixed positions of the lens, or grinding mechanical structures are mostly used to change the optical axis angle. However, such optical axis debugging methods have problems such as complex structure, low reliability, large human error, and long debugging cycle. Summary of the Invention

[0003] Embodiments of the present invention provide a laser ranging receiving optical path assembly and an optical axis debugging method to solve the problem of low reliability of the optical axis debugging method in the prior art.

[0004] According to the laser ranging receiving optical path assembly of the embodiments of the present invention, in the light propagation direction, the laser ranging receiving optical path assembly sequentially includes an object-side telecentric lens group, a collimating lens group, and a converging lens group that are arranged at intervals;

[0005] After being collimated by the collimating lens group, the light exits in the form of parallel light;

[0006] The converging lens group is used to correct the aberration of the front-end lens group, and the light is focused on the image plane after passing through the converging lens group.

[0007] According to some embodiments of the present invention, the laser ranging device further includes:

[0008] A field stop, located between the object-side telecentric lens group and the collimating lens group and at the position of the primary image plane, and the opening diameter of the field stop matches the field angle of the lens.

[0009] According to some embodiments of the present invention, the laser ranging device further includes:

[0010] A stray light stop, located between the collimating lens group and the converging lens group.

[0011] According to some embodiments of the present invention, the laser ranging device further includes: a narrowband filter and a polarizer located between the collimating lens group and the converging lens group.

[0012] According to some embodiments of the present invention, the collimating lens group includes at least one lens with positive optical power;

[0013] The converging lens group includes at least one lens with positive optical power;

[0014] The object-side telecentric lens group includes:

[0015] An objective lens group including at least one lens with positive optical power;

[0016] A field lens group including at least one lens with positive or negative optical power;

[0017] The field lens group is located between the objective lens group and the collimating lens group.

[0018] According to some embodiments of the present invention, the lenses are all K9 pieces or quartz pieces.

[0019] According to some embodiments of the present invention, the surfaces of the lenses are all spherical or aspherical, and the aspherical surface satisfies the following equation:

[0020]

[0021] Wherein, Z is the sagitta of the aspherical surface along the optical axis at a position with a height of Y, measured from the vertex of the aspherical surface, R is the paraxial curvature radius of the lens, K is the conic coefficient, and A, B, C, and D are all high-order aspherical coefficients.

[0022] According to some embodiments of the present invention, the f / # of the laser ranging receiving optical path assembly satisfies: 0.5 ≤ f / # ≤ 10, and the aperture D0 satisfies: -500 mm ≤ D0 ≤ -5 mm;

[0023] The optical total length L of the laser ranging receiving optical path assembly and the focal length f' satisfy the condition: 0.5f' ≤ L ≤ 4f';

[0024] The laser ranging receiving optical path assembly is adapted to receive laser light with a wavelength of 500 nm to 2000 nm.

[0025] According to some embodiments of the present invention, the laser ranging receiving optical path assembly is in an L shape, a U shape, or a Z straight tube shape.

[0026] According to the optical axis alignment method of the embodiments of the present invention, the optical axis alignment method is applicable to the laser ranging receiving optical path assembly as described above;

[0027] The method includes:

[0028] Translating the collimating lens group and the converging lens group as a whole.

[0029] By adopting the embodiment of the present invention, the image quality requirements can be met directly after the lens processing is completed, without processes such as lapping / padding, which is beneficial to mass production, and has universality, has good applicability to lasers of different bands, and has a large adjustable space. By translating part of the lens group to replace the traditional methods such as grinding and adding gaskets for axis adjustment, it has the advantages of high reliability, high axis adjustment accuracy, and high debugging efficiency.

[0030] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are specifically given below. Brief Description of the Drawings

[0031] By reading the following detailed description of the embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. In the drawings:

[0032] Figure 1 is a schematic structural diagram of the laser ranging receiving optical path assembly in the embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of the distortion and field curvature curves of the laser ranging receiving optical path assembly in the embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of the MTF curve of the optical transfer function at room temperature in the embodiment of the present invention;

[0035] Figure 4 is a schematic structural diagram of the laser ranging receiving optical path assembly in the embodiment of the present invention;

[0036] Figure 5 is a schematic diagram of the distortion and field curvature curves of the laser ranging receiving optical path assembly in the embodiment of the present invention;

[0037] Figure 6 is a schematic diagram of the MTF curve of the optical transfer function at room temperature in the embodiment of the present invention. Detailed Embodiments

[0038] The exemplary embodiments of the present invention will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0039] The object of the present invention is to provide a laser ranging receiving optical path assembly and an optical axis debugging method. Aiming at the problems of tight debugging space, low assembly and adjustment efficiency, and poor reliability existing in the laser ranging optical path of a multi-band common optical path system, by changing the light path direction of the traditional laser receiving optical path and designing an intermediate image plane with an image-side telecentricity, the purpose of changing the optical axis angle by radially translating part of the lens group is realized, thereby improving the assembly and adjustment accuracy, efficiency, and system reliability.

[0040] Specifically, an embodiment of the first aspect of the present invention proposes a laser ranging receiving optical path assembly. As Figure 1 and Figure 4 shown, in the light propagation direction, the laser ranging receiving optical path assembly successively includes an object-side telecentric lens group, a collimating lens group 30, and a converging lens group 40 arranged at intervals;

[0041] The principal rays after passing through the object-side telecentric lens group are approximately parallel to the optical axis at the intermediate image plane, and the image plane size of the principal rays at the intermediate image plane is a constant value.

[0042] The light rays are collimated by the collimating lens group 30 and emitted in the form of parallel light;

[0043] The converging lens group (or imaging lens group) 40 is used to correct the aberration of the front-end lens group, and the light rays are focused on the image plane after passing through the converging lens group 40.

[0044] By adopting the embodiment of the present invention, the image quality requirements can be met directly by combining the lenses after the lens processing is completed, without the need for processes such as grinding / padding, which is beneficial to mass production, and has universality, has good applicability to lasers of different bands, and has a large adjustable space. By translating part of the lens group to replace the traditional methods such as grinding and adding gaskets to adjust the axis, it has the advantages of high reliability, high axis adjustment accuracy, and high debugging efficiency.

[0045] On the basis of the above embodiment, various variant embodiments are further proposed. Here, it should be noted that, for the sake of brief description, only the differences from the above embodiment are described in each variant embodiment.

[0046] As Figure 1 and Figure 4 shown, according to some embodiments of the present invention, the laser ranging device further includes:

[0047] A field stop 50, located between the object-side telecentric lens group and the collimating lens group 30 and at the position of the primary image plane. The opening aperture of the field stop 50 matches the field angle of the lens. The primary image plane is the place where the light rays converge after passing through the object-side telecentric lens group. By designing the field stop 50, the lens can be ensured to have an accurate receiving field angle.

[0048] As Figure 1 and Figure 4As shown, according to some embodiments of the present invention, the laser ranging device further includes:

[0049] A stray light elimination diaphragm 60, located between the collimating lens group 30 and the converging lens group 40.

[0050] According to some embodiments of the present invention, the laser ranging device further includes: a narrowband filter and a polarizer located between the collimating lens group 30 and the converging lens group 40.

[0051] By adding a narrowband filter, a polarizer, etc. at the stray light elimination diaphragm 60 to suppress stray light, the signal-to-noise ratio can be improved.

[0052] According to some embodiments of the present invention, the collimating lens group 30 includes at least one lens with positive optical power;

[0053] The converging lens group 40 includes at least one lens with positive optical power;

[0054] As Figure 1 and Figure 4 shown, the object-side telecentric lens group includes:

[0055] An objective lens group 10, including at least one lens with positive optical power;

[0056] A field lens group 20, including at least one lens with positive or negative optical power;

[0057] The field lens group 20 is located between the objective lens group 10 and the collimating lens group 30.

[0058] According to some embodiments of the present invention, the lenses are all K9 parts or quartz parts.

[0059] According to some embodiments of the present invention, the surfaces of the lenses are all spherical or aspherical, and the aspherical surface satisfies the following equation:

[0060]

[0061] where Z is the sagitta of the aspherical surface along the optical axis at a position with a height of Y, measured from the vertex of the aspherical surface, R is the paraxial curvature radius of the lens, K is the conic coefficient, and A, B, C, and D are all high-order aspherical coefficients.

[0062] According to some embodiments of the present invention, all the lenses in the embodiments of the present invention can be glass parts, so as to ensure that the lenses have good athermalization effect.

[0063] The embodiments of the present invention can adopt aspherical technology, with simple system structure, high transmittance, and high imaging performance.

[0064] According to some embodiments of the present invention, the f / # of the laser ranging receiving optical path assembly satisfies: 0.5 ≤ f / # ≤ 10, and the aperture D0 satisfies: -500 mm ≤ D0 ≤ -5 mm;

[0065] The optical total length L of the laser ranging receiving optical path assembly and the focal length f' satisfy the condition: 0.5f' ≤ L ≤ 4f';

[0066] The laser ranging receiving optical path assembly is adapted to receive laser with a wavelength of 500 nm to 2000 nm.

[0067] According to some embodiments of the present invention, the laser ranging receiving optical path assembly is in an L shape, a U shape or a Z straight tube shape.

[0068] According to some embodiments of the present invention, the laser ranging receiving optical path assembly is adapted to be applied to a multi-band common optical path optoelectronic system and a complex laser ranging system.

[0069] An embodiment of the second aspect of the present invention provides an optical axis debugging method, and the optical axis debugging method is applicable to the laser ranging receiving optical path assembly described in the first aspect embodiment above;

[0070] The method includes:

[0071] Translating the collimating lens group and the converging lens group as a whole.

[0072] In the traditional debugging method, it is necessary to first determine the size of the circle drawn by the laser emission spot, place the laser receiver at the theoretical position, and adjust the position of the laser receiving lens according to the position of the circle drawn by the laser emission spot so that its field of view includes the position of the circle drawn by the laser emission. Then, the specific method of debugging the laser receiving lens usually adopts methods such as grinding, translation or adding gaskets. According to the situation, grinding, translation or adding gaskets are carried out, and further adjustment is made so that its field of view includes the position of the circle drawn by the laser emission; if it is not achieved, further iteration is carried out until the field of view of the laser receiving end completely encompasses the circle spot and position drawn by the laser emission and is located at the center position of the laser receiving field of view.

[0073] However, in the debugging method of the embodiment of the present invention, since the problem of the angular deviation between the laser receiving end and the mechanical structure is fully considered in the design process, the design of object space telecentricity is adopted to avoid angular deviation, that is, there is no need to carry out the process of grinding or adding gaskets, and only translation is required, which greatly reduces the assembly and adjustment difficulty and the iteration time, thereby reducing the assembly and adjustment difficulty, improving the accuracy, and further improving the performance of laser ranging.

[0074] The following refers to Figures 1 - 6A laser ranging receiving optical path component and an optical axis debugging method according to an embodiment of the present invention are described in detail with a specific embodiment. It should be understood that the following description is only an exemplary illustration and not a specific limitation of the present invention. All similar structures and similar changes using the present invention shall be included in the protection scope of the present invention.

[0075] An embodiment of the present invention provides a laser ranging receiving optical path component. The f / # of the laser ranging receiving optical path component satisfies: 0.5 ≤ f / # ≤ 10, and the aperture D0 of the laser ranging receiving optical path component satisfies: -500 mm ≤ D0 ≤ -5 mm. The optical total length L of the laser ranging receiving optical path component and the focal length f' satisfy the condition: 0.5f' ≤ L ≤ 4f'. The laser ranging receiving optical path component is applicable to the reception of lasers with wavelengths from 500 nm to 2000 nm.

[0076] As Figure 1 and Figure 4 shown, the laser ranging receiving optical path component of the embodiment of the present invention is successively provided with an objective lens group 10, a field lens group 20, a field stop 50, a collimating lens group 30, a stray light stop 60, and a converging lens group 40 along the incident direction of the light from left to right.

[0077] The objective lens group 10 can be a lens group including spherical or aspherical lenses, and includes at least one lens with positive optical power. The lens can be a material piece such as K9 or fused silica that matches the wavelength.

[0078] The field lens group 20 can be a lens group including spherical or aspherical lenses, and includes at least one lens with positive or negative optical power. The lens can be a material piece such as K9 or quartz that matches the wavelength.

[0079] The collimating lens group 30 can be a lens group including spherical or aspherical lenses, and includes at least one plano-convex lens with positive optical power. The lens can be a material piece such as K9 or quartz that matches the wavelength, and the outgoing light after being collimated by the collimating lens group 30 exits in the form of parallel light.

[0080] The converging lens group 40 can be a lens group including spherical or aspherical lenses, and includes at least one lens with positive optical power. The lens can be a material piece such as K9 or quartz that matches the wavelength, and is used to correct the aberration of the front lens group, and the light will be focused on the image plane after passing through the converging lens group 40.

[0081] The field stop 50 is located at the position of the primary image plane, and is between the field lens group 20 and the collimating lens group 30, and the opening aperture of the field stop 50 matches the field angle of the lens.

[0082] The aperture stop of the stray light elimination diaphragm 60 is located between the collimating lens group 30 and the converging lens group 40, and narrowband filters, polarizers, etc. can be added to its position to achieve the effect of filtering and suppressing stray light.

[0083] The objective lens group 10 and the field lens group 20 are designed as object-space and image-space telecentric lens groups. For the light rays of each field of view converged by the objective lens group 10 and the field lens group 20, the chief ray is approximately parallel to the optical axis at the intermediate image plane. The image plane size of the chief ray at the field stop 50 is a constant value, and the central field of view ray is parallel to the optical axis.

[0084] When performing optical axis alignment on the laser ranging receiving optical path assembly of the embodiment of the present invention, it is achieved by translating the field stop 50, the collimating lens group 30, the stray light elimination diaphragm 60, the converging lens group 40, and the laser receiver as a whole in a plane perpendicular to the optical axis.

[0085] The overall optical structure type of the above system can be designed into shapes such as L-shaped, U-shaped, and Z-straight tube-shaped according to the requirements of the actual space layout volume.

[0086] Figure 1 This is a specific implementation manner of the laser ranging receiving optical path assembly of the embodiment of the present invention. In this embodiment, the focal length of the optical system is 93 mm, f / # is 2, the field of view angle is ±0.3°, the total length of the optical system is 182 mm, and the designed wavelength is 1064 μm. The specific parameters of this system are shown in Table 1.

[0087] Table 1

[0088] Surface serial number Surface type Radius of curvature Central thickness Material S1 Spherical surface 51.04 10.00 K9 S2 Aspherical surface -738.51 80.02 S3 Spherical surface -15.50 3.00 K9 S4 Aspherical surface -12.51 6.97 S5 (Field stop 50) Spherical surface infinity 22.39 S6 Spherical surface 26.94 6 K9 S7 Aspherical surface -21.49 12.67 S8 (Stray light stop) Spherical surface infinity 12.67 S9 Aspherical surface 21.49 6 K9 S10 Spherical surface -26.94 22.24 Image plane Spherical surface infinity 0

[0089] The rotationally symmetric even aspherical surface satisfies the following equation:

[0090]

[0091] In the above formula, Z is the sagitta of the aspherical surface from the vertex of the aspherical surface at the position with a height of Y along the optical axis direction, R is the paraxial curvature radius of the lens, K is the conic coefficient, and A, B, C, and D are the aspherical coefficients of higher order. Table 2 shows the aspherical parameters of this embodiment.

[0092] Table 2

[0093]

[0094]

[0095] The spot diagram curve of the optical system of this embodiment is as Figure 2 shown, and the MTF curve of the optical system is as Figure 3 shown.

[0096] Figure 4This is another specific implementation of the laser ranging receiving optical path component in the embodiments of the present invention. In this embodiment, the focal length of the optical system is 93 mm, f / # is 2, the field of view angle is ±0.3°, the total length of the optical system is 209 mm, and the designed wavelength is 1064 μm. The specific parameters of this system are shown in Table 3.

[0097] Table 3

[0098] Component name Surface type Radius of curvature Central thickness Material S1 Spherical surface 117.18 15 K9 S2 Spherical surface -1602.37 7.56 S3 Spherical surface 58.32 5.83 K9 S4 Spherical surface Infinity 74.4 S5 Aspherical surface -19.35 15 K9 S6 Spherical surface -9.74 9.16 S7 (Field stop) Spherical surface Infinity 22.39 S8 Spherical surface 26.94 6 K9 S9 Aspherical surface -21.49 12.67 S10 (Stray light stop) Spherical surface Infinity 12.67 S11 Spherical surface 21.49 6 K9 S12 Aspherical surface -26.94 22.24 Image plane Spherical surface infinity 0.00

[0099] The rotationally symmetric even aspherical surface satisfies the following equation:

[0100]

[0101] In the above formula, Z is the sagitta of the aspherical surface from the vertex of the aspherical surface at the position with height Y along the optical axis direction, R is the paraxial curvature radius of the lens, K is the conic coefficient, and A, B, C, and D are the high-order aspherical coefficients. Table 4 shows the aspherical parameters of this embodiment.

[0102] Table 5

[0103]

[0104]

[0105] The spot diagram curve of the optical system in this embodiment is as shown in Figure 5 shown, and the MTF curve of the optical system is as shown in Figure 6 shown.

[0106] The embodiments of the present invention have the following advantages:

[0107] 1. By translating some lens groups to replace the traditional methods such as grinding and adding shims for axis adjustment, the present invention has the advantages of high reliability, high axis adjustment accuracy, and high debugging efficiency;

[0108] 2. By designing the field stop 50, the present invention ensures that the lens has an accurate receiving field of view angle;

[0109] 3. The present invention has universality, has good applicability to lasers of different wavelengths, and has a large adjustable space;

[0110] 4. The optical system of the present invention can adopt aspherical technology, with a simple system structure, high transmittance, and high imaging performance;

[0111] 5. The optical system of the present invention can add narrow-band filters, polarizers, etc. at the stray light stop to suppress stray light and improve the signal-to-noise ratio;

[0112] 6. The optical system of the present invention has good processability. After the lenses are processed, they can be directly combined to meet the image quality requirements, without processes such as grinding / padding, which is conducive to mass production;

[0113] 7. The optical system lens of the present invention is made of glass material to ensure good athermalization effect;

[0114] 8. The optical system of the present invention has good structural plasticity and can be changed into L-shaped, U-shaped, straight-cylindrical and other shapes according to volume requirements.

[0115] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0116] The terms "comprises", "includes" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0117] Any reference symbol within brackets shall not be construed as limiting the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The use of the words first, second, and third, etc., does not indicate any order. These words may be interpreted as names.

Claims

1. A laser ranging receiving optical path component, characterized in that, In the light propagation direction, the laser ranging receiving optical path assembly sequentially includes an object-side telecentric lens group, a collimating lens group, and a converging lens group that are arranged at intervals; The collimating lens group includes at least one lens with a positive optical power; The converging lens group includes at least one lens with a positive optical power; The object-side telecentric lens group includes: An objective lens group, including at least one lens with a positive optical power; A field lens group, including at least one lens with a positive or negative optical power; The field lens group is located between the objective lens group and the collimating lens group; The light is collimated by the collimating lens group and exits in the form of parallel light; The converging lens group is used to correct the aberration of the front-end lens group, and the light is focused on the image plane after passing through the converging lens group; The chief ray after passing through the object-side telecentric lens group is approximately parallel to the optical axis at the intermediate image plane, and the image plane size of the chief ray at the intermediate image plane is a constant value; The laser ranging receiving optical path assembly further includes: A stray light diaphragm, located between the collimating lens group and the converging lens group; A narrowband filter and a polarizer located between the collimating lens group and the converging lens group; When the laser ranging receiving optical path assembly is performing optical axis debugging, it is achieved by integrally translating the field diaphragm, the collimating lens group, the stray light diaphragm, the converging lens group, and the laser receiver in a plane perpendicular to the optical axis.

2. The laser ranging receiving optical path assembly according to claim 1, wherein The field diaphragm is located between the object-side telecentric lens group and the collimating lens group and at the position of the primary image plane, and the opening aperture of the field diaphragm matches the field angle of the lens.

3. The laser ranging receiving optical path component according to claim 1, wherein, The lenses are all K9 parts or quartz parts.

4. The laser ranging receiving optical path component according to claim 1, characterized in that, The surfaces of the lenses are all spherical or aspherical, and the aspherical surface satisfies the following equation: ， Where Z is the sagitta of the aspherical surface along the optical axis at the position with a height of Y, measured from the vertex of the aspherical surface, R is the paraxial curvature radius of the lens, K is the conic coefficient, and A, B, C, and D are all high-order aspherical coefficients.

5. The laser ranging receiving optical path assembly according to claim 1, characterized in that, The satisfies: , the aperture D0 satisfies: ; The total optical length L and focal length of the laser ranging receiving optical path assembly satisfy the condition: ; The laser ranging receiving optical path assembly is suitable for receiving lasers with wavelengths in the range of 500 nm to 2000 nm.

6. The laser ranging receiving optical path component according to claim 1, characterized in that, The laser ranging receiving optical path assembly is in an L shape, a U shape, or a Z straight tube shape.

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