A cassegrain rangefinding receiving lens and a laser rangefinding device

Abstract

This application discloses a Cassegrain ranging receiver lens and a laser ranging device, relating to optoelectronic technology. It includes: a hollow shaft, a centrally hollow shaft-like structure with a primary mirror and a secondary mirror mounted at each end; a primary mirror mounted at the first end of the hollow shaft, on the other side of the mounting flange facing the secondary mirror, its optical surface being a parabolic reflective surface, and its back surface employing a flexible structure; and a secondary mirror mounted at the second end of the hollow shaft, opposite the primary mirror, its optical surface being an even-order aspherical reflective surface, and its back surface employing a flexible structure. The hollow shaft contains, in sequence, a stray aperture, a field aperture, a collimation assembly, a filter assembly, and a focusing assembly. This application can solve the problems of continuously increasing size, weight, and cost of traditional long-range ranging transmissive receiver lenses, as well as the insufficient axial dimension compression and poor structural stability in harsh environments inherent in classic Cassegrain barrel-shaped structures.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, and in particular to a Cassegrain ranging receiver lens and a laser ranging device. Background Technology

[0002] In laser ranging applications, echo energy is directly proportional to the square of the receiver lens aperture. Therefore, increasing the receiver lens aperture can significantly improve ranging capability. However, increasing the aperture of traditional transmissive receiver lenses inevitably leads to increased size, weight, and cost. The classic Cassegrain lens, employing a catadioptric system, significantly reduces its axial dimensions and weight for the same receiver aperture, giving it a natural advantage and making it significant for long-range ranging applications.

[0003] A classic Casio lens has a barrel-shaped structure, with the primary and secondary lenses fixed inside a cylindrical barrel. The portion of the aperture obscured by the secondary lens is completely wasted. In rangefinding applications, a narrow-band filter needs to be added to the receiving lens. This narrow-band filter requires parallel light to be incident perpendicularly, necessitating beam collimation, filtering, and focusing operations behind the classic Casio system for proper functioning. Using this barrel-shaped structure still requires adding these three components behind the primary lens, increasing the axial dimensions and failing to fully utilize the advantages of the Casio lens's reflective optical path. Furthermore, this structure is difficult to stabilize and is unsuitable for harsh environments. Summary of the Invention

[0004] This application provides a Cassegrain ranging receiver lens and a laser ranging device, which solves the problems of increasing size, weight and cost of traditional long-range ranging transmissive receiver lenses, as well as insufficient axial dimension compression and poor structural stability in harsh environments caused by the classic Cassegrain barrel structure.

[0005] This application provides a Cassegrain ranging receiver lens, including: Hollow shaft 2 is a hollow shaft structure with a central core. A primary mirror 1 and a secondary mirror 3 are respectively mounted at both ends. The first end of the hollow shaft 2 has a mounting flange. One side of the mounting flange is used to mount the ranging receiving lens to the target device. The center of the hollow shaft 2 is positioned according to the optical path of the lens. The front end of the hollow shaft 2, corresponding to the position of the secondary mirror 3, has a slot to form multiple oblique support arms. The multiple oblique support arms are used to provide the mounting position of the secondary mirror 3 and to allow the light reflected by the primary mirror 1 to enter the secondary mirror 3 through the slot. The primary mirror 1 is installed at the first end of the hollow shaft 2, on the other side of the mounting flange facing the secondary mirror 3. Its optical surface is a parabolic reflective surface, and its back surface adopts a flexible structure. Secondary mirror 3 is installed at the second end of hollow shaft 2, opposite to primary mirror 1. Its optical surface is an even-order aspherical reflecting surface, and its back surface adopts a flexible structure. The hollow shaft 2 is sequentially equipped with a stray aperture 4, a field aperture 5, a collimation component 6, a filter component 7, and a focusing component 8.

[0006] This application provides a laser ranging device, including the Cassegrain ranging receiving lens as described above.

[0007] This application presents a novel Cassegrain receiving lens design based on classic Cassegrain and traditional transmissive rangefinder lenses. It uses a hollow shaft to connect the primary and secondary mirrors and integrates sub-modules such as stray light reduction, collimation, filtering, and focusing into the hollow shaft. This ensures that the final image plane and the rear end face of the hollow shaft are in the same axial position, fully leveraging the advantages of the Cassegrain lens's catadioptric system and making full use of the space obscured by the secondary mirror. This achieves the goal of compressing axial length and weight, solving the problems of continuously increasing size, weight, and cost of traditional long-range transmissive rangefinder lenses, as well as the insufficient axial dimension compression and poor structural stability of the classic Cassegrain barrel structure in harsh environments.

[0008] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0009] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the Cassegrain ranging receiving lens according to an embodiment of this application; Figure 2 This is a schematic cross-sectional view of the Cassegrain ranging receiving lens according to an embodiment of this application. Figure 3 This is a schematic diagram of the component structure of the Cassegrain ranging receiving lens according to an embodiment of this application. Detailed Implementation

[0010] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0011] This application designs a novel Cassegrain receiving lens based on classic Cassegrain and traditional transmission-type rangefinder lenses. It uses a hollow shaft to connect the primary and secondary mirrors, and integrates stray light reduction, collimation, filtering, and focusing sub-modules into the hollow shaft, ensuring that the final image plane and the rear end face of the hollow shaft are essentially in the same axial position. Specifically, this application proposes a Cassegrain rangefinder receiving lens, such as... Figure 1 , Figure 2 As shown, it includes: The hollow shaft 2 is a centrally hollow shaft structure with a primary mirror 1 and a secondary mirror 3 mounted at its two ends. The first end of the hollow shaft 2 has a mounting flange, one side of which is used to mount the ranging receiving lens to the target device. The center of the hollow shaft 2 is positioned according to the optical path of the lens. The hollow shaft 2 has a slot at its front end corresponding to the position of the secondary mirror 3 to form multiple oblique support arms. For example, at least three oblique support arms can be formed by slotting. The support arms serve to provide the mounting position of the secondary mirror 3 and allow light reflected by the primary mirror 1 to enter the secondary mirror 3 through the slots between the support arms.

[0012] The primary mirror 1 is mounted on the first end of the hollow shaft 2, on the other side of the mounting flange facing the secondary mirror 3. Its optical surface is a parabolic reflective surface, and its back surface has a flexible structure. The optical surface of the primary mirror 1 is a spherical or aspherical reflective surface, and its light transmission diameter can be up to 200mm. Threaded holes are machined on it, for example, three M3 threaded holes are machined at 120° intervals. It is then mounted on the hollow shaft using screws.

[0013] Secondary mirror 3 is installed at the second end of hollow shaft 2, opposite to primary mirror 1. Its optical surface is an even-order aspherical reflective surface, and its back surface adopts a flexible structure. Specifically, the optical surface of secondary mirror 3 is a spherical or aspherical reflective surface, and three M2 threaded holes are machined on it at 120° intervals. It is then installed on the hollow shaft using screws.

[0014] The hollow shaft 2 is sequentially equipped with a stray aperture 4, a field aperture 5, a collimation component 6, a filter component 7, and a focusing component 8.

[0015] The novel Casio receiving lens of this application embodiment has a receiving aperture of 120mm, a weight of <600g, and a length of <150mm, which is more than 50% smaller than traditional transmission lenses of the same aperture. Compared with the classic Casio lens, it is simpler to adjust in length, easier to manufacture, and more reliable.

[0016] In some embodiments, both the stray aperture 4 and the field aperture 5 are annular structures with a central opening, wherein the diameter of the opening of the stray aperture 4 is larger than the diameter of the opening of the field aperture 5. For example, in some examples, the stray aperture 4 is an annular structure with a central opening of φ4mm, and the field aperture 5 is an annular structure with a central small opening of φ0.8mm.

[0017] In some embodiments, such as Figure 3 As shown, the stray aperture 4 and the field aperture 5 are set based on the second end of the collimation component 6; The collimation assembly 6 includes a collimating optical group 61 and a collimating lens barrel 63. The collimating optical group 61 is mounted on the collimating lens barrel 63, and the collimating lens barrel 63 is entirely inserted into the hollow shaft 2. The collimating optical group 61 can be a single lens or a lens group composed of multiple lenses. After evaluation of usage conditions, the method of fixing the lens using a collimating fixing ring 62 can be replaced by fixing it with professional optical adhesive.

[0018] In some embodiments, such as Figure 3 As shown, the filter assembly 7 is disposed based on the first end of the collimation assembly 6; The filter assembly 7 includes a filter optical group 71 and a filter lens barrel 73. The filter optical group 71 is a single narrowband filter, which is disposed within the filter lens barrel 73. The filter lens barrel 73 is entirely inserted into the hollow shaft 2. The filter optical group 71 can be a single filter or a filter group composed of multiple filters. After evaluation of usage conditions, the method of fixing the lens using the filter fixing ring 72 can be replaced by fixing with professional optical adhesive.

[0019] In some embodiments, such as Figure 3 As shown, the focusing assembly 8 is mounted to the first end of the hollow shaft 2 based on the mounting flange; The focusing assembly 8 includes a focusing optical group 81 and a focusing lens barrel 83. The focusing optical group 81 is disposed inside the focusing lens barrel 83, and the focusing lens barrel 83 is entirely placed inside the hollow shaft 2.

[0020] In some embodiments, the focusing optical group 81 is a lens group composed of two spherical lenses. The focusing optical group 81 can be a single lens or a lens group composed of multiple lenses; after evaluation of usage conditions, the method of fixing the lens by the focusing fixing ring 82 can be replaced by fixing with professional optical glue.

[0021] In some embodiments, the primary lens 1, secondary lens 3, hollow shaft 2, and each lens barrel assembly are all made of aluminum alloy substrate material. The field stop, collimation assembly 6, filter assembly 7, and focusing assembly 8 are all integrated inside the hollow shaft 2 and fixed to the hollow shaft using screws or clamping rings. In this application, the center of gravity of the lens is close to one end of the mounting flange, and the back of the hollow shaft is used as the mounting flange, which is then mounted to the entire unit using screws.

[0022] This application connects the primary and secondary lenses into a single unit using a hollow shaft, with all other components integrated inside the hollow shaft. This design maximizes axial length, reducing overall size, weight, and cost. The integrated design reduces the number of parts, minimizes sources of manufacturing errors, and significantly lowers assembly and adjustment difficulty. The lens's components are concentrated on one side of the primary lens, resulting in a concentrated weight distribution, which is beneficial for equipment stability. The primary and secondary lenses are the main optical components affecting lens performance, and their materials are consistent with the central axis, avoiding field-of-view shift issues caused by thermal mismatch between large-diameter glass and mechanical structure, thus improving the overall environmental reliability of the lens.

[0023] By fixing all the optical lenses within a hollow shaft, the sources of manufacturing errors are reduced, significantly lowering the difficulty of assembly and adjustment, and consequently reducing the overall manufacturing complexity. The lens's components are concentrated on one side of the primary lens, resulting in a more balanced weight distribution, which contributes to the stability of the equipment. The primary and secondary lenses, the main optical elements affecting lens performance, are made of the same material as the central axis, avoiding field-of-view shift issues caused by thermal mismatch between large-diameter glass and the mechanical structure. This improves the lens's overall high and low temperature reliability, enabling stable operation within an ambient temperature range (-40℃ to +70℃).

[0024] This application utilizes a hollow shaft integrated design, which can effectively reduce the number of lens parts by more than 30% and significantly shorten the assembly and adjustment time from more than 3 hours to less than 1 hour, greatly reducing processing costs and assembly and adjustment time, and improving the cost-effectiveness of the lens.

[0025] This application also proposes a laser ranging device, including the aforementioned Cassegrain ranging receiving lens.

[0026] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0027] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0028] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A Cassegrain ranging receiver lens, characterized in that, include: Hollow shaft (2) is a hollow shaft structure with a central core. A primary mirror (1) and a secondary mirror (3) are respectively installed at both ends. The first end of the hollow shaft (2) has a mounting flange. One side of the mounting flange is used to mount the ranging receiving lens target device. The center of the hollow shaft (2) is positioned according to the optical path of the lens. The hollow shaft (2) has a slot at the front end corresponding to the position of the secondary mirror (3) to form multiple oblique support arms. The multiple oblique support arms are used to provide the mounting position of the secondary mirror (3) and to allow the light reflected by the primary mirror (1) to enter the secondary mirror (3) through the slot. The primary mirror (1) is installed at the first end of the hollow shaft (2), on the other side of the mounting flange facing the secondary mirror (3), and its optical surface is a parabolic reflective surface, and its back surface adopts a flexible structure; The secondary mirror (3) is installed at the second end of the hollow shaft (2) and is opposite to the primary mirror (1). Its optical surface is an even-order aspherical reflecting surface, and its back surface adopts a flexible structure. The hollow shaft (2) is provided with a stray aperture (4), a field aperture (5), a collimation component (6), a filter component (7), and a focusing component (8) arranged sequentially inside.

2. The Cassegrain ranging receiver lens as described in claim 1, characterized in that, Both the stray aperture (4) and the field aperture (5) are annular structures with a central opening, wherein the opening diameter of the stray aperture (4) is larger than the opening diameter of the field aperture (5).

3. The Cassegrain ranging receiver lens as described in claim 2, characterized in that, The stray aperture (4) and the field aperture (5) are set based on the second end of the collimation component (6); The collimation assembly (6) includes a collimation optical group (61) and a collimation lens tube (63). The collimation optical group (61) is disposed on the collimation lens tube (63), and the collimation lens tube (63) is inserted entirely into the hollow shaft (2).

4. The Cassegrain ranging receiver lens as described in claim 3, characterized in that, The filter assembly (7) is disposed based on the first end of the collimation assembly (6); The filter assembly (7) includes a filter optical group (71) and a filter tube (73). The filter optical group (71) is a single narrowband filter. The filter optical group (71) is disposed inside the filter tube (73). The filter tube (73) is entirely placed inside the hollow shaft (2).

5. The Cassegrain ranging receiver lens as described in claim 4, characterized in that, The focusing assembly (8) is mounted to the first end of the hollow shaft (2) based on the mounting flange; The focusing assembly (8) includes a focusing optical group (81) and a focusing lens barrel (83). The focusing optical group (81) is disposed inside the focusing lens barrel (83), and the focusing lens barrel (83) is entirely placed inside the hollow shaft (2).

6. The Cassegrain ranging receiver lens as described in claim 5, characterized in that, The focusing optical group (81) is a lens group composed of two spherical lenses.

7. The Cassegrain ranging receiver lens as described in claim 5, characterized in that, The primary mirror (1), secondary mirror (3), hollow shaft (2), and each mirror tube assembly are all made of aluminum alloy base material.

8. The Cassegrain ranging receiver lens as described in claim 5, characterized in that, The collimation component (6), the filter component (7), and the focusing component (8) are fixed by corresponding fixing rings or optical adhesives.

9. A laser ranging device, characterized in that, Includes the Cassegrain ranging receiver lens as described in any one of claims 1-8.

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