Novel coaxial light device suitable for large-aperture telecentric lens

Abstract

The utility model relates to a novel coaxial light device suitable for a large-aperture telecentric lens, which comprises a flat beam splitter, an illumination assembly, a first lens and a lens main body, the flat beam splitter is obliquely arranged between the first lens and the illumination assembly, and one side of the flat beam splitter facing the first lens is a reflection beam splitting surface; one side facing the illumination assembly is an illumination transmission surface; the illumination assembly is used for emitting illumination light to an illumination transmission surface of the flat beam splitter, and the illumination light is transmitted by the flat beam splitter, penetrates through the first lens and irradiates a to-be-measured surface of an object; the first lens is used for receiving light reflected by the to-be-measured surface and converting the light into signal light to be emitted to the reflection light splitting surface of the flat light splitting sheet; the signal light is reflected to the lens main body through the flat beam splitter; and the lens main body is arranged in the reflected light direction of the flat light splitting sheet and is used for receiving the signal light reflected by the flat light splitting sheet and converging the signal light to an image surface.

Description

Technical Field

[0001] The utility model relates to the technical field of coaxial light illumination, and more specifically to a novel coaxial light device suitable for a large-aperture telecentric lens. Background Art

[0002] With the continuous advancement of optical technology, lighting methods have always been a necessary consideration in the field of machine vision. Despite the rapid development of current lighting solutions, the main lighting methods are still limited to backlighting (backlight panel lighting), ringlighting (lighting between the lens and the subject), and lens-mounted coaxial lighting (light reflected by a prism inside the lens). Because both backlighting and ringlighting require installation outside the lens, using these two lighting methods increases the machine space required for the optical system. Therefore, lens-mounted coaxial lighting is preferred when optical space is limited.

[0003] The principle of coaxial illumination is as follows: light emitted by the light source module is reflected onto the object surface by the semi-transparent, semi-reflective surface of the beam splitter prism. The reflected light from the object surface passes through multiple lenses in sequence before reaching the beam splitter prism, directly passing through the semi-transparent, semi-reflective surface to the lens group before forming an image. However, this solution also has its drawbacks. Because current coating levels cannot completely eliminate reflections on the lens surface, the illumination light is reflected twice each time it passes through a lens, resulting in a reduced signal-to-noise ratio and affected image quality. To address the stray light caused by reflections between the illumination light and the lens, shifting the entire illumination light path toward the object will reduce stray light caused by lens reflections. This lighting method also has the problem of the beam splitter prism being too large and heavy, and occupying the working distance. Utility Model Content

[0004] The technical problem to be solved by the present invention is to provide a new coaxial light device suitable for large-aperture telecentric lenses in view of the above-mentioned defects of the prior art.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] A novel coaxial light device suitable for a large-aperture telecentric lens is constructed, comprising a flat beam splitter, an illumination assembly, a first lens, and a lens body, wherein:

[0007] The flat beam splitter is obliquely arranged between the first lens and the lighting assembly, and the side facing the first lens is a reflective beam splitting surface, and the side facing the lighting assembly is a lighting transmission surface;

[0008] The lighting assembly is used to emit illumination light onto the illumination transmission surface of the flat beam splitter. After being transmitted by the flat beam splitter, the illumination light passes through the first lens and illuminates the surface to be measured of the object.

[0009] The first lens is used to receive the light reflected by the surface to be measured and convert it into signal light that is emitted to the reflective beam splitting surface of the flat beam splitter; the signal light is reflected by the flat beam splitter to the lens body;

[0010] The lens body is arranged in the direction of the reflected light of the flat beam splitter, and is used to receive the signal light reflected by the flat beam splitter and converge it onto the image plane.

[0011] Preferably, the flat beam splitter is coated with an antireflection film on the side facing the lighting assembly to form an illumination transmission surface, and is coated with a semi-transparent and semi-reflective film on the side facing the lens body to form a reflection beam splitting surface.

[0012] Preferably, the lighting assembly includes a light source module and a reflective lens, the light source module is used to emit illumination light to the reflective lens; the reflective lens is used to reflect the illumination light to the illumination transmission surface of the flat beam splitter.

[0013] Preferably, the flat beam splitter and the reflective lens are arranged at an inclination of 45°.

[0014] The beneficial effect of the present invention is that by placing the flat beam splitter behind the first lens of the lens in the new design of the patent, the number of lens surfaces that will be reflected can be greatly reduced, thereby reducing stray light and improving the signal-to-noise ratio. The design of the new patented design in which the illumination light path and the signal light light path pass through the beam splitter together, the signal light only passes through its own lens and the reflection of the beam splitter once, and the imaging quality will not be deteriorated due to the signal light passing through the beam splitter. The anti-reflection film side of the flat beam splitter is the illumination light path. Since the illumination system is a large aberration system, the influence of the tilted flat glass on it can be ignored. Such a design can reduce the stray light caused by the reflection of the coaxial light on the lens without affecting the imaging, and at the same time do not have to bear the large volume and weight brought by the beam splitter prism. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0016] Figure 1 This is a structural diagram of a novel coaxial light device suitable for a large-aperture telecentric lens in a preferred embodiment of the present utility model;

[0017] Figure 2 This is a detailed structural diagram of a novel coaxial light device suitable for a large-aperture telecentric lens in a preferred embodiment of the utility model;

[0018] Figure 3It is a structural diagram of the prior art solution 1;

[0019] Figure 4 This is the first structural diagram of the second prior art solution;

[0020] Figure 5 This is the second structural diagram of the prior art solution 2;

[0021] Figure 6 This is the first structural diagram of the existing technical solution three

[0022] Figure 7 This is the second structural diagram of the prior art solution three. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The preferred embodiment of the present invention is a novel coaxial light device suitable for large-aperture telecentric lenses. Figure 1 As shown, see Figure 2 , including a flat beam splitter 1, an illumination assembly 2, a first lens 3 and a lens body 4, wherein,

[0025] The flat beam splitter 1 is tilted and arranged between the first lens 3 and the lighting assembly 2, and the side thereof facing the first lens 3 is a reflective beam splitting surface 11, and the side facing the lighting assembly 2 is a lighting transmission surface 12;

[0026] The lighting assembly 2 is used to emit illumination light onto the illumination transmission surface 12 of the flat beam splitter 1. After being transmitted by the flat beam splitter 1, the illumination light passes through the first lens 3 and illuminates the surface to be measured (object surface) of the object.

[0027] The first lens 3 is used to receive the light reflected by the surface to be measured (object surface) and convert it into signal light to be emitted to the reflective splitting surface 11 of the flat beam splitter 1; the signal light is reflected by the flat beam splitter 1 to the lens body 4;

[0028] The lens body 4 is arranged in the direction of the reflected light of the flat beam splitter 1 , and is used to receive the signal light reflected by the flat beam splitter 1 and converge it onto the image plane.

[0029] Compared with the solution of the present invention, the existing coaxial light illumination system solution is as follows Figure 3As shown, the coaxial light lens lighting system includes a front lens group 51, a dichroic prism 61, a rear lens group 71 and an illumination module 81. The dichroic prism 61 is located in front of the aperture (closer to the object plane), and the middle of the dichroic prism is coated with a semi-transparent and semi-reflective film.

[0030] The principle is as follows: the light emitted by the lighting module 81 is reflected by the semi-transparent and semi-reflective surface of the dichroic prism 61 to the front lens group 51, and then illuminates the object surface. The reflected light from the object surface passes through multiple lenses of the front lens group 51 in sequence and reaches the dichroic prism 61, directly passes through the semi-transparent and semi-reflective surface to reach the rear lens group 71, and finally forms an image in the camera. The disadvantage of this solution is that the current coating level cannot completely eliminate the reflection on the lens surface, resulting in two reflections each time the lighting light passes through a lens. Figure 3 As shown in the image above, some of the reflected light will eventually enter the image plane, reducing the signal-to-noise ratio and affecting image quality. To address the stray light problem caused by reflections between the illumination light and the lens, shifting the entire illumination light path toward the object will reduce stray light caused by lens reflections.

[0031] In order to solve the above problems, the following Figure 4-5 The second coaxial light lens lighting system shown in FIG. 1 also includes a front lens group 51, a beam splitter prism 61, a rear lens group 71 and a lighting module 81. The difference between the previous solution and the present solution is that the beam splitter prism 61 is placed between the first lens group and the second lens group of the front lens group 51 (as shown in FIG. 1 ). Figure 4 As shown in FIG. 1 ), the specific optical path is as follows: the light emitted by the illumination module 81 is reflected by the semi-transparent and semi-reflective surface of the dichroic prism 61, passes through the first lens group to illuminate the object surface, and then the imaging light passes through the front lens group 51, the dichroic prism 61, and the rear lens group 71 in sequence to reach the image surface. Figure 5 As shown, the dichroic prism 61 can also be placed in front of the front lens group 51, so that the reflection of the illumination light on the lenses inside the lens group can be completely eliminated. The illumination light path is that the illumination light emitted by the illumination module 81 is reflected to the object surface through the dichroic prism 61, and then the imaging light passes through the front lens group 51, the dichroic prism 61, and the rear lens group 71 in sequence to reach the image surface.

[0032] Figure 4-5 Both structures can reduce stray light caused by lens reflection, but for large-aperture telecentric lenses, Figure 4 The dichroic prism 61 shown in FIG needs to be close to the first lens group diameter of the front lens group 51 in order to meet the clearance requirement, and the dichroic prism 61 shown in FIG5 needs to be at least larger than the object side FOV in order to meet the clearance requirement. Figure 4-5 The two coaxial illumination structures shown require a large and heavy prism to meet the light transmission requirements, and Figure 5The beam splitter prism 61 is positioned outside the lens and occupies a portion of the working distance of the lens. The larger the aperture, the more space it occupies.

[0033] In order to solve the problems of the beam splitter being too large, too heavy, and occupying the working distance, the beam splitter can be replaced with a flat beam splitter. Figure 6 and Figure 7 As shown in the third scheme, the difference between the third scheme and the second scheme is that the beam splitter prism is replaced by a flat beam splitter 91. Figure 6 and Figure 7 The specific optical path of the solution is Figure 4 and 5 same, Figure 6 and Figure 7 The two structures shown can simultaneously solve the problem of stray light caused by mirror reflection of illumination light and the problem of the overall system being too heavy due to the large size of the prism. Figure 4 The imaging light path in the structure shown passes through a flat beam splitter 91 tilted at 45 degrees, which has a significant impact on the image quality.

[0034] The solution of the present invention can solve the problems of the above solutions. Specifically: the workflow of the present invention includes:

[0035] Light source illumination stage: Light emitted by the illumination component 2 passes through the illumination transmission surface 12 of the flat beam splitter 1 and enters the optical system. The illumination light penetrates the flat beam splitter and illuminates the surface of the object to be measured, thus achieving uniform illumination.

[0036] During the phase of receiving the reflected light from the object, the surface of the object to be measured receives the reflected light through the first lens 3 and converts it into signal light. The signal light then travels toward the reflective beam splitting surface 11 of the flat beam splitter.

[0037] Beam splitter reflection stage: the signal light reaches the reflective beam splitting surface 11 and is reflected and enters the lens body 4 .

[0038] Imaging stage: The lens body 4 receives the reflected signal light from the flat beam splitter and converges it onto the image plane, completing the imaging process. The lens body 4 is equipped with multiple lens groups to focus the light reflected from the object plane and guide it onto the image plane to form a clear image.

[0039] Because the flat beamsplitter is positioned after the first lens element, the signal light only needs to reflect once through the beamsplitter during its optical path, significantly reducing the source of stray light. This reduces the number of reflective surfaces in the optical component and improves the signal-to-noise ratio. The signal light path and the illumination light path are separated but share the same beamsplitter, preventing aberrations caused by the signal light passing through the beamsplitter, thus ensuring image quality. Using a flat beamsplitter instead of a traditional beamsplitter prism avoids the bulk and weight associated with a beamsplitter prism. The tilted design of the flat beamsplitter reduces the complexity and size of the overall system without affecting the illumination light path. The coaxial illumination and signal light paths pass through the same beamsplitter, simplifying the optical system layout and component installation. The anti-reflection coating design reduces light energy loss while making the impact of the illumination light on the imaging system negligible. The illumination light passes directly through the beamsplitter onto the object surface, while the signal light is reflected from the beamsplitter and enters the lens, avoiding the image degradation that can occur due to multiple reflections of the signal light in traditional optical systems. Reducing the use of beam splitters reduces the manufacturing cost of the system, and the flat beam splitter is simple to process and low in cost.

[0040] like Figure 1-2 As shown, the flat beam splitter 1 has an antireflection film coated on the side facing the lighting assembly 2 to form an illumination transmission surface, and a semi-transparent and semi-reflective film coated on the side facing the lens body 4 to form a reflection beam splitting surface 11 .

[0041] The purpose of the antireflection coating design (on the illumination transmission side, facing the illumination component 2): After the illumination light passes through the antireflection coating, the light transmission efficiency is greatly improved, reducing light energy loss due to reflection on the beamsplitter surface. The antireflection coating can also reduce interference spots caused by reflections, thereby achieving more uniform illumination on the object surface. The illumination light has fewer reflections after passing through, reducing stray light caused by multiple reflections, thereby improving the signal-to-noise ratio of the entire optical system.

[0042] The purpose of the translucent film design (reflective beam splitter surface, facing the lens body 4): The translucent film efficiently reflects signal light from the object surface toward the lens body while suppressing its transmission, thereby ensuring that signal light intensity is not lost. This film limits the transmission of unnecessary light, preventing other irrelevant light from interfering with the signal light and improving image quality.

[0043] Antireflection coatings improve illumination efficiency, while translucent and reflective coatings optimize signal light reflection, ultimately enhancing the optical system's overall light energy utilization. The coating design effectively reduces light loss and interference from excess light, resulting in clearer images and more precise signal light transmission. The coating's high efficiency reduces optical path fluctuations caused by multiple reflections in optical components, making the optical system more stable and reliable. By designing both the antireflection coating and translucent and reflective coating on the same flat-panel beamsplitter, the need for separate components is reduced, thereby reducing the size and weight of the optical system and meeting lightweight requirements.

[0044] By coating both sides of the flat beamsplitter with an antireflection coating and a semi-transparent, semi-reflective coating, this design achieves efficient transmission of the illumination light path and precise reflection of the signal light, significantly improving the overall performance of the optical system. This design optimizes optical efficiency while reducing stray light and light loss, ensuring a high signal-to-noise ratio and high imaging quality while maintaining the advantages of miniaturization and lightweight.

[0045] like Figure 1-2 As shown, the illumination assembly 2 includes a light source module 21 and a reflector lens 22. The light source module 21 is used to illuminate the reflector lens 22; the reflector lens 22 is used to reflect the illumination light onto the illumination transmission surface 12 of the flat beam splitter 1. The flat beam splitter is placed behind the first lens element of the imaging lens at a 45° angle. The overall optical path of the imaging lens is broken 90° at the beam splitter. The light source module is then placed on the other side of the imaging optical path. If the required length of the light source module is too long, the illumination optical path can be broken 90° using a 45° reflector to reduce the overall lens footprint.

[0046] By placing the flat beam splitter at a 45° angle behind the first lens element of the imaging lens and folding the optical path 90°, the optical system space is effectively utilized, significantly reducing the overall lens footprint. This folded optical path reduces the space required between the light source module and the imaging lens, making the system more compact and suitable for space-constrained scenarios.

[0047] The light source module is designed to further break the optical path using a reflector. If the light source module is too long, this design allows the illumination path to be folded another 90° using a 45° reflector, further optimizing the layout. This provides more layout flexibility for the optical system, adapting to scenarios requiring miniaturization or portability.

[0048] Flat-plate beamsplitters simultaneously distribute light for both the illumination and imaging paths, integrating both functions on a single beamsplitter, reducing the number of optical components and system complexity. Leveraging the reflective and transmissive properties of flat-plate beamsplitters, the illumination and imaging paths are effectively separated, preventing mutual interference and improving system imaging clarity and illumination uniformity.

[0049] The folded optical path design makes it easier to control the directly reflected light from the light source module. The tilted beamsplitter reduces stray light caused by multiple reflections, thereby improving the signal-to-noise ratio. The rational distribution of the imaging and illumination optical paths ensures pure signal light transmission and prevents stray light from interfering with image quality. The optical path breakup and light source module layout adjustments not only save space but also maintain the symmetry of the optical system, reducing aberrations caused by excessively long optical paths or improper layout.

[0050] The optimized folded optical path uniformly illuminates the object surface, while the imaging light is simultaneously transmitted to the imaging surface through a 90° folded path, ensuring high-quality imaging. The combination of light source modules and reflective lenses enables flexible optical path design, allowing adjustments to the folding angle and light source layout to suit different application scenarios, adapting to imaging systems of varying sizes and performance requirements.

[0051] This design combines optical path folding with the functional optimization of a flat beamsplitter, effectively separating the illumination and imaging light paths while sharing space. This design offers benefits such as reduced size, a compact system, reduced stray light, improved imaging quality, and flexible layout design, significantly enhancing the performance and adaptability of the optical system.

[0052] In summary, this utility model successfully achieves a new telecentric lens coaxial optical design with low stray light, high signal-to-noise ratio, miniaturization, and lightweight performance through the innovative placement of a flat beamsplitter in front of the first lens and the clever design of the division of labor between the illumination and signal light paths. This design not only improves image quality but also significantly optimizes the size, weight, and cost of the optical system, providing a high-quality solution for high-precision imaging applications.

[0053] It should be understood that the present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive various other forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A novel coaxial light device suitable for large-aperture telecentric lenses, characterized in that: It comprises a flat beam splitter (1), an illumination assembly (2), a first lens (3) and a lens body (4), wherein: The flat beam splitter (1) is obliquely arranged between the first lens (3) and the lighting assembly (2), and the side thereof facing the first lens (3) is a reflective beam splitting surface (11), and the side thereof facing the lighting assembly (2) is an illumination transmission surface (12); The lighting assembly (2) is used to emit lighting light onto the lighting transmission surface (12) of the flat beam splitter (1); the lighting light is transmitted through the flat beam splitter (1) and then passes through the first lens (3) to illuminate the surface to be measured of the object; The first lens (3) is used to receive light reflected from the surface to be measured and convert it into signal light that is emitted to the reflective beam splitting surface (11) of the flat beam splitter (1); the signal light is reflected by the flat beam splitter (1) to the lens body (4); The lens body (4) is arranged in the direction of the reflected light of the flat beam splitter (1), and is used to receive the signal light reflected by the flat beam splitter (1) and converge it onto the image plane.

2. The novel coaxial light device suitable for large-aperture telecentric lenses according to claim 1, characterized in that: The flat beam splitter (1) is coated with an antireflection film on the side facing the lighting component (2) to form an illumination transmission surface, and is coated with a semi-transparent and semi-reflective film on the side facing the lens body (4) to form a reflection beam splitting surface (11).

3. The novel coaxial light device suitable for large-aperture telecentric lenses according to claim 1, characterized in that: The lighting assembly (2) comprises a light source module (21) and a reflective lens (22); the light source module (21) is used to emit lighting light to the reflective lens (22); and the reflective lens (22) is used to reflect the lighting light to the lighting transmission surface (12) of the flat beam splitter (1).

4. The novel coaxial light device suitable for large-aperture telecentric lenses according to claim 3, characterized in that: The flat beam splitter (1) and the reflective lens (22) are arranged at an angle of 45°.

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