A 95mm long focal length catadioptric zoom imaging optical system

Abstract

This invention provides a 95mm telephoto fixed-focus imaging optical system, comprising a cemented sheet coaxial with the object side, an aperture stop, a first lens, and a second lens coaxial with the image side. A plane mirror is disposed at a 45° angle to the right of the first lens. The angle between the axis of the first lens and the normal of the plane mirror is the same as the angle between the axis of the second lens and the normal of the plane mirror. The system has a focal length of 95mm, a total optical length of 35mm, an initial focusing object distance of 120mm, and an image distance of 5mm. The curvature of the left side of the lens is defined as the object surface curvature, and the curvature of the right side is defined as the image surface curvature, with the convex surface of the curvature facing the object side being positive and the convex surface of the curvature facing the image side being negative. The object surface curvature radius of the cemented sheet is 8mm, and the image surface curvature radius is 15mm. The object surface curvature radius of the first lens is -12.4mm, and the image surface curvature radius is -13mm. The object surface curvature radius of the second lens is 20mm, and the image surface curvature radius is -35mm. This invention features a compact structure, reduces the overall optical length of the lens, and solves the problem of large size when using a fixed-focus system to inspect small-sized parts.

Description

Technical Field

[0001] This invention relates to the field of machine vision, and in particular to a 95mm telephoto fixed-focus imaging optical system. Background Technology

[0002] Machine vision systems often encounter two problems when using standard fixed-focus lenses: 1. Currently, the maximum focal length of standard industrial fixed-focus lenses on the market is only 75mm, making it impossible to find a suitable standard lens when inspecting small-sized parts (with dimensions less than 50mm); 2. As the focal length of a fixed-focus lens increases, the overall optical length of the lens becomes very long, increasing its size and occupying a large amount of space.

[0003] When encountering the above problems, the only option is to choose a more expensive telecentric lens, but a telecentric lens has only a fixed optical magnification and a fixed working distance, making it less versatile. Summary of the Invention

[0004] The purpose of this invention is to provide a 95mm telephoto fixed-focus imaging optical system to solve the above-mentioned technical problems.

[0005] The present invention provides a 95mm telephoto catadioptric fixed-focus imaging optical system, including a cemented sheet coaxially arranged with the object side, an aperture stop, a first lens, and a second lens coaxially arranged with the image side. A plane mirror arranged at 45° is provided on the side of the first lens away from the cemented sheet.

[0006] The angle between the axis of the first lens and the normal of the plane mirror is the same as the angle between the axis of the second lens and the normal of the plane mirror;

[0007] The system has a focal length of 95mm, a total optical length of 35mm, an object side located on the far left with an initial focusing object distance of 120mm, and an image side located on the far top with an image distance of 5mm.

[0008] The curvature of the lens surface near the object side is defined as the object surface curvature, and the curvature of the lens surface near the image side is defined as the image surface curvature. Curvature with the convex surface facing the object side is considered positive, and curvature with the convex surface facing the image side is considered negative.

[0009] The lamination sheet has an object surface curvature radius of 8 mm and an image surface curvature radius of 15 mm.

[0010] The first lens has an object plane radius of curvature of -12.4 mm and an image plane radius of curvature of -13 mm.

[0011] The second lens has an object plane curvature radius of 20 mm and an image plane curvature radius of -35 mm.

[0012] Furthermore, the adhesive sheet includes a first lens and a second lens connected by optical adhesive. The first lens has an object surface curvature radius of 8 mm and an image surface curvature radius of -18 mm. The second lens has an object surface curvature radius of -18 mm and an image surface curvature radius of 15 mm.

[0013] Furthermore, the object surface of the first lens is convex, and the image surface is convex; the object surface of the second lens is concave, and the image surface is concave.

[0014] Furthermore, the first lens is made of heavy flint glass, and the second lens is made of crown glass.

[0015] Furthermore, the object surface of the first lens is concave, and the image surface is convex; the object surface of the second lens is convex, and the image surface is convex.

[0016] Furthermore, the first lens is made of heavy phosphorus crown glass; the second lens is made of flint glass.

[0017] Furthermore, the planar reflector is made of crown glass.

[0018] Furthermore, the optical distance between the adhesive sheet and the aperture stop is 3mm ± 0.02mm;

[0019] The optical distance between the aperture stop and the first lens is 3.21 mm ± 0.02 mm;

[0020] The optical distance between the first lens and the plane mirror is 10.81 mm ± 0.02 mm;

[0021] The optical distance between the plane mirror and the second lens is 10.81 mm ± 0.02 mm.

[0022] Furthermore, the surface tolerance for all curvatures is f / 3-5, with a local aperture of f / 3-0.5.

[0023] Furthermore, the system has an aperture of F / 11, an image plane diameter of 9.4 mm, a diagonal field of view of 12°, a magnification of 0.36x, and operates in a visible light environment with a wavelength range of 486 nm to 650 nm.

[0024] This invention features a compact structure that extends the focal length from 75mm to 95mm. Furthermore, it incorporates a 90-degree rotating optical path design within the lens, reducing the overall optical length of the lens and addressing the issue of large size in existing fixed-focus vision inspection systems for inspecting small parts. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the optical path of the optical system of the present invention;

[0027] Figure 2 This is a partially enlarged view of the optical path of the optical system of the present invention;

[0028] Figure 3 This is a schematic diagram of the optical system of the present invention;

[0029] Figure 4 This is a fan-shaped diagram of the optical system of the present invention;

[0030] Figure 5 The field curvature and distortion diagrams of the optical system of the present invention are shown.

[0031] Figure 6 This is a graph of the modulation optical transfer function of the optical system of the present invention;

[0032] Figure 7 This is a graph showing the image plane illuminance of the optical system of the present invention.

[0033] Figure 8 This is a schematic diagram of the circle of confusion of the optical system of the present invention;

[0034] Explanation of reference numerals in the attached figures:

[0035] In the diagram: 1-plywood, 11-first lens, 12-second lens, 2-aperture stop, 3-first lens, 4-plane mirror, 5-second lens, 6-object side, 7-image side; Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Example 1

[0040] like Figures 1-8 As shown:

[0041] A 95mm telephoto catadioptric fixed-focus imaging optical system includes an object 6 located on the far left, an image 7 located on the far top, a cemented sheet 1 coaxially arranged with the object 6, an aperture stop 2, a first lens 3, and a second lens 5 coaxially arranged with the image 7. A plane mirror 4 is arranged at 45° to the right side of the first lens 3.

[0042] The angle between the axis of the first lens 3 and the normal of the plane mirror 4 is the same as the angle between the axis of the second lens 5 and the normal of the plane mirror 4.

[0043] The system has a focal length of 95mm, an optical length of 35mm, an object side 6 located on the far left with an initial focusing object distance of 120mm, and an image side 7 located at the top with an image distance of 5mm.

[0044] like Figure 1-3 As shown, the plywood 1 includes a first lens 11 and a second lens 12 connected by optical adhesive.

[0045] The surface of the lens closest to object 6 is defined as the object surface, and the curvature of the surface of the lens closest to object 6 is the object surface curvature. The surface of the lens closest to image 7 is defined as the image surface, and the curvature of the surface of the lens closest to image 7 is the image surface curvature.

[0046] The curvature convex surface facing the object is set to 6 as positive, and the curvature convex surface facing the image is set to 7 as negative.

[0047] The curvature profile data for each lens are as follows:

[0048] The object surface of the first lens 11 of the laminate 1 is convex, the radius of curvature of the object surface of the first lens 11 is 8mm, and the image surface of the first lens 11 is convex, with a radius of curvature of -18mm.

[0049] The object surface of the second lens 12 of the laminate 1 is concave, the radius of curvature of the object surface of the second lens 12 is -18mm, and the image surface of the second lens 12 is concave, with a radius of curvature of 15mm.

[0050] The object surface of the first lens 3 is concave, and the radius of curvature of the object surface of the first lens 3 is -12.4mm. The image surface is convex, and the radius of curvature of the image surface is -13mm.

[0051] The object surface of the second lens 5 is convex, with a radius of curvature of 20mm. The image surface is also convex, with a radius of curvature of -35mm.

[0052] The surface tolerance for all curvatures is f / 3-5, with local apertures of f / 3-0.5.

[0053] The material data for each lens is as follows:

[0054] All lenses are made of colorless glass. The first lens 11 is made of heavy flint glass, the second lens 12 is made of heavy crown glass, the first lens 3 is made of heavy phosphorus crown glass, the second lens 5 is made of flint glass, and the plane mirror 4 is made of crown glass.

[0055] The optical distance between the plywood 1 and the aperture stop 2 is 3mm ± 0.02mm;

[0056] The optical distance between aperture stop 2 and first lens 3 is 3.21mm ± 0.02mm;

[0057] The optical distance between the first lens 3 and the plane mirror 4 is 10.81mm ± 0.02mm;

[0058] The optical distance between the plane mirror 4 and the second lens 5 is 10.81mm ± 0.02mm.

[0059] The system has an aperture of F / 11, an image plane diameter of 9.4 mm, a diagonal field of view of 12°, and a magnification of 0.36x.

[0060] The system operates in a visible light environment, with a working wavelength between 486nm and 650nm.

[0061] like Figure 4 As shown, the set of aberrations generated in different fields of view is displayed, and the difference between the meridional plane and the sagittal plane aberrations can be seen in each field of view.

[0062] like Figure 5 The diagram shows the field curvature and distortion of the system. The left side shows the field curvature (image plane curvature), where different curves represent different wavelengths. The maximum deviation of the image plane curvature is no more than 0.0554 mm, which can be ignored. The right side shows the optical distortion. Generally, the largest distortion occurs at the edge of the entire field of view, and the maximum optical distortion is less than 0.3666%, meeting the design requirements.

[0063] like Figure 6 As shown, this represents the spatial transfer function of the entire optical system within the operating wavelength range. It's a representation of the overall imaging quality of the system, with the horizontal axis representing line pairs per millimeter and the vertical axis representing frequency. Different lines represent different fields of view and differences in meridion or sagittal.

[0064] like Figure 7 As shown, this figure illustrates the illumination distribution in different areas of the image plane after light passes through this optical system, demonstrating the attenuation of illuminance across different fields of view. This figure is an important indicator for evaluating the image plane illuminance of the entire optical system. The figure shows that the image illuminance at the edges can reach over 88% of the illuminance at the center.

[0065] like Figure 8 As shown, this illustrates the diffusion of all entrance pupil rays converging onto the image plane in different field-of-view regions. Different curves represent different wavelengths, which is also an important way to evaluate the overall imaging characteristics of an optical system. It can be seen that within the design wavelength range, the geometric radii of both the center and edge field-of-view blur spots can reach within 9.8261 micrometers.

[0066] This invention features a compact structure that extends the focal length from 75mm to 95mm. Furthermore, it incorporates a 90-degree rotating optical path design within the lens, reducing the overall optical length of the lens and addressing the issue of large size in existing fixed-focus vision inspection systems for inspecting small parts.

[0067] 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. A 95mm telephoto catadioptric fixed-focus imaging optical system, characterized in that: The imaging optical system has a total of 4 lenses and a total of 4 lenses, including a cemented sheet coaxially arranged with the object side, an aperture stop, a first lens, and a second lens coaxially arranged with the image side. A plane mirror is provided at a 45° angle on the side of the first lens away from the cemented sheet. The angle between the axis of the first lens and the normal of the plane mirror is the same as the angle between the axis of the second lens and the normal of the plane mirror; The system has a focal length of 95mm, a total optical length of 35mm, an object side located on the far left with an initial focusing object distance of 120mm, and an image side located on the far top with an image distance of 5mm. The mirror curvature closer to the object side is defined as the object surface curvature, and the mirror curvature closer to the image side is defined as the image surface curvature. Curvature convexity facing the object side is positive, and curvature convexity facing the image side is negative. The lamination sheet has an object surface curvature radius of 8 mm and an image surface curvature radius of 15 mm. The first lens has an object plane radius of curvature of -12.4 mm and an image plane radius of curvature of -13 mm. The second lens has an object surface curvature radius of 20 mm and an image surface curvature radius of -35 mm. The laminate includes a first lens and a second lens connected by optical adhesive. The first lens has an object surface curvature radius of 8 mm and an image surface curvature radius of -18 mm. The second lens has an object surface curvature radius of -18 mm and an image surface curvature radius of 15 mm. The object plane of the first lens is convex, and the image plane is convex; the object plane of the second lens is concave, and the image plane is concave.

2. The 95mm telephoto catadioptric fixed-focus imaging optical system according to claim 1, characterized in that: The first lens is made of heavy flint glass, and the second lens is made of crown glass.

3. The 95mm telephoto telephoto fixed-focus imaging optical system according to claim 1, characterized in that: The object plane of the first lens is concave, and the image plane is convex; the object plane of the second lens is convex, and the image plane is convex.

4. The 95mm telephoto catadioptric fixed-focus imaging optical system according to claim 1, characterized in that: The first lens is made of heavy phosphorus crown glass; the second lens is made of flint glass.

5. The 95mm telephoto telephoto fixed-focus imaging optical system according to claim 1, characterized in that: The plane mirror is made of crown glass.

6. The 95mm telephoto catadioptric fixed-focus imaging optical system according to claim 1, characterized in that: The optical distance between the plywood and the aperture stop is 3mm ± 0.02mm; The optical distance between the aperture stop and the first lens is 3.21 mm ± 0.02 mm; The optical distance between the first lens and the plane mirror is 10.81 mm ± 0.02 mm; The optical distance between the plane mirror and the second lens is 10.81 mm ± 0.02 mm.

7. The 95mm telephoto telephoto fixed-focus imaging optical system according to claim 1, characterized in that: The surface tolerance for all curvatures is f / 3-5, with local apertures of f / 3-0.

5.

8. The 95mm telephoto catadioptric fixed-focus imaging optical system according to claim 1, characterized in that: The system has an aperture of F / 11, an image plane diameter of 9.4 mm, a diagonal field of view of 12°, a magnification of 0.36x, and operates in a visible light environment with a wavelength range of 486 nm to 650 nm.

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