Ultraviolet visible light confocal object image double telecentric imaging optical system

Abstract

The invention relates to the field of industrial visual inspection, and discloses an ultraviolet visible light confocal object image double telecentric imaging optical system which comprises a first lens, a second lens, a first gluing piece, a diaphragm, a second gluing piece, a third lens and a fourth lens which are sequentially arranged from an object plane to an image plane, and an optical axis serves as a rotation center. Wherein the object surface of the first lens is a convex spherical surface, the curvature radius of the first lens is 110.02 mm, the image surface of the first lens is a concave spherical surface, and the curvature radius of the first lens is 65.59 mm; the object surface of the second lens is a concave spherical surface, the curvature radius of the second lens is-200.11 mm, the image surface of the second lens is a convex spherical surface, and the curvature radius of the second lens is-130.80 mm. The system can be suitable for measuring an object with the object distance of 110 mm and an industrial camera with the imaging image surface diameter of 11 mm or below, the aperture of the system is F / 8, the system is also suitable for ultraviolet and visible light environments, it is ensured that lossless and high-contrast imaging can still be achieved in different light source environments, and therefore high-precision and high-reliability surface defect recognition and classification tasks are supported.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial visual inspection, and in particular to an ultraviolet-visible light confocal object image double-telecentric imaging optical system. Background Art

[0002] For projects involving refined detection of surface defect features in industrial visual inspection, in pursuit of high resolution and high contrast, blue light or ultraviolet light is often used in conjunction with telecentric lenses or ultraviolet telecentric lenses for imaging. However, this type of inspection generally requires the use of multiple light sources. Telecentric lenses in the ultraviolet band will reduce resolution due to defocus under other light sources. Therefore, a telecentric imaging system that can achieve confocality in the ultraviolet and visible light bands is the best choice for such applications. Currently, the market lacks high-performance telecentric lenses that can achieve confocality in the ultraviolet and visible light bands, especially under the most widely used 1X optical magnification condition. Based on this demand, this telecentric system that can achieve confocality in the ultraviolet and visible light bands was designed with a 1X magnification as the design basis, providing a new solution for high-precision surface defect detection. Summary of the Invention

[0003] Based on the above description, the present invention provides an ultraviolet-visible light confocal object image dual-telecentric imaging optical system to solve the problem of using blue light or ultraviolet light in combination with a telecentric lens or an ultraviolet telecentric lens for imaging. However, this type of detection generally requires the use of multiple light sources. If the telecentric lens in the ultraviolet band is under other light sources, the resolution will be reduced due to defocus. There is currently a lack of high-performance telecentric lenses on the market that can achieve confocality in the ultraviolet and visible light bands.

[0004] The present invention solves the above-mentioned technical problem with the following technical solution: an ultraviolet-visible light confocal object-image dual-telecentric imaging optical system, comprising a first lens, a second lens, a first cemented sheet, an aperture, a second cemented sheet, a third lens, and a fourth lens, which are arranged in sequence from the object plane to the image plane, and rotate around the optical axis; in: The object surface of the lens 1 is a convex spherical surface with a curvature radius of 110.02 mm. The image surface of the lens 1 is a concave spherical surface with a curvature radius of 65.59 mm; The object surface of the second lens is a concave spherical surface with a curvature radius of -200.11 mm. The image surface of the second lens is a convex spherical surface with a curvature radius of -130.80 mm; The object surface of the first sheet of the laminated sheet 1 is a convex spherical surface with a curvature radius of 41.14 mm. The image surface of the first sheet of the laminated sheet 1 is a concave spherical surface with a curvature radius of 20.97 mm; The object surface of the second piece of the laminated sheet is a convex spherical surface, and its curvature is consistent with the curvature of the image surface of the first piece of the laminated sheet. The image surface of the second sheet of the first laminate is a concave spherical surface with a curvature radius of 65.9 mm; The object surface of the first sheet of the second laminate is a concave spherical surface with a curvature radius of -65.17 mm. The image surface of the first sheet of the second laminate is a concave spherical surface with a curvature radius of 10.27 mm. The object surface of the second piece of the laminated sheet 2 is a convex spherical surface, and its curvature is consistent with the curvature of the image surface of the first piece of the laminated sheet 4. The image surface of the second sheet of the second laminated sheet is a convex spherical surface with a curvature radius of -30.44 mm; The object surface of the lens 3 is a concave spherical surface with a curvature radius of -25.61 mm. The image surface of the lens 3 is a plane; The object surface of the lens 4 is a convex spherical surface with a curvature radius of 50.46 mm. The image surface of the lens 4 is a convex spherical surface with a curvature radius of -50.46 mm; The surface tolerance of all curvatures of lens 1, lens 2, laminate 1, aperture, laminate 2, lens 3 and lens 4 is aperture 3-5, and the local aperture is 0.3-0.5; The lens 1 is made of heavy crown glass. The second lens is made of flint glass. The first lens of the laminated sheet 1 is made of lanthanum crown glass. The second lens of the laminated sheet 1 is made of heavy flint glass. The first lens of the second laminated sheet is made of heavy crown glass. The second lens of the second laminated sheet is made of heavy lanthanum flint glass. The lens 3 is made of heavy crown glass. The lens 4 is made of heavy flint glass.

[0005] Through the above technical solution, this optical system is suitable for measuring objects at an object distance of 110mm and industrial cameras with imaging surface diameters of 11mm or less. The system has an aperture of F / 8 and is also suitable for ultraviolet and visible light environments, ensuring non-destructive, high-contrast imaging in different light source environments, thereby supporting high-precision and high-reliability surface defect recognition and classification tasks.

[0006] On the basis of the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the total optical length of the optical system is 120 mm.

[0008] Furthermore, the optical spacing between lens 1 and lens 2 is 15.18 mm, with a tolerance of ±0.02 mm. The optical spacing from the second lens to the first adhesive sheet is 7.06mm, with a tolerance of ±0.05mm. The optical distance from the aperture to the second glued piece is 10.59mm, with a tolerance of ±0.02mm. The optical spacing from the second glued sheet to the third lens is 3.73mm, with a tolerance of ±0.02mm. The optical interval between the lens 3 and the lens 4 is 31.93 mm, with a tolerance of ±0.02 mm.

[0009] Furthermore, the working environment of the optical system is an ultraviolet and visible light environment, and the working band is 350, 486nm-650nm.

[0010] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: This optical system is suitable for measuring objects at a distance of 110mm and for industrial cameras with image diameters of 11mm or less. The system has an aperture of F / 8 and is suitable for both ultraviolet and visible light environments, ensuring non-destructive, high-contrast imaging under different light sources, thereby supporting high-precision and high-confidence surface defect identification and classification tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the optical path structure of the optical system according to an embodiment of the present invention; Figure 2 A light fan diagram of an optical system according to an embodiment of the present invention; Figure 3 Graphs showing field curvature and distortion of the optical system according to an embodiment of the present invention; Figure 4 is a graph showing a modulated optical transfer function of an optical system according to an embodiment of the present invention; Figure 5 is an image plane illumination attenuation curve diagram of the optical system according to an embodiment of the present invention; Figure 6 Schematic diagram of the confusion circle of the optical system according to an embodiment of the present invention.

[0012] Figure numerals: 1, lens one; 2, lens two; 3, cemented sheet one; 4, aperture; 5, cemented sheet two; 6, lens three; 7, lens four. DETAILED DESCRIPTION

[0013] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0015] Example: Reference Figure 1 A UV-visible confocal object-image double-telecentric imaging optical system consists of a spherical glass lens and an aperture 4. All lenses and the aperture 4 are arranged in sequence with the optical axis as the rotation center; from the object plane to the image plane, they are lens 1 1, lens 2 2, cemented piece 1 3, aperture 4, cemented piece 2 5, lens 3 6 and lens 4 7.

[0016] The main parameters of an optical system are the curvature, center thickness, focal length, aperture, optical spacing between lenses, and the material of each lens (because different materials have different optical properties, mainly different refractive index and dispersion coefficient). Below we will describe the parameters of the optical path.

[0017] The object plane of the entire optical path structure is on the left, and the starting focusing object distance is 110mm; the image plane is on the right, and the image distance is 25mm. We define the left curvature of each lens as the object plane curvature of the lens, and the right curvature as the image plane curvature. The curvature is positive when the convex side faces the object plane, and negative when the convex side faces the image plane. The following describes the parameters of the curvature of the system lenses.

[0018] The curvature surface data of each lens are as follows: The object surface of lens 1 is a convex spherical surface with a curvature radius of 110.02 mm, and the image surface is a concave spherical surface with a curvature radius of 65.59 mm; The object surface of lens 2 is a concave spherical surface with a curvature radius of -200.11 mm, and the image surface is a convex spherical surface with a curvature radius of -130.80 mm; The object surface of the first piece of laminated sheet 3 is a convex spherical surface with a curvature radius of 41.14 mm, and the image surface is a concave spherical surface with a curvature radius of 20.97 mm; The object surface of the second piece of laminated sheet 3 is a convex spherical surface, and its curvature is consistent with the curvature of the image surface of the first piece of laminated sheet 3. The image surface is a concave spherical surface with a curvature radius of 65.9 mm. The object surface of the first piece of laminated sheet 2 5 is a concave spherical surface with a curvature radius of -65.17 mm, and the image surface is a concave spherical surface with a curvature radius of 10.27 mm. The object surface of the second piece of laminated sheet 5 is a convex spherical surface, and its curvature is consistent with the image surface curvature of the first piece of laminated sheet 4. The image surface is a convex spherical surface with a curvature radius of -30.44 mm. The object surface of lens 36 is a concave spherical surface with a curvature radius of -25.61 mm, and the image surface is a flat surface; The object surface of lens 97 is a convex spherical surface with a curvature radius of 50.46 mm, and the image surface is a convex spherical surface with a curvature radius of -50.46 mm; The surface tolerance of all curvatures is aperture 3-5, and the local aperture is 0.3-0.5 (detected by interferometer); The material data of each lens is as follows: All lenses are made of Chengdu Guangming colorless glass and are indicated by Chengdu Guangming's brand. In order to ensure the subsequent industrial production, all brands are currently recommended for mass production.

[0019] Lens 1 is made of heavy crown glass (H-ZK9B); Lens 2 is made of flint glass (H-F4); the first lens of laminate 3 is made of lanthanum crown glass (H-LAK7A), and the second lens is made of heavy flint glass (H-ZF7LA); the first lens of laminate 5 is made of heavy crown glass (H-ZK3A), and the second lens is made of heavy lanthanum flint glass (H-ZLAF4LA); Lens 3 is made of heavy crown glass (H-ZK9B); Lens 4 is made of heavy flint glass (H-ZF7LA).

[0020] The center thickness data of each lens group are as follows: The center thickness of lens 1 is 2.25mm, with a tolerance of ±0.02mm; the center thickness of lens 2 is 2.1mm, with a tolerance of ±0.02mm; the center thickness of the first lens of laminate 3 is 1.52mm, with a tolerance of ±0.02mm, and the center thickness of the second lens is 1.85mm, with a tolerance of ±0.02mm; the center thickness of the first lens of laminate 2 5 is 1mm, with a tolerance of ±0.02mm, and the center thickness of the second lens is 1.66mm, with a tolerance of ±0.02mm; the center thickness of lens 3 6 is 2.8mm, with a tolerance of ±0.02mm; and the center thickness of lens 4 7 is 2.1mm, with a tolerance of ±0.02mm.

[0021] The focal length data of each lens group are as follows: The focal length of lens 1 is 55.029 mm; the focal length of lens 2 is 606.33 mm; the focal length of laminate 3 is 650.861 mm; the focal length of laminate 5 is 250.299 mm; the focal length of lens 3 is -42.05 mm; and the focal length of lens 4 is 56.491 mm.

[0022] The aperture data of each lens group are as follows: The diameter of lens 1 is 22 mm; the diameter of lens 2 is 17 mm; the diameter of glued piece 3 is 12 mm; the diameter of glued piece 2 is 10 mm; the diameter of lens 3 is 10 mm; and the diameter of lens 4 is 15 mm.

[0023] refer to Figure 1 The system consists of six groups of eight glass lenses and an optical path of an aperture 4. The system aperture 4 of the entire optical system is located between the laminate 1 3 and the laminate 2 5. The total optical length of the system (from the center of curvature of the first surface of lens 1 to the image plane) is 120 mm. The optical spacing from lens 1 to lens 2 is 15.18 mm, with a tolerance of ±0.02 mm; the optical spacing from lens 2 to laminate 1 is 7.06 mm, with a tolerance of ±0.05 mm; the optical spacing from laminate 1 to aperture 4 is 6.22 mm, with a tolerance of ±0.02 mm; the optical spacing from aperture 4 to laminate 2 5 is 10.59 mm, with a tolerance of ±0.02 mm; the optical spacing from laminate 2 5 to lens 3 6 is 3.73 mm, with a tolerance of ±0.02 mm; and the optical spacing from lens 3 6 to lens 4 7 is 31.93 mm, with a tolerance of ±0.02 mm.

[0024] The aperture of this optical system is F / 8; the image plane diameter is 11.2mm; the working distance is 110mm; the magnification is 1X; the object space telecentricity is 0.1°; the image space telecentricity is 0.1°; The working environment of this optical system is ultraviolet and visible light environment, and the working band is 350, 486nm-650nm.

[0025] refer to Figure 1 , the optical system consists of 4 groups of single lens, 2 groups of cemented lenses, and aperture according to certain optical intervals, such as Figure 1 As shown in the figure, the leftmost side is the focused object plane of the system, the rightmost side is the ideal image plane of the entire system, and the distance from the center of the focused object plane to the image plane is 230mm.

[0026] refer to Figure 2 , shows the aberration set produced by different field of view areas. The differences in meridian and sagittal aberrations can be seen in each field of view area.

[0027] refer to Figure 3 The left figure shows the field curvature and distortion of the optical system. The left figure shows the field curvature (image curvature). It can be seen that different curves represent different wavelengths. The maximum deviation of the image curvature is 0.0362mm and can be ignored. The right figure shows the optical distortion. Generally, the position with the maximum distortion appears at the edge of the entire field of view, and the maximum optical distortion is less than 0.0523%.

[0028] refer to Figure 4, which represents the spatial transfer function of the entire optical system within the working band. It is a form of expression that reflects the imaging quality of the entire imaging system. The horizontal axis is line pairs / mm, and the vertical axis is frequency. Different lines represent different fields of view and differences in meridians or sagittals.

[0029] refer to Figure 5 , which mainly reflects the illumination distribution in different areas of the image plane after the light passes through this optical system, and reflects the attenuation of illumination in different fields of view. This graph is an important indicator for evaluating the illumination of the image plane of the entire optical system. It can be seen from the graph that the light energy of the entire image has almost no attenuation.

[0030] refer to Figure 6 , represents the diffusion of all pupil light rays converging onto the image plane in different fields of view. Different curves represent different wavelengths and are 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 diameter of the diffuse spot in all fields of view can be kept within 3.598 microns.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A UV-visible confocal object image dual telecentric imaging optical system, characterized by: The lens comprises lens 1 (1), lens 2 (2), cemented sheet 1 (3), aperture (4), cemented sheet 2 (5), lens 3 (6) and lens 4 (7) which are arranged in sequence from the object plane to the image plane, and the optical axis is used as the rotation center; in: The object surface of the lens 1 (1) is a convex spherical surface with a curvature radius of 110.02 mm. The image surface of the lens 1 (1) is a concave spherical surface with a curvature radius of 65.59 mm; The object surface of the lens 2 (2) is a concave spherical surface with a curvature radius of -200.11 mm. The image surface of the lens 2 (2) is a convex spherical surface with a curvature radius of -130.80 mm; The object surface of the first sheet of the plywood 1 (3) is a convex spherical surface with a curvature radius of 41.14 mm. The image surface of the first sheet of the laminated sheet (3) is a concave spherical surface with a curvature radius of 20.97 mm; The object surface of the second piece of the laminated sheet (3) is a convex spherical surface, and its curvature is consistent with the curvature of the image surface of the first piece of the laminated sheet (3). The image surface of the second piece of the laminated sheet (3) is a concave spherical surface with a curvature radius of 65.9 mm; The object surface of the first sheet of the second glued sheet (5) is a concave spherical surface with a curvature radius of -65.17 mm. The image surface of the first sheet of the second glued sheet (5) is a concave spherical surface with a curvature radius of 10.27 mm. The object surface of the second piece of the laminated sheet 2 (5) is a convex spherical surface, and its curvature is consistent with the curvature of the image surface of the first piece of the laminated sheet 4. The image surface of the second piece of the second glued piece (5) is a convex spherical surface with a curvature radius of -30.44 mm; The object surface of the lens three (6) is a concave spherical surface with a curvature radius of -25.61 mm. The image surface of the lens three (6) is a plane; The object surface of the lens 4 (7) is a convex spherical surface with a curvature radius of 50.46 mm. The image surface of the lens four (7) is a convex spherical surface with a curvature radius of -50.46 mm; The surface tolerance of the curvature of the lens 1 (1), lens 2 (2), glued sheet 1 (3), aperture (4), glued sheet 2 (5), lens 3 (6) and lens 4 (7) is an aperture of 3-5, and a local aperture of 0.3-0.5; The lens 1 (1) is made of heavy crown glass. The second lens (2) is made of flint glass. The first lens of the laminated sheet (3) is made of lanthanum crown glass. The second lens of the laminated sheet 1 (3) is made of heavy flint glass. The first lens of the second laminated sheet (5) is made of heavy crown glass. The second lens of the second glued sheet (5) is made of heavy lanthanum flint glass. The lens 3 (6) is made of heavy crown glass. The lens four (7) is made of heavy flint glass.

2. The ultraviolet-visible light confocal object image dual-telecentric imaging optical system according to claim 1, characterized in that: The total optical length of this optical system is 120 mm.

3. The ultraviolet-visible light confocal object image dual-telecentric imaging optical system according to claim 2, characterized in that: The optical spacing between lens 1 (1) and lens 2 (2) is 15.18 mm, with a tolerance of ±0.02 mm. The optical spacing between the lens 2 (2) and the adhesive sheet 1 (3) is 7.06mm, with a tolerance of ±0.05mm. The optical spacing from the aperture (4) to the second glued sheet (5) is 10.59 mm, with a tolerance of ±0.02 mm. The optical spacing from the second glue sheet (5) to the third lens (6) is 3.73mm, with a tolerance of ±0.02mm. The optical spacing between lens three (6) and lens four (7) is 31.93 mm, with a tolerance of ±0.02 mm.

4. The ultraviolet-visible light confocal object image dual-telecentric imaging optical system according to claim 1, characterized in that: The working environment of this optical system is ultraviolet and visible light environment, and the working band is 350, 486nm-650nm.

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