Telecentric lens and processing equipment

Abstract

The utility model discloses a telecentric lens and processing equipment, and relates to the technical field of optical systems. The telecentric lens comprises a front optical group, a diaphragm and a rear optical group, the diaphragm is arranged between the front optical group and the rear optical group, the front optical group is sequentially provided with a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from front to back in the light incidence direction, and the first lens, the second lens and the fourth lens are all biconvex lenses. The third lens and the fifth lens are biconcave lenses, and the sixth lens is a positive meniscus lens; the curvature radius of the front surface of the first lens is smaller than the curvature radius of the rear surface of the first lens, the curvature radius of the front surface of the second lens is smaller than the curvature radius of the rear surface of the second lens, and the curvature radius of the front surface of the fourth lens is smaller than the curvature radius of the rear surface of the fourth lens. And the curvature radius of the front surface of the sixth lens is smaller than that of the rear surface of the sixth lens. The telecentric lens solves the technical problem that an existing telecentric lens is high in distortion.

Description

Technical Field

[0001] The utility model relates to the technical field of optical systems, in particular to a telecentric lens and processing equipment. Background Art

[0002] Telecentric lens is a special optical lens, and its design principle and working mode are different from those of ordinary lenses. Its main feature is that during the imaging process, no matter how far the object is from the lens, its magnification remains unchanged, which is the so-called "constant magnification"; the edge imaging of the telecentric lens will not bend, and even at the edge of the lens, the lines still maintain the same intersection angle with the central axis of the lens, so high-precision images can be taken; due to the special internal optical structure, the telecentric lens can keep the light entering the lens parallel at all positions, that is, the image lines taken by the lens will remain straight without bending or deformation. These characteristics make telecentric lenses widely used in machine vision, precision measurement and other fields.

[0003] With the development of optical equipment technology and the increase in production demand, telecentric lenses have been widely used. The existing lenses have the problem of improving clarity at the expense of image distortion in design, resulting in high distortion of existing telecentric lenses, which are difficult to meet the demand. Utility Model Content

[0004] In view of this, the utility model provides a telecentric lens and processing equipment, which are used to solve the technical problem of high distortion of existing telecentric lenses.

[0005] In order to solve the above technical problems, the first technical solution adopted by the utility model is:

[0006] A telecentric lens, comprising a front optical group, an aperture and a rear optical group, wherein the aperture is arranged between the front optical group and the rear optical group, the front optical group is provided with a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens in sequence along a light incident direction, the first lens, the second lens and the fourth lens are all biconvex lenses, the third lens and the fifth lens are biconcave lenses, and the sixth lens is a positive meniscus lens;

[0007] The radius of curvature of the front surface of the first lens is smaller than the radius of curvature of its rear surface, the radius of curvature of the front surface of the second lens is smaller than the radius of curvature of its rear surface, the radius of curvature of the front surface of the fourth lens is smaller than the radius of curvature of its rear surface, and the radius of curvature of the front surface of the sixth lens is smaller than the radius of curvature of its rear surface.

[0008] In some embodiments of the telecentric lens, the total focal length of the telecentric lens is a first focal length, the focal length of the front optical group is a second focal length, and the absolute value of the ratio of the second focal length to the first focal length is greater than 0 and less than 0.5;

[0009] And / or, the focal length of the rear optical group is a third focal length, and an absolute value of a ratio of the third focal length to the first focal length is greater than 0 and less than 0.8.

[0010] In some embodiments of the telecentric lens, the second lens is glued to the third lens, the refractive index of the second lens is 1.57 and the dispersion coefficient is 71.4, and the refractive index of the third lens is 1.75 and the dispersion coefficient is 35;

[0011] The fourth lens is glued to the fifth lens, the refractive index of the fourth lens is 1.44 and the dispersion coefficient is 95, and the refractive index of the fifth lens is 1.83 and the dispersion coefficient is 43.

[0012] In some embodiments of the telecentric lens, the front surface radius of curvature of the first lens is 155±2 mm, and the rear surface radius of curvature is -355±2 mm;

[0013] The second lens has a front surface curvature radius of 43±2 mm and a rear surface curvature radius of -85±2 mm;

[0014] The third lens has a front surface curvature radius of -85±2 mm and a rear surface curvature radius of 55±2 mm;

[0015] The front surface curvature radius of the fourth lens is 44±2 mm, and the back surface curvature radius is -90±2 mm;

[0016] The front surface curvature radius of the fifth lens is -90±2mm, and the back surface curvature radius is 33±2mm;

[0017] The front surface curvature radius of the sixth lens is 28±2 mm, and the back surface curvature radius is 555±2 mm.

[0018] In some embodiments of the telecentric lens, the distance between the front surface of the first lens and the object plane is 250 mm, the distance between the front surface of the second lens and the back surface of the first lens is 54 mm, the distance between the front surface of the fourth lens and the back surface of the third lens is 0.2 mm, the distance between the front surface of the sixth lens and the back surface of the fifth lens is 0.2 mm, and the distance between the aperture and the back surface of the sixth lens is 42 mm.

[0019] In some embodiments of the telecentric lens, the rear optical group is provided with a seventh lens, an eighth lens and a ninth lens in sequence front and back along the incident direction of light, the seventh lens is a positive meniscus lens, the eighth lens is a biconcave lens, and the ninth lens is a biconvex lens.

[0020] In some embodiments of the telecentric lens, the distance between the front surface of the seventh lens and the aperture is 4.2 mm, the distance between the front surface of the eighth lens and the back surface of the seventh lens is 12 mm, the distance between the front surface of the ninth lens and the back surface of the eighth lens is 11.3 mm, and the distance between the image plane and the back surface of the ninth lens is 17.8 mm.

[0021] In some embodiments of the telecentric lens, the effective apertures of the first lens, the second lens, and the third lens are all 44±1 mm; the effective apertures of the fourth lens and the fifth lens are all 36±1 mm; and the effective aperture of the sixth lens is 32±1 mm;

[0022] The effective aperture of the seventh lens is 12±1 mm; the effective aperture of the eighth lens is 14±1 mm; and the effective aperture of the ninth lens is 30±1 mm.

[0023] In some embodiments of the telecentric lens, the center thickness of the first lens is 10±0.2 mm; the center thickness of the second lens is 9±0.2 mm; the center thickness of the third lens is 3±0.2 mm; the center thickness of the fourth lens is 9±0.2 mm; the center thickness of the fifth lens is 2.5±0.2 mm; the center thickness of the sixth lens is 6±0.2 mm;

[0024] The center thickness of the seventh lens is 7±0.2 mm; the center thickness of the eighth lens is 1±0.2 mm; and the center thickness of the ninth lens is 5±0.2 mm.

[0025] In order to solve the above technical problems, the second technical solution adopted by the utility model is:

[0026] A processing device comprises the telecentric lens described in the above embodiment.

[0027] Implementing the embodiments of the present utility model will have at least the following beneficial effects:

[0028] The above-mentioned telecentric lens is applied to processing equipment, which can make itself and the processing equipment have the technical effect of low distortion. Specifically, the first lens, the second lens, the fourth lens and the sixth lens in the telecentric lens of the utility model all have a front surface curvature radius that is smaller than the rear surface curvature radius. This can effectively reduce the distortion of the telecentric lens and solve the technical problem of high distortion of existing telecentric lenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 is a schematic diagram of the structure of a telecentric lens in one embodiment;

[0031] Figure 2 It is the MTF modulation function diagram of the telecentric lens of the utility model;

[0032] Figure 3 This is a distortion diagram of the present utility model. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively with reference to the relevant drawings. The drawings provide preferred embodiments of the present invention. However, the present invention can be implemented in many other different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0036] like Figure 1-3 As shown, in a telecentric lens embodiment, the telecentric lens includes a front optical group, an aperture 10 and a rear optical group, the aperture 10 is arranged between the front optical group and the rear optical group, the front optical group is sequentially provided with a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5 and a sixth lens 6 along the incident direction of light, the first lens 1, the second lens 2 and the fourth lens 4 are all biconvex lenses, the third lens 3 and the fifth lens 5 are biconcave lenses, and the sixth lens 6 is a positive meniscus lens. The radius of curvature of the front surface of the first lens 1 is smaller than the radius of curvature of the rear surface, the radius of curvature of the front surface of the second lens 2 is smaller than the radius of curvature of the rear surface, the radius of curvature of the front surface of the fourth lens 4 is smaller than the radius of curvature of the rear surface, and the radius of curvature of the front surface of the sixth lens 6 is smaller than the radius of curvature of the rear surface.

[0037] In this embodiment, the first lens 1, the second lens 2, the fourth lens 4 and the sixth lens 6 in the telecentric lens all have a front surface curvature radius that is smaller than the rear surface curvature radius, which can effectively reduce the distortion of the telecentric lens and solve the technical problem of high distortion of existing telecentric lenses.

[0038] In a telecentric lens embodiment, the rear optical group is provided with a seventh lens 7, an eighth lens 8 and a ninth lens 9 in sequence along the incident direction of light, the seventh lens 7 is a positive meniscus lens, the eighth lens 8 is a biconcave lens, and the ninth lens 9 is a biconvex lens.

[0039] In combination with the previous embodiments, the specific parameters of each lens may be:

[0040] The first lens 1 has a front surface curvature radius of 155±2 mm, a rear surface curvature radius of -355±2 mm, a refractive index of 1.91, a dispersion coefficient of 35, an effective aperture of 80±1 mm, and a center thickness of 10±0.2 mm.

[0041] The front surface curvature radius of the second lens 2 is 43±2mm, the back surface curvature radius is -85±2mm, the refractive index is 1.57, the dispersion coefficient is 71.4, the effective aperture is 44±1mm, and the center thickness of the lens is 9±0.2mm.

[0042] The third lens 3 has a front surface curvature radius of -85±2 mm, a rear surface curvature radius of 55±2 mm, a refractive index of 1.75, a dispersion coefficient of 35, an effective aperture of 44±1 mm, and a center thickness of 3±0.2 mm.

[0043] The fourth lens 4 has a front surface curvature radius of 44±2 mm, a rear surface curvature radius of -90±2 mm, a refractive index of 1.44, a dispersion coefficient of 95, an effective aperture of 36±1 mm, and a center thickness of 9±0.2 mm.

[0044] The front surface curvature radius of the fifth lens 5 is -90±2mm, the rear surface curvature radius is 33±2mm, the refractive index is 1.83, the dispersion coefficient is 43, the effective aperture is 36±1mm, and the center thickness of the lens is 2.5±0.2mm.

[0045] The sixth lens 6 has a front surface curvature radius of 28±2 mm, a rear surface curvature radius of 555±2 mm, a refractive index of 1.44, a dispersion coefficient of 95, an effective aperture of 32±1 mm, and a center thickness of 6±0.2 mm.

[0046] The seventh lens 7 has a front surface curvature radius of 21±2 mm, a rear surface curvature radius of 122±2 mm, a refractive index of 1.74, a dispersion coefficient of 49.2, an effective aperture of 12±1 mm, and a center thickness of 7±0.2 mm.

[0047] The front surface curvature radius of the eighth lens 8 is -18±2mm, the rear surface curvature radius is 25±2mm, the refractive index is 1.63, the dispersion coefficient is 55, the effective aperture is 14±1mm, and the center thickness of the lens is 1±0.2mm.

[0048] The ninth lens 9 has a front surface curvature radius of 50±2 mm, a rear surface curvature radius of -60±2 mm, a refractive index of 1.81, a dispersion coefficient of 41, an effective aperture of 30±1 mm, and a center thickness of 5±0.2 mm.

[0049] Among them, the second lens 2 and the third lens 3 form a close bonding group, and the fourth lens 4 and the fifth lens 5 form a close bonding group. Further, the distance between the front surface of the first lens 1 and the object plane is 250mm, the distance between the front surface of the second lens 2 and the back surface of the first lens 1 is 54mm, the distance between the front surface of the fourth lens 4 and the back surface of the third lens 3 is 0.2mm, the distance between the front surface of the sixth lens 6 and the back surface of the fifth lens 5 is 0.2mm, and the distance between the aperture 10 and the back surface of the sixth lens 6 is 42mm. The distance between the front surface of the seventh lens 7 and the aperture 10 is 4.2mm, the distance between the front surface of the eighth lens 8 and the back surface of the seventh lens 7 is 12mm, the distance between the front surface of the ninth lens 9 and the back surface of the eighth lens 8 is 11.3mm, and the distance between the image plane and the back surface of the ninth lens 9 is 17.8mm.

[0050] Further preferably, the total focal length of the telecentric lens is a first focal length, the focal length of the front optical group is a second focal length, and the absolute value of the ratio of the second focal length to the first focal length is greater than 0 and less than 0.5. The focal length of the rear optical group is a third focal length, and the absolute value of the ratio of the third focal length to the first focal length is greater than 0 and less than 0.8.

[0051] The beneficial effect of the telecentric lens of the present invention is that it can achieve a large target surface and high resolution. By adopting two groups of glued groups, both groups of glued lenses are low refractive index and high dispersion coefficient glued lenses, and high refractive index and low dispersion coefficient glued lenses, a large target surface is ensured while chromatic aberration is effectively eliminated. By adopting multiple lenses whose front surface curvature radius is smaller than the rear surface curvature radius, the distortion of the lens is effectively reduced, and the telecentricity of the object is ensured, so as to achieve high-resolution imaging of the lens, which can adapt to the operating requirements of the lens for precision parts in automated production, and can identify micron-level defects. The feasible high-resolution imaging is fully adapted to the assembly and quality monitoring of complex fine structural parts, and can enable the picture to obtain better imaging quality and improve the brightness uniformity of the picture.

[0052] In addition, it is understandable that the size of a general spectroscopic element is 20 mm, and 25 mm is generally reserved for installation. In the utility model, the distance between the aperture 10 and the rear surface of the sixth lens 6 is 42 mm, and the spare space is relatively large, so the spectroscopic element can be inserted to form an inner coaxial light lens, which is beneficial to the reprocessing of the lens.

[0053] Combined with the previous embodiments, the telecentric lens of the utility model adopts the diffraction limit method in the design to ensure that the optical system can reach the standard of the megapixel lens, so that when the spatial frequency of each field of view is 108lp / mm, the MTF of all fields of view is greater than 0.3 to reach the diffraction limit setting, there is no image plane vignetting phenomenon, the imaging quality is high, and it meets the use of cameras with a size of 1.8" and below. The distortion value of the entire system is less than 0.05%, which plays a very important role in the true restoration of large target surface imaging.

[0054] The utility model also relates to a processing device, comprising the telecentric lens in the foregoing embodiment.

[0055] By applying the telecentric lens in front, the object can be effectively imaged and magnified so that people can clearly see the monitoring and operation accuracy of smaller and more precise component structure monitoring or peripheral wiring of circuit board chips, etc., which can further meet the needs of monitoring and precise operations of small objects.

[0056] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above embodiments only express several implementation methods of the utility model, and the descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A telecentric lens, characterized in that: The telecentric lens comprises a front optical group, an aperture and a rear optical group, wherein the aperture is arranged between the front optical group and the rear optical group, and the front optical group is provided with a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens in sequence along the incident direction of light, wherein the first lens, the second lens and the fourth lens are all biconvex lenses, the third lens and the fifth lens are biconcave lenses, and the sixth lens is a positive meniscus lens; The radius of curvature of the front surface of the first lens is smaller than the radius of curvature of its rear surface, the radius of curvature of the front surface of the second lens is smaller than the radius of curvature of its rear surface, the radius of curvature of the front surface of the fourth lens is smaller than the radius of curvature of its rear surface, and the radius of curvature of the front surface of the sixth lens is smaller than the radius of curvature of its rear surface.

2. The telecentric lens according to claim 1, wherein: The total focal length of the telecentric lens is a first focal length, the focal length of the front optical group is a second focal length, and the absolute value of the ratio of the second focal length to the first focal length is greater than 0 and less than 0.5; And / or, the focal length of the rear optical group is a third focal length, and an absolute value of a ratio of the third focal length to the first focal length is greater than 0 and less than 0.

8.

3. The telecentric lens according to claim 1, wherein: The second lens is glued to the third lens, the refractive index of the second lens is 1.57 and the dispersion coefficient is 71.4, and the refractive index of the third lens is 1.75 and the dispersion coefficient is 35; The fourth lens is glued to the fifth lens, the refractive index of the fourth lens is 1.44 and the dispersion coefficient is 95, and the refractive index of the fifth lens is 1.83 and the dispersion coefficient is 43.

4. The telecentric lens according to claim 3, characterized in that: The front surface curvature radius of the first lens is 155±2mm, and the back surface curvature radius is -355±2mm; The second lens has a front surface curvature radius of 43±2 mm and a rear surface curvature radius of -85±2 mm; The third lens has a front surface curvature radius of -85±2 mm and a rear surface curvature radius of 55±2 mm; The front surface curvature radius of the fourth lens is 44±2 mm, and the back surface curvature radius is -90±2 mm; The front surface curvature radius of the fifth lens is -90±2mm, and the back surface curvature radius is 33±2mm; The front surface curvature radius of the sixth lens is 28±2 mm, and the back surface curvature radius is 555±2 mm.

5. The telecentric lens according to claim 3, characterized in that: The distance between the front surface of the first lens and the object plane is 250 mm, the distance between the front surface of the second lens and the back surface of the first lens is 54 mm, the distance between the front surface of the fourth lens and the back surface of the third lens is 0.2 mm, the distance between the front surface of the sixth lens and the back surface of the fifth lens is 0.2 mm, and the distance between the aperture and the back surface of the sixth lens is 42 mm.

6. The telecentric lens according to claim 1 or 5, characterized in that: The rear optical group is provided with a seventh lens, an eighth lens and a ninth lens in sequence along the incident direction of light, the seventh lens is a positive meniscus lens, the eighth lens is a biconcave lens, and the ninth lens is a biconvex lens.

7. The telecentric lens according to claim 6, characterized in that: The distance between the front surface of the seventh lens and the aperture is 4.2 mm, the distance between the front surface of the eighth lens and the back surface of the seventh lens is 12 mm, the distance between the front surface of the ninth lens and the back surface of the eighth lens is 11.3 mm, and the distance between the image plane and the back surface of the ninth lens is 17.8 mm.

8. The telecentric lens according to claim 6, wherein: The effective apertures of the first lens, the second lens and the third lens are all 44±1 mm; the effective apertures of the fourth lens and the fifth lens are all 36±1 mm; the effective aperture of the sixth lens is 32±1 mm; The effective aperture of the seventh lens is 12±1 mm; the effective aperture of the eighth lens is 14±1 mm; and the effective aperture of the ninth lens is 30±1 mm.

9. The telecentric lens according to claim 6, wherein: The center thickness of the first lens is 10±0.2mm; the center thickness of the second lens is 9±0.2mm; the center thickness of the third lens is 3±0.2mm; the center thickness of the fourth lens is 9±0.2mm; the center thickness of the fifth lens is 2.5±0.2mm; the center thickness of the sixth lens is 6±0.2mm; The center thickness of the seventh lens is 7±0.2 mm; the center thickness of the eighth lens is 1±0.2 mm; and the center thickness of the ninth lens is 5±0.2 mm.

10. A processing equipment, characterized in that: Comprising a telecentric lens as described in any one of claims 1-9.

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