CN107884912B - Fixed-magnification double-telecentric optical system - Google Patents
Fixed-magnification double-telecentric optical system Download PDFInfo
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- CN107884912B CN107884912B CN201711302506.8A CN201711302506A CN107884912B CN 107884912 B CN107884912 B CN 107884912B CN 201711302506 A CN201711302506 A CN 201711302506A CN 107884912 B CN107884912 B CN 107884912B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/22—Telecentric objectives or lens systems
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
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Abstract
The invention relates to a fixed-power double-telecentric optical system, wherein a front group, a diaphragm C and a rear group are sequentially arranged in the optical system of a lens along the incident direction of light rays from left to right, and the front group comprises a double convex lens G-1 with positive focal power, a meniscus lens G-2 with positive focal power, a double concave lens G-3 with negative focal power and a meniscus lens G-4 with positive focal power which are sequentially arranged; the rear group comprises a meniscus lens G-5 with negative focal power, a meniscus lens G-6 with positive focal power, a double convex lens G-7 with positive focal power and a meniscus lens G-8 with negative focal power which are sequentially arranged, and the structure is simple.
Description
Technical Field
The invention relates to a fixed-magnification double-telecentric optical system.
Background
At present, various industrial lenses are applied to the field of machine vision and industrial detection in the market, but the industrial lenses are generally difficult to realize short-distance measurement, have heavy volume and small depth of field, and cannot keep the same magnification ratio for imaging in different object distance ranges, so that image proportion distortion is caused, and visual errors are caused. The object placing height is influenced by external conditions during industrial measurement, various external interferences can change the object height, the common telecentric lens cannot realize the function of parallax elimination under different object distances, and simultaneously, the image edge is deformed due to the edge distortion of the lens, so that the measurement precision is reduced.
Disclosure of Invention
Aiming at the defects, the invention provides a fixed-magnification double-telecentric optical system with a simple structure.
The technical scheme of the invention is that a fixed-power double-telecentric optical system is characterized in that a front group, a diaphragm C and a rear group are sequentially arranged in the optical system of a lens along the incident direction of light rays from left to right, wherein the front group comprises a double convex lens G-1 with positive focal power, a meniscus lens G-2 with positive focal power, a double concave lens G-3 with negative focal power and a meniscus lens G-4 with positive focal power which are sequentially arranged; the rear group comprises a meniscus lens G-5 with negative focal power, a meniscus lens G-6 with positive focal power, a double convex lens G-7 with positive focal power and a meniscus lens G-8 with negative focal power which are sequentially arranged.
Further, the focal power of the front group is positive, and the focal power of the rear group is negative; the front group of biconcave lens G-3 with negative focal power and the meniscus lens G-4 with positive focal power form a gluing group, the total focal power of the gluing group is negative, and the gluing group mainly plays a role in correcting spherical aberration and chromatic aberration; the double convex lens G-7 with positive focal power and the meniscus lens G-8 with negative focal power form a bonding group, and the total focal power is positive.
Further, the air space between the biconvex lens G-1 and the meniscus lens G-2 is 12.6mm, the distance between the meniscus lens G-2 and the biconcave lens G-3 is 0.4mm, the distance between the positive plate G-4 of the cemented sheet formed by the biconcave lens G-3 and the meniscus lens G-4 and the diaphragm C is 24.8mm, the distance between the diaphragm C and the meniscus lens G-5 is 0.1mm, the distance between the meniscus lens G-5 and the meniscus lens G-6 is 15.5mm, and the distance between the meniscus lens G-6 and the positive plate G-7 of the cemented sheet formed by the biconvex lens G-7 and the meniscus lens G-8 and the diaphragm C-7 is 8.1 mm.
Furthermore, the concave surface of the front group of meniscus lenses G-2 with positive focal power bends to the diaphragm, and the double-concave lens G-3 with negative focal power and the meniscus lens G-4 with positive focal power form a gluing surface of the gluing group to bend to the diaphragm; the rear group of meniscus lenses G-6 with positive focal power has a concave surface bent towards the diaphragm, and the rear group of biconvex lenses G-7 with positive focal power and the meniscus lenses G-8 with negative focal power form a gluing surface bent towards the diaphragm of the gluing group.
Further, the distance from the front group to the rear group of the lens is 24.9mm, and the ratio of the focal power of the front group to the focal power of the rear group is 2.0.
Compared with the prior art, the invention has the following beneficial effects: the structure is simplified, the size is smaller, the weight is light, the distortion is low, the depth of field is high, the resolution ratio is high, the problem of inconsistent imaging multiplying power caused by external vibration interference can be solved within the depth of field range, the technical guarantee is provided for the precision detection field, and the method is applicable to various detection fields.
Drawings
The invention is further described with reference to the following figures.
FIG. 1 is a diagram of an optical system according to an embodiment of the present invention.
FIG. 2 is a graph of the modulation transfer function at 30lp/mm for an embodiment of the present invention;
FIG. 3 is a graph of the modulation transfer function at 50lp/mm for an embodiment of the present invention;
FIG. 4 is a graph of the modulation transfer function at 80lp/mm for an embodiment of the present invention;
FIG. 5 is a dot diagram of an embodiment of the present invention;
FIG. 6 is a graph of field curvature and distortion for an embodiment of the present invention;
fig. 7 is a graph of image plane illuminance in accordance with an embodiment of the present invention.
In the figure:
c diaphragm C, G-1 biconvex lens G-1, G-2 meniscus lens G-2, G-3 biconcave lens G-3, G-4 meniscus lens G-4, G-5 meniscus lens G-5, G-6 meniscus lens G-6, G-7 biconvex lens G-7, G-8 meniscus lens G-8.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
As shown in fig. 1 to 7, in an optical system of a lens, a front group, a diaphragm C, and a rear group are sequentially arranged along a left-to-right incident direction of light in the optical system of the lens, and the front group includes a double convex lens G-1 with positive focal power, a meniscus lens G-2 with positive focal power, a double concave lens G-3 with negative focal power, and a meniscus lens G-4 with positive focal power, which are sequentially arranged; the rear group comprises a meniscus lens G-5 with negative focal power, a meniscus lens G-6 with positive focal power, a double convex lens G-7 with positive focal power and a meniscus lens G-8 with negative focal power which are sequentially arranged.
In this embodiment, the front group power is positive, and the back group power is negative; the front group of biconcave lens G-3 with negative focal power and the meniscus lens G-4 with positive focal power form a gluing group, the total focal power of the gluing group is negative, and the gluing group mainly plays a role in correcting spherical aberration and chromatic aberration; the double convex lens G-7 with positive focal power and the meniscus lens G-8 with negative focal power form a bonding group, and the total focal power is positive.
In this embodiment, the air distance between the biconvex lens G-1 and the meniscus lens G-2 is 12.6mm, the distance between the meniscus lens G-2 and the biconcave lens G-3 is 0.4mm, the distance between the positive plate G-4 of the cemented sheet composed of the biconcave lens G-3 and the meniscus lens G-4 and the diaphragm C is 24.8mm, the distance between the diaphragm C and the meniscus lens G-5 is 0.1mm, the distance between the meniscus lens G-5 and the meniscus lens G-6 is 15.5mm, and the distance between the meniscus lens G-6 and the positive plate G-7 of the cemented sheet composed of the biconvex lens G-7 and the meniscus lens G-8 is 8.1 mm.
In this embodiment, the concave curved diaphragm of the front group of meniscus lenses G-2 with positive focal power, the cemented surface curved diaphragm of the cemented group consisting of the double concave lens G-3 with negative focal power and the meniscus lens G-4 with positive focal power; the rear group of meniscus lenses G-6 with positive focal power has a concave surface bent towards the diaphragm, and the rear group of biconvex lenses G-7 with positive focal power and the meniscus lenses G-8 with negative focal power form a gluing surface bent towards the diaphragm of the gluing group.
In this embodiment, the distance from the front group to the rear group of the lens is 24.9mm, and the ratio of the power of the front group to the power of the rear group is 2.0.
In the present embodiment, the optical system constituted by the lens group achieves the following optical indexes:
the object space working distance is =111mm, the numerical aperture NA =0.026, the magnification ratio β =0.5, the object space and image space telecentricity is less than or equal to 0.02 degrees, the optical distortion is less than or equal to-0.006 percent, and the relative illumination is more than or equal to 98.6 percent (phi 11 mm);
the total lens length TTL is less than or equal to 123.6mm, and the optical back focus is more than or equal to 22 mm;
the fixed-magnification double telecentric lens can be compatible with 2/3' inch (phi 11 mm) and used by an industrial chip with the pixel size of 3.45 um;
in this embodiment, the fixed-magnification double telecentric optical system has the following features: when the system focal length is f, the focal lengths of the optical system from left to right are f1, f2, f3, f4, f5, f6, f7 and f8. in sequence, wherein:
0.017＜f1/f＜0.021；
0.02＜f2/f＜0.024；
-0.01＜f3/f＜-0.006；
0.01＜f4/f＜0.015；
-0.015＜f5/f＜-0.009；
0.01＜f6/f＜0.017；
0.004＜f7/f＜0.006；
-0.01＜f8/f＜-0.006；
in this example, the parameters for each lens are shown in the following table:
in the embodiment, the object-side telecentricity is less than or equal to 0.02 and the image-side telecentricity is less than or equal to 0.02 according to the double telecentricity performance parameters, the chief rays of the object-side light beam and the image-side light beam are parallel to the optical axis, so that the imaging magnification ratio of the object-side light beam and the image-side light beam in the field depth range is constant, and meanwhile, the illumination of the image surface is more uniform due to the image-side telecentricity, the imaging stability is ensured, the overall detection performance is improved, and the double-telecentricity performance parameter can be applied; the optical distortion of the double telecentric lens is less than or equal to-0.006 percent according to the double telecentric performance parameters, and the total lens length TTL is less than or equal to 123.6mm, so that the double telecentric lens can effectively control the distortion rate of the detected image, the small total length ensures that the double telecentric lens has good applicability, and the lens is beautiful and small; the characteristics of the double telecentric lens show that the lens has excellent performances of wide depth of field, low distortion, high resolution and the like.
In this embodiment, as can be seen from fig. 1, the present invention sequentially comprises, along the light incident direction, a double convex lens G-1 with positive optical power, a meniscus lens G-2 with positive optical power, a double concave lens G-3 with negative optical power, a meniscus lens G-4 with positive optical power, a meniscus lens G-5 with negative optical power, a meniscus lens G-6 with positive optical power, a double convex lens G-7 with positive optical power, and a meniscus lens G-8 with negative optical power. Wherein, the diaphragm C is positioned on an image space focal plane of the front set system and is positioned on an object space focal plane of the rear set system to form a double telecentric light path; the front group of biconvex lens G-1 adopts lanthanide series materials, the meniscus lens G-2 adopts barite flint materials, and the veneer consisting of the front group of biconcave lens G-3 and the meniscus lens G-4 is matched by lanthanide series and lanthanide series materials; the rear group of meniscus lenses G-5 is made of heavy flint material, the meniscus lenses G-6 are made of lanthanide series material, and the back group of biconvex lenses G-7 and the meniscus lenses G-8 are made of two heavy lanthanide series materials for matching, so that the combination can fully correct spherical aberration and chromatic aberration, and simultaneously, the characteristic of cancellation of aberration of a symmetrical structure is kept.
In this embodiment, as can be seen from fig. 2, 3 and 4, the transfer function value of the lens at 30lp/mm is close to 0.8; the transfer function value at 50lp/mm reaches 0.6; the transfer function value at 80lp/mm is 0.4, so that the lens has excellent resolving power. The point spread function diagram of the double telecentric lens in FIG. 5 shows that the aberration of the lens is well corrected, the diffusion circles of all the fields are in a very small level, the convergence of the light energy is high, and the accurate imaging of the lens can be ensured. As can be seen from FIG. 6, the optical distortion of the double telecentric lens is much less than-0.006%, so that the lens will provide an extremely high image restoration degree for industrial inspection. As can be seen from the image plane illuminance curve chart of the double telecentric lens in FIG. 7, the illuminance of the lens in the whole field range is almost not attenuated, the illuminance distribution is uniform, and a good illuminance environment is provided for the detected object.
The above-mentioned preferred embodiments, further illustrating the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned are only preferred embodiments of the present invention and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. A double telecentric optical system with fixed magnification is characterized in that: the optical system is sequentially provided with a front group, a diaphragm C and a rear group along the incident direction of light rays from left to right, wherein the front group consists of a double convex lens G-1 with positive focal power, a meniscus lens G-2 with positive focal power, a double concave lens G-3 with negative focal power and a meniscus lens G-4 with positive focal power which are sequentially arranged; the rear group consists of a meniscus lens G-5 with negative focal power, a meniscus lens G-6 with positive focal power, a double convex lens G-7 with positive focal power and a meniscus lens G-8 with negative focal power which are arranged in sequence; the focal power of the front group is positive, and the focal power of the rear group is negative; the front group of biconcave lens G-3 with negative focal power and the meniscus lens G-4 with positive focal power form a gluing group, the total focal power of the gluing group is negative, and the gluing group mainly plays a role in correcting spherical aberration and chromatic aberration; the double convex lens G-7 with positive focal power and the meniscus lens G-8 with negative focal power form a gluing group, and the total focal power is positive; the air space between the double convex lens G-1 and the meniscus lens G-2 is 12.6mm, the distance between the meniscus lens G-2 and the double concave lens G-3 is 0.4mm, the distance between the meniscus lens G-4 and the diaphragm C of the bonding sheet formed by the double concave lens G-3 and the meniscus lens G-4 is 24.8mm, the distance between the diaphragm C and the meniscus lens G-5 is 0.1mm, the distance between the meniscus lens G-5 and the meniscus lens G-6 is 15.5mm, and the distance between the meniscus lens G-6 and the double convex lens G-7 of the bonding sheet formed by the double convex lens G-7 and the meniscus lens G-8 is 8.1 mm; the concave surface of the front group of meniscus lenses G-2 with positive focal power bends to the diaphragm, the double concave lenses G-3 with negative focal power and the meniscus lenses G-4 with positive focal power form a gluing surface of the gluing group bends to the diaphragm; the rear group of meniscus lenses G-6 with positive focal power has a concave surface bent towards the diaphragm, and the rear group of biconvex lenses G-7 with positive focal power and meniscus lenses G-8 with negative focal power form a gluing surface bent towards the diaphragm of the gluing group; the distance from the front group to the rear group is 24.9mm, and the ratio of the focal power of the front group to the focal power of the rear group is 2.0.
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| CN201711302506.8A CN107884912B (en) | 2017-12-11 | 2017-12-11 | Fixed-magnification double-telecentric optical system |
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| CN201711302506.8A CN107884912B (en) | 2017-12-11 | 2017-12-11 | Fixed-magnification double-telecentric optical system |
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| CN108107557B (en) * | 2018-01-10 | 2024-01-16 | 佛山华国光学器材有限公司 | High-magnification double-side telecentric lens with long working distance |
| CN109164558B (en) * | 2018-10-11 | 2023-11-28 | 佛山科学技术学院 | Miniaturized object image bilateral telecentric optical system |
| CN109188660B (en) * | 2018-10-11 | 2023-11-28 | 佛山科学技术学院 | Miniaturized object space telecentric optical system |
| CN109254388B (en) * | 2018-11-21 | 2023-09-19 | 福建福光股份有限公司 | Telecentric optical imaging system and imaging method |
| CN110895366B (en) * | 2019-11-22 | 2024-06-07 | 福建福光天瞳光学有限公司 | 0.5-Time 110mm object distance high-resolution industrial double telecentric lens |
| CN110895367B (en) * | 2019-11-22 | 2024-03-05 | 福建福光天瞳光学有限公司 | 1.0 times 110mm object distance high-resolution industrial double telecentric lens |
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| CN105301744A (en) * | 2015-11-24 | 2016-02-03 | 福建福光股份有限公司 | Telephoto type super-large image plane high definition lens and installation method thereof |
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| JP3715735B2 (en) * | 1997-01-24 | 2005-11-16 | マミヤ・オーピー株式会社 | telescope lens |
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| CN105301744A (en) * | 2015-11-24 | 2016-02-03 | 福建福光股份有限公司 | Telephoto type super-large image plane high definition lens and installation method thereof |
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