CN107884916B - Fixed-focus bilateral telecentric optical lens - Google Patents
Fixed-focus bilateral telecentric optical lens Download PDFInfo
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- CN107884916B CN107884916B CN201711302499.1A CN201711302499A CN107884916B CN 107884916 B CN107884916 B CN 107884916B CN 201711302499 A CN201711302499 A CN 201711302499A CN 107884916 B CN107884916 B CN 107884916B
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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
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
Abstract
The invention relates to a fixed-focus bilateral telecentric optical lens, wherein a front group A with positive focal power, a diaphragm C and a rear group B with negative focal power are sequentially arranged in an optical system of the lens along the incident direction of light rays from left to right, and the front group A comprises a bonding group consisting of a double convex positive lens A1, a meniscus positive lens A2, a double concave negative lens A3 and a meniscus positive lens A4 which are sequentially arranged; the rear group B comprises a gluing group consisting of a double-concave negative lens B1, a double-convex positive lens B2, a meniscus positive lens B3 and a meniscus negative lens B4 which are sequentially arranged, and the rear group B is simple in structure.
Description
Technical Field
The invention relates to a fixed-focus bilateral telecentric optical lens.
Background
Various double-side telecentric lenses are applied to the field of industrial detection in the existing market, but the detection effect of many double-side telecentric lenses is still not ideal enough, and many lenses still have the problems of larger edge distortion, larger telecentricity, heavy volume and the like. Therefore, it is meaningful to provide a double-sided telecentric lens with small volume, high resolution, high detection accuracy and wide depth of field.
Disclosure of Invention
The invention aims to overcome the defects and provides the fixed-focus double-side telecentric optical lens with a simple structure.
The technical scheme includes that a fixed-focus bilateral telecentric optical lens is characterized in that a front group A with positive focal power, a diaphragm C and a rear group B with negative focal power are sequentially arranged in an optical system of the lens along the incident direction of light rays from left to right, wherein the front group A comprises a double convex positive lens A1, a meniscus positive lens A2, a double concave negative lens A3 and a cementing group consisting of a meniscus positive lens A4 which are sequentially arranged; the rear group B comprises a gluing group consisting of a double-concave negative lens B1, a double-convex positive lens B2, a meniscus positive lens B3 and a meniscus negative lens B4 which are sequentially arranged.
Further, the meniscus positive lens a2 of the lens front group a is concave and curved to the diaphragm side; the biconcave negative lens A3 and the meniscus positive lens A4 of the lens front group A form a bonding sheet, and the bonding surface of the bonding sheet is bent to the diaphragm side; the concave surface of the meniscus positive lens A4 of the front lens group A is bent to the diaphragm side; the concave surface of a biconvex positive lens B2 of the lens rear group B is bent to the diaphragm side; the positive meniscus lens B3 and the negative meniscus lens B4 of the rear lens group B form a cemented sheet, and the cemented surface of the cemented sheet bends to the diaphragm side; the concave surface of a meniscus positive lens B3 of the rear lens group B is bent to the diaphragm side; the meniscus negative lens B4 of the rear lens group B is curved concavely to the diaphragm side.
Further, the biconvex positive lens a1 of the lens front group a is made of flint glass; the meniscus positive lens A2 is made of crown glass; the meniscus positive lens A4 is made of flint glass; the biconcave negative lens A3 is made of flint glass; the double-convex positive lens B2 of the lens rear group B is made of flint glass; the meniscus positive lens B3 is made of flint glass; the double-concave negative lens B1 is made of flint glass; the material adopted by the meniscus negative lens B4 is flint glass.
Further, the air gap between the lens double convex positive lens a1 and the meniscus positive lens a2 is 1.8mm, the air gap between the meniscus positive lens a2 and the double concave negative lens A3 is 1mm, the air gap between the meniscus positive lens a4 and the diaphragm C is 27.2mm, the air gap between the diaphragm C and the double concave negative lens B1 is 6.1mm, the air gap between the double concave negative lens B1 and the double convex positive lens B2 is 8.5mm, and the air gap between the double convex positive lens B2 and the meniscus positive lens B3 is 29.5 mm.
Further, the air gap between the front lens group a and the rear lens group B is 33.3 mm.
Compared with the prior art, the invention has the following beneficial effects: the structure is simple, the volume is small, the processing performance is good, and the imaging performance is excellent at a short distance; the telecentric degree is small and has a fixed magnification, the magnification of the image can be kept consistent in a certain object distance range, the distortion of the image is greatly reduced due to extremely small distortion, the detection precision of the image is further improved, and the method can be fully applied to the future industrial detection field.
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 modulation transfer function at 30 line pairs according to an embodiment of the present invention;
FIG. 3 is a graph of modulation transfer function at 50 line pairs according to an embodiment of the present invention;
FIG. 4 is a graph of modulation transfer function at 80 line pairs according to an embodiment of the present invention;
FIG. 5 is a graph of field curvature and distortion for an embodiment of the present invention;
FIG. 6 is a RayFan diagram of an embodiment of the invention;
FIG. 7 is a graph of illuminance in accordance with an embodiment of the present invention.
In the figure:
front group a A, C diaphragm C, B rear group B, A1 biconvex positive lens a1, a2 meniscus positive lens a2, A3 biconcave negative lens A3, a4 meniscus positive lens a4, B1 biconcave negative lens B1, B2 biconvex positive lens B2, B3 meniscus positive lens B3, B4 meniscus negative lens B4.
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 the lens, a front group a with positive focal power, a diaphragm C, and a rear group B with negative focal power are sequentially disposed along a left-to-right incident direction of light, where the front group a includes a cemented group consisting of a double convex positive lens a1, a meniscus positive lens a2, a double concave negative lens A3, and a meniscus positive lens a 4; the rear group B comprises a gluing group consisting of a double-concave negative lens B1, a double-convex positive lens B2, a meniscus positive lens B3 and a meniscus negative lens B4 which are sequentially arranged.
In the present embodiment, the meniscus positive lens a2 of the lens front group a is concave-curved to the diaphragm side; the biconcave negative lens A3 and the meniscus positive lens A4 of the lens front group A form a bonding sheet, and the bonding surface of the bonding sheet is bent to the diaphragm side; the concave surface of the meniscus positive lens A4 of the front lens group A is bent to the diaphragm side; the concave surface of a biconvex positive lens B2 of the lens rear group B is bent to the diaphragm side; the positive meniscus lens B3 and the negative meniscus lens B4 of the rear lens group B form a cemented sheet, and the cemented surface of the cemented sheet bends to the diaphragm side; the concave surface of a meniscus positive lens B3 of the rear lens group B is bent to the diaphragm side; the meniscus negative lens B4 of the rear lens group B is curved concavely to the diaphragm side.
In this embodiment, the biconvex positive lens a1 of the lens front group a is made of flint glass; the meniscus positive lens A2 is made of crown glass; the meniscus positive lens A4 is made of flint glass; the biconcave negative lens A3 is made of flint glass; the double-convex positive lens B2 of the lens rear group B is made of flint glass; the meniscus positive lens B3 is made of flint glass; the double-concave negative lens B1 is made of flint glass; the material adopted by the meniscus negative lens B4 is flint glass.
In this embodiment, the air gap between the lens double convex positive lens a1 and the meniscus positive lens a2 is 1.8mm, the air gap between the meniscus positive lens a2 and the double concave negative lens A3 is 1mm, the air gap between the meniscus positive lens a4 and the diaphragm C is 27.2mm, the air gap between the diaphragm C and the double concave negative lens B1 is 6.1mm, the air gap between the double concave negative lens B1 and the double convex positive lens B2 is 8.5mm, and the air gap between the double convex positive lens B2 and the meniscus positive lens B3 is 29.5 mm.
In the present embodiment, the air gap between the lens front group a and the rear group B is 33.3 mm.
In the present embodiment, the optical system constituted by the lens group achieves the following optical indexes:
numerical aperture NA = 0.05;
the optical back focus is not less than 22.9 mm;
working Distance Work Distance =111 mm;
magnification = 1.0;
the Optical Distortion is less than or equal to-0.006%;
the Object space Telecentricity Object Size Telecentricity is less than or equal to 0.015;
the Image space Telecentricity is less than or equal to 0.025;
the total optical length TTL is less than or equal to 139 mm;
the relative illumination is more than or equal to 99.5 percent (phi 11 mm);
image Size = Φ 11 mm;
in this embodiment, the double-sided telecentric lens has the following features: setting the focal length as f, and sequentially setting the focal lengths of the optical lenses from the object plane to the image plane as f 1-f 8; both have the following characteristics: f1/f = 0.01; f2/f = 0.025; f3/f = -0.005; f4/f = 0.006; f5/f = -0.004; f6/f = 0.01; f7/f = 0.008; f8/f = -0.01.
In this example, the parameters for each lens are shown in the following table:
in the embodiment, the performance index of the double-side telecentric lens indicates that the Optical Distortion of the double-side telecentric lens is less than or equal to-0.006 percent, the scheme of the invention is far smaller than the Distortion numerical values of the same object distance and the same multiplying power on the market at present, the image edge Distortion is effectively reduced, and the detection precision is further improved; according to the performance indexes of the double-side telecentric lens, the Object-side Telecentricity Object Size Telecentricity of the double-side telecentric lens is less than or equal to 0.015, which indicates that the Object-side chief ray of the lens is fully parallel to the optical axis and converges at the infinite Object-side position. Therefore, within the depth of field, no matter how the object distance changes, the ratio of the image space to the object space is constant, and the lens is provided with good capability of eliminating visual difference. The Image space Telecentricity of the bilateral telecentric lens is less than or equal to 0.025, which indicates that the Image space chief ray of the lens is fully parallel to the optical axis, and the convergence center of the Image space chief ray is infinitely distant from the Image space. Therefore, the lens has no color cast and other problems, and can ensure the uniformity of the light receiving area of the chip and make the image surface illumination more uniform. The total optical length TTL of the lens is less than or equal to 139mm according to the performance index parameters of the lens, and compared with a double-side telecentric lens on the market, the lens is small in length, small in size and light in weight, and the utilization rate of the lens in different detection fields is improved. The lens performance index parameters include: the relative illumination is more than or equal to 99.5 percent (phi 11 mm), the Size Image Size = phi 11mm, the relative illumination at the position of the maximum Image plane phi 11mm is close to hundred percent, a good illumination condition is provided for the detection process, and the brightness of the Image plane can be further improved by using a proper light source. According to the lens parameter table, the maximum half aperture of the front group of the lens is only 11.8mm, the maximum half aperture of the rear group of the lens is only 7.85mm, and the structure size of the outer wall of the lens is reduced due to the smaller outer diameter size of the lens, so that the lens is easier to process and assemble, and the lens is smaller and lighter.
In this embodiment, as can be seen from fig. 1, the double-sided telecentric lens is composed of eight spherical lenses, the front group adopts four positive focal power lens groups, the rear group adopts four negative focal power lens groups to realize the balance of focal powers, and the similar focal powers make the image space and the object space principal rays parallel to the optical axis, so as to realize the corresponding telecentric function. The double-convex positive lens A1 of the lens front group A is made of lanthanide materials, so that the spherical aberration of the lens can be reduced, and the correction of chromatic aberration can be realized. The meniscus positive lens A2 is made of crown materials, so that chromatic aberration of the lens can be effectively reduced, the concave surface of the meniscus positive lens A2 and the gluing surface of the gluing sheet consisting of the biconcave negative lens A3 and the meniscus positive lens A4 are both bent towards one side of the diaphragm, and introduction of spherical aberration can be effectively reduced. The double-concave negative lens B1 of the rear lens group B is made of flint material, so that the spherical aberration of the lens is reduced. Similarly, the gluing surfaces of the gluing sheets B3 and B4 of the rear lens group B are bent towards the diaphragm, so that the beam aberration of the rear lens group B inclined to the optical axis is reduced, and the effects of correcting spherical aberration can be achieved by matching B3 and B4 according to different refractive indexes. The astigmatism curvature of field can be well corrected under a small field of view, the lens can be normally used under high and low temperature environments through material optimization and improvement of the focal length of the sensitive film, the overall sensitivity of the lens is reduced through reasonable focal power distribution, and the productivity of the bilateral telecentric lens is improved.
In this embodiment, as can be seen from fig. 2, the modulation transfer function value of the double-sided telecentric lens is close to 0.8 at 30 line pairs, the transfer function value of the double-sided telecentric lens at 50 line pairs is 0.6 as can be seen from fig. 3, and the transfer function value of the double-sided telecentric lens at 80 line pairs is 0.4 as can be seen from fig. 4, where T, S respectively corresponds to the meridional transfer function value and the sagittal transfer function value, and the upper value thereof represents the size of the corresponding image plane. As can be seen from fig. 2, 3 and 4, the transfer functions are close to the diffraction limit, so that the lens has the advantages of large depth of field and good detection resolution.
In this embodiment, it can be seen from FIG. 5 that the distortion of the double-sided telecentric lens is within-0.006%, and the field distortion and the wavelength distortion are at a uniform level. Fig. 6 is a RayFan diagram of the lens, and it can be seen that the spherical aberration and other aberrations of the lens are all at a lower level, and the imaging quality of the lens is good. Fig. 7 is a graph of the illuminance of the lens, which shows that the illuminance of the lens is uniformly distributed at each position of the chip, and the brightness uniformity of the detection screen is ensured.
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 fixed-focus double-side telecentric optical lens is characterized in that: a front group A with positive focal power, a diaphragm C and a rear group B with negative focal power are sequentially arranged in an optical system of the lens along the incident direction of light rays from left to right, and the front group A consists of a bonding group consisting of a double convex positive lens A1, a meniscus positive lens A2, a double concave negative lens A3 and a meniscus positive lens A4 which are sequentially arranged; the rear group B consists of a gluing group consisting of a double-concave negative lens B1, a double-convex positive lens B2, a meniscus positive lens B3 and a meniscus negative lens B4 which are sequentially arranged; the concave surface of a meniscus positive lens A2 of the lens front group A is bent to the diaphragm side; the biconcave negative lens A3 and the meniscus positive lens A4 of the lens front group A form a bonding sheet, and the bonding surface of the bonding sheet is bent to the diaphragm side; the concave surface of the meniscus positive lens A4 of the front lens group A is bent to the diaphragm side; the positive meniscus lens B3 and the negative meniscus lens B4 of the rear lens group B form a cemented sheet, and the cemented surface of the cemented sheet bends to the diaphragm side; the concave surface of a meniscus positive lens B3 of the rear lens group B is bent to the diaphragm side; the concave surface of a meniscus negative lens B4 of the rear lens group B is bent to the diaphragm side; the double-convex positive lens A1 of the lens front group A is made of flint glass; the meniscus positive lens A2 is made of crown glass; the meniscus positive lens A4 is made of flint glass; the biconcave negative lens A3 is made of flint glass; the double-convex positive lens B2 of the lens rear group B is made of flint glass; the meniscus positive lens B3 is made of flint glass; the double-concave negative lens B1 is made of flint glass; the meniscus negative lens B4 is made of flint glass; the air gap between the lens double-convex positive lens A1 and the meniscus positive lens A2 is 1.8mm, the air gap between the meniscus positive lens A2 and the double-concave negative lens A3 is 1mm, the air gap between the meniscus positive lens A4 and the diaphragm C is 27.2mm, the air gap between the diaphragm C and the double-concave negative lens B1 is 6.1mm, the air gap between the double-concave negative lens B1 and the double-convex positive lens B2 is 8.5mm, and the air space between the double-convex positive lens B2 and the meniscus positive lens B3 is 29.5 mm; the air gap between the front lens group a and the rear lens group B was 33.3 mm.
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| CN201711302499.1A CN107884916B (en) | 2017-12-11 | 2017-12-11 | Fixed-focus bilateral telecentric optical lens |
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| CN201711302499.1A CN107884916B (en) | 2017-12-11 | 2017-12-11 | Fixed-focus bilateral telecentric optical lens |
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| CN109143548B (en) * | 2018-10-11 | 2023-11-28 | 佛山科学技术学院 | Long-working-distance high-resolution object image bilateral telecentric optical system |
| CN109164558B (en) * | 2018-10-11 | 2023-11-28 | 佛山科学技术学院 | Miniaturized object image bilateral 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 |
| CN111458853B (en) * | 2020-04-13 | 2022-04-15 | 苏州科技大学 | Small depth of field high resolution double telecentric optical lens |
| CN112213840B (en) * | 2020-07-22 | 2024-04-02 | 南阳利达光电有限公司 | High-definition lens applied to objective imaging system |
| CN113933978B (en) * | 2021-11-03 | 2023-03-21 | 广东奥普特科技股份有限公司 | 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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