阅读说明：本技术 用于镜片疵病检测的从广角到双远心变焦镜头系统 (-angle double telecentric zoom lens system for lens defect detection ) 是由 李琦 张合 向阳 董萌 王晓旭 闫帅 于 2019-11-19 设计创作，主要内容包括：本发明提供了一种用于镜片疵病检测的从广角到双远心变焦镜头系统,涉及机器视觉测量技术领域,解决了人工目测检查疵病效率低、成本高的技术问题。该变焦镜头系统,包括沿光轴方向设置的前固定组、变倍组、补偿组和后固定组,变倍组和补偿组为联动结构；通过变倍组和补偿组的同步远离或同步靠近能实现变焦镜头系统从大视场像方远心系统到物像方双远心系统的变换。本发明用于在线实时镜片疵病检测,利用前固定组和变焦像方远心系统相结合的方式改变物方视场,在不同倍档时可以用于不同视场的镜片疵病检测,全面提高镜片检测效率,保证检测准确度。(The invention provides lens defect detection-based system from angles to double telecentric zoom lenses, relates to the technical field of machine vision measurement, and solves the technical problems of low defect detection efficiency and high cost of manual visual inspection.)

The zoom lens system is characterized by comprising a front fixed group, a zoom group, a compensation group and a rear fixed group which are sequentially arranged from an object direction to an image direction, wherein the zoom group and the compensation group are in a linkage structure, and the zoom lens system can be changed from a large-view-field image space telecentric system to an object image space double telecentric system through synchronous distance or synchronous approach of the zoom group and the compensation group.

2. The -angle-to-double-telecentric zoom lens system for lens defect detection according to claim 1, wherein the zoom lens system has a field angle of 74 ° when it is in the large-field-of-view image-side telecentric system.

3. An -degree-double-telecentric zoom lens system for lens defect detection according to claim 1 or 2, wherein the front fixed group comprises a front cemented lens group and a front meniscus lens group, the front cemented lens group is a positive power lens group, the front meniscus lens group is a positive meniscus lens, and the convex surface faces the object space, the front cemented lens group comprises a -degree lens and a second lens, the -degree lens is a double convex lens, the second lens is a negative meniscus lens, the concave surface of the second lens faces the object space, and the convex surface of the -degree lens and the concave surface of the second lens are cemented.

4. The system according to claim 3, wherein said lens and said front meniscus lens are made of crown glass of low dispersion system, and said second lens is made of flint glass of high refractive index.

5. The system according to claim 1, 2 or 4, wherein the variable power group comprises a fourth lens, a fifth lens and a variable power cemented lens group, the variable power cemented lens group is a negative power lens group, the fourth lens and the fifth lens are negative meniscus lenses, the concave surfaces of the fourth lens and the fifth lens face the image side, the variable power cemented lens group comprises a sixth lens and a seventh lens, the sixth lens is a biconcave lens, and the seventh lens is a biconvex lens.

6. The system of claim 5, wherein the variable power group is linearly moved in the lens barrel by an amount of 1-48 mm.

7. An angle-double telecentric zoom lens system for lens defect detection according to claim 1, 2, 4 or 6, wherein the compensation group comprises an eighth lens, a compensation cemented lens group and an aperture stop, the compensation cemented lens group is a positive power lens group, the eighth lens is a double convex lens, the compensation cemented lens group comprises a ninth lens and a tenth lens, the ninth lens is a negative meniscus lens with the concave surface facing the image side, the tenth lens is a double convex lens, and the distance between the tenth lens and the aperture stop is 27.5-72.5 mm.

8. The system of claim 7, wherein the compensation group moves non-linearly in the lens barrel by an amount of 1-45 mm.

9. An angle-double telecentric zoom lens system for lens defect detection according to claim 1, 2, 4, 6 or 8, wherein the rear fixed group comprises a tenth lens and a rear cemented lens group, the rear cemented lens group is a positive power lens group, the tenth lens is a negative meniscus lens, the concave surface faces the object side, the rear cemented lens group comprises a twelfth lens and a thirteenth lens, the twelfth lens is a double convex lens, and the thirteenth lens is a double concave lens.

10. An -degree-of-freedom double telecentric zoom lens system for lens defect detection according to claim 1, 2, 4, 6 or 8, wherein the front fixed group is arranged in the lens barrel, the lens barrel is 40mm in length, the zoom group and the compensation group are both slidably arranged in the second lens barrel, the second lens barrel is 245mm in length, the rear fixed group is arranged in the third lens barrel, adjacent lens barrels are connected through threads, the distance from the third lens barrel to the image side is 20mm, and the distance from the lens barrel to the object side is 100 mm.

Technical Field

The invention relates to the technical field of machine vision measurement, in particular to zoom lens systems from degrees to double telecentricity for online lens defect detection.

Background

The detection of lens defects is which is the most important step in the lens production process, and under the background of widespread application of optical lenses , the requirement on the detection of lens defects is higher and higher, and the corresponding detection requirements are stricter and stricter.

The applicant has found that the prior art has at least the following technical problems:

at present, the optical lens processing enterprises mainly aim at manual visual detection, aiming at lens defects such as scratches, pocks, bubbles and the like, the limit resolution angle of human eyes is small, some defects cannot be detected, the detection efficiency is low, the labor cost is high, the detection standard is not , and the optical lens processing enterprises are easily influenced by artificial subjectivity.

Disclosure of Invention

The invention aims to provide double-telecentric zoom lens systems from angles (large view field image space) to an object image space for online real-time lens defect detection, so as to solve the technical problems of low defect detection efficiency and high cost of manual visual inspection in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme:

the zoom lens system from angle to double telecentricity for detecting lens defects changes the object space view field by combining the front fixed group and the zooming image space telecentric system, comprises the front fixed group, the zoom group, the compensation group and the rear fixed group which are sequentially arranged from the object space to the image space along the optical axis direction, wherein the zoom group and the compensation group are in a linkage structure, and the zoom lens system can be changed from the large view field image space telecentric system to the object image space double telecentric system by the synchronous distance or synchronous approach of the zoom group and the compensation group.

As a further improvement of the present invention, the zoom lens system has a field angle of 74 ° when it is in a large-field image-side telecentric system.

The zoom lens system provided by the invention has the advantages that the focal depth is large, the depth of focus is long, the object height is small, the defect details of a local single group of lenses can be detected, the small-field object space system can eliminate the error caused by inaccurate focusing of the object space, the telecentric degree of the image space is 0.02 degrees in two states, the telecentric system of the image space can eliminate the measurement error caused by inaccurate focusing of the image space, the backlight source irradiation is matched, the lens defect images with different sizes (the diagonal length of the whole lens is 150mm, the local object space field is 30mm) produced on line can be collected into a computer through the image system, the defect detection of the defects can be visually and clearly completed through image processing, the defect detection efficiency of workers is improved, and the detection accuracy of the traditional eye defect detection mode is guaranteed.

As a further improvement , all the surfaces of the lens groups in the zoom lens system are spherical or planar.

As a further improvement , the front fixed group includes a front cemented lens group and a front meniscus lens group, the front cemented lens group is a positive power lens group, the front meniscus lens group is a positive meniscus lens, and the convex surface of the front cemented lens group faces the object space, the front cemented lens group includes a th lens and a second lens, the th lens is a biconvex lens, the second lens is a negative meniscus lens, the concave surface of the second lens faces the object space, and the convex surface of the th lens is cemented with the concave surface of the second lens.

As a further improvement , the second lens element is connected with the front meniscus lens group by a spacer, and the distance is 7 +/-0.5 mm.

As a further improvement, the th lens and the front meniscus lens are both made of crown glass of a low dispersion system and the second lens is made of flint glass of a high refractive index.

As a further improvement, the abbe numbers (abbe number is the reciprocal abbe number) of the th lens and the front meniscus lens are 55.49 and 54.67, respectively.

As a further improvement of the invention at , the second lens has a refractive index of 1.69.

As a further improvement , the variable power group includes a fourth lens, a fifth lens and a variable power cemented lens group, the variable power cemented lens group is a negative focal power lens group, the fourth lens and the fifth lens are negative meniscus lenses, concave surfaces of the positive meniscus lenses face the image space, the variable power cemented lens group includes a sixth lens and a seventh lens, the sixth lens is a biconcave lens, and the seventh lens is a biconvex lens.

As a further improvement , the zoom group moves linearly in the lens barrel by the designed cam curve, and the movement is 1-48 mm.

As a further improvement , the compensation group comprises an eighth lens, a compensation cemented lens group and an aperture diaphragm, the compensation cemented lens group is a positive focal power lens group, the eighth lens is a double-convex lens, the compensation cemented lens group comprises a ninth lens and a tenth lens, the ninth lens is a negative meniscus lens, the concave surface of the ninth lens faces the image space, the tenth lens is a double-convex lens, and the distance between the tenth lens and the aperture diaphragm is 27.5-72.5 mm.

As a further improvement , the compensation group moves non-linearly in the lens barrel by the designed cam curve, and the movement is 1-45 mm.

As a further improvement, the rear fixing group includes a tenth lens and a rear cemented lens group, the rear cemented lens group is a positive power lens group, the tenth lens is a negative meniscus lens, and a concave surface faces an object space, the rear cemented lens group includes a twelfth lens and a thirteenth lens, the twelfth lens is a double convex lens, and the thirteenth lens is a double concave lens.

As a further improvement , the front fixing group is arranged in a lens barrel, the length of the lens barrel is 40mm, the zoom group and the compensation group are arranged in a second lens barrel in a sliding mode and slide back and forth in the lens barrel through designed cam curves, the length of the second lens barrel is 245mm, the rear fixing group is arranged in a third lens barrel, adjacent lens barrels are connected through threads, the distance from the third lens barrel to the image space is 20mm, and the distance from the lens barrel to the object space is 100 mm.

Compared with the existing fixed-focus -angle lens, the invention has the following advantages and positive effects:

1. the invention changes the object space view field by combining the front fixed group and the zooming image space telecentric system, can be used for detecting the lens defects of different view fields at different times, can focus to the object space double telecentric system from angle by moving the zooming group and the compensation group through the linkage of the motor double groups, detects the defects of the whole lens (4 x 8) at angle (74 degree of field angle), can locally detect the defect details of a single group of lenses at the time of small view field object space telecentric, has constant multiplying power of the object image double telecentric system under the required object distance, integrates the characteristics of the object space telecentric light path, has large depth of field and long focal depth, accurately measures the size of the defects, can eliminate the measurement error and the focusing error, can collect the online produced lens defect images into a computer through the image system in real time by being matched with the illumination of a backlight source, can visually and clearly complete the defect detection through the image processing, comprehensively improves the efficiency of workers, and ensures the detection accuracy.

2. The invention adopts a zooming structure of a mechanical compensation method, which comprises a front fixed group, a zooming group, a compensation group and a rear fixed group.

3. The zoom lens system achieves the zoom effect by adjusting the zoom group and the compensation group, the zoom group moves linearly, and the compensation group moves nonlinearly, so that the change from a large view field to object space telecentricity is realized.

4. The invention adopts crown glass with low dispersion coefficient, and the imaging is clearer when the dispersion coefficient is smaller.

5. The surface types of the lenses adopted by the invention are all spherical surfaces or planes, and no aspheric surface is introduced, so that the processing and adjusting difficulty is reduced, and the cost is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a zoom structure diagram from to double telecentric zoom lens system from to double telecentric for lens defect detection according to the present invention;

FIG. 2 is a diagram showing the variation of the zoom group and the compensation group in the zoom lens system from angle to double telecentric for detecting lens defects according to the present invention;

FIG. 3 is a schematic structural diagram of an angle -double telecentric zoom lens system for detecting lens defects according to the present invention.

In the figure, the lens comprises a front fixed group 1, a zoom group 2, a compensation group 3, a rear fixed group 4, a G1 lens lens, a G2 lens, a second lens 3 lens, a front meniscus lens, a G4 lens, a fourth lens, a G5 lens, a fifth lens, a G6 lens, a sixth lens, a G7 lens, a seventh lens, a G8 lens, an eighth lens, a G9 lens, a ninth lens, a G10 lens, a tenth lens, a G11 lens, a tenth lens, a G12 lens, a twelfth lens, a G13 lens, a thirteenth lens, a G14 lens and an aperture diaphragm.

Detailed Description

The technical solution of the present invention will be described in detail below to make the objects, technical solutions and advantages of the present invention clearer.

As shown in FIGS. 1-3, the invention provides zoom lens systems from angles to double telecentricity for lens defect detection, which change the object side view field by combining a front fixed group and a zooming image side telecentric system, and comprise a front fixed group 1, a zoom group 2, a compensation group 3 and a rear fixed group 4 which are arranged along the optical axis direction from the object side to the image side in sequence, wherein the zoom group 2 and the compensation group 3 are in a linkage structure, and the zoom lens system can be changed from a large-view-field image side telecentric system to an object side double telecentric system by synchronous distance or synchronous approach of the zoom group 2 and the compensation group 3.

The field angle of the zoom lens system is 74 degrees when the zoom lens system is in the large-field image-side telecentric system.

The zoom lens system provided by the invention has the advantages that the focal depth is large, the depth of focus is long, the object height is small, the defect details of a local single group of lenses can be detected, the small-field object space system can eliminate the error caused by inaccurate focusing of the object space, the telecentric degree of the image space is 0.02 degrees in two states, the telecentric system of the image space can eliminate the measurement error caused by inaccurate focusing of the image space, the backlight source irradiation is matched, the lens defect images with different sizes (the diagonal length of the whole lens is 150mm, the local object space field is 30mm) produced on line can be collected into a computer through the image system, the defect detection of the defects can be visually and clearly completed through image processing, the defect detection efficiency of workers is improved, and the detection accuracy of the traditional eye defect detection mode is guaranteed.

As an optional implementation manner, all the surfaces of the lens groups in the zoom lens system are spherical or planar, and no aspheric surface is introduced, so that the processing and adjusting difficulty is reduced, and the cost is reduced.

The front fixed group 1 comprises a front cemented lens group and a front meniscus lens group G3, the front cemented lens group is a positive focal power lens group, the front meniscus lens group G3 is a positive meniscus lens, the convex surface of the front cemented lens group faces the object space, the front cemented lens group comprises a th lens G1 and a second lens G2, the th lens G1 is a double convex lens, the second lens G2 is a negative meniscus lens, the concave surface of the second lens G2 faces the object space, and the convex surface of the th lens G1 is cemented and connected with the concave surface of the second lens G2.

The second lens G2 and the front meniscus lens group G3 are connected by a space ring, and the distance is 7 +/-0.5 mm.

, the G1 and the front meniscus G3 are made of crown glass of low dispersion system, and the second G2 is made of flint glass of high refractive index.

Further , the abbe numbers (the abbe numbers are reciprocal abbe numbers) of the th lens G1 and the front meniscus lens G3 are 55.49 and 54.67, respectively.

The refractive index of the second lens G2 was 1.69.

As an alternative embodiment, the variable power group 2 includes a fourth lens G4, a fifth lens G5, and a variable power cemented lens group, which is a negative power lens group; the fourth lens element G4 and the fifth lens element G5 are both negative meniscus lenses, the concave surfaces of which face the image, the variable power cemented lens group includes a sixth lens element G6 and a seventh lens element G7, the sixth lens element G6 is a biconcave lens element, and the seventh lens element G7 is a biconvex lens element.

The variable magnification group 2 moves linearly in the lens barrel through a designed cam curve, and the moving amount is 1-48 mm.

The compensation group 3 comprises an eighth lens G8, a compensation cemented lens group and an aperture diaphragm G14, and the compensation cemented lens group is a positive focal power lens group; the eighth lens element G8 is a biconvex lens, the compensating cemented lens group includes a ninth lens element G9 and a tenth lens element G10, the ninth lens element G9 is a negative meniscus lens element, and the concave surface faces the image; the tenth lens G10 is a biconvex lens; the distance between the tenth lens G10 and the aperture stop G14 is 27.5-72.5 mm. When the compensation group 3 moves back and forth, the distance between the tenth lens G10 and the aperture stop G14 is increased or decreased, the maximum distance is 72.5mm, and the minimum distance is 27.5 mm. The movement of the zoom group 2 and the compensation group 3 is a stepped movement mode, and comprises three stages of movement gears.

The compensation group 3 moves in the lens barrel in a non-linear way through a designed cam curve, and the moving amount is 1-45 mm.

The rear fixed group 4 comprises a tenth lens G11 and a rear cemented lens group, the rear cemented lens group is a positive power lens group, the tenth lens G11 is a negative meniscus lens, the concave surface faces the object space, the rear cemented lens group comprises a twelfth lens G12 and a thirteenth lens G13, the twelfth lens G12 is a double convex lens, and the thirteenth lens G13 is a double concave lens.

The front fixing group 1 is arranged in a th lens barrel, the length of the th lens barrel is 40mm, the zoom group 2 and the compensation group 3 are arranged in a second lens barrel in a sliding mode and slide back and forth in the lens barrel through designed cam curves, the length of the second lens barrel is 245mm, the rear fixing group 4 is arranged in a third lens barrel, adjacent lens barrels are connected through threads, the distance from the third lens barrel to an image space is 20mm, and the distance from the th lens barrel to an object space is 100 mm.