CN116299965A - Moke lens and industrial camera - Google Patents

Abstract

The invention provides a kind of lens of the poloxamer used for industrial camera, comprising: the lens comprises a first lens group, a second lens group and a third lens group which are sequentially arranged from an object side to an image side along an optical axis of the lens, wherein the first lens group, the second lens group and the third lens group are all positive focal power lens groups; the clear aperture of the second lens group is used as an aperture diaphragm of the poloxamer lens, the ratio of the clear aperture of the third lens group to the clear aperture of the first lens group is 0.6-1.1, and the number of lenses in the first lens group is equal to the number of lenses in the third lens group. The invention optimally designs the poloxamer lens for industrial 3D measurement, meets the requirement of clear imaging of the whole field of view of the target, and has the characteristics of small volume, high resolution and low distortion.

Description

Moke lens and industrial camera

Technical Field

The present disclosure relates to the technical field of optical systems, and in particular, to a camera lens for an industrial camera and an industrial camera.

Background

With the development of image processing and computer technology, 3D non-contact measurement technology is on stage. It has the advantages of high precision, high speed, high stability, etc. The lens is an important component, the resolution and distortion can influence the reconstruction precision of the 3D point cloud, and the traditional lens is difficult to clearly image the whole field of view of the target due to the limitation of a near-large-far-small imaging rule and a depth of field.

The application of the law of the Mooney in the imaging light path can obtain a very large clear range. In the optical path of the poloxamer, the main plane of the lens, the target plane to be imaged clearly and the plane on which the surface of the CMOS chip is positioned need to be intersected. Different from the traditional imaging light path, in order to realize the imaging effect of the optical path of the poloxamer, the optical axis of the lens is not vertical to the surface of the CMOS chip any more, but a certain included angle exists.

Whether it be an industrial camera or a CMOS module, the chip surface is typically provided with cover glass that takes care of protection, the cover glass being parallel to the CMOS chip surface. However, the cover glass causes spherical aberration to the converging light beams, and coma aberration and astigmatism are caused when the cover glass is not perpendicular to the optical axis of the lens, so that the imaging quality in the two directions of meridian and sagittal in the optical path is greatly different. The contrast ratio of the horizontal direction and the vertical direction in the image is very different, which is unfavorable for focusing the light path and the actual imaging effect. The thicker the cover plate glass or the larger the size of the CMOS target surface, the larger the difference of imaging quality is, and the more unfavorable the image is to truly and accurately present object information.

If the cover plate glass is perpendicular to the optical axis of the lens in the optical path of the optical fiber, the cover plate glass is not parallel to the surface of the CMOS chip, an angular sealing structure for fixing the cover plate glass is specially designed, and the cover plate glass on the surface of the CMOS chip is dismounted and then is mounted on the angular sealing structure again, so that the sealing and the protection of the CMOS chip can be realized. The common CMOS chip requires the cover glass to be disassembled and assembled in a hundred-grade clean environment, the construction and maintenance of the hundred-grade clean environment are high, and the disassembly and assembly of the cover glass require professional operators. The angle between the surface of the CMOS chip and the cover plate glass depends on the magnification and the lens angle of the optical path of the optical fiber, and a general angle cannot be designed generally.

In summary, the cover glass parallel to the surface of the CMOS chip is more convenient and feasible in practical application, although the imaging quality is significantly reduced.

The matters in the background section are only those known to the public inventor and do not, of course, represent prior art in the field.

Disclosure of Invention

In view of one or more of the drawbacks of the prior art, the present invention provides a lens assembly for an industrial camera, comprising: a first lens group, a second lens group and a third lens group which are arranged in order from an object side to an image side along an optical axis of the lens,

the first lens group, the second lens group and the third lens group are all positive focal power lens groups;

the clear aperture of the second lens group is used as an aperture diaphragm of the poloxamer lens, the ratio of the clear aperture of the third lens group to the clear aperture of the first lens group is 0.6-1.1, and the number of lenses in the first lens group is equal to the number of lenses in the third lens group.

According to one aspect of the invention, the focal length of the poloxamer lens is 40-70mm, the working wave band is 380-780 nm, the ratio TTL/IH of the total optical length to the half height of the image space is 3.0-7.5mm, and the included angle between the light-transmitting cover plate and the optical axis of the lens is 46-80 degrees.

According to one aspect of the present invention, wherein a focal length of the first lens group is 70 to 100mm, a focal length of the second lens group is 135 to 165mm, a focal length of the third lens group is 25 to 55mm, an air space between the first lens group and the second lens group on the lens optical axis is 3 to 8mm, and an air space between the second lens group and the third lens group on the lens optical axis is 6 to 11mm.

According to an aspect of the present invention, wherein the first lens group includes three spherical lenses, the second lens group includes two spherical lenses, and the third lens group includes three spherical lenses, each of which has a front surface radius of curvature and a rear surface radius of curvature greater than 0.

According to one aspect of the invention, wherein the second lens group comprises: a fourth lens and a fifth lens arranged in order from an object side to an image side along an optical axis of the lens,

the fourth lens has negative focal power, the object side surface is a convex surface, the image side surface is a concave surface, and the image side surface of the fourth lens is used as an aperture diaphragm of the poloxamer lens;

the fifth lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

wherein the front surface radius of curvature of the fifth lens is larger than the rear surface radius of curvature.

According to one aspect of the invention, wherein the first lens group comprises: a first lens, a second lens and a third lens which are arranged in order from the object side to the image side along the optical axis of the lens,

the first lens has positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

the second lens has positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

the third lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

wherein the radius of curvature of the front surface of the third lens is larger than the radius of curvature of the rear surface.

According to one aspect of the present invention, wherein the second lens and the third lens are cemented lenses, the second lens and the third lens are made of materials different in refractive index and abbe number.

According to one aspect of the invention, the abbe number difference between the second lens and the third lens is greater than 10.

According to an aspect of the present invention, wherein the third lens group includes: a sixth lens, a seventh lens, and an eighth lens arranged in order from an object side to an image side along an optical axis of the lens,

the sixth lens is provided with negative focal power, the object side surface is a concave surface, and the image side surface is a convex surface;

the seventh lens has negative focal power, the object side surface is concave, and the image side surface is convex;

the eighth lens has positive focal power, the object side surface is a convex surface, and the image side surface is a convex surface;

wherein the front surface radius of curvature of the eighth lens is larger than the rear surface radius of curvature.

According to one aspect of the present invention, wherein the sixth lens and the seventh lens are cemented lenses, the sixth lens and the seventh lens are made of materials different in refractive index and abbe number.

According to one aspect of the invention, the abbe number difference between the sixth lens and the seventh lens is greater than 10.

The invention also relates to an industrial camera comprising:

a lens of a poloxamer as described above;

a photosensitive element; and

the light-transmitting cover plate covers the photosensitive element, is parallel to the imaging plane of the photosensitive element and is not perpendicular to the optical axis of the lens.

The sand lens is optimally designed aiming at the inclined light-transmitting cover plate, the light-transmitting cover plate is arranged in parallel with the surface of the photosensitive element and is not perpendicular to the optical axis of the lens, and the sand lens can be adapted to a 1.4' large-target-surface CMOS chip, so that the clear range is enlarged in industrial 3D measurement, and the accurate measurement of depth is realized. The lens is ensured to meet the requirement of clear imaging of the whole field of view of the target, and has the characteristics of small volume, high resolution and low distortion.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure. In the drawings:

FIG. 1 shows a schematic diagram of the principles of Mooney imaging;

FIG. 2 shows a schematic view of a lens of an embodiment of the invention;

FIG. 3a shows a schematic view of a poloxamer lens comprising eight lenses according to one embodiment of the present invention;

FIG. 3b shows a schematic view of an industrial camera configuration using the poloxamer lens of FIG. 3 a;

FIG. 4 shows an optical speckle pattern of the poloxamer lens of FIG. 3 a;

FIG. 5 shows a schematic diagram of the modulation transfer function MTF of the FIG. 3a lens;

fig. 6 shows a field curvature and astigmatism schematic of the poloxamer lens of fig. 3 a.

Detailed Description

Hereinafter, only certain exemplary embodiments are briefly described. As will be recognized by those of skill in the pertinent art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be fixedly connected, detachably connected, or integrally connected, and may be mechanically connected, electrically connected, or may communicate with each other, for example; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is less level than the second feature.

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

The sand lens is optimally designed aiming at the inclined light-transmitting cover plate, the light-transmitting cover plate is arranged in parallel with the surface of the photosensitive element and is not perpendicular to the optical axis of the lens, and the sand lens can be adapted to a 1.4' large-target-surface CMOS chip, so that the clear range is enlarged in industrial 3D measurement, and the accurate measurement of depth is realized. The lens is ensured to meet the requirement of clear imaging of the whole field of view of the target, and has the characteristics of small volume, high resolution and low distortion.

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.

Fig. 1 shows a schematic diagram of the principle of imaging of the law of the poloxamer, according to which, when the extension lines of the target plane, the lens main plane and the CMOS chip plane intersect at a line, and when the intersecting line is unique, the whole inclined target visual field range can be clearly imaged, and the following sham relation is required to be satisfied:

tanα/tanβ＝b’/a’

wherein, alpha is the included angle between the target plane and the optical axis of the lens, beta is the included angle between the CMOS chip plane and the optical axis of the lens, a 'is the object distance of the point D on the optical axis of the lens, b' is the image distance of the point D on the optical axis, and b '/a' is the magnification of the lens.

The included angle beta between the plane of the CMOS chip and the optical axis of the lens needs to satisfy the following relation:

where f' is the focal length of the lens.

According to the law of the above-mentioned Mooney, the invention sets up lens, transparent cover plate and photosensitive element sequentially, wherein the transparent cover plate is used for protecting the photosensitive element, for example CMOS chip, and set up parallel with surface of the photosensitive element.

FIG. 2 shows a schematic view of a juvenile camera of one embodiment of the present invention, a juvenile camera for an industrial camera, comprising: the lens comprises a first lens group 1, a second lens group 2 and a third lens group 3 which are sequentially arranged from an object side to an image side along an optical axis of the lens, wherein the first lens group 1, the second lens group 2 and the third lens group 3 are all positive focal power lens groups.

Wherein the clear aperture of the second lens group 2 is used as an aperture stop of the poloxamer lens, the ratio of the clear aperture of the third lens group 3 to the clear aperture of the first lens group 1 is 0.6-1.1, and the number of lenses in the first lens group 1 is equal to the number of lenses in the third lens group 3.

The first lens group 1 is used to collect light energy so that information of the target area is fully entered into the camera imaging system. The first lens group 1 is a positive power lens group, and includes at least one lens, and may be all spherical lenses, all aspherical lenses, or both spherical lenses and aspherical lenses. The aspherical lens can not only effectively eliminate spherical aberration and other forms of aberration generated by the lens, but also can be used for compensating distortion aberration. In an industrial lens, various aberrations must be corrected, and only spherical lenses are used for correction, so that not only is the number of lens combinations large, but also the technical requirements on the lens are high, and sometimes the aberrations cannot be corrected to meet the performance requirements. The spherical lens in the lens combination is replaced by an aspherical lens, so that the spherical aberration caused by the spherical lens in the collimation and focusing system can be obviously corrected. Alternatively, the first lens group 1 includes an aspherical lens, and by adjusting the curve constant and the aspherical coefficient, the optical quality can be improved, the system stability can be improved, and the overall cost can be reduced. If the first lens group 1 includes a plurality of lenses, the plurality of lenses may be double-split lenses or cemented lenses, which is not limited in the present invention.

The second lens group 2 is arranged between the first lens group 1 and the third lens group 3, plays a role of an aperture diaphragm of the lens, can reduce aberration of the lens, improves imaging resolution, can limit clear aperture, and controls the size of the light flux of the whole lens. The second lens group 2 is a positive power lens group, and includes at least one lens, and may be all spherical lenses, all aspherical lenses, or both spherical lenses and aspherical lenses. The aspherical lens can not only effectively eliminate spherical aberration and other forms of aberration generated by the lens, but also can be used for compensating distortion aberration. Optionally, the second lens group 2 includes an aspherical lens, and by adjusting the curved surface constant and the aspherical coefficient, the optical quality can be improved, the system stability can be improved, and the overall cost can be reduced. If the second lens group 2 includes a plurality of lenses, the plurality of lenses may be double-split lenses or cemented lenses, which is not limited in the present invention.

The third lens group 3 condenses the light beams of the respective fields of view onto the surface of the photosensitive element, and is used to correct aberrations. The third lens group 3 is a positive power lens group, and includes at least one lens, and may be all spherical lenses, all aspherical lenses, or both spherical lenses and aspherical lenses. The aspherical lens can not only effectively eliminate spherical aberration and other forms of aberration generated by the lens, but also can be used for compensating distortion aberration. Optionally, the third lens group 3 includes an aspherical lens, and by adjusting a curved surface constant and an aspherical coefficient, it is possible to improve optical quality, improve system stability, and reduce overall cost. If the third lens group 3 includes a plurality of lenses, the plurality of lenses may be double-split lenses or cemented lenses, which is not limited in the present invention.

The clear aperture of the second lens group 2 is used as an aperture diaphragm of the poloxamer lens, and the ratio of the clear aperture of the third lens group 3 to the clear aperture of the first lens group 1 is 0.6-1.1. Preferably, the ratio of the clear aperture of the third lens group 3 to the clear aperture of the first lens group 1 ranges between 0.71 and 1.0.

The number of lenses in the first lens group 1 and the number of lenses in the third lens group 3 are equal. Preferably, the total lens number of the lens assembly is symmetrically arranged on two sides of a first surface, and the first surface is a surface of one lens of the second lens group 2. For example, the first lens group 1 includes four lenses, the second lens group 2 includes two lenses, the third lens group 3 includes four lenses, the first surface is a rear surface of a first lens in the second lens group 2 or is a front surface of a second lens, five lenses are respectively provided on both sides of the first surface, that is, one side of the first surface is the four lenses in the first lens group 1 and the first lens in the second lens group 2, and the other side of the first surface is the second lens in the second lens group 2 and the four lenses in the third lens group 3. Preferably, the number of lenses in the first lens group 1 and the second lens group 2 is 3 or more.

The lens material is colorless optical glass and optical plastic. The optical plastic has low cost, easy processing of aspheric surface and light weight in mass production. The optical glass has stable mechanical property and thermal property, and can eliminate chromatic aberration and improve imaging quality through the combination of different refractive indexes and Abbe numbers. Industrial robots are used in a variety of environments and require high environmental temperature stability. Preferably, the spherical lens may use optical glass, and the aspherical lens may use optical plastic. Preferably, the lenses in the first lens group 1 are all optical glass.

According to a preferred embodiment of the invention, the focal length of the lens is 40-70mm, the working wave band is 380-780 nm, the ratio TTL/IH of the total optical length to the half height of the image space is 3.0-7.5mm, and the included angle between the light-transmitting cover plate and the optical axis of the lens is 46-80 degrees.

The industrial camera comprises a photosensitive element and a light-transmitting cover plate, wherein the light-transmitting cover plate covers the photosensitive element and is arranged parallel to the surface of the photosensitive element, and the light-transmitting cover plate is not perpendicular to the optical axis of the lens. Preferably, the focal length of the lens is 40-60mm, the working wave band is 390-485 nm, the ratio TTL/IH of the total optical length to the half height of the image space is 3.4-6.9mm, and the included angle between the light-transmitting cover plate and the optical axis of the lens is 51-76 degrees.

According to a preferred embodiment of the present invention, wherein the focal length of the first lens group 1 is 70 to 100mm, the focal length of the second lens group 2 is 135 to 220mm, preferably 190 to 210, the focal length of the third lens group 3 is 25 to 55mm, the air space between the first lens group 1 and the second lens group 2 on the lens optical axis is 3 to 8mm, and the air space between the second lens group 2 and the third lens group 3 on the lens optical axis is 6 to 11mm.

In one embodiment, the key parameters of the poloxamer lens are as shown in table 1:

TABLE 1

Focal length (mm)	F-number	Visual field (mm)	Target surface (mm)
				38～59	2.0～5.0	107～142	20～24

According to a preferred embodiment of the present invention, wherein the first lens group 1 comprises three lenses, the second lens group 2 comprises two lenses, and the third lens group 3 comprises three lenses.

According to a preferred embodiment of the present invention, wherein the first lens group 1 comprises: the first lens, the second lens and the third lens are arranged in order from the object side to the image side along the optical axis of the lens. The first lens has positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the second lens has positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the third lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface.

According to a preferred embodiment of the present invention, wherein the second lens group 2 comprises: a fourth lens and a fifth lens which are sequentially arranged from an object side to an image side along an optical axis of the lens, wherein the fourth lens has negative focal power, the object side is a convex surface, the image side is a concave surface, and the image side of the fourth lens is used as an aperture stop of the poloxamer lens; the fifth lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface.

According to a preferred embodiment of the present invention, wherein the third lens group 3 comprises: a sixth lens, a seventh lens and an eighth lens which are sequentially arranged from an object side to an image side along an optical axis of the lens, wherein the sixth lens has negative focal power, the object side is a concave surface, and the image side is a convex surface; the seventh lens has negative focal power, the object side surface is concave, and the image side surface is convex; the eighth lens has positive focal power, and the object side surface is a convex surface and the image side surface is a convex surface.

FIG. 3a is a schematic view of each lens in a lens assembly according to an embodiment of the present invention, wherein the lens assembly comprises eight lenses, and the first lens group comprises three lenses, a first lens G1, a second lens G2 and a third lens G3 in order from an object side to an image side; the second lens group comprises two lenses, namely a fourth lens G4 and a fifth lens G5 in sequence from the object side to the image side; the third lens group includes three lenses, in order from the object side to the image side, a sixth lens G6, a seventh lens G7, and an eighth lens G8.

With continued reference to fig. 3a, the surface shapes of the individual lenses are in order: g1 is a convex-concave lens, G2 is a convex-concave lens, G3 is a convex-concave lens, G2 and G3 are cemented lenses, G4 is a convex-concave lens and plays a role of an aperture stop, G5 is a convex-concave lens, G6 is a concave-convex lens, G7 is a concave-convex lens, G6 and G7 are cemented lenses, and G8 is a biconvex lens.

With continued reference to fig. 3a, the air spacing between the lenses is in turn: the distance between the air spaces of the G1 lens and the G2 lens on the optical axis is 0-2; the G2 lens and the G3 lens are cemented lenses, so that distortion can be counteracted; the distance between the air gap of the G3 lens and the G4 lens on the optical axis is 3-6; the distance between the air gap of the G4 lens and the air gap of the G5 lens on the optical axis is 0-2; the distance between the air gap of the G5 lens and the air gap of the G6 lens on the optical axis is 6-10; the G6 lens and the G7 lens are cemented lenses, so that distortion can be counteracted; the distance between the air spaces of the G7 lens and the G8 lens on the optical axis is 0-2, and the units are millimeter.

According to a preferred embodiment of the present invention, wherein the first lens group includes three spherical lenses, the second lens group includes two spherical lenses, and the third lens group includes three spherical lenses, each of which has a front surface radius of curvature and a rear surface radius of curvature greater than 0.

According to a preferred embodiment of the present invention, the radius of curvature of the front surface of the third lens G3 is larger than the radius of curvature of the rear surface.

According to a preferred embodiment of the present invention, the front surface radius of curvature of the fifth lens G5 is larger than the rear surface radius of curvature.

According to a preferred embodiment of the present invention, the front surface radius of curvature of the eighth lens G8 is larger than the rear surface radius of curvature.

With continued reference to fig. 3a, each lens includes a front surface facing the object side and a rear surface facing the image side, the radii of curvature of the respective lenses being in order: the curvature radius of the front surface of the G1 lens is 26-29, and the curvature radius of the rear surface is 76-80; the radius of curvature of the front surface of the G2 lens is 17-20, and the radius of curvature of the rear surface is 192-195; the curvature radius of the front surface of the G3 lens is 192-195, and the curvature radius of the rear surface is 13-16; the curvature radius of the front surface of the G4 lens is 30-33, and the curvature radius of the rear surface is 55-58; the curvature radius of the front surface of the G5 lens is 16-19, and the curvature radius of the rear surface is 11-14; the curvature radius of the front surface of the G6 lens is 9-12, and the curvature radius of the rear surface is 7-10; the curvature radius of the front surface of the G7 lens is 7-10, and the curvature radius of the rear surface is 13-16; the radius of curvature of the front surface of the G8 lens is 78-81, and the radius of curvature of the rear surface is 29-32, all in millimeters.

With continued reference to fig. 3a, the center thickness of each lens is, in order: the center thickness of the G1 lens is 3-5; the center thickness of the G2 lens is 3-5; the center thickness of the G3 lens is 2-4; the center thickness of the G4 lens is 2-4; the center thickness of the G5 lens is 5-7; the center thickness of the G6 lens is 3-5; the center thickness of the G7 lens is 2-4; the center thickness of the G8 lens is 5-7 mm.

With continued reference to fig. 3a, the air spacing between the lenses is in turn: the distance between the air spaces of the G1 lens and the G2 lens on the optical axis is 0-2; the G2 lens and the G3 lens are cemented lenses; the distance between the air gap of the G3 lens and the G4 lens on the optical axis is 3-6; the distance between the air gap of the G4 lens and the air gap of the G5 lens on the optical axis is 0-2; the distance between the air gap of the G5 lens and the air gap of the G6 lens on the optical axis is 6-10; the G6 lens and the G7 lens are cemented lenses; the distance between the air spaces of the G7 lens and the G8 lens on the optical axis is 0-2, and the units are millimeter.

With continued reference to fig. 3a, the optical power of each lens is, in order: the focal power of the G1 lens is 61-63; the focal power of the G2 lens is 28-30; the focal power of the G3 lens is-18 to-20; the focal power of the G4 lens is 85-87; the focal power of the G5 lens is-105 to-107; the focal power of the G6 lens is-20 to-22; the focal power of the G7 lens is 33-35; the optical power of the G8 lens is 33-35, and the units are millimeter.

According to a preferred embodiment of the present invention, the second lens G2 and the third lens G3 are cemented lenses, and the second lens G2 and the third lens G3 are made of materials having different refractive indexes and abbe numbers.

According to a preferred embodiment of the present invention, the abbe number difference between the second lens G2 and the third lens G3 is greater than 10.

According to a preferred embodiment of the present invention, wherein the sixth lens G6 and the seventh lens G7 are cemented lenses, the sixth lens G6 and the seventh lens G7 are made of materials having different refractive indexes and abbe numbers.

According to a preferred embodiment of the present invention, the abbe number difference between the sixth lens G6 and the seventh lens G7 is greater than 10.

With continued reference to fig. 3a, the optical parameters of each lens are, in order: the refractive index of the G1 lens is 1.6-1.7, and the Abbe number is 60-63; the refractive index of the G2 lens is 1.6-1.7, and the Abbe number is 60-63; the refractive index of the G3 lens is 1.7-1.8, and the Abbe number is 33-36; the refractive index of the G4 lens is 1.7-1.8, and the Abbe number is 33-36; the refractive index of the G5 lens is 1.9-2.0, and the Abbe number is 16-19; the refractive index of the G6 lens is 1.5-1.6, and the Abbe number is 63-66; the refractive index of the G7 lens is 1.6-1.7, and the Abbe number is 37-40; the refractive index of the G8 lens is 1.6-1.7, and the Abbe number is 60-63.

In summary, the lens of fig. 3a is composed of eight lenses, and each lens or lens group includes a specific functional emphasis, so that the performance parameters are more optimized. Two sets of cemented lenses were used: the first group of cemented lenses includes a G2 lens and a G3 lens, and the second group of cemented lenses includes a G6 lens and a G7 lens. The two lenses in each group are made of two different glass materials, so that the magnification of an imaged image cannot be changed, and the two glass combinations can offset chromatic aberration caused by the properties of the lenses, so that the lens can be better applied to short wave bands. For example, the G2 lens in the first group of cemented lenses is crown glass, the G3 lens is flint glass, and the refractive index and the Abbe number of the two optical glasses are different, so that chromatic aberration can be eliminated, and imaging quality can be improved. Crown glasses are optical glasses with low refractive index and high abbe number. Crown-type optical glasses are classified into fluorine crown (FK), light crown (QK), phosphorus crown (PK), dense phosphorus crown (ZPK), crown (K), dense crown (ZK), barium crown (BaK), lanthanum crown (LaK), titanium crown (TiK), and Tercrown (TK), etc. Flint glass is an optical glass having a high refractive index and a low abbe number. Flint optical glasses are classified into light flint (QF), flint (F), heavy flint (ZF), barium flint (BaF), heavy barium flint (ZBaF), lanthanum flint (LaF), heavy lanthanum flint (ZLaF), titanium flint (TiF), crown flint (KF), and special flint (TF), and the like. They are distributed in different areas in the image of refractive index versus dispersion coefficient. The invention does not limit the lens material, and only ensures that the cemented lens group adopts materials with different refractive indexes and Abbe numbers, and the cemented lens group is within the protection scope of the invention.

The two lenses in the cemented lens are coaxial, which allows the light rays to cancel the distortion effects of the lens itself to the maximum extent upon incidence and emergence. The two groups of cemented lenses are mainly responsible for balancing the overall distortion of the lens, and are matched with each other, so that the final distortion of the lens can be offset to the greatest extent. The G4 lens functions as an aperture stop, and the G5 lens following it can effectively cancel out the aberration of the first lens group, and the optical imaging system composed of the eight lenses is an approximately symmetrical system with respect to the aperture stop position, for example, the number of lenses of the first lens group and the third lens group is the same, or the number of lenses on both sides of the first surface is the same, or the like. By means of the adjustment of the approximately symmetrical structure, aberration correction capability of the optical imaging system can be effectively improved, and astigmatism, coma aberration and spherical aberration caused by the inclined arrangement of the light-transmitting cover plate in the optical path of the optical imaging system are effectively reduced.

The invention also relates to an industrial camera comprising: the optical transmission cover plate covers the photosensitive element, is parallel to the imaging plane of the photosensitive element and is not perpendicular to the optical axis of the optical transmission lens.

Fig. 3b shows a schematic diagram of an industrial camera using the poloxamer lens of fig. 3a, the industrial camera comprising the poloxamer lens, a photosensitive element and a light-transmitting cover plate. The object side inclined surface of the lens represents a target plane, the two inclined surfaces of the image side of the lens represent a transparent cover plate and a photosensitive element surface in sequence, the transparent cover plate is a glass cover plate, the photosensitive element is a CMOS chip, and the glass cover plate is parallel to the CMOS chip surface, namely an imaging plane and is not perpendicular to the optical axis of the lens.

The lens comprises eight lenses, wherein the G2 lens and the G3 lens are cemented lenses, so that distortion can be counteracted; the G6 lens and the G7 lens are cemented lenses, so that distortion can be counteracted; the G1 lens and the G8 lens can reduce aberration caused by tilting of the light-transmitting cover plate. The G4 lens functions as an aperture stop, and the G5 lens can cancel out aberration of the first lens group.

In the embodiment, the working distance of the poloxamer lens is 260nm, the diameter of the entrance pupil is 20, and the working wave band is 400nm-480nm.

Fig. 4 shows an optical speckle pattern of the lens of fig. 3a, wherein OBJ is the object field, IMA is the image field, and the units are millimeters. The RMS RADIUS and GEO RADIUS units are both microns. As can be seen from the optical diffuse speckle pattern: in the central field of view, RMS RADIUS is 2.573 μm and GEO RADIUS is 4.586 μm; in the fringe field of view, the RMS RADIUS is 3.703 μm, the GEO RADIUS14.314 μm, and the on-axis and off-axis point energy concentration and aberration correction are very good, so that the ideal resolution is achieved.

Fig. 5 shows a schematic diagram of the modulation transfer function MTF of the poloxamer lens of fig. 3a, from which the modulation transfer function MTF map can be seen: the abscissa is the spatial resolution in line pairs per millimeter, the ordinate is the contrast, the range is 0-1, and TS represents the meridian and sagittal components of MTF at different fields. As can be seen, the contrast ratio of each view field MTF value is greater than 0.65 at 60 line pairs/mm, and the lens can be seen to have very high contrast ratio and resolution.

FIG. 6 shows a field curvature and astigmatism diagram of the lens of FIG. 3a, the left diagram being the field curvature diagram, the ordinate being the field of view, the abscissa being the astigmatism value, in microns; the right graph is a distortion graph, the ordinate is the field of view, and the abscissa is the distortion value. The lens has excellent astigmatism correcting capability, and the field curvature astigmatism value of the lens in the full field of view of the corresponding coaxial light path is less than 0.05. The distortion value of the lens in the whole field of view corresponding to the coaxial light path is less than 0.1%, and the lens has extremely low distortion value.

As can be seen from fig. 3a to fig. 6, the inventive lens has high contrast and resolution, low distortion and astigmatism, and is suitable for large-target photosensitive element.

In summary, the sand lens is optimally designed aiming at the inclined light-transmitting cover plate, the light-transmitting cover plate is arranged in parallel with the surface of the photosensitive element and is not perpendicular to the optical axis of the lens, and the sand lens can be adapted to a 1.4' large-target-surface CMOS chip, so that the clear range is enlarged in industrial 3D measurement, and the accurate measurement of depth is realized. The lens is ensured to meet the requirement of clear imaging of the whole field of view of the target, and has the characteristics of small volume, high resolution and low distortion.

Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (12)

1. A poloxamer lens for an industrial camera, comprising: a first lens group, a second lens group and a third lens group which are arranged in order from an object side to an image side along an optical axis of the lens, characterized in that,

the first lens group, the second lens group and the third lens group are all positive focal power lens groups;

the clear aperture of the second lens group is used as an aperture diaphragm of the poloxamer lens, the ratio of the clear aperture of the third lens group to the clear aperture of the first lens group is 0.6-1.1, and the number of lenses in the first lens group is equal to the number of lenses in the third lens group.

2. The lens according to claim 1, wherein the focal length of the lens is 40-70mm, the working wavelength is 380-780 nm, the ratio of the total optical length to the half height of the image space, TTL/IH, is 3.0-7.5mm, and the included angle between the transparent cover plate and the optical axis of the lens is 46-80 degrees.

3. The poloxamer lens of claim 1, wherein the first lens group has a focal length of 70-100mm, the second lens group has a focal length of 135-165mm, the third lens group has a focal length of 25-55mm, the first lens group and second lens group have an air spacing of 3-8mm on the lens optical axis, and the second lens group and third lens group have an air spacing of 6-11mm on the lens optical axis.

4. The poloxamer lens of any one of claims 1-3, wherein the first lens group comprises three spherical lenses, the second lens group comprises two spherical lenses, and the third lens group comprises three spherical lenses, each spherical lens having a front surface radius of curvature and a rear surface radius of curvature that are greater than 0.

5. The poloxamer lens of claim 4, wherein the second lens group comprises: a fourth lens and a fifth lens which are arranged in order from an object side to an image side along an optical axis of the lens, characterized in that,

the fourth lens has negative focal power, the object side surface is a convex surface, the image side surface is a concave surface, and the image side surface of the fourth lens is used as an aperture diaphragm of the poloxamer lens;

the fifth lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

wherein the front surface radius of curvature of the fifth lens is larger than the rear surface radius of curvature.

6. The poloxamer lens of claim 4, wherein the first lens group comprises: the first lens, the second lens and the third lens are sequentially arranged from an object side to an image side along an optical axis of the lens, and the lens is characterized in that the first lens has positive focal power, the object side is a convex surface, and the image side is a concave surface;

the second lens has positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

the third lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface;

wherein the radius of curvature of the front surface of the third lens is larger than the radius of curvature of the rear surface.

7. The poloxamer lens of claim 6, wherein the second lens and the third lens are cemented lenses, the second lens and the third lens being made of materials having different refractive indices and abbe numbers.

8. The poloxamer lens of claim 7, the abbe number difference of the second lens and the third lens being greater than 10.

9. The poloxamer lens of claim 4 wherein the third lens group comprises: the lens comprises a sixth lens, a seventh lens and an eighth lens which are sequentially arranged from an object side to an image side along an optical axis of the lens, and is characterized in that the sixth lens has negative focal power, the object side is a concave surface, and the image side is a convex surface;

the seventh lens has negative focal power, the object side surface is concave, and the image side surface is convex;

the eighth lens has positive focal power, the object side surface is a convex surface, and the image side surface is a convex surface;

wherein the front surface radius of curvature of the eighth lens is larger than the rear surface radius of curvature.

10. The poloxamer lens of claim 9, wherein the sixth lens and the seventh lens are cemented lenses, the sixth lens and the seventh lens being made of materials having different refractive indices and abbe numbers.

11. The poloxamer lens of claim 10, the abbe number difference of the sixth lens and the seventh lens being greater than 10.

12. An industrial camera, comprising:

the poloxamer lens of any one of claims 1-11;

a photosensitive element; and

the light-transmitting cover plate covers the photosensitive element, is parallel to the imaging plane of the photosensitive element and is not perpendicular to the optical axis of the lens.

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