CN112098425B

CN112098425B - High-precision imaging system and method, image acquisition device and detection equipment

Info

Publication number: CN112098425B
Application number: CN202011284550.2A
Authority: CN
Inventors: 崔忠伟
Original assignee: Beijing Leader Intelligent Equipment Co ltd
Current assignee: Beijing Leader Intelligent Equipment Co ltd
Priority date: 2020-11-17
Filing date: 2020-11-17
Publication date: 2021-11-23
Anticipated expiration: 2040-11-17
Also published as: CN112098425A

Abstract

The embodiment of the invention discloses a high-precision imaging system, a high-precision imaging method, an image acquisition device and a detection device, wherein the imaging system comprises: the lens comprises a lens, a first lens group, a carrying platform and a first light emitting surface; the first lens group comprises at least one lens with equivalent positive focal power, a focal point and a first lens optical axis; the position difference between the first light-emitting surface and the equivalent focal plane of the first lens group does not exceed a first preset range; the lens is provided with a lens optical axis, and the included angle between the lens optical axis and the normal of the carrying platform is 20-60 degrees; the optical axis of the first lens is provided with a first reflecting shaft relative to the object carrying platform, and the angular deviation between the optical axis of the lens and the first reflecting shaft does not exceed a second preset range; the first preset range is the distance deviation +/-10 mm and/or the angle deviation +/-20 degrees; the second predetermined range is the angular deviation ± 15 degrees. According to the invention, the illumination and the imaging lens are integrally arranged, so that the imaging consistency is effectively improved, and a high-precision and stable workpiece image can be obtained.

Description

High-precision imaging system and method, image acquisition device and detection equipment

Technical Field

The invention relates to the technical field of imaging equipment, in particular to a high-precision imaging system and method, an image acquisition device and detection equipment.

Background

In the field of workpiece detection at present, the defect detection of small workpieces, particularly fine parts, also depends on the visual detection of assembly line workers to a great extent. In order to improve the detection efficiency, the prior art attempts to introduce a machine vision technology based on image recognition, and detects and discovers defects on a workpiece by intelligently recognizing the acquired workpiece image.

However, machine vision technology has long been faced with many challenges, especially, metal surface parts have high light reflection characteristics and have long been difficult to perform stable high quality imaging. Machine vision techniques rely heavily on the quality of the acquired image, which is affected by many factors. The light path design of the light source illumination and imaging optical system (lens) has the greatest influence on the imaging quality, and the image acquisition device is arranged in the second place. At present, in a workpiece detection system, a workpiece is generally irradiated by a common light source such as coaxial light, annular light, semi-annular light, planar light, strip light or dome light, and then an image of the workpiece is transmitted to an image sensor through a common industrial lens.

However, the inventor finds that the machine vision detection method in the prior art still has obvious defects in the process of implementing the related technical scheme of the embodiment of the invention: the imaging consistency of the workpiece in the field of view of the lens is poor, the imaging presented by the workpiece when placed in different positions is different, and when the workpiece is located in certain positions within the field of view, slight defects such as scratches cannot be imaged clearly, resulting in very unstable detection of certain surface defects of the workpiece. In a shallow tool mark defect as shown in fig. 1, the geometrical features of the shallow tool mark at the defect are usually not very different from the surface of the workpiece, and under the imaging of ordinary illumination, the fine defect can not be revealed at all.

Therefore, when the prior art is adopted for detection, the workpiece needs to be placed at a specific position in a visual field, and defects on the workpiece and a light source are kept at a special position, so that a certain quality of collected images can be obtained. However, in an automated inspection line, the workpiece usually keeps a moving state, and the inspection requirement is not matched with an actual working scene, so that the prior art cannot obtain an ideal acquired image in a dynamic inspection process (because the inspection position requirement cannot be ensured), and has poor imaging quality, low accuracy and low detectable rate of surface defects of the workpiece.

Disclosure of Invention

Aiming at the technical problems in the prior art, the embodiment of the invention provides a high-precision imaging system, a high-precision imaging method, an image acquisition device and a detection device, so as to solve the problem of poor dynamic detection imaging quality in the prior art.

A first aspect of embodiments of the present invention provides a high-precision imaging system, including: lens 110, first lens group 120, stage 130 and first light-emitting surface 141; wherein the first lens group 120 comprises at least one lens having an equivalent positive power, a focal point, and a first lens optical axis; the position difference between the first light emitting surface 141 and the equivalent focal plane of the first lens group 120 does not exceed a first preset range; the lens 110 has a lens optical axis, and an included angle between the lens optical axis and a normal of the object stage 130 is 20-60 degrees; the first lens optical axis has a first reflection axis relative to the object stage 130, and the angular deviation between the lens optical axis and the first reflection axis does not exceed a second preset range; the first preset range is a distance deviation of +/-10 mm and/or an angle deviation of +/-20 degrees; the second preset range is an angle deviation of +/-15 degrees.

In some embodiments, the imaging system further comprises: a second lens group 160 and a second light emitting surface 181; wherein,

the second lens group 160 includes at least one lens having an equivalent positive power, a focal point, and a second lens optical axis;

the position difference between the second light emitting surface 181 and the equivalent focal plane of the second lens group 160 does not exceed the first preset range;

the second lens optical axis has a second reflection axis relative to a vertical plane of the object stage 130, and the angular deviation between the lens optical axis and the second reflection axis does not exceed the second preset range.

In some embodiments, the first and/or second

light emitting faces

141, 181 are produced by a light source shining on a diffuser plate, or by a planar light emitting device.

In some embodiments, the first and/or second

light emitting surfaces

141, 181 have a single color light emitting area with a boundary shape that is asymmetrical with respect to the first and/or second lens optical axis; alternatively, the first light emitting surface 141 and/or the second light emitting surface 181 have two or more monochromatic light emitting areas with different colors.

In some embodiments, the first light emitting surface 141 and/or the second light emitting surface 181 have three monochromatic light emitting areas which are distributed in a Y shape and have three colors of red, green and blue.

In some embodiments, the lens 110 is a telecentric lens or a quasi-telecentric lens.

In some embodiments, the telecentric or quasi-telecentric lens has an adjustable stop.

In some embodiments, the first preset range is a distance deviation ± 5mm and/or an angle deviation ± 15 degrees; the second preset range is an angle deviation of +/-10 degrees.

In some embodiments, the light emitting area of the first light emitting face 141 and/or the second light emitting face 181 is generally approximately circular, the circle has a radius R, the first lens group 120 and/or the second lens group 160 has an equivalent focal length f, and the characteristic angle of illumination is Ω = arctan (R/f), wherein the characteristic angle of illumination Ω is not greater than 10 degrees.

In some embodiments, the light emitted from the first light emitting surface 141 and/or the second light emitting surface 181 is refracted to form emergent light, and the image formed by the emergent light irradiated on the metal surface is output by the imaging system through the lens 110.

A second aspect of an embodiment of the present invention provides a high-precision imaging system, including: a lens 210, a first lens group 220, a stage 230, a first diaphragm 240, and a first light emitter 250; wherein the first lens group 220 comprises at least one lens having an equivalent positive power, a focal point, and a first lens optical axis; the difference between the plane of the first stop 240 and the equivalent focal plane of the first lens group 220 is not more than a first preset range; the lens 210 has a lens optical axis, and an included angle between the lens optical axis and a normal of the object stage 230 is 20-60 degrees; the first lens optical axis has a first reflection axis relative to the object stage 230, and the angular deviation between the lens optical axis and the first reflection axis does not exceed a second preset range; the first preset range is a distance deviation of +/-10 mm and/or an angle deviation of +/-20 degrees; the second preset range is an angle deviation of +/-15 degrees.

In some embodiments, the imaging system further comprises: a second lens group 260, a second stop 280 and a second light emitter 270; wherein,

the second lens group 260 includes at least one lens having an equivalent positive power, a focal point, and a second lens optical axis;

the position difference of the second diaphragm 280 and the equivalent focal plane of the second lens group 260 does not exceed the first preset range;

the second lens optical axis has a second reflection axis relative to a vertical plane of the object stage 230, and the angular deviation between the lens optical axis and the second reflection axis does not exceed the second preset range.

In some embodiments, the light-transmitting portion of the first diaphragm 240 and/or the second diaphragm 280 is a light-transmitting hole, and the profile of the light-transmitting hole is an asymmetric shape; alternatively, the first diaphragm 240 and/or the second diaphragm 280 may be variable aperture diaphragms.

In some embodiments, the imaging system further comprises: and a filter 242 disposed proximate to the first stop 240 and/or the second stop 280, wherein the filter 242 includes two or more bandpass filter regions having different passbands.

In some embodiments, the filtering device 242 is a filter, and the distance between the filter and the first diaphragm 240 and/or the second diaphragm 280 is not more than 10 mm; the filter film comprises red, green and blue band-pass filter regions which are distributed in a Y shape.

In some embodiments, the lens 210 is a telecentric lens or a quasi-telecentric lens.

In some embodiments, the light-transmissive portion of the first stop 240 and/or the second stop 280 is generally approximately circular, the circle having a radius R, the first lens group 220 and/or the second lens group 260 having an equivalent focal length f, and a characteristic angle of illumination Ω = arctan (R/f), wherein the characteristic angle of illumination Ω is no greater than 10 degrees.

In some embodiments, the light transmitted by the first diaphragm 240 and/or the second diaphragm 280 is refracted to form emergent light, and the image system outputs the image formed by the emergent light on the metal surface through the lens 210.

A third aspect of embodiments of the present invention provides a high-precision imaging system, including: a lens 310, a first lens group 320, and a first light emitting surface 341; wherein the first lens group 320 comprises at least one lens having an equivalent positive power, a focal point, and a first lens optical axis; the position difference between the first light emitting surface 341 and the equivalent focal plane of the first lens group 320 does not exceed a first preset range; the lens 310 has a lens optical axis, and an included angle between the lens optical axis and a normal of the plane to be imaged 390 is 20-60 degrees; the first lens optical axis has a first reflection axis relative to the plane 390 to be imaged, and the angular deviation between the lens optical axis and the first reflection axis does not exceed a second preset range. The first preset range is a distance deviation of +/-10 mm and/or an angle deviation of +/-20 degrees; the second preset range is an angle deviation of +/-15 degrees.

In some embodiments, the first luminescent surface 341 is generated by the light source 350 shining on the diffuser plate 340, or by a planar light emitting device.

In some embodiments, the first light emitting surface 341 has a single color light emitting region having a boundary shape that is asymmetrical with respect to the first lens optical axis; alternatively, the first light emitting surface 341 has two or more monochromatic light emitting areas with different colors.

In some embodiments, the first light emitting surface 341 has three single color light emitting areas, which are distributed in a Y-shape and have three colors of red, green and blue.

In some embodiments, the lens 310 is a telecentric lens or a quasi-telecentric lens.

In some embodiments, the light emitting area of the first light emitting surface 341 is generally approximately circular, the circle having a radius R, the first lens group 320 having an equivalent focal length f, and a characteristic angle of illumination Ω = arctan (R/f), wherein the characteristic angle of illumination Ω is not greater than 10 degrees.

In some embodiments, the light emitted from the first light emitting surface 341 is refracted to form an emergent light, and the image formed by the emergent light irradiated on the metal surface is output by the imaging system through the lens 310.

A fourth aspect of an embodiment of the present invention provides a high-precision imaging system, including: a lens 410, a first lens group 420, a first diaphragm 440, and a first light emitter 450; wherein the first lens group 420 comprises at least one lens having an equivalent positive power, a focal point, and a first lens optical axis; the position difference between the plane of the first diaphragm 440 and the equivalent focal plane of the first lens group 420 is not more than a first preset range; the lens 410 is provided with a lens optical axis, and the included angle between the lens optical axis and the normal of the to-be-imaged plane 490 is 20-60 degrees; the first lens optical axis has a first reflection axis with respect to the plane 490 to be imaged, and the angular deviation between the lens optical axis and the first reflection axis does not exceed a second preset range. The first preset range is a distance deviation of +/-10 mm and/or an angle deviation of +/-20 degrees; the second preset range is an angle deviation of +/-15 degrees.

In some embodiments, the light-transmitting portion of the first diaphragm 440 is a light-transmitting hole, and the profile of the light-transmitting hole is asymmetric; alternatively, the first diaphragm 440 is a variable aperture diaphragm.

In some embodiments, the imaging system further comprises: a filtering device 442 disposed proximate to the first aperture 440, the filtering device 442 including two or more bandpass filtering regions having different passbands.

In some embodiments, the filtering device 442 is a filter, and the distance between the filter and the first stop 440 is not more than 10 mm; the filter film comprises red, green and blue band-pass filter regions which are distributed in a Y shape.

In some embodiments, the lens 410 is a telecentric lens or a quasi-telecentric lens.

In some embodiments, the light-transmissive portion of the first stop 440 generally approximates a circle having a radius R, the first lens group 420 has an equivalent focal length f, and a characteristic angle of illumination Ω = arctan (R/f), wherein the characteristic angle of illumination Ω is no greater than 10 degrees.

In some embodiments, the light transmitted by the first diaphragm 440 is refracted to form emergent light, and the image forming system outputs the emergent light through the lens 410 to irradiate an image formed on a metal surface.

A fifth aspect of embodiments of the present invention provides an image capturing apparatus, including an image sensor for capturing an optical image output by the lens, and the imaging system as described above.

In some embodiments, a target surface of the image sensor is disposed obliquely with respect to the lens optical axis.

A sixth aspect of embodiments of the present invention provides a high precision imaging method using an imaging system as described above to obtain an image of at least one surface of an item to be inspected.

A seventh aspect of the embodiments of the present invention provides a detection apparatus, including: the high-precision imaging system, the image acquisition device and the image recognition device are described above; the object carrying platform can carry an object to be tested and dynamically move the object to be tested into or out of the observation range of the imaging system; the imaging system is used for projecting light rays to the article to be detected and outputting an optical image through the lens; the image acquisition device is used for acquiring the optical image; the image recognition device is used for recognizing the collected optical image so as to detect the defect condition of the object to be detected.

According to the technical scheme provided by the embodiment of the invention, the consistency and the quality of imaging are effectively improved through the integrated arrangement of the illumination and the imaging lens, particularly, the imaging capacity of fine defects of workpieces is effectively improved through the inclined arrangement of the lens, and high-precision and stable workpiece images can be obtained.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

FIG. 1 is a schematic diagram of a conventional shallow cut defect in the art;

FIG. 2 is a schematic diagram of a high precision imaging system according to some embodiments of the present invention;

FIG. 3 is a schematic diagram of a high precision imaging system according to further embodiments of the present invention;

FIG. 4 is a schematic diagram of a high precision imaging system according to further embodiments of the present invention;

FIG. 5 is a schematic diagram of a high precision imaging system according to further embodiments of the present invention;

FIG. 6A is an example of an asymmetric shape of a single monochromatic light emitting area or aperture clear hole, shown in accordance with some embodiments of the present invention;

FIG. 6B is an example of a configuration of a plurality of bandpass filtering regions of a plurality of monochromatic light-emitting areas or filtering devices according to some embodiments of the present invention;

fig. 7 is a schematic diagram of an image capture device according to some embodiments of the present invention.

Detailed Description

In the following detailed description, numerous specific details of the invention are set forth by way of examples in order to provide a thorough understanding of the relevant disclosure. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. It should be understood that the use of "system," "device," "unit" and/or "module" terminology herein is a method for distinguishing between different components, elements, portions or assemblies at different levels of sequential arrangement. However, these terms may be replaced by other expressions if they can achieve the same purpose.

It will be understood that when a device, unit or module is referred to as being "on" … … "," connected to "or" coupled to "another device, unit or module, it can be directly on, connected or coupled to or in communication with the other device, unit or module, or intervening devices, units or modules may be present, unless the context clearly dictates otherwise. Although the terms "top," "bottom," "front," "back," "side," and the like may be used in this specification to describe various example features and elements of the invention, these terms are used herein for convenience only, e.g., in the orientation of the examples described in the figures. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of the invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. As used in the specification and claims of this application, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" are intended to cover only the explicitly identified features, integers, steps, operations, elements, and/or components, but not to constitute an exclusive list of such features, integers, steps, operations, elements, and/or components. For example, as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

These and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will be better understood upon consideration of the following description and the accompanying drawings, which form a part of this specification. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. It will be understood that the figures are not drawn to scale.

Various block diagrams are used in the present invention to illustrate various variations of embodiments according to the present invention. It should be understood that the foregoing and following configurations are not intended to limit the present invention. The protection scope of the invention is subject to the claims.

In the prior art, the efficiency and the accuracy of workpiece detection are expected to be improved by a machine vision technology, but when a common light source and a common industrial lens are adopted, the imaging quality of an acquired image cannot be ensured, the dynamic detection requirement cannot be met, the increasingly severe workpiece surface defect detection requirement cannot be met, and the method is particularly not suitable for the detection of metal surface parts. In view of this, the embodiment of the present invention provides a high-precision imaging system, which effectively improves the consistency of illumination and imaging by integrally arranging the illumination and imaging lenses, and can obtain a high-precision and stable workpiece image.

In one embodiment of the present invention, as shown in fig. 2, the high precision imaging system comprises: lens 110, first lens group 120, stage 130 and first light-emitting surface 141; wherein the first lens group 120 has equivalent positive focal power (i.e. diopter is positive, and diopter power is equivalent to a convex lens), a focal point and a first lens optical axis, and the position difference between the first light emitting surface 141 and an equivalent focal plane of the first lens group 120 (a plane passing through the equivalent focal point and perpendicular to the first lens optical axis) does not exceed a first preset range; the lens 110 is provided with a lens optical axis, and an included angle alpha between the lens optical axis and a normal of the carrying platform is 20-60 degrees; the first lens optical axis has a first reflection axis with respect to the object stage (i.e. an incident angle β of the first lens optical axis with respect to the normal of the object stage is equal to a reflection angle of the first reflection axis with respect to the normal of the object stage, and both of them can be considered to satisfy a reflection law with respect to the object stage), and an angular deviation of the lens optical axis from the first reflection axis does not exceed a second preset range. Through the inclined arrangement of the lens, the geometric characteristics of the surface of the object to be detected are changed from normal distribution to skewed distribution relative to the optical axis of the lens, so that the imaging capacity of fine defects is further enlarged, and better imaging quality is realized by matching with integrally designed illumination light rays matched with angles.

In the embodiment of the present invention, the first lens group 120 is located between the first light emitting surface 141 and the object-carrying platform 130, light emitted from the first light emitting surface 141 is refracted by the first lens group 120 and then irradiates on the object-carrying platform 130, an object to be detected (a workpiece, a micro component, etc.) is usually carried on the object-carrying platform 130, the object to be detected (the workpiece, the micro component, etc.) has an upper surface parallel (or substantially parallel) to the object-carrying platform 130, and light reflected by the object-carrying platform 130 and/or the object to be detected (the upper surface) enters the lens 110 to form an optical image. Defects of the article to be inspected can then be detected from the optical image by manual or machine vision (recognition after image acquisition with an image sensor or the like).

In the preferred embodiment of fig. 2, the imaging system may further include a second lens group 160 and a second light emitting face 181; the second lens group 160 has equivalent positive focal power, a focal point and a second lens optical axis, and the position difference between the second light emitting surface 181 and the equivalent focal plane of the second lens group 160 does not exceed the first preset range; a vertical plane of the second lens optical axis relative to the stage 130 has a second reflection axis (i.e. an incident angle γ of the second lens optical axis relative to a normal of the vertical plane is equal to a reflection angle of the second reflection axis, and both of the incident angle γ and the reflection angle are considered to satisfy a reflection law relative to the vertical plane), and an angular deviation of the lens optical axis from the second reflection axis does not exceed the second preset range. Wherein, a vertical surface of the object stage 130 actually corresponds to a side surface (an object plane vertical or approximately vertical to the object stage) of an object to be detected (a workpiece, a micro component, etc.) placed on the object stage, and since the object to be detected may be placed at any position of the object stage at any angle during the dynamic detection process, the direction and position of the vertical surface/side surface are not unique, as long as it is ensured that the lens 110 and the second light emitting surface 181 are disposed at a certain angular relationship (i.e. the angular deviation between the normal angle θ between the optical axis of the lens and the vertical surface/side surface and the reflection angle of the second reflection axis is not large), so that the light emitted from the second light emitting surface 181 is refracted by the second lens set 160 and then illuminates on the vertical surface/side surface, and the reflected light can effectively enter the lens 110 to form an optical image (i.e. it is ensured that the lens includes a part of the field of view or the whole light source illumination range, an image of the side of the item to be inspected can be effectively obtained). The arrangement of the second light emitting surface 181 enables the technical scheme of the preferred embodiment of the invention to effectively irradiate the side surface of the article to be detected, and the angle of the irradiated light is matched with the lens relative to the surface to be detected, so that reliable high-definition side imaging can be simultaneously obtained through the lens, and possible defects on the side surface of the workpiece can be simultaneously identified and detected.

In the embodiment of the present invention, in order to ensure that light emitted from the first light emitting surface 141 and/or the second light emitting surface 181 can effectively enter the lens 110, it is preferable that the first light emitting surface 141 and/or the second light emitting surface 181 have a certain corresponding relationship with an angle of the lens 110. In a preferred embodiment of the present invention, the first light-emitting surface 141 coincides with a position of an equivalent focal plane of the first lens group 120, the lens optical axis and the first lens optical axis are parallel to each other with respect to a first reflection axis of the stage, and a lens field of view is set corresponding to an illumination range (a lens field of view includes a part or all of the illumination range of the light source). However, it should be understood by those skilled in the art that the above two overlapping/parallel situations are only preferred embodiments, and in fact, the technical problem of the present invention can be solved when the first light-emitting surface 141 has a certain translation and/or tilt relative to the focal plane, or when the optical axis of the lens has a certain tilt relative to the first reflection axis, or even when both situations occur, so that the overlapping/parallel positions should not be considered as limiting the specific embodiments of the present invention. The second light-emitting surface 181 is similar in case, and the overlapping/parallel condition is only the best embodiment, and in fact, the technical problem to be solved by the present invention can be solved within a certain deviation range.

Optionally, the first preset range is a distance deviation of ± 10mm (or 10% of an effective focal length of the corresponding lens group, based on a distance of the corresponding lens optical axis passing through two points of the corresponding light emitting surface and the corresponding focal plane) and/or an angle deviation of ± 20 degrees; preferably, the first preset range is a distance deviation ± 5mm (or 5% of the effective focal length of the corresponding lens group) and/or an angle deviation ± 10 degrees; and more preferably, the first preset range is a distance deviation ± 3mm (or 3% of an effective focal length of the corresponding lens group) and/or an angle deviation ± 5 degrees. The second predetermined range is an angular deviation of ± 15 degrees, preferably the second predetermined range is an angular deviation of ± 10 degrees, more preferably the angular deviation is ± 5 degrees. It will be understood by those skilled in the art that smaller deviations in the more preferred embodiments mean better technical results, but it should be noted that even the largest deviations in the above-mentioned claims may still achieve sufficient technical results, and that the preferred or optimal embodiments should not be considered as a specific limitation of the first preset range and/or the second preset range of the present invention.

In the embodiment of the present invention, the first lens group 120 and/or the second lens group 160 may be a single lens or a group of lenses, and a single convex lens is exemplified in fig. 2, but it should be understood by those skilled in the art that a group of lenses may also be equivalent to a convex lens effect, which is also applicable to the technical solution of the present invention, and thus the form of the lens herein should not be considered as a limitation to the specific embodiment of the present invention. In addition, the convex lens can adopt a traditional convex lens, and also can adopt a Fresnel lens. The Fresnel lens is also called as a screw lens, is mostly formed by injection molding of polyolefin materials and can also be made of glass or organic glass, one surface of the lens surface of the Fresnel lens is a smooth surface, and the other surface of the lens surface of the Fresnel lens is a concentric circle from small to large.

In one embodiment of the present invention, the first light emitting surface 141 can be an equivalent light emitting plane, and there are various implementations. For example, in the preferred embodiment shown in fig. 2, light from a light source 150 is directed at a diffuser plate 140 to form a first light emitting surface 141. Further, the first light emitting surface 141 may be configured to obtain more desirable emitted light. For example, the first light emitting surface 141 may have a single color light emitting area whose boundary shape is an asymmetric shape; or the first light emitting surface 141 may have more than two monochromatic light emitting areas (each monochromatic light emitting area is different in color). More preferably, referring to fig. 6A, when there is only one single color light emitting area, the arrangement of the asymmetrical shape with respect to the optical axis of the first lens (the dots near the shapes in fig. 6A indicate the points where the optical axis of the first lens passes through the light emitting surface) may have various forms such as a fan shape, a fan ring, an offset rectangle, an arbitrary asymmetrical closed curve, or a plurality of combined asymmetrical shapes. While referring to fig. 6B, there may be more than two monochromatic light emitting areas of different colors, and there are many other arrangements that are symmetrical or asymmetrical, fig. 6B shows several exemplary preferred embodiments, in which different numbers indicate monochromatic light emitting areas of different colors. More preferably, the luminous surface of the invention comprises 3 single-color luminous zones with different colors, and the 3 single-color luminous zones are all fan-shaped and distributed on the same circular surface, such as two preferred embodiments in the first row of fig. 6B. Preferably, the 3 monochromatic light emitting areas are distributed in a Y shape, and the colors are red, green and blue. The monochromatic light emitting area can be a color coating with a specific shape on the diffusion plate or a filter with a specific shape which is additionally arranged independently.

In another preferred embodiment of the present invention, the first light emitting surface 141 can also be formed by a planar light emitting device, such as various display panels or display screens, including but not limited to liquid crystal display (LCD or LED type), CRT display, PDP display, etc. In this embodiment, the single-color light-emitting area shown in fig. 6A or 6B may preferably be realized by a specific display screen output by the planar light-emitting device. Through the arrangement of the plurality of single-color light emitting areas in the preferred embodiment of the invention, emergent light projected on any point on the surface of an object to be detected can have different color partitions at different phases (different directions), light collection is carried out through the lens at the specific position in the invention, and then images collected from different directions can show different color effects, so that fine defects on the object to be detected (a miniature workpiece) can show obvious differences in collected images (the surface of the workpiece at the defect position has geometric differences, and the collected images can show color differences at the position), thereby improving the imaging quality of the defect position, improving the precision and the accuracy of defect detection, and being suitable for dynamic detection. Similarly, when only one monochromatic light emitting area is provided, emergent light projected on any point of the surface of an object to be detected can be enabled to present illumination subareas with different intensities (or light has or does not have) on different phases (directions) through the arrangement of the asymmetric shape relative to the optical axis of the first lens, light collection is carried out through the lens at the specific position in the invention, and further images collected from different directions can present different gray scale effects, so that fine defects on the object to be detected (a miniature workpiece) can present differences in collected images (the surface of the workpiece at the defect position has geometric differences, and the collected images can present gray scale differences at the position), thereby improving the imaging quality of the defect position, improving the precision and accuracy of defect detection, and being applicable to dynamic detection.

More preferably, in the embodiment of the present invention, the light emitting area of the first light emitting area 141 is generally circular or approximately circular (i.e., the whole light emitting area is generally distributed in a circular or approximately circular area), the circular area has a radius R, the first lens group 120 has an equivalent focal length f, and the characteristic angle of lighting is Ω = arctan (R/f), wherein the characteristic angle of lighting Ω is not greater than 10 degrees. By limiting the size of the characteristic angle Ω of the light striking, the divergence degree of the light emitted by the first light emitting surface 141 can be controlled, so that the final emergent light angle is matched with the geometric characteristics of the metal surface, and the defects on the metal surface can be better imaged through the lens specially arranged in the invention.

In another preferred embodiment of the present invention, the light emitting area of the light emitting surface 141 may be generally rectangular, elliptical, or a generally closed curve shape, the size of the generally closed curve shape is further limited to obtain a better lighting effect, and specifically, the generally closed curve shape (including rectangular, elliptical) and the like has a minimum circumscribed rectangle, the maximum inscribed circle of the minimum circumscribed rectangle has a radius r, the first lens group 120 has an equivalent focal length f, and the lighting characteristic angle θ = arctan (r/f), wherein the lighting characteristic angle θ is not greater than 10 degrees. By limiting the size of the lighting characteristic angle θ, the divergence degree of the light emitted from the light emitting surface 141 can be controlled, so that the final emergent light has a better visual angle and is concentrated in a certain visual field range.

Specifically, the light emitted from the first light emitting surface 141 is refracted and/or reflected to form an emergent light, and the imaging system outputs the emergent light through the lens 110 to illuminate an image formed on a metal surface (a surface of a metal product or a surface of any product plated with metal). Typical metal-plated surfaces are usually nickel-plated, chrome-plated, zinc-plated, etc., but obviously other forms are also applicable to the solution of the present invention, so that no specific limitation is made to the specific form of the metal surface here. By adopting the technical scheme of the embodiment of the invention, the metal surface with high light reflection property can have excellent imaging effect, and the technical problem which cannot be solved for a long time in the prior art is effectively solved.

It should be particularly noted that although the above embodiment has been described by taking the first light emitting surface 141 as an example, the second light emitting surface 181 may obviously adopt a similar implementation manner due to similar structure and principle of the second light emitting surface 181, and the description is not repeated here. Corresponding conversions and/or transformations for the various implementations of the second light emitting surface 181 are not inventive for those skilled in the art and are intended to be within the scope of the present invention.

Through the arrangement of the position relation of the light-emitting surface and the lens in the preferred embodiment of the invention, the light angle projected to the surface to be detected is standardized, the defect display of inhibition of redundant stray light is avoided, meanwhile, the position of the optical axis of the lens is specially regulated, so that the imaging optical path and the illumination optical path are matched with each other, through the inclined arrangement of the lens, the geometric characteristics of the surface of an object to be detected are changed from normal distribution to skewed distribution relative to the optical axis of the lens, the imaging capability of fine defects is further amplified, and the detection capability of the corresponding metal surface is greatly improved by matching with integrally designed illumination light rays with matched angles. Through the setting of a plurality of monochromatic luminous areas in preferred embodiment, can let the emergent light of throwing on waiting to detect article have the subregion of different colours, based on the reflection relation of camera lens and illumination, and then the image of gathering from different directions can demonstrate different colour effects, this makes to detect slight defect on article (miniature work piece, metal surface etc.) can demonstrate apparent difference in the collection image (defect department work piece surface has geometric difference, it can demonstrate the color difference to gather the image in this department), thereby defect department image quality has been promoted, defect detection's precision and accuracy have been improved, it is applicable in dynamic detection.

Fig. 3 is a schematic structural diagram of a high-precision imaging system in another embodiment of the present invention, as shown in fig. 3, the high-precision imaging system includes: a lens 210, a first lens group 220, a stage 230, a first diaphragm 240, and a first light emitter 250; wherein the first lens group 220 has equivalent positive power, focus and first lens optical axis, and the position difference between the plane (the first light emitting surface 241 in fig. 3) where the first diaphragm 240 is located and the equivalent focal plane of the first lens group 220 does not exceed a first preset range; the lens 210 has a lens optical axis, and an included angle α between the lens optical axis and a normal of the object stage 230 is 20-60 degrees; the first lens optical axis has a first reflection axis relative to the object stage 230, and the angular deviation between the lens optical axis and the first reflection axis does not exceed a second preset range.

In the preferred embodiment of fig. 3, the imaging system may further comprise a second lens group 260, a second stop 280 and a second illuminant 270; wherein the second lens group 260 has equivalent positive power, focal point and second lens optical axis; the position difference of the second diaphragm 280 and the equivalent focal plane of the second lens group 260 does not exceed the first preset range; the second lens optical axis has a second reflection axis relative to a vertical plane of the object stage 230, and the angular deviation between the lens optical axis and the second reflection axis does not exceed the second preset range. The two reflection axes are defined as above and the description of the angles α, β, γ, θ in fig. 3 is omitted here. As described above, the arrangement of the second diaphragm 280 enables the technical solution of the preferred embodiment of the present invention to form the irradiation of the lens which is effectively matched with the specific angle arrangement on the side surface of the object to be detected, so that the reliable high-definition side surface imaging can be simultaneously obtained through the lens, and the defects possibly existing on the side surface of the workpiece can be simultaneously identified and detected. A vertical plane of the object stage 230 actually corresponds to a side surface of an object to be detected (a workpiece, a micro component, etc.) placed on the object stage, and since the object to be detected may be placed at any position of the object stage at any angle in the dynamic detection process, the direction and position of the vertical plane/side surface are not unique, as long as it is ensured that the lens 210 and the second diaphragm 280 have a certain angular relationship, light emitted by the second illuminant 270 is refracted by the second diaphragm 280 through the second lens group 260 and then illuminates the vertical plane/side surface, and then the reflected light can effectively enter the lens 210 to form an optical image (i.e., it is ensured that the field of view of the lens includes a part or all of the illumination range of the light source, and imaging of the side surface of the object to be detected can be effectively obtained).

Compared with fig. 2, the embodiment of fig. 3 mainly adjusts the light emitting form, and the light emitted by the first light emitter 250 forms the emergent light through the adjustment of the first diaphragm 240. Here, the first aperture 240 is a device including a light shielding portion and a light transmitting portion, and light emitted from the first light emitter 250 passes through the light transmitting portion of the first aperture 240 (i.e., the emergent light adjusted by the first aperture 240 is formed at the first light emitting surface 241) and irradiates the first lens group 220. In a preferred embodiment of the present invention, the light-transmitting portion of the first diaphragm 240 is a light-transmitting hole, and the profile of the light-transmitting hole is an asymmetric shape, such as a sector structure of a semicircle, a quarter circle, etc.; see in particular the various arrangements of the asymmetrical shape with respect to the optical axis of the first lens shown in fig. 6A. In another preferred embodiment of the invention, the first diaphragm 240 is a variable aperture diaphragm, such as in the form of an iris diaphragm. Preferably, first diaphragm 240 can have and shelter from blade and hole, and it can set up a plurality ofly to shelter from the blade, and a plurality of blades that shelter from form the hole jointly, and the blade that shelters from is used for sheltering from some light rays, and another some light can be followed the hole and passed through, and first diaphragm 240 hole size is adjustable to control light emitting area boundary size and/or shape, and then adjust the defect of light-emitting effect in order to be suitable for the work piece on different surfaces or different characteristics.

Furthermore, in one embodiment of the present invention, the imaging system may further include a filter device 242 disposed proximate to the first aperture 240, wherein the filter device 242 includes two or more bandpass filter regions with different passbands (i.e., the bandpass filter regions emit different colors of light under white light illumination); such as the arrangement of various symmetrical or asymmetrical shapes shown in fig. 6B. Preferably, the filtering means is a filter, and the distance between the filter and the diaphragm 240 is not more than 10mm, more preferably not more than 5 mm; the filter film comprises three band-pass filter areas distributed in a Y shape. Preferably, the three band-pass filtering regions are three colors of red, green and blue. Similar to the effect of setting the monochromatic light emitting area in the preferred embodiment of fig. 2, the shape of the first diaphragm 240 and/or the setting of the filtering device 242 are also for obtaining ideal emergent light, so that the fine defects on the object to be detected (the miniature workpiece) can show significant difference in the collected image, thereby improving the imaging quality at the defect position and improving the precision and accuracy of defect detection. More preferably, in the embodiment of the present invention, the light-transmitting portion of the first diaphragm 240 is generally circular or approximately circular (i.e. the entire light-emitting area is generally distributed in a circular or approximately circular area), the circular area has a radius R, the first lens group 220 has an equivalent focal length f, and the characteristic angle of light striking is Ω = arctan (R/f), wherein the characteristic angle of light striking Ω is not greater than 10 degrees. By limiting the size of the light striking characteristic angle Ω, the divergence degree of the light transmitted by the first diaphragm 240 can be controlled, so that the final emergent light angle is matched with the geometric characteristics of the metal surface, and the defects on the metal surface can be better imaged through the lens specially arranged in the invention. In another preferred embodiment of the present invention, the light-transmitting portion of the first diaphragm 240 may be generally rectangular, elliptical, or a generally closed curve shape, the size of which is further limited to obtain a better illumination effect, specifically, the generally closed curve shape (including rectangular, elliptical) and the like has a minimum circumscribed rectangle, the maximum inscribed circle of the minimum circumscribed rectangle has a radius r, the first lens group 220 has an equivalent focal length f, and the lighting characteristic angle has θ = arctan (r/f), wherein the lighting characteristic angle θ is not more than 10 degrees. By limiting the size of the light striking characteristic angle θ, the divergence degree of the light emitted from the first diaphragm 240 can be controlled, so that the final emergent light has a better visual angle and is concentrated in a certain visual field range.

Specifically, the light transmitted through the first diaphragm 240 is refracted to form emergent light, and the imaging system outputs the emergent light through the lens 210 to irradiate an image formed on a metal surface (the surface of a metal product or the surface of any product plated with metal). Typical metal-plated surfaces are usually nickel-plated, chrome-plated, zinc-plated, etc., but obviously other forms are also applicable to the solution of the present invention, so that no specific limitation is made to the specific form of the metal surface here. By adopting the technical scheme of the embodiment of the invention, the metal surface with high light reflection property can have excellent imaging effect, and the technical problem which cannot be solved for a long time in the prior art is effectively solved.

In the preferred embodiment of fig. 3, the first lens group 220 can be implemented in a manner similar to the description of the preferred embodiment of fig. 2, and can also be a single lens or a lens group consisting of a plurality of lenses; the positional relationship of lens 210, first lens group 220, stage 230, etc. and the angular disposition of lens 210 are similar to those of the preferred embodiment of fig. 2, and will not be described again.

Similarly to the aforementioned preferred embodiment of fig. 2, in a preferred embodiment of the present invention, the plane (the light emitting surface 241 in fig. 3) of the first stop 240 coincides with the position of the equivalent focal plane of the first lens group 220, the lens optical axis is parallel to the first lens optical axis relative to the first reflection axis of the stage, and the lens field of view is set corresponding to the illumination range (including part or all of the illumination range of the light source in the lens field of view). However, it should be understood by those skilled in the art that the above two cases of coincidence/parallelism are only preferred embodiments, and in fact, the technical problem of the present invention can be solved when the first diaphragm 240 has a certain translation and/or tilt relative to the focal plane, or when the optical axis of the lens has a certain tilt relative to the first reflection axis, or even when both of them occur, so that the position coincidence/parallelism herein should not be considered as a limitation to the specific embodiments of the present invention. The second diaphragm 280 is similar in case, and the coincidence/parallelism case is only the most preferred embodiment, and in fact, the technical problem to be solved by the present invention can be solved within a certain deviation range.

Further, in a preferred embodiment of the present invention, the lens used in the embodiment of fig. 2 or fig. 3 may be further optimized, and a telecentric lens (such as an object-side telecentric lens or a double telecentric lens) or a quasi-telecentric lens is used to replace the common industrial lens. The quasi-telecentric lens is characterized in that the position difference (distance on an optical axis) between the center of a lens diaphragm and the image space focus of a front group of lenses is less than 10% of the effective focal length of the front group of lenses, and the front group of lenses are lens groups positioned on the front side (object side) of the diaphragm in the lens. The telecentric lens or the quasi-telecentric lens has a specific parallel light path design, so that the magnification of the presented image does not change along with the distance in a certain object distance range, and the parallax problem of the traditional industrial lens can be effectively corrected. However, in the technical field, a telecentric lens is generally used for size measurement, and a common industrial FA lens is generally used for defect detection, instead of using the telecentric lens during defect detection (in the prior art, it is generally considered that an industrial lens can obtain a clearer image through focusing, so that the application range of the telecentric lens is limited). The preferred embodiment of the invention realizes the optimal matching of the illumination and imaging light paths by using the telecentric lens and matching with the special light source and the specific position relation of a plurality of components, and especially can realize the optimal optical matching with the illumination light path with the light ray angle specified, thereby realizing better imaging consistency and fine defect expression by using the telecentric lens, realizing the optimal effect, effectively breaking the technical bias and obtaining unexpected technical effect.

More preferably, the telecentric lens has an adjustable diaphragm. The adjustable diaphragm can adjust the angle of light rays entering the lens according to needs. In the preferred embodiment of the invention, because the specially-made light source with good consistency is adopted, and the telecentric lens is adopted, the slight defect can present an obvious difference image, and the defect detection precision is obviously improved. However, in some cases, the workpiece is allowed to have certain tolerance and/or slight flaw, and the overhigh detection precision may cause certain false alarm, and the later software identification algorithm is required to consume calculation force for screening and removing. Therefore, in the preferred embodiment of the invention, the adjustable diaphragm can properly adjust (such as widening or tightening) the imaging precision by adjusting the angle of the light rays entering the lens, so that whether certain fine flaws are imaged or not is selected according to needs, the false alarm condition is reduced in the imaging link, and the computational power requirement of later software is effectively reduced.

Fig. 4 is a schematic structural diagram of a high-precision imaging system in another embodiment of the present invention, and compared with the embodiment shown in fig. 2, only the reference coordinate system is replaced by the object-carrying platform as the plane to be imaged, and the second lens group and the second light-emitting surface for side illumination are deleted, and the rest of the structure and the principle are the same as or similar to those in the embodiment shown in fig. 2, and are not repeated. The reference coordinate system is replaced by the plane to be imaged, so that the application range of the scheme is further expanded (for example, a workpiece with the thickness of more than 60 mm) and the position relation among all the parts is more accurate, thereby achieving a better imaging effect.

Fig. 5 is a schematic structural diagram of a high-precision imaging system in another embodiment of the present invention, and compared with the embodiment shown in fig. 3, only the reference coordinate system is replaced by the object-carrying platform as the plane to be imaged, and the second lens group, the second diaphragm, and the second light emitter for side illumination are deleted, and the rest of the structure and the principle are the same as or similar to those in the embodiment shown in fig. 3, and are not repeated. The reference coordinate system is replaced by the plane to be imaged, so that the application range of the scheme is further expanded (for example, a workpiece with the thickness of more than 60 mm) and the position relation among all the parts is more accurate, thereby achieving a better imaging effect.

In a preferred embodiment of the present invention, as shown in fig. 7, there is also provided an image pickup apparatus including: an image sensor 560 and an imaging system as described above, wherein the image sensor 560 is used to capture an optical image output by the lens 510. Preferably, the target surface of the image sensor 560 is disposed obliquely (shown at 561) with respect to the lens optical axis 511 of the lens 510. In general, the photosensitive Device of the image sensor is a CMOS (Complementary Metal Oxide Semiconductor) or CCD (Charge Coupled Device) element, so the target surface of the image sensor described herein is preferably referred to as a CMOS target surface or a CCD target surface. The sensor is arranged in an inclined mode relative to the optical axis of the lens, so that the imaging quality can be further improved, and the detection capability of the system for workpiece defects is improved. In the oblique setting, an angle T 'between a normal line of the target surface of the image sensor/camera 560 and the optical axis 511 of the lens is tan (T') = M tan (T); t is the angle of the lens optical axis 511 relative to the normal of the stage 540, and M is the lens magnification, specifically, the lens magnification at the intersection of the lens optical axis 511 and the stage 540 (or with the workpiece upper surface/first to-be-imaged plane 550). Of course, the tilt angle T' may have a deviation within 1 ° to 2 ° due to the presence of higher-order aberrations.

Further, in an embodiment of the present invention, there is also provided a high-precision imaging method for obtaining images of a plurality of surfaces of an object to be detected using the imaging system as described above.

Further, in an embodiment of the present invention, there is also provided a detection apparatus, including the high-precision imaging system, the image acquisition device and the image recognition device as described above; the object carrying platform can carry an object to be tested and dynamically move the object to be tested into or out of the observation range of the imaging system; the imaging system is used for projecting light rays to the article to be detected and outputting an optical image through the lens; the image acquisition device is used for acquiring the optical image; the image recognition device is used for recognizing the collected optical image so as to detect the defect condition of the object to be detected. Preferably, detecting the defect condition of the object to be detected refers to: and detecting whether the article to be detected has defects, and further detecting the positions and/or types of the defects when the defects exist.

It should be understood by those skilled in the art that the claims and the embodiments of the specification of the present invention are only examples of the preferred embodiments, and should not be construed as limiting the embodiments of the present invention. Typically, the subject in various positional relationships illustrated may be an objective subject, or the virtual image may be constructed by a plane mirror or other feasible means, so that the subject in various positional relationships is a virtual image of the objective subject. Those skilled in the art can make various conversions on various positional relationships of examples and their subjects without creative efforts, and the results of the conversions should be considered to be within the scope of the claims of the present invention.

In summary, embodiments of the present invention provide a high-precision imaging system, method, image capturing device and detection apparatus, which effectively improve the consistency of imaging and obtain a high-precision and stable workpiece image by integrally arranging an illumination lens and an imaging lens. More specifically, in the preferred embodiment of the invention, the imaging consistency of the part to be detected in the lens field of view is improved, the shape and/or color of the light-emitting region in the imaging system can be further improved, the defect imaging effect is further improved, the defects of the illumination and imaging system which affect the imaging stability are further eliminated, and the better realization of the machine vision dynamic detection is ensured.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims

1. A high precision imaging system, characterized in that it comprises: the lens comprises a lens (110), a first lens group (120), a carrying platform (130) and a first light emitting surface (141); wherein,

the first lens group (120) comprises at least one lens having an equivalent positive power, a focal point and a first lens optical axis;

said first luminous surface (141) is produced by a light source shining on a diffuser plate, or by a planar lighting device; the first light emitting surface (141) is provided with three single-color light emitting areas which are distributed in a Y shape and have three colors of red, green and blue; the position difference of the first light-emitting surface (141) and the equivalent focal plane of the first lens group (120) does not exceed a first preset range;

the lens (110) is a telecentric lens or a quasi-telecentric lens, the lens (110) is provided with a lens optical axis, and an included angle between the lens optical axis and a normal of the carrying platform (130) is 20-60 degrees;

the first lens optical axis has a first reflection axis relative to the object stage (130), and the angle deviation between the lens optical axis and the first reflection axis does not exceed a second preset range;

the first preset range is a distance deviation of +/-10 mm and/or an angle deviation of +/-20 degrees; the second preset range is an angle deviation of +/-15 degrees.

2. The imaging system of claim 1, further comprising: a second lens group (160) and a second light emitting surface (181); wherein,

the second lens group (160) comprises at least one lens having an equivalent positive power, a focal point and a second lens optical axis;

the position difference between the second light-emitting surface (181) and the equivalent focal plane of the second lens group (160) does not exceed the first preset range;

the second lens optical axis has a second reflection axis relative to a vertical plane of the object stage (130), and the angular deviation between the lens optical axis and the second reflection axis does not exceed the second preset range.

3. An imaging system according to claim 2, wherein the second light emitting face (181) is generated by illumination of a light source on a diffuser plate or by a planar light emitting device.

4. An imaging system according to claim 2, wherein the second light emitting face (181) has a monochromatic light emitting area with a boundary shape being asymmetric with respect to the first lens optical axis and/or the second lens optical axis; alternatively, the second light emitting surface (181) has two or more monochromatic light emitting areas of different colors.

5. An imaging system according to claim 4, wherein the second light emitting face (181) has three monochromatic light emitting areas which are Y-shaped and are three colors red, green and blue respectively.

6. The imaging system of any of claims 1-5, wherein the telecentric or quasi-telecentric lens has an adjustable stop.

7. The imaging system of any of claims 1-5, wherein the first preset range is a distance deviation ± 5mm and/or an angle deviation ± 15 degrees; the second preset range is an angle deviation of +/-10 degrees.

8. The imaging system of claim 1 or 2, wherein the light emitting area of the first (141) and/or second (181) light emitting face generally approximates a circle having a radius R, the first lens group (120) and/or second lens group (160) having an equivalent focal length f, a characteristic angle of shine Ω = arctan (R/f), wherein the characteristic angle of shine Ω is not more than 10 degrees.

9. The imaging system of claim 8, wherein the light emitted from the first light emitting surface (141) and/or the second light emitting surface (181) is refracted to form an emergent light, and the imaging system outputs the image formed by the emergent light irradiating on the metal surface through the lens (110).

10. A high precision imaging system, characterized in that it comprises: the lens comprises a lens (210), a first lens group (220), a carrying platform (230), a first diaphragm (240) and a first light emitter (250); wherein,

the first lens group (220) comprises at least one lens having an equivalent positive power, a focal point and a first lens optical axis;

the position difference between the plane of the first diaphragm (240) and the equivalent focal plane of the first lens group (220) does not exceed a first preset range; a filtering device (242) is arranged close to the first diaphragm (240), and the filtering device (242) comprises red, green and blue three band-pass filtering areas which are distributed in a Y shape;

the lens (210) is a telecentric lens or a quasi-telecentric lens, the lens (210) is provided with a lens optical axis, and an included angle between the lens optical axis and a normal of the carrying platform (230) is 20-60 degrees;

the first lens optical axis has a first reflection axis relative to the object stage (230), and the angle deviation between the lens optical axis and the first reflection axis does not exceed a second preset range;

11. The imaging system of claim 10, further comprising: a second lens group (260), a second diaphragm (280) and a second light emitter (270); wherein,

the second lens group (260) comprises at least one lens having equivalent positive power, a focal point and a second lens optical axis;

the difference in position of the second stop (280) and the equivalent focal plane of the second lens group (260) does not exceed the first preset range;

the second lens optical axis has a second reflection axis relative to a vertical plane of the object stage (230), and the angular deviation between the lens optical axis and the second reflection axis does not exceed the second preset range.

12. The imaging system according to claim 10 or 11, characterized in that the light-transmitting portion of the first diaphragm (240) and/or the second diaphragm (280) is a light-transmitting aperture, the profile of which is of asymmetric shape; alternatively, the first diaphragm (240) and/or the second diaphragm (280) is a variable aperture diaphragm.

13. The imaging system of claim 11, further comprising: a filtering device (242) disposed proximate to the second stop (280), the filtering device (242) including more than two bandpass filtered regions having different passbands.

14. The imaging system according to claim 13, characterized in that the filtering means (242) is a filter, which is at a distance of not more than 10mm from the first diaphragm (240) and/or the second diaphragm (280); the filter film comprises red, green and blue band-pass filter regions which are distributed in a Y shape.

15. An imaging system according to claim 10, 11 or 14, wherein the telecentric or quasi-telecentric lens has an adjustable diaphragm.

16. The imaging system of claim 10, 11 or 14, wherein the first preset range is a distance deviation ± 5mm and/or an angle deviation ± 15 degrees; the second preset range is an angle deviation of +/-10 degrees.

17. The imaging system of claim 10 or 11, wherein the light-transmissive portion of the first stop (240) and/or the second stop (280) generally approximates a circle having a radius R, the first lens group (220) and/or the second lens group (260) having an equivalent focal length f, and a characteristic angle of glare Ω = arctan (R/f), wherein the characteristic angle of glare Ω is no greater than 10 degrees.

18. The imaging system of claim 17, wherein the light transmitted by the first diaphragm (240) and/or the second diaphragm (280) is refracted to form an emergent light, and the imaging system outputs the image formed by the emergent light on the metal surface through the lens (210).

19. A high precision imaging system, characterized in that it comprises: a lens (310), a first lens group (320) and a first light emitting surface (341); wherein,

the first lens group (320) comprises at least one lens having an equivalent positive power, a focal point and a first lens optical axis;

the first light emitting surface (341) is provided with three single-color light emitting areas which are distributed in a Y shape and have three colors of red, green and blue; the position difference of the first light-emitting surface (341) and the equivalent focal plane of the first lens group (320) does not exceed a first preset range;

the lens (310) is a telecentric lens or a quasi-telecentric lens, the lens (310) is provided with a lens optical axis, and the included angle between the lens optical axis and the normal of the plane (390) to be imaged is 20-60 degrees;

the first lens optical axis has a first reflection axis relative to the plane (390) to be imaged, and the angular deviation of the lens optical axis and the first reflection axis does not exceed a second preset range;

20. An imaging system according to claim 19, characterized in that the first luminescent face (341) is generated by a light source (350) shining on a diffuser plate (340) or by a planar light emitting device.

21. The imaging system of claim 19, wherein the first luminescent surface (341) has a single color light emitting zone having a boundary shape that is asymmetrically shaped with respect to the first lens optical axis; alternatively, the first light emitting surface (341) has two or more monochromatic light emitting areas different in color.

22. The imaging system of any of claims 19-21, wherein the telecentric lens or quasi-telecentric lens has an adjustable stop.

23. The imaging system of any of claims 19-21, wherein the first preset range is a distance deviation ± 5mm and/or an angle deviation ± 15 degrees; the second preset range is an angle deviation of +/-10 degrees.

24. The imaging system of any of claims 19-21, wherein a light emitting area of the first light emitting surface (341) generally approximates a circle having a radius R, the first lens group (320) has an equivalent focal length f, and a characteristic angle of illumination Ω = arctan (R/f), wherein the characteristic angle of illumination Ω is no greater than 10 degrees.

25. The imaging system of claim 24, wherein the light emitted from the first light emitting surface (341) is refracted to form an exit light, and wherein the imaging system outputs the exit light through the lens (310) to illuminate an image formed on a metal surface.

26. A high precision imaging system, characterized in that it comprises: a lens (410), a first lens group (420), a first diaphragm (440), and a first light emitter (450); wherein,

the first lens group (420) comprises at least one lens having an equivalent positive power, a focal point and a first lens optical axis;

the position difference between the plane of the first diaphragm (440) and the equivalent focal plane of the first lens group (420) does not exceed a first preset range; a light filtering device (442) is arranged close to the first diaphragm (440), and the light filtering device (442) comprises red, green and blue band-pass light filtering areas which are distributed in a Y shape;

the lens (410) is a telecentric lens or a quasi-telecentric lens, the lens (410) is provided with a lens optical axis, and the included angle between the lens optical axis and the normal of the plane (490) to be imaged is 20-60 degrees;

the first lens optical axis has a first reflection axis relative to the plane (490) to be imaged, and the angular deviation of the lens optical axis from the first reflection axis does not exceed a second preset range;

27. The imaging system of claim 26, wherein the light-transmissive portion of the first stop (440) is a light-transmissive aperture having an asymmetric profile; alternatively, the first diaphragm (440) is a variable aperture diaphragm.

28. The imaging system of claim 26 or 27, further comprising: the filtering means (442) comprises more than two band-pass filtering regions with different passbands.

29. The imaging system of claim 28, wherein the filtering means (442) is a filter, the filter being located no more than 10mm from the first aperture (440).

30. The imaging system of claim 26, 27 or 29, wherein the telecentric or quasi-telecentric lens has an adjustable stop.

31. The imaging system of claim 26, 27 or 29, wherein the first preset range is a distance deviation ± 5mm and/or an angle deviation ± 15 degrees; the second preset range is an angle deviation of +/-10 degrees.

32. The imaging system of claim 26 or 27, wherein the light-transmissive portion of the first stop (440) generally approximates a circle having a radius R, the first lens group (420) has an equivalent focal length f, and a characteristic angle of illumination Ω = arctan (R/f), wherein the characteristic angle of illumination Ω is no greater than 10 degrees.

33. The imaging system of claim 32, wherein the light transmitted by the first aperture (440) is refracted to form an emergent light, and the imaging system outputs the image formed by the emergent light on the metal surface through the lens (410).

34. An image capture device comprising an imaging system as claimed in any one of claims 1 to 33 and an image sensor for capturing an optical image output by the lens.

35. The image capturing device of claim 34, wherein the target surface of the image sensor is disposed obliquely with respect to the optical axis of the lens.

36. A high precision imaging method, characterized in that an imaging system according to any of claims 1-33 is used to obtain an image of at least one surface of an object to be inspected.

37. A detection apparatus, comprising: the high precision imaging system, image capture device and image recognition device of any of claims 1-33; wherein,

carrying an article to be tested on a carrying platform and dynamically moving the article to be tested into or out of the observation range of the imaging system;

the imaging system is used for projecting light rays to the article to be detected and outputting an optical image through the lens;

the image acquisition device is used for acquiring the optical image;

the image recognition device is used for recognizing the collected optical image so as to detect the defect condition of the object to be detected.