CN115598805B - Low-cost large-view-field telecentric lens with variable working distance and detection method thereof - Google Patents
Low-cost large-view-field telecentric lens with variable working distance and detection method thereof Download PDFInfo
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- CN115598805B CN115598805B CN202211275277.6A CN202211275277A CN115598805B CN 115598805 B CN115598805 B CN 115598805B CN 202211275277 A CN202211275277 A CN 202211275277A CN 115598805 B CN115598805 B CN 115598805B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/22—Telecentric objectives or lens systems
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/0002—Inspection of images, e.g. flaw detection
- G06T7/0004—Industrial image inspection
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/60—Analysis of geometric attributes
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/10—Image acquisition modality
- G06T2207/10004—Still image; Photographic image
Abstract
The invention discloses a low-cost large-view-field telecentric lens with variable working distance, which comprises the following components in sequence from an object space to an image space according to a light path: a reflecting mirror group for changing the light path, a first incident lens group, a diaphragm, a second lens group and an imaging device; the reflection group changes the direction of the incident light source to form a converging light path. The invention also creatively provides a detection method, which solves the problems that the imaging and detection quality cannot be influenced by errors such as phase difference, chromatic aberration and the like in industrial detection application of ultra-large object detection, and utilizes error elimination processing to the image acquired by the image in the detection process to optimize the image quality so that the detection quality is better. The scheme of the invention achieves good balance and improvement on cost. When a larger object to be detected is encountered, the method is adopted to carry out scanning detection by using the telecentric lens with low cost, so that a clearer image can be obtained, and the problem of image distortion detection is solved.
Description
Technical Field
The invention relates to a low-cost large-view-field telecentric lens with variable working distance and a detection method thereof, and belongs to the technical field of optics.
Background
Industrial lenses are important imaging elements in machine vision systems, which must be able to meet the requirements if the system is to fully function. With the wide application of machine vision systems in the field of precision detection, common industrial lenses are difficult to meet detection requirements; in particular, regarding large-size part inspection, there is no strict definition of the size range of large-size parts academically. Parts having a size in the range of 1m to 3m are commonly referred to as large-sized parts. As the current testing level and manufacturing level increase, the definition of large-sized parts is also slowly changing. In terms of the current development trend of large-size industrial detection in China, the length direction of the dimension of the future large-size part can reach 3-5 m, and the width direction is about 2m, and the dimension is mainly a part of a large-size thin-wall plate and the like, such as an automobile body, an airplane shell, a large-size ship plate, a high-speed axle, an automobile bottom beam and the like.
Correspondingly, an industrial solution capable of detecting large-size telecentric lens detection is needed, and the telecentric lens of the industrial lens adopts a lens with the front end lens diameter matched with the object to be detected, so that the processing cost of the lens is increased, and a scheme capable of solving and achieving good balance and improvement in cost is needed. It is known that errors (aberrations) occur whenever light is reflected by a curved surface or refracted, so that too large a mirror surface needs to be compensated for and not too large, which is a solution that needs to be provided if a larger object to be detected is encountered.
Disclosure of Invention
The invention aims to provide a low-cost large-view-field telecentric lens and a detection method, so as to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions: a low-cost large-view-field variable working distance telecentric lens is characterized in that: the method sequentially comprises the following steps from an object side to an image side according to an optical path: a reflecting mirror group for changing the light path, a first incident lens group, a diaphragm, a second lens group and an imaging device;
the mirror group sequentially includes along the light path: a first concave mirror and an opposing second mirror; the first concave reflecting mirror and the opposite second reflecting mirror are arranged in a mirror face opposite way, and the reflecting mirror group has positive diopter, so that an incident light source forms a converging light path; the light path changes the direction of the light path after passing through the reflecting mirror group, then enters the first incident lens group, and the parallel light emitted from the object is parallel to the optical axis formed by the first incident lens group and the second lens group, namely the reflecting mirror group only converges and translates the incident light, and then enters the first incident lens group;
the first incident lens group at least comprises two parts of lenses, wherein the first part of lenses are negative diopter lenses, so that the converging light paths diverge to form parallel light, and the second part of lenses are positive diopters, so that the parallel light paths converge again and pass through the diaphragm;
the second lens group comprises at least one positive diopter lens, so that light rays passing through the diaphragm form parallel light rays to the imaging device;
the first incident lens group, the diaphragm, the second lens group and the imaging device are positioned in the same optical axis lens barrel device; the reflector group is fixed on the rotating device singly or together with the lens barrel device and rotates along the optical axis.
The first concave reflecting mirror is a spherical reflecting mirror or an aspherical reflecting mirror, and the second reflecting mirror is a corresponding concave spherical reflecting mirror or a concave aspherical reflecting mirror.
The second reflecting mirror is a plane reflecting mirror.
The second reflector is a convex reflector, and the absolute value of the focal length of the first concave reflector is smaller than that of the second convex reflector.
A first lens in the first incidence lens group is a first compensation lens, and a second lens is a converging lens; the first compensation lens is matched with the reflector group to form a parallel light path for incidence, and the parallel light path passes through the diaphragm after passing through the second lens; the first lens group is fixed relative to the aperture diaphragm and the lens barrel, and the second lens group is adjustable along the optical axis.
The first incident lens group is a fixed lens group, and the second lens group is a movable lens group; when the variable working distance variable magnification telecentric lens performs variable magnification variable working distance, the relative position of the aperture diaphragm and the first incident lens group is kept fixed, and the second lens group moves along the optical axis towards the direction approaching or far from the diaphragm.
A detection method using a low-cost large-view-field variable working distance telecentric lens comprises the telecentric lens and an imaging device, wherein the imaging device comprises an image processing system and is characterized in that: s1, a mark which is obviously compared with a background is arranged in the outline of the vertical projection of the edge and a specific position on the object to be detected and the edge corresponding to the first concave reflector;
s2, setting a pre-stored detected object comparison chart in an image processing system;
s3, rotating the detection lens by taking the center of the object to be detected as the center of a circle in the whole range of the object to be detected; on the lens side, parallel light between the object to be detected and the first reflecting mirror surface is parallel to the optical axis of the lens, the reflecting mirror group rotates by taking the optical axis of the lens as the center, and because the lens performs rotation detection, the view field is in the change, the edge and the special position on the object to be detected are calibrated, so that the identification of the object to be detected in the rotation detection process is more clear and accurate;
s4, storing the detected object image obtained by the rotary scanning into an image processing system so as to form a standard image of the detected object through system calculation;
in the step S4, S4 stores the detected object image obtained by the rotary scanning into an image processing system so as to form a standard image of the detected object through system calculation;
the image processing system performs system calculation on the image of the detected object obtained through telecentric lens scanning, and comprises image angle and lens rotation angle comparison analysis, and the image is compared with the first image;
extracting feature points in the images, extracting the edge and the feature points of each image, and particularly extracting marks with obvious contrast;
cutting the image, cutting edges of the scanned image of each needle, and removing the image distortion part;
and (3) image reorganization, wherein the image processing system performs image reorganization and splicing according to the comparison of the pre-stored images to obtain a complete monitoring image of the object to be detected, and the overlapping part is optimized. .
Compared with the prior art, the invention has the beneficial effects that: according to the invention, an industrial solution for solving the problem of ultra-large fittings of telecentric lens is provided, the telecentric lens of the industrial lens adopts a lens with the front lens diameter matched with the object to be detected, the lens is processed to be increased along with the increase, and the lens adopts a spherical or non-spherical reflecting mirror with a reflecting principle at the incident end to replace a large-size incident lens with high cost, so that good balance and improvement are achieved in performance and cost. The method can solve the problem of detecting image distortion when encountering larger objects to be detected.
The invention also creatively provides a detection method, which solves the problems that the imaging and detection quality cannot be influenced by errors such as phase difference, chromatic aberration and the like in industrial detection application of ultra-large object detection, and utilizes error elimination processing of images acquired by images in the detection process to optimize the image quality so that the detection quality is better. The scheme of the invention achieves good balance and improvement on cost. When a larger object to be detected is encountered, the method is adopted to carry out scanning detection by using the telecentric lens with low cost, so that a clearer image can be obtained, and the problem of image distortion detection is solved.
Drawings
For a clearer description of embodiments of the present application or of the solutions in the prior art, the drawings that are needed in the embodiments will be briefly described, it being obvious that the drawings in the following description are only some embodiments described in the present invention, and that other drawings may be obtained according to these drawings for a person skilled in the art;
fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a technical scheme that: the invention aims to provide a low-cost large-view-field variable working distance telecentric lens structure so as to solve the problems in the background art.
In order to achieve the above purpose, the present invention provides the following technical solutions: referring to fig. 1 of the specification, a low-cost large-field-of-view variable working distance telecentric lens sequentially comprises, from an object side to an image side according to an optical path: the light emitted by the object to be detected 1 reaches the second reflecting mirror after being reflected by the first concave reflecting mirror 2, so that the direction of the light path is changed, and the working distance between the object to be detected 1 and the reflecting mirror group can be adjusted at will according to actual needs, so long as the requirements of observation and detection are met; the working distance adjustable range is enlarged, the optical path is changed, and then the optical path is changed, the optical path enters a first incident lens group, the first incident lens group comprises a compensating lens 4 and a lens group 5, in practice, the compensating lens 4 can be a lens group, the compensating lens 4 can be positive diopter or negative diopter according to the reality, but the diopter of the whole first incident lens group is positive, then the optical path can enter a diaphragm 6, then enters a second lens group 7, and finally the optical path is imaged on an imaging device 8, and the imaging device 8 adopts a CCD imaging device in the invention.
The mirror group sequentially includes along the light path: a first concave mirror and an opposing second mirror; the first concave reflecting mirror and the opposite second reflecting mirror are arranged in a mirror face opposite way, and the reflecting mirror group has positive diopter, so that an incident light source forms a converging light path; the light path changes the direction of the light path after passing through the reflecting mirror group, then enters the first incident lens group, and the parallel light emitted from the object is parallel to the optical axis formed by the first incident lens group and the second lens group, namely, the reflecting mirror group only converges and translates the incident light.
The mirror group sequentially passes through paths along the light path, and comprises: the first concave mirror 2 and the opposite second mirror 3 form a converging light, where the mirror group replaces the largest incident mirror group at the forefront in the existing telecentric lens; the first concave reflecting mirror and the second reflecting mirror are arranged in opposite directions, so that an incident light source forms a converging light path; the light path changes the direction of the light path after passing through the reflecting mirror group and then enters the first incident lens group.
The reflector group can be combined in various ways, including:
a first reflecting spherical mirror and an opposite second reflecting spherical mirror; the first reflecting spherical mirror and the second reflecting spherical mirror are arranged in opposite directions, so that the incident light source forms a converging light path.
The first concave reflecting mirror is a spherical reflecting mirror, the second reflecting mirror is a spherical reflecting mirror, and the focal length of the first spherical reflecting mirror is smaller than or equal to that of the second spherical reflecting mirror.
The first concave reflecting mirror is an aspheric reflecting mirror, and the second reflecting mirror is an aspheric reflecting mirror.
The second reflecting mirror is a plane reflecting mirror.
The second reflector is a convex reflector, and the absolute value of the focal length of the first concave reflector is smaller than that of the convex reflector.
The first lens in the first incidence lens group is a first compensation lens 4, the first compensation lens is matched with the reflecting mirror group, parallel light is formed or light paths are converged to be incident, and then the light is transmitted through the lens group 5 and then enters the aperture stop. The relative position of the lens group at the front end of the aperture diaphragm is fixed.
The optimal combination of the reflector sets is that the two reflectors are aspheric concave reflectors, curvature can be made to be larger to form converging light, at the moment, the first compensating lens adopts a converging lens with large curvature, the whole first lens set is a converging lens with positive diopter, at the moment, the diameters of the first lens sets which are opposite to each other are relatively large, and at the moment, the length of the whole lens can be relatively long. When a mirror group having a relatively small curvature is used, the diameter of the first lens group can be made smaller.
The second lens group 7 may be a moving lens group; besides the distance between the reflecting mirror group and the object to be detected can be adjusted, the distance between the lens group 7 and the diaphragm can be adjusted to realize zoom ratio and work distance, the relative position of the aperture diaphragm and the first incident lens group is kept fixed, and the second lens group moves along the optical axis towards the direction close to the diaphragm. However, the design is not stable enough and the realization cost is high, and the scheme of the invention can realize the working distance adjustment by adjusting the distance between the reflecting mirror group and the object to be detected, so that the design cost of the telecentric lens can be reduced.
The first incident lens group is a fixed lens group, the first lens 4 is used as a compensating lens of incident light, a large curvature concave surface or convex surface design is adopted, convergent light is formed after passing through the lens 5, when a low-cost design is adopted, the reflecting mirror group adopts a design with smaller curvature, so that light passing through the reflecting mirror group not only changes direction, but also has larger convergent degree, namely, is reduced by more times, at the moment, the diameters of the first lens group and the second lens group at the back can be smaller, and the cost is reduced more; a balanced design can be made according to the requirements for imaging quality.
The second lens group is a movable lens group; when the variable magnification variable working distance is needed, the relative position of the aperture diaphragm and the first incident lens group is kept fixed, and the second lens group moves along the optical axis towards the direction approaching or far from the diaphragm.
In the above embodiment, the first incident lens group includes at least two lenses, where the first lens is a negative diopter lens to make the converging light path diverge to form parallel light, and the second lens is a positive diopter lens to make the parallel light path converge through the diaphragm;
the second lens group comprises at least one positive diopter lens, so that light rays passing through the diaphragm form parallel light rays to the imaging device; the centers of the optical axes of the first incident lens group, the diaphragm, the second lens group and the imaging device are the same center and are positioned on the same optical axis; the reflector group, the first incidence lens group, the diaphragm, the second lens group and the imaging device form a whole telecentric lens detection system, the whole detection system is arranged on the rotating device, and the object to be detected can be detected in a rotating manner along the optical axis as the center, so that a larger detection surface can be obtained. In another detection scheme, the reflector group can be independently arranged on the rotating device, namely, the reflector group and the lens barrel of the fixed reflector group can be rotatably arranged, the rotation is also carried out along the optical axis, the fixing device of the reflector group is fixedly sleeved with the end of the lens group, the reflector group is linked with the end of the lens group through the rotating ring, lubricating oil can be added to enable the reflector group to rotate stably, and the angle adjusting and fixing device is arranged. The rotation device can adopt a precise rotation bearing, the whole system or the rotation of the reflector group can also adopt an electric control rotation device to control the rotation angle and speed, and the control system is connected with a calculation system of the imaging device to calculate the acquired image position and angle.
In addition to the above-mentioned telecentric lens with low cost design, the present invention also provides a detection method of telecentric lens with variable working distance and variable magnification according to the low cost, and the method is applied to industrial lens, especially when detecting oversized objects, the detected objects need to be subjected to plane scanning. S1, arranging marks which are obviously compared with the background at the edges and specific positions of an object to be detected, and arranging the marks which are obviously compared with the background in the outline corresponding to the vertical edge of the first concave reflector; the mark is made on the detected object, so that the image acquired by the telecentric lens is clearer, the contrast is more obvious, and the subsequent processing of the image is facilitated.
S2, pre-storing a detected object contrast diagram in an image processing system, wherein the purpose is to carry out local image contrast recombination;
s3, rotating the detection lens by taking the center of the object to be detected as the center of a circle in the whole range of the object to be detected; on the lens side, parallel light between the object to be detected and the first reflecting mirror surface is parallel to the optical axis of the lens, the reflecting mirror group rotates by taking the optical axis of the lens as the center, and because the lens performs rotation detection, the view field is in the change, the edge and the special position on the object to be detected are calibrated, so that the identification of the object to be detected in the rotation detection process is more clear and accurate; the rotation detection is to make the detection system more stable, or the scanning detection of up, down, left and right can be adopted, so that a stable micro-electromechanical moving device is required to be used; the method of post image processing is the same. Because the rotation detection is performed by taking the optical axis of the lens group as the center, all images in the detection range of the detected object enter the image processing system, and the detected object cannot be detected in the part corresponding to the middle of the lens of the catadioptric telecentric lens, for example, the catadioptric telecentric lens with circular middle reflection, which is used for preventing local missed detection of the detected object due to shielding or blank.
S4, storing the detected object image obtained by the rotary scanning into an image processing system so as to form a standard image of the detected object through system calculation; the image storage and processing step needs to consume a large amount of calculation amount, firstly, the detected object image obtained by rotary scanning is stored in an image processing system, the image processing system carries out system calculation on the detected object image obtained by telecentric lens scanning, the system comprises image angle and lens rotation angle comparison analysis, and the comparison analysis is carried out with a pre-stored image;
the characteristic points in the images are respectively extracted, the edge and the characteristic point of each image are extracted, and particularly, the marks with obvious contrast are extracted; cutting the image after extracting the image, cutting edges of the scanned image of each needle, and removing the distortion part of the image; when the images are recombined, the image processing system performs image recombination and splicing according to the comparison of the pre-stored images, only performs angle adjustment on the acquired images during splicing, the lens is the front at the beginning, the acquired image angle is vertical to the front, and the images acquired corresponding to the rotating angle are correspondingly inclined, so that the angle adjustment is needed during calculation.
The method has the advantages that the whole monitoring image of the object to be detected is obtained, the overlapped part is optimized, the obtained scanning image is processed in the whole process, compared with the pre-stored image, the obtained image with clearer detection is obtained, the distortion part generated by the lens is removed, but a large amount of calculation resources are required to be consumed in the post-processing of the lens, a system with low calculation power can be adopted for reducing the cost, and the speed is influenced. In the method, when a rotary scanning mode is adopted, a mode that the reflector group rotates and the two subsequent lens groups and the imaging device are fixed can be adopted, and because the reflector group rotates around the lens optical axis as a center, the mode that the reflector group rotates and the subsequent image processing system processes is unchanged as long as the reflector group rotates, at the moment, the acquired images are all positive, and the image processing system processes the images, including cutting and splicing.
The design of the invention can be simulated by using common ZMAX software, and optimal parameters including the collocation of which reflector group is adopted are simulated and designed according to the size of the object to be detected. The final design result is that the reflector group has positive diopter along the light path, so that the incident light source forms a converging light path; the light path changes the direction of the light path after passing through the reflecting mirror group, then enters the first incident lens group, and the parallel light emitted from the object is parallel to the optical axis formed by the first incident lens group and the second lens group, namely, the reflecting mirror group only converges and translates the incident light. In actual implementation, the reflector is manufactured and installed according to various optical parameters of analog design, and the lens group is manufactured and installed, so that the low-cost variable-working-distance variable-magnification telecentric lens and the detection system thereof are manufactured.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, an industrial solution for solving the problem of ultra-large fittings of telecentric lens is provided, the telecentric lens adopts a lens with the front lens diameter matched with the object to be detected, the lens is processed to be increased along with the increase, the lens adopts a spherical or non-spherical reflecting mirror with a reflection principle at the incident end to replace a large-size incident lens with high cost, because the light paths are converged through the reflecting surface, the refraction process of the incident lens is reduced, the influence of chromatic aberration is reduced, and the imaging quality is improved. The scheme of the invention achieves good balance and improvement on cost. When a larger object to be detected is encountered, the method is adopted to carry out scanning detection by using the telecentric lens with low cost, so that a clearer image can be obtained, and the problem of image distortion detection is solved.
The drawings of the present invention are only for the purpose of presenting a principle that is readily understood by one of ordinary skill in the art. Because of the limitation of the page size of the patent application, in order to clearly show the principle, in the drawings, where the proportion of the size of each part may not be consistent with the actual product, those skilled in the art will understand that, for example, in the drawings, to highlight the structural principle of a certain part, the part is purposely drawn to be large, while the other part is too small, etc., which can be understood in this way, based on the principle of the present invention, those skilled in the art can naturally utilize the industrialized more reasonable design to make each part smaller and more exquisite, and more practical, which are all the ways known to those skilled in the art.
In the description of the present invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "another end," "upper," "one side," "top," "inner," "front," "center," "two ends," etc. indicate orientations or positional relationships based on the orientation 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 devices or elements 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.
Based on the fact that no product is only advantageous and has no defects, the invention is only used for specific environments in the background technology, such as scenes mentioned in the background technology, if some users consider price factors, inconvenient carrying and the like, the purchase of the application is not suggested, and the product is only used for and suggested by users who need to mention the scenes in the background technology and can accept and ignore other negative factors at the same time.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "configured," "connected," "secured," "screwed," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intermediaries, or in communication with each other or in interaction with each other, unless explicitly defined otherwise, the meaning of the terms described above in this application will be understood by those of ordinary skill in the art in view of the specific circumstances.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. .
While certain exemplary embodiments of the present invention have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that modifications may be made to the described embodiments in various different ways without departing from the spirit and scope of the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive of the scope of the invention, which is defined by the appended claims.
Claims (8)
1. A low-cost large-view-field variable working distance telecentric lens is characterized in that: the method sequentially comprises the following steps from an object side to an image side according to an optical path: a reflecting mirror group for changing the light path, a first incident lens group, a diaphragm, a second lens group and an imaging device;
the mirror group sequentially includes along the light path: a first concave mirror and an opposing second mirror; the first concave reflecting mirror and the opposite second reflecting mirror are arranged in a mirror face opposite way, and the reflecting mirror group has positive diopter, so that an incident light source forms a converging light path; the light path changes the direction of the light path after passing through the reflecting mirror group, then enters the first incident lens group, and the parallel light emitted from the object is parallel to the optical axis formed by the first incident lens group and the second lens group, namely the reflecting mirror group only converges and translates the incident light, and then enters the first incident lens group;
the first incident lens group at least comprises two parts of lenses, wherein the first part of lenses are negative diopter lenses, so that the converging light paths diverge to form parallel light, and the second part of lenses are positive diopters, so that the parallel light paths converge again and pass through the diaphragm;
the second lens group comprises at least one positive diopter lens, so that light rays passing through the diaphragm form parallel light rays to the imaging device;
the first incident lens group, the diaphragm, the second lens group and the imaging device are positioned in the same optical axis lens barrel device;
the reflector group is independently arranged on the rotating device, namely, the reflector group and the lens barrel of the fixed lens group can be rotatably arranged, the rotation is also carried out along the optical axis, the fixing device of the reflector group is fixedly sleeved with the end of the lens group, the reflector group is linked through the rotating ring, lubricating oil can be added to ensure that the reflector group rotates stably, and the angle adjusting and fixing device is arranged; the rotating device adopts a precise rotating bearing, the rotation of the whole reflecting mirror group adopts an electrically-controlled rotating device to control the rotating angle and speed, and the control system is connected with a computing system of the imaging device to calculate the acquired image position and angle.
2. The low cost large field of view variable working distance telecentric lens according to claim 1, wherein:
the first concave reflecting mirror is a spherical reflecting mirror or an aspherical reflecting mirror, and the second reflecting mirror is a corresponding concave spherical reflecting mirror or a concave aspherical reflecting mirror.
3. The low cost large field of view variable working distance telecentric lens according to claim 1, wherein: the second reflecting mirror is a plane reflecting mirror.
4. A low cost large field of view variable working distance telecentric lens according to claim 2, wherein: the second reflector is a convex reflector, and the absolute value of the focal length of the first concave reflector is smaller than that of the second convex reflector.
5. A low cost large field of view variable working distance telecentric lens according to any of claims 1-4, wherein: the optical path is still parallel to the original optical path from the object side to the direction of the optical path after being changed by the reflecting mirror group, namely the direction of the optical path is only translated and converged by the reflecting mirror group after being changed, and a first lens in the first incident lens group is a first compensating lens and a second lens is a converging lens; the first compensation lens is matched with the reflector group to form a parallel light path for incidence, and the parallel light path passes through the diaphragm after passing through the second lens; the first incident lens group is fixed relative to the aperture diaphragm and the lens barrel, and the second lens group is adjustable along the optical axis.
6. The low cost large field of view variable working distance telecentric lens according to claim 5, wherein: the first incident lens group is a fixed lens group, and the second lens group is a movable lens group; when the variable working distance variable magnification telecentric lens performs variable magnification variable working distance, the relative position of the aperture diaphragm and the first incident lens group is kept fixed, and the second lens group moves along the optical axis towards the direction approaching or far from the diaphragm.
7. A method of inspection using the low cost large field of view variable working distance telecentric lens of claim 6, the imaging device comprising an image processing system, characterized by: s1, a mark which is obviously compared with a background is arranged in the outline of the vertical projection of the edge and a specific position on the object to be detected and the edge corresponding to the first concave reflector;
s2, setting a pre-stored detected object comparison chart in an image processing system;
s3, rotating the detection lens by taking the center of the object to be detected as the center of a circle in the whole range of the object to be detected; on the lens side, parallel light between the object to be detected and the first reflecting mirror surface is parallel to the optical axis of the lens, the reflecting mirror group rotates by taking the optical axis of the lens as the center, and because the lens performs rotation detection, the view field is in the change, the edge and the special position on the object to be detected are calibrated, so that the identification of the object to be detected in the rotation detection process is more clear and accurate;
s4, storing the detected object image obtained by the rotary scanning into an image processing system so as to form a standard image of the detected object through system calculation;
in the step S3, a mode that the reflector group rotates and the two lens groups and the imaging device are fixed is adopted, and the reflector group rotates around the optical axis of the lens as the center;
in the step S4, the detected object image obtained by rotary scanning is stored in an image processing system so as to form a standard image of the detected object through system calculation;
the image processing system performs system calculation on the image of the detected object obtained through telecentric lens scanning, and comprises image comparison analysis and comparison with a pre-stored detected object comparison chart;
extracting feature points in the images, and extracting edges and feature points of each image;
cutting the image, cutting edges of the scanned image of each needle, and removing the image distortion part;
and (3) image reorganization, wherein the image processing system performs image reorganization and splicing according to the comparison of the pre-stored images to obtain a complete monitoring image of the object to be detected, and the overlapping part is optimized.
8. The detection method according to claim 7, characterized in that:
in the step S3, the whole lens comprises a reflecting mirror group, a lens group and an imaging device part, and the rotation of the detection lens is carried out by taking the center of an object to be detected as the center of a circle; on the lens side, the lens rotates by taking the optical axis of the lens as the center, and because the lens performs rotation detection, the detected object image obtained by rotation scanning is stored in an image processing system, and when the image processing system processes the image, the image processing system comprises image angle and lens rotation angle contrast analysis; then extracting feature points in the images, and extracting the edge and the feature points of each image;
cutting the image, cutting edges of the scanned image of each needle, and removing the image distortion part;
and (3) image reorganization, wherein the image processing system performs image reorganization and splicing according to the comparison of the pre-stored images to obtain a complete monitoring image of the object to be detected, and the overlapping part is optimized.
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