CN112730235B - Dynamic fine line abrupt junction automatic detection device and method based on optical diffraction - Google Patents
Dynamic fine line abrupt junction automatic detection device and method based on optical diffraction Download PDFInfo
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- CN112730235B CN112730235B CN202011508903.2A CN202011508903A CN112730235B CN 112730235 B CN112730235 B CN 112730235B CN 202011508903 A CN202011508903 A CN 202011508903A CN 112730235 B CN112730235 B CN 112730235B
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Abstract
The invention discloses an automatic detection device and method for dynamic hairline burl junctions based on optical diffraction, wherein the method comprises the following steps: the fine wire fixing device stably and accurately realizes that the fine wire passes through the optical acquisition area at a constant speed; performing optical Fresnel diffraction on the thin line by the optical detection area; collecting an optical diffraction image by using a camera; the image similarity method is used for quickly identifying the diffraction image of the thin line abrupt junction, and dynamic thin line abrupt junction detection is achieved. According to the principle of optical fresnel diffraction, when the protruding junction passes through the optical detection area, the diffraction image generated by the laser irradiating the thin line is obviously different from the diffraction image without the protruding junction. The method is based on the image of optical Fresnel diffraction, utilizes a camera to record the diffraction image for detection, does not relate to a contact type measuring instrument, solves the problem that the knot of the thin line is not easy to capture due to high moving speed of the thin line in the existing detection method, and realizes knot detection of the thin line which dynamically changes.
Description
Technical Field
The invention belongs to the field of fine line detection, and particularly relates to a dynamic fine line abrupt junction automatic detection device and method based on optical diffraction.
Background
With the development of modern processes, miniaturization is a trend in many industrial fields, such as various fine metal wires, enameled wires and optical fibers, where maintaining a stable diameter size is a key to ensure product quality, and thus research on the detection of fine structures is of great practical value.
In the existing thin line detection field, a contact measurement or optical measurement instrument method is often adopted for thin line detection. The thin line is measured by using a contact measurement method, on one hand, the contact with an object to be measured inevitably causes deformation of the object to be measured, and for thin line detection, the deformation greatly causes measurement errors; on the other hand, the contact type measuring method is difficult to detect the dynamically changed thin line in real time. With the optical measuring instrument, the optical diffraction effect of the thin line causes a large error in the measurement. Therefore, the existing detection method has the problems of measurement errors caused by contact measurement, measurement errors caused by optical diffraction and incapability of detecting the dynamic thin line in real time.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of the prior art and provides a dynamic fine line bump automatic detection device and method based on optical diffraction.
In order to solve the technical problem, in a first aspect, the invention discloses an automatic detection device for a dynamic hairline burl based on optical diffraction, which comprises a hairline to be detected, a hairline fixing device, a laser, an optical fresnel diffraction receiving screen and a camera;
the fine wire fixing device is used for fixing the fine wire to be detected, so that the fine wire to be detected is kept in a straightened state, the fine wire to be detected can keep constant-speed and rapid movement in the direction of the fine wire in a laser irradiation area under the condition that power is supplied by the fine wire fixing device, and the position of the fine wire to be detected is kept stable except the movement of the fine wire to be detected in the direction of the fine wire;
the laser is positioned on one side of the thin wire to be detected and is used for directly irradiating the thin wire to be detected with emitted laser, and the direct laser irradiation direction is perpendicular to the movement direction of the thin wire to be detected;
the optical Fresnel diffraction receiving screen is positioned on the other side of the thin line to be detected, is perpendicular to the horizontal plane and is parallel to the thin line to be detected, and is used for generating an optical Fresnel diffraction image when the thin line to be detected is irradiated by a laser; the central point of the optical Fresnel diffraction receiving screen and the central point of the laser are on the same straight line, and the straight line is perpendicular to the thin line to be detected and intersects at one point;
the camera is positioned above the laser and used for recording Fresnel diffraction images of the thin lines to be detected.
With reference to the first aspect, in one implementation manner, the thin wire fixing device is composed of a first rolling scroll and a second rolling scroll, and the first rolling scroll and the second rolling scroll are respectively located at two ends of the thin wire to be detected to fix the thin wire; under the drive of the first rolling scroll and the second rolling scroll, the first rolling scroll pays off, the second rolling scroll takes up or pays off, and the first rolling scroll takes up to keep the thin wire to be detected in a straightening state and keep constant-speed and rapid movement along the direction of the thin wire.
In a second aspect, the invention discloses an automatic detection method for dynamic hairline burl based on optical diffraction, which comprises the following steps:
step 1, fixing a thin wire to be detected by using a thin wire fixing device to keep the thin wire to be detected in a straightening state;
step 2, calculating the standard distance between the thin line to be detected and the optical Fresnel diffraction receiving screen according to the standard diameter of the thin line to be detected and the wavelength of the laser;
step 3, placing a fine line fixing device and an optical Fresnel diffraction receiving screen for controlling the movement of the fine line to be detected according to the standard distance obtained by calculation in the step 2, placing a laser so that the laser can directly irradiate the fine line to be detected, and placing a camera so that the camera can record Fresnel diffraction images of the fine line to be detected;
step 4, selecting a section of standard fine wire without protruding knots on the fine wire to be detected to manufacture a standard diffraction sample image;
step 5, irradiating the thin line to be detected which moves rapidly and stably at a constant speed by using a laser, and shooting and recording a diffraction image on an optical Fresnel diffraction receiving screen by using a camera;
and 6, comparing the similarity of the diffraction image shot and recorded by the camera in the step 5 with the standard diffraction sample image, detecting the protruding knots of the thin line to be detected, counting the number of the protruding knots in the detection, and realizing the classification of the quality of the thin line.
With reference to the second aspect, in one implementation manner, the step 1 includes: the fine wire fixing device fixes the fine wire to be detected, so that the fine wire to be detected can keep a straightening state, the fine wire to be detected can keep constant-speed and quick movement in a laser irradiation area under the condition that the fine wire fixing device provides power, and the fine wire to be detected keeps stable in position except the movement of the fine wire to be detected in the direction of the fine wire.
With reference to the second aspect, in an implementation manner, in step 2, the standard distance z between the thin line to be detected and the optical fresnel diffraction receiving screen and the laser wavelength λ satisfy the following constraint condition:
wherein (x)0,y0) The coordinates of the points on the thin line to be detected are shown, and (x, y) the coordinates of the points on the optical Fresnel diffraction receiving screen are shown.
With reference to the second aspect, in one implementation manner, the step 3 includes:
3-1, placing the optical Fresnel diffraction receiving screen according to the standard distance between the thin line to be detected and the optical Fresnel diffraction receiving screen, which is obtained by calculation in the step 2, wherein the receiving screen is vertical to the horizontal plane and is parallel to the thin line to be detected;
3-2, respectively positioning a laser and an optical Fresnel diffraction receiving screen at two sides of the thin wire to be detected, wherein laser emitted by the laser directly irradiates the thin wire to be detected, and the direct laser irradiation direction is vertical to the movement direction of the thin wire to be detected;
and 3-3, placing a camera above the laser so that the camera can record the optical Fresnel diffraction image of the thin line to be detected.
With reference to the second aspect, in one implementation manner, the step 4 includes:
step 4-1, screening a section of standard fine line without protruding knots on the fine line to be detected, fixing the fine line to be detected by using a fine line fixing device, keeping the fine line fixed relative to the whole device, emitting laser to directly irradiate the fine line to be detected by using a laser, generating Fresnel diffraction on the fine line, receiving a corresponding static optical Fresnel diffraction image on an optical Fresnel diffraction receiving screen, shooting and recording the obtained diffraction image by using a camera, analyzing the diffraction image, wherein the Fresnel diffraction image of the fine line is uniformly and linearly distributed according to the principle of optical Fresnel diffraction, if the protruding knots exist, the diffraction image generates concentric circular disturbance, continuously emitting the laser to directly irradiate other sections of the fine line to be detected by using the laser, and shooting and recording the obtained diffraction image by using the camera until the diffraction image is the uniform linear diffraction image without the concentric circular disturbance, the corresponding section of the thin wire to be detected is the standard thin wire without the protruding knot; the burs are abnormal knots on the uniform thin wire, and the diameter of the knots is usually several times of the diameter and the width of the uniform thin wire;
step 4-2, fixing the standard fine wire without the protruding knots by a fine wire fixing device, turning on a laser, directly irradiating the standard fine wire without the protruding knots by laser, and starting the fine wire fixing device to enable the standard fine wire without the protruding knots to move along the fine wire direction;
4-3, shooting an optical Fresnel diffraction image when the standard thin line without the protruding knots moves by using a camera;
and 4-4, selecting a clear and non-fuzzy optical Fresnel diffraction image from the shot optical Fresnel diffraction images as a standard diffraction sample image.
With reference to the second aspect, in one implementation manner, the step 5 includes:
step 5-1, turning on a laser, starting a mechanical power device for controlling the movement of the thin wire to be detected, and directly irradiating the thin wire to be detected with laser;
and 5-2, shooting and recording a diffraction image on the optical Fresnel diffraction receiving screen when the thin line to be detected moves by using a camera.
With reference to the second aspect, in an implementation manner, in step 6, the diffraction image recorded in step 5 and the standard diffraction sample image obtained in step 4 are compared in image similarity by using a peak signal to noise ratio PSNR method of the image;
recording a diffraction image of a thin line to be detected as K, recording a standard diffraction sample image as I, wherein the scales of the two images are mxn, and then defining the peak signal-to-noise ratio (PSNR) of the image I and the K as:
wherein, MAXIA maximum value representing a pixel value on the standard diffraction sample image I;
where MSE represents the mean square error, the formula is as follows:
i (a, b) represents the pixel value of the pixel point (a, b) on the standard diffraction sample image I, and K (a, b) represents the pixel value of the pixel point (a, b) on the diffraction image K of the thin line to be detected;
and when the peak signal-to-noise ratio PSNR of the two images is smaller than a threshold value T, judging that the abrupt junction is detected on the thin line to be detected.
Has the advantages that: in the invention, a standard optical Fresnel diffraction image is firstly obtained for a standard thin line without a protruding knot, then the diffraction image is continuously recorded for the dynamically changed thin line which possibly has the protruding knot, and whether an abnormal protruding knot exists in the thin line can be detected in real time by comparing the similarity between the continuously recorded image and the standard optical Fresnel diffraction image. Compared with the prior art, the invention solves the problems of measurement errors caused by pressure deformation caused by contacting an object to be measured in contact measurement and measurement errors caused by diffraction in optical measurement; meanwhile, because the light propagation in the air is extremely fast, the formation of the diffraction image can be considered to have no time delay, and the invention utilizes the diffraction image to detect the thin line abrupt junction, thereby solving the problem that the dynamic detection is difficult in the prior art.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a schematic diagram illustrating a position distribution of an optical diffraction-based dynamic fine-line bump automatic detection apparatus according to an embodiment of the present invention;
fig. 2 is a schematic diagram of optical fresnel diffraction in a dynamic fine-line bump automated detection method based on optical diffraction according to an embodiment of the present invention;
FIG. 3 is a diffraction image of a fine line without nodules provided in part by an embodiment of the invention;
figure 4 is a diffraction image of a fine line with nodules provided in part by an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, a first embodiment of the present invention discloses an automatic detection apparatus for a dynamic hairline burl based on optical diffraction, which includes a hairline to be detected, a hairline fixing device, a laser, an optical fresnel diffraction receiving screen, and a camera;
the fine wire fixing device is used for fixing the fine wire to be detected, so that the fine wire to be detected is kept in a straightened state, the fine wire to be detected can keep constant-speed and rapid movement in the direction of the fine wire in a laser irradiation area under the condition that power is supplied by the fine wire fixing device, and the position of the fine wire to be detected is kept stable except the movement of the fine wire to be detected in the direction of the fine wire;
the laser is positioned on one side of the thin wire to be detected and is used for directly irradiating the thin wire to be detected with emitted laser, and the direct laser irradiation direction is perpendicular to the movement direction of the thin wire to be detected; in the embodiment, the laser adopts a line laser and can emit a line laser source;
the optical Fresnel diffraction receiving screen is positioned on the other side of the thin line to be detected, is perpendicular to the horizontal plane and is parallel to the thin line to be detected, and is used for generating an optical Fresnel diffraction image when the thin line to be detected is irradiated by a laser; the central point of the optical Fresnel diffraction receiving screen and the central point of the laser are on the same straight line, and the straight line is perpendicular to the thin line to be detected and intersects at one point;
the camera is positioned above the laser and used for recording Fresnel diffraction images of the thin lines to be detected.
In the first embodiment of the present invention, the thin wire fixing device is composed of a first rolling scroll and a second rolling scroll, the first rolling scroll and the second rolling scroll are respectively located at two ends of the thin wire to be detected to fix the thin wire; under the drive of the first rolling scroll and the second rolling scroll, the first rolling scroll pays off, the second rolling scroll takes up or pays off, and the first rolling scroll takes up to keep the thin wire to be detected in a straightening state and keep constant-speed and rapid movement along the direction of the thin wire.
The second embodiment of the invention discloses an automatic detection method of dynamic hairline abrupt junctions based on optical diffraction, which comprises the following steps:
step 1, fixing a textile fine wire to be detected by using a fine wire fixing device, and ensuring that the textile fine wire can keep stable position, uniform speed and rapid advance in a certain area; in this embodiment, the diameter of the standard fine textile thread to be detected is 60um, the diameter of the abnormal knot is about 180um, and the fine textile thread stably passes through the optical detection area at a speed of 2 m/s.
Step 2, calculating the standard distance between the fine yarn and the optical Fresnel diffraction receiving screen according to the standard diameter of the textile fine yarn to be detected and the wavelength of the laser; in this embodiment, the standard diameter of the thin textile wire to be detected is 60um, the wavelength of the laser is 532nm, and the length of the laser wire emitted by the line laser is 35 mm.
And 3, as shown in fig. 1, placing a fine line fixing device and an optical fresnel diffraction receiving screen for controlling the movement of the fine line according to the standard distance, placing a laser so that the laser can directly irradiate the fine textile line, and placing a camera so that the camera can record a fresnel diffraction image of the fine textile line. In this embodiment, the standard distance is the standard distance calculated in step 2.
And 4, selecting a section of standard textile fine line without knots to manufacture a standard diffraction sample image of the diffraction pattern. In this example, the standard knot-free textile fine wire is a standard knot-free textile fine wire having a standard diameter of 60um in step 1.
And 5, irradiating the textile fine line which moves stably at a constant speed and quickly by laser, and continuously recording diffraction images on the optical Fresnel diffraction receiving screen by the camera. In this embodiment, the diffraction image refers to an optical fresnel diffraction image generated after the thin textile wire to be detected is irradiated by laser.
And 6, comparing the similarity of the image recorded by the camera with the standard diffraction sample image, and detecting the knots of the textile fine lines. In this embodiment, the image recorded by the camera includes an optical fresnel diffraction image of a fine woven wire without knots and including knots.
In a second embodiment of the present invention, the step 1 includes: the fine rule fixing device fixes the weaving fine rule, makes it can keep the state of flare-outing, and under the fine rule fixing device provided power's the circumstances, the weaving fine rule can keep at the uniform velocity and move fast in the laser irradiation region to except the motion of weaving fine rule along weaving fine rule direction, keep the position stable.
Specifically, in this step, the fixed weaving fine rule that waits to detect of two roll reels, the fixed weaving fine rule of roll reel makes it just keep straightening and do not take place deformation, and under the drive of roll reel, the weaving fine rule passes through the laser direct projection district before optics fresnel diffraction receiving screen with the speed of 2m/s, and the weaving fine rule does not have other direction movements.
In a second embodiment of the present invention, the step 2 includes: in order to obtain an optical Fresnel diffraction image of the textile fine line, which is convenient to observe, the distance from the textile fine line to the Fresnel diffraction receiving screen under the detection condition needs to be calculated by utilizing the standard diameter of the textile fine line to be detected and the wavelength of a laser used in the detection.
Specifically, in this embodiment, based on the knowledge about the optical diffraction, it can be known that the constraint condition for generating the fresnel diffraction is:
as shown in FIG. 2, z represents the distance from the diffraction screen to the receiving screen, λ represents the wavelength of the laser light illuminating the diffraction screen, and (x)0,y0) And (2) representing coordinates of points on the diffraction screen, wherein (x, y) represent coordinates of points on the receiving screen, the diffraction screen is a plane where the thin textile line to be detected is located, the plane is vertical to the horizontal plane, and the receiving screen is the optical Fresnel diffraction receiving screen.
The standard diameter of the textile fine line which generates diffraction is 60um, the diameter of the protruding node is 180um, the distance from the textile fine line to the optical Fresnel diffraction receiving screen is 9.6cm, the optical diffraction receiving area on the receiving screen is 20cm multiplied by 20cm, and the condition of Fresnel diffraction generation is met.
In a second embodiment of the present invention, the step 3 includes:
3-1, placing the optical Fresnel diffraction receiving screen according to the standard distance between the textile fine line and the optical Fresnel diffraction receiving screen calculated in the step 2, wherein the receiving screen is vertical to the horizontal plane and is parallel to the textile fine line; in this embodiment, as shown in fig. 1, the standard distance is 9.6cm from the textile fine line calculated in step 2 to the fresnel diffraction receiving screen.
Step 3-2, as shown in fig. 1, the laser and the optical fresnel diffraction receiving screen are respectively positioned at two sides of the thin wire to be detected, the laser emitted by the laser directly irradiates the thin wire to be detected, and the direct irradiation direction of the laser is perpendicular to the movement direction of the thin wire to be detected;
step 3-3, as shown in fig. 1, a camera is placed above the laser so that it can record the optical fresnel diffraction image of the thin textile line.
In a second embodiment of the present invention, the step 4 includes:
4-1, screening a section of standard textile fine line without knots;
in the embodiment, a standard textile fine line without protruding knots with a diameter of 60um is screened, the screening method is that the fine line to be detected is fixed by a fine line fixing device and is kept fixed relative to the whole device, laser of a laser emission line is utilized to directly irradiate the fine line to be detected, fresnel diffraction occurs on the fine line, a corresponding static optical fresnel diffraction image can be received on an optical fresnel diffraction receiving screen, a camera is utilized to shoot a diffraction screen area, the image is cut, the diffraction image area is reserved, an interference background is cut and removed, a uniform linear diffraction image without concentric circular disturbance in the cut image is screened out, and the corresponding textile fine line to be detected is the standard textile fine line without protruding knots; the burs are abnormal knots on the uniform thin wire, and the diameter of the knots is usually several times of the diameter and the width of the uniform thin wire; fig. 3 shows a diffraction image of a fine line without knots, and fig. 4 shows a diffraction image of a fine line with knots.
Step 4-2, fixing the standard fine wire without the protruding knots by a fine wire fixing device, turning on a laser, directly irradiating the standard fine wire without the protruding knots by laser, and starting the fine wire fixing device to enable the standard fine wire without the protruding knots to move along the fine wire direction;
4-3, shooting an optical Fresnel diffraction image of the standard textile fine line without the burred knots by using a camera during movement;
and 4-4, selecting a clear and non-fuzzy optical Fresnel diffraction image from the shot optical Fresnel diffraction images as a standard diffraction sample image.
In a second embodiment of the present invention, the step 5 includes:
step 5-1, turning on a laser, starting a mechanical power device for controlling the movement of the thin textile threads, and directly irradiating the thin textile threads to be detected by the laser; in this embodiment, the mechanical power device is two rolling reels, and the wavelength of the laser is 532 nm.
Step 5-2, the camera continuously records diffraction images on the optical fresnel diffraction receiving screen, and the camera adopted in the embodiment shoots 60 diffraction images per second.
In a second embodiment of the present invention, in step 6, the diffraction image recorded in step 5 and the standard diffraction sample image obtained in step 4 are compared in image similarity by using a peak signal-to-noise ratio PSNR method of the image.
From the knowledge about optical diffraction, it can be known that the image of fresnel diffraction is related to the diffraction screen where diffraction occurs, and the light intensity distribution formula of fresnel diffraction is as follows:
as shown in FIG. 2, z represents the distance from the diffraction screen to the receiving screen, λ represents the wavelength of the laser light illuminating the diffraction screen, j represents the imaginary unit, k represents the wave number
(x0,y0) Coordinates representing a point on the diffraction screen, (x, y) coordinates representing a point on the receiving screen, U0(x0,y0) The light intensity distribution of incident laser passing through the diffraction screen is shown, the light intensity distribution on the optical Fresnel diffraction receiving screen is shown in U (x, y), the formula shows that different optical Fresnel diffraction images generated by laser irradiation of the textile fine line containing and not containing the burs can detect the burs in the textile fine line by comparing the diffraction images, and the quantity of the burs can be counted in the detection, so that the quality of the fine line can be classified.
Recording a diffraction image of a to-be-detected textile fine line as K, recording a standard diffraction sample image as I, wherein the scales of the two images are mxn, and then defining the peak signal-to-noise ratio (PSNR) of the image I and the K as:
wherein, MAXIA maximum value representing a pixel value on the standard diffraction sample image I;
where MSE represents the mean square error, the formula is as follows:
i (a, b) represents the pixel value of the pixel point (a, b) on the standard diffraction sample image I, and K (a, b) represents the pixel value of the pixel point (a, b) on the diffraction image K of the thin line to be detected;
similarity analysis is carried out on the diffraction image recorded in the step 5 and the standard diffraction sample image obtained in the step 4 by utilizing the peak signal-to-noise ratio PSNR of the images, a certain judgment threshold value T is set, and when the peak signal-to-noise ratios PSNR of the two images are smaller than the threshold value T, the detection of the protruding knot on the thin line to be detected is judged, wherein in the embodiment, the threshold value T is set to be 40.
The invention provides a dynamic hairline burl junction automatic detection device and a method based on optical diffraction, and the required types of a laser and a camera do not limit the patent; the resolution of the recorded diffraction image is not limiting to this patent; the image similarity comparison method used is not limiting to this patent. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.
Claims (8)
1. An automatic detection method for dynamic hairline abrupt junctions based on optical diffraction is characterized by comprising the following steps:
step 1, fixing a thin wire to be detected by using a thin wire fixing device to keep the thin wire to be detected in a straightening state;
step 2, calculating the standard distance between the thin line to be detected and the optical Fresnel diffraction receiving screen according to the standard diameter of the thin line to be detected and the wavelength of the laser;
step 3, placing a fine line fixing device and an optical Fresnel diffraction receiving screen for controlling the movement of the fine line to be detected according to the standard distance calculated in the step 2, placing a laser so that the laser can directly irradiate the fine line to be detected, and placing a camera above the laser so that the camera can record Fresnel diffraction images of the fine line to be detected;
step 4, selecting a section of standard fine wire without protruding knots on the fine wire to be detected to manufacture a standard diffraction sample image;
step 5, irradiating the thin line to be detected which moves rapidly and stably at a constant speed by using a laser, and shooting and recording a diffraction image on an optical Fresnel diffraction receiving screen by using a camera;
and 6, comparing the similarity of the diffraction image shot and recorded by the camera in the step 5 with the standard diffraction sample image, detecting the protruding knots of the thin line to be detected, and counting the number of the protruding knots in the detection.
2. The method for automatically detecting the dynamic hairline-knot based on the optical diffraction is characterized in that a dynamic hairline-knot automatic detection device based on the optical diffraction is used for detection, and the dynamic hairline-knot automatic detection device based on the optical diffraction comprises a hairline fixing device, a laser, an optical Fresnel diffraction receiving screen and a camera;
the fine wire fixing device is used for fixing the fine wire to be detected, so that the fine wire to be detected is kept in a straightened state, the fine wire to be detected can keep constant-speed and rapid movement in the direction of the fine wire in a laser irradiation area under the condition that power is supplied by the fine wire fixing device, and the position of the fine wire to be detected is kept stable except the movement of the fine wire to be detected in the direction of the fine wire;
the laser is positioned on one side of the thin wire to be detected and is used for directly irradiating the thin wire to be detected with emitted laser, and the direct laser irradiation direction is perpendicular to the movement direction of the thin wire to be detected;
the optical Fresnel diffraction receiving screen is positioned on the other side of the thin line to be detected, is perpendicular to the horizontal plane and is parallel to the thin line to be detected, and is used for receiving an optical Fresnel diffraction image generated when the laser irradiates the thin line to be detected; the central point of the optical Fresnel diffraction receiving screen and the central point of the laser are on the same straight line, and the straight line is perpendicular to the thin line to be detected and intersects at one point;
the camera is positioned above the laser and used for recording Fresnel diffraction images of the thin lines to be detected.
3. The method for automatically detecting the dynamic fine line knot based on the optical diffraction is characterized in that the fine line fixing device consists of a first rolling scroll and a second rolling scroll, and the first rolling scroll and the second rolling scroll are respectively positioned at two ends of the fine line to be detected to fix the fine line; under the drive of the first rolling scroll and the second rolling scroll, the first rolling scroll pays off, the second rolling scroll takes up or pays off, and the first rolling scroll takes up to keep the thin wire to be detected in a straightening state and keep constant-speed and rapid movement along the direction of the thin wire.
4. The method for automatically detecting the dynamic hairline burl based on the optical diffraction as claimed in claim 2, wherein in the step 2, the standard distance z between the hairline to be detected and the optical fresnel diffraction receiving screen and the laser wavelength λ satisfy the following constraint conditions:
wherein (x)0,y0) The coordinates of the points on the thin line to be detected are shown, and (x, y) the coordinates of the points on the optical Fresnel diffraction receiving screen are shown.
5. The method for automatically detecting the dynamic fine line bump junction based on the optical diffraction as claimed in claim 2, wherein the step 3 comprises:
3-1, placing the optical Fresnel diffraction receiving screen according to the standard distance between the thin line to be detected and the optical Fresnel diffraction receiving screen, which is obtained by calculation in the step 2, wherein the receiving screen is vertical to the horizontal plane and is parallel to the thin line to be detected;
3-2, respectively positioning a laser and an optical Fresnel diffraction receiving screen at two sides of the thin wire to be detected, wherein laser emitted by the laser directly irradiates the thin wire to be detected, and the direct laser irradiation direction is vertical to the movement direction of the thin wire to be detected;
and 3-3, placing a camera above the laser so that the camera can record the optical Fresnel diffraction image of the thin line to be detected.
6. The method for automatically detecting the dynamic fine line bump junction based on the optical diffraction is characterized in that the step 4 comprises the following steps:
step 4-1, screening a section of standard fine line without protruding knots on the fine line to be detected, fixing the fine line to be detected by using a fine line fixing device, keeping the fine line fixed relative to the whole device, directly irradiating the section of the fine line to be detected by using laser emitted by a laser, generating Fresnel diffraction on the fine line, receiving a corresponding static optical Fresnel diffraction image on an optical Fresnel diffraction receiving screen, shooting and recording the obtained diffraction image by using a camera, analyzing the diffraction image, and if the protruding knots exist, enabling the diffraction image to be in uniform linear distribution, enabling the diffraction image to generate concentric circular disturbance, continuously directly irradiating the other sections of the fine line to be detected by using the laser emitted by the laser, and shooting and recording the obtained diffraction image by using the camera until the diffraction image is the uniform linear diffraction image without the concentric circular disturbance, the corresponding section of the thin wire to be detected is the standard thin wire without the protruding knot; the burs are abnormal knots on the uniform thin wire, and the diameter of the knots is usually several times of the diameter and the width of the uniform thin wire;
step 4-2, fixing the standard fine wire without the protruding knots by a fine wire fixing device, turning on a laser, directly irradiating the standard fine wire without the protruding knots by laser, and starting the fine wire fixing device to enable the standard fine wire without the protruding knots to move along the fine wire direction;
4-3, shooting an optical Fresnel diffraction image when the standard thin line without the protruding knots moves by using a camera;
and 4-4, selecting a clear and non-fuzzy optical Fresnel diffraction image from the shot optical Fresnel diffraction images as a standard diffraction sample image.
7. The method for automatically detecting the dynamic fine line bump junction based on the optical diffraction as claimed in claim 2, wherein the step 5 comprises:
step 5-1, turning on a laser, starting a thin wire fixing device for controlling the movement of the thin wire to be detected, and directly irradiating the thin wire to be detected with the laser;
and 5-2, shooting and recording a diffraction image on the optical Fresnel diffraction receiving screen when the thin line to be detected moves by using a camera.
8. The method for automatically detecting the dynamic fine line bump junction based on the optical diffraction is characterized in that the diffraction image recorded in the step 5 is compared with the standard diffraction sample image obtained in the step 4 in image similarity by adopting a peak signal-to-noise ratio (PSNR) method of the image in the step 6;
recording a diffraction image of a thin line to be detected as K, recording a standard diffraction sample image as I, wherein the scales of the two images are mxn, and then defining the peak signal-to-noise ratio (PSNR) of the image I and the K as:
wherein, MAXIA maximum value representing a pixel value on the standard diffraction sample image I;
where MSE represents the mean square error, the formula is as follows:
i (a, b) represents the pixel value of the pixel point (a, b) on the standard diffraction sample image I, and K (a, b) represents the pixel value of the pixel point (a, b) on the diffraction image K of the thin line to be detected;
and when the PSNR of the two images is smaller than a threshold value T, judging that the knot is detected on the thin line to be detected.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| CN101482503A (en) * | 2009-02-20 | 2009-07-15 | 山东师范大学 | Coherent diffraction imaging method and its processing equipment |
| CN207662821U (en) * | 2016-09-15 | 2018-07-27 | 宾德股份公司 | Detecting devices and sorting device for detected object |
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| CN101482503A (en) * | 2009-02-20 | 2009-07-15 | 山东师范大学 | Coherent diffraction imaging method and its processing equipment |
| CN207662821U (en) * | 2016-09-15 | 2018-07-27 | 宾德股份公司 | Detecting devices and sorting device for detected object |
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