Transparent uniformity detection method

Abstract

The invention provides a transparency uniformity detection method. The method comprises the following steps: calibrating the position of each linear spectrum confocal sensor by adopting a transparent calibration object with known thickness; each line spectrum confocal sensor sequentially scans an object to be detected to obtain at least one spectrogram corresponding to each position of any surface of the object to be detected; acquiring a spectrogram of any position of the to-be-measured object based on each line spectrum confocal sensor, and acquiring the measured thickness of the current position of the to-be-measured object scanned by the line spectrum confocal sensors; calculating the position thickness corresponding to the current position based on the installation position relation of the linear spectrum confocal sensor and the spectrogram of the current position; if the difference between the measured thickness and the position thickness falls into the threshold range, the interior of the current position of the to-be-measured object is uniform; otherwise, non-uniformity is achieved. According to the invention, the thickness of the to-be-measured object is measured through the line spectrum confocal sensor so as to judge the uniformity; and the refractive index change of the incident light in different media is fully considered, the measurement result is compensated, and the accuracy of the detection result is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of optical detection, and particularly relates to a method for detecting transparency uniformity. Background Art

[0002] The prior art detects the thickness of a transparent material, and determines whether the transparent material meets the processing requirements by judging the thickness of the transparent material. For example, the thickness detection methods are respectively recorded in patents CN 113514425 B, CN 115308822 B, and CN 117704977 B.

[0003] In the fields of optics and precision instrument manufacturing, the finished product inspection of transparent materials requires judging the internal uniformity. For transparent materials such as lenses, microscopes, and telescopes, if the interior is non-uniform, when light passes through the above-mentioned transparent materials, different degrees of refraction will occur, resulting in chaotic light propagation directions, and the observed image will be distorted. For the internal non-uniformity of a mobile phone display screen, the different regions of the display screen show inconsistent brightness and colors, affecting the display effect.

[0004] In addition, the non-uniformity inside the transparent material may be caused by various factors such as density non-uniformity, composition non-uniformity, temperature gradient, and stress non-uniformity. Due to the non-uniformity inside the transparent material, when the transparent material is affected by temperature changes, the internal thermal expansion coefficients are inconsistent, and it is impossible to maintain the stability of its shape and size; when subjected to external forces, it is prone to damage.

[0005] Therefore, when detecting the uniformity of a transparent material, not only the surface thickness uniformity of the transparent material needs to be detected, but also the detection requirements for internal uniformity need to be met.

[0006] Chinese Patent CN 114486912 A discloses an optical element defect detection device and method based on line spectrum confocal technology. In this patent, the imaging receiving fiber bundle adopts a fiber linear array arrangement receiving method, which can effectively avoid stray light interference and optical signal crosstalk between different channels to improve the lateral detection resolution of the system. By adopting a total reflection type structure spectral imaging detection method, the chromatic aberration effect is eliminated, and it can adapt to different wavelength ranges, so as to adapt to the detection requirements of different types of samples to be detected. This patent proposes a solution for detecting defects on the surface or subsurface of an optical element, which is different from the technical problem solved by this application.

[0007] Chinese Patent CN 117491378 A discloses a transparent laminate detection method and its device, and a computer-readable storage medium. This patent utilizes the z-value information provided by a line spectral confocal sensor to accurately locate the layer where a defect lies in an optical component such as a curved or non-curved transparent laminate, the optical component to be tested, so as to control the defect size according to different parameters, and accurately determine the defect size to obtain a detection result of defect non-conformance (NG) or conformance (OK) information. This patent does not mention how to determine defects, which is different from the technical solution described in this application.

[0008] CN 116148277 B discloses a three-dimensional detection method for transparent body defects. This patent uses a line spectral confocal sensor to collect three-dimensional point cloud data of multiple layers of a transparent body, and based on the three-dimensional point cloud data, adopts three-dimensional data processing and detection methods to achieve three-dimensional spatial positioning and geometric measurement of each defect in the transparent body. This patent uses the method of least squares fitting of a plane to fit the second surface of the transparent body to accurately extract the second feature points used to characterize the second surface of the transparent body, and then separates the third feature points representing defects in the point cloud data to obtain the three-dimensional positioning of the defects. It is different from the technical means of this application. Summary of the Invention

[0009] The present invention proposes a transparent uniformity detection method, which solves at least one of the above technical problems.

[0010] To achieve the above object, the present invention proposes the following technical solutions: A transparent uniformity detection method, at least one line spectral confocal sensor is respectively arranged on any two opposite surfaces of a test object composed of a transparent material; the method includes: Using a transparent calibration object with a known thickness to calibrate the position of each line spectral confocal sensor; The transparent calibration object includes a horizontal part with at least two opposite and parallel planes and an inclined part with at least two opposite and non-parallel inclined planes; wherein, any inclined plane has an inclined angle with the calibration coordinate system XOY plane, and any inclined angle does not exceed the maximum reception angle allowed by any line spectral confocal sensor; Each line spectral confocal sensor scans the test object in sequence to obtain at least one spectral image corresponding to each position on any surface of the test object; based on the spectral images of the test object obtained by each line spectral confocal sensor, obtain the measured thickness of the current position of the test object scanned by this line spectral confocal sensor; based on the installation position relationship of the line spectral confocal sensors and the spectral images of the current position, calculate the position thickness corresponding to the current position; If the difference between the measured thickness and the position thickness falls within the threshold range, the interior of the current position of the test object is uniform; otherwise, it is non-uniform.

[0011] Further, based on the first measurement distance, the second measurement distance, and the refractive index of the object to be measured corresponding to the first peak wavelength and the second peak wavelength respectively in the spectral diagram of any position of the object to be measured obtained by any line spectral confocal sensor, calculate the compensated distance corresponding to the second peak wavelength; use the difference between the compensated distance and the first measurement distance as the first thickness; use the first thickness as the measured thickness.

[0012] Further, it further includes: sequentially calculating the first thickness of each line spectral confocal sensor scanning the current position of the object to be measured, and using the average value of the first thickness as the average thickness; using the average thickness as the measured thickness.

[0013] Further, a transparent calibration object with a known thickness is used to calibrate the positions of each line spectral confocal sensor, including: Adjust the installation positions of the line spectral confocal sensors so that the X axes of the sensor coordinate systems corresponding to the line spectral confocal sensors are parallel to each other and are respectively parallel to the X axis of the calibration coordinate system; the Y axes of each sensor coordinate system are parallel to each other, and the Z axes of each sensor coordinate system are parallel to each other; Each line spectral confocal sensor sequentially scans the transparent calibration object to obtain at least one spectral diagram in the first direction of each position of any surface of the transparent calibration object; the transparent calibration object rotates 90 degrees around the Z axis direction of the calibration coordinate system, and each line spectral confocal sensor sequentially scans the transparent calibration object to obtain at least one spectral diagram in the second direction of each position of any surface of the transparent calibration object; Based on the spectral diagrams, calculate the scanning thickness of each line spectral confocal sensor scanning the current position respectively; Determine the reference position, and based on the scanning thickness of each line spectral confocal sensor scanning any position and the shape of the transparent calibration object, calculate the offset of each line spectral confocal sensor in the current scanning direction; the current scanning direction includes the first direction and the second direction, and the direction of the scanning line projected by each line spectral confocal sensor on the surface of the transparent calibration object is perpendicular to the current scanning direction; Based on the offset of each line spectral confocal sensor in the current scanning direction, construct the scanning line trajectory model of each line spectral confocal sensor to match the coordinate relationship between the line spectral confocal sensors, and calibrate the positions of each line spectral confocal sensor.

[0014] Further, the scanning thickness includes: Based on the spectral diagram obtained by any line spectral confocal sensor scanning any position of the transparent calibration object, obtain the first measurement height and the second measurement height corresponding to the first peak wavelength and the second peak wavelength respectively in the spectral diagram, calculate the compensated height corresponding to the second peak wavelength, and use the difference between the compensated height and the first measurement height as the scanning thickness.

[0015] Further, the compensated height corresponding to the second peak wavelength includes: based on the spectral graph obtained by scanning any position of a transparent calibration object with any line spectral confocal sensor, the first measured height and the second measured height corresponding to the first peak wavelength and the second peak wavelength respectively, as well as the first angle and the second angle of the second peak wavelength; correcting the second measured height to obtain the compensated height corresponding to the second peak wavelength.

[0016] Further, the offset of each line spectral confocal sensor in the current scanning direction includes: Extract spectral graphs with the same position of the scanning lines of each line spectral confocal sensor, calculate the scanning thickness corresponding to each spectral graph with the same position of the scanning lines, and calculate the deviation of the optical axis direction of each line spectral confocal sensor relative to the reference position based on the first measured height corresponding to the first peak wavelength in each spectral graph with the same position of the scanning lines and the installation position relationship of the line spectral confocal sensors; calculate the offset of each line spectral confocal sensor in the current scanning direction based on the deviation of the optical axis direction and the shape of the transparent calibration object.

[0017] Further, the offset of each line spectral confocal sensor in the current scanning direction includes: Extract spectral graphs with the same position of the scanning lines of each line spectral confocal sensor, calculate the scanning thickness corresponding to each spectral graph with the same position of the scanning lines, and calculate the offset of each line spectral confocal sensor in the current scanning direction based on the reference position and the shape of the transparent calibration object.

[0018] Further, using a transparent calibration object with a known thickness to calibrate the position of each line spectral confocal sensor includes: Establish a sensor coordinate system corresponding to each line spectral confocal sensor and a calibration coordinate system corresponding to the transparent calibration object; Each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral graph corresponding to each position on any surface of the transparent calibration object; Based on the relative movement between the transparent calibration object and the line spectral confocal sensor, obtain the offset of each sensor coordinate system and the calibration coordinate system in the current scanning direction, and the relative rotation angle between each sensor coordinate system and the calibration coordinate system; Based on the offset and relative rotation angle in the current scanning direction, transform each sensor coordinate system to calibrate the position of each line spectral confocal sensor.

[0019] Further, it also includes: If the difference between the measured thickness at the current position and the position thickness does not fall within the threshold range, then based on the position thickness and the first measurement distance and the second measurement distance corresponding to the first peak wavelength and the second peak wavelength in the spectral map corresponding to the current position, calculate the new refractive index of the object to be measured; based on the new refractive index of the object to be measured, calculate the new compensated distance corresponding to the second peak wavelength, and based on the first measurement distance, calculate the new measured thickness; If the difference between the new measured thickness and the position thickness falls within the threshold range, then the interior of the current position of the object to be measured is uniform, and update the refractive index of the object to be measured to the new refractive index; otherwise, it is non-uniform.

[0020] On the other hand, the present invention also proposes a detection device for implementing the above method, specifically including: At least two line spectral confocal sensors are respectively arranged on any two opposite surfaces of the object to be measured for scanning the object to be measured. Among them, any two opposite surfaces refer to the upper surface and the lower surface of the object to be measured, or the left surface and the right surface of the object to be measured, or the front surface and the back surface of the object to be measured.

[0021] A spectrometer is opposite to the reflecting surface of the line spectral confocal sensor for acquiring and analyzing the wavelength distribution of the reflected light of the object to be measured to generate a spectral map.

[0022] An upper computer acquires the spectral map and implements the above detection method.

[0023] The beneficial effects of the present invention are as follows: In a transparent uniformity detection method proposed in the present application, for different installation positions of multiple line spectral confocal sensors, two calibration methods are proposed to solve the calibration problem of line spectral confocal sensors in the detection of transparent materials.

[0024] In the calibration process proposed for the line spectral confocal sensors installed at special positions in the present application, the same position of the scanning line of the line spectral confocal sensors is used as the bridge for position calibration between multiple line spectral confocal sensors, and based on this, the offset of the line spectral confocal sensors relative to the calibration coordinate system in the current scanning direction is calculated, thereby realizing the calibration of the line spectral confocal sensors.

[0025] ]According to the imaging principle of the line spectral confocal sensor, in the present application, by measuring the thickness of the object to be measured of the transparent material, it is judged whether the interior of the object to be measured is uniform; and the change of the refractive index of the incident light from the propagation medium where the dispersion lens group of the line spectral confocal sensor enters the interior of the object to be measured is fully considered, and the compensation process of the refractive index is supplemented, making the detection result more accurate.

[0026] In addition to compensating for the measured height (distance) of the line spectral confocal sensor, the present application also proposes a calculation of the actual refractive index (new refractive index) of the object to be measured based on the actual height, and further verifies the reliability of the internal uniformity detection of the object to be measured. This is to exclude the situation where the internal uniformity of the object to be measured cannot be determined due to inaccurate refractive index, and to ensure the accuracy of the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic flowchart of the detection method proposed by the present invention; Figure 2 is a schematic structural diagram of a first example of a transparent calibration object in the present invention; Figure 3 is a schematic structural diagram of a second example of a transparent calibration object in the present invention; Figure 4 is a schematic flowchart of the calibration process in Embodiment 1 of the present invention; Figure 5 is a schematic diagram of the coordinate system in Embodiment 1 of the present invention; Figure 6 is Figure 5 a schematic projection diagram of the calibration coordinate system YOZ plane; Figure 7 is a schematic diagram of the deviation amount in the optical axis direction in Embodiment 1 of the present invention; Figure 8 is Figure 7 a schematic projection diagram of the calibration coordinate system YOZ plane; Figure 9 is a schematic diagram of detecting the object to be measured in the present invention; Figure 10 is a schematic flowchart of the method in Embodiment 3 of the present invention; Figure 11 is a schematic structural diagram of Embodiment 3 of the present invention; [[ID=4l]] Figure 12 is a schematic flowchart of the method in Embodiment 4 of the present invention; Figure 13 is a schematic structural diagram of the detection device of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0029] As Figure 1 shown, the present application proposes a transparent uniformity detection method, which is specifically as follows: At least one line spectrum confocal sensor is respectively arranged on any two opposite surfaces of the object to be measured composed of a transparent material; the method includes: Using a transparent calibration object with a known thickness to calibrate the positions of each line spectrum confocal sensor.

[0030] Among them, the transparent calibration object includes a horizontal part with at least two opposite and parallel planes and an inclined part with at least two opposite and non-parallel inclined planes; among them, any inclined plane has an inclined angle with the calibration coordinate system XOY plane, and any inclined angle does not exceed the maximum reception angle allowed by any line spectrum confocal sensor.

[0031] Select three mutually perpendicular edges in the horizontal part as the three coordinate axes of the calibration coordinate system respectively, and use the intersection point of the three mutually perpendicular edges as the origin of the calibration coordinate system. Take the vertical direction as the Z-axis, and the two mutually perpendicular edges in the horizontal direction are respectively set as the X-axis and the Y-axis.

[0032] The transparent calibration object is a transparent material with a known refractive index, and any two opposite surfaces of the calibration object (the inclined part) are inclined, the angle α1 between the first opposite surface of the calibration object and the horizontal plane and the angle α2 between the second opposite surface of the calibration object and the horizontal plane.

[0033] Among them, α1≤β, α2≤β; β is the maximum reception angle allowed by any spectrum confocal sensor.

[0034] If the surface inclination angle of the transparent calibration object (the angle α1 between the first opposite surface of the calibration object and the horizontal plane, the angle α2 between the second opposite surface of the calibration object and the horizontal plane) is greater than the maximum incident angle, the spectrometer cannot receive the reflected light.

[0035] Among them, any two opposite surfaces refer to the upper surface and the lower surface of the transparent calibration object, or the left surface and the right surface of the transparent calibration object, or the front surface and the back surface of the transparent calibration object.

[0036] Preferably, as Figure 2 shown, the first example of the transparent calibration object is proposed in this application.

[0037] In this embodiment, the horizontal part is a cube, which can be a cuboid or a cube. The inclined part is a trapezoid, and the top surface of the trapezoid has the same area as the right side surface of the horizontal part cube and is completely attached. Among them, the horizontal part and the inclined part can be an integral structure or a split structure.

[0038] The top surface of the trapezoid is a rectangle or a square, which is consistent with the right side surface of the horizontal part cube.

[0039] All four side surfaces of the frustum are trapezoids. Since the top surface of the frustum fits with the right side surface of the horizontal cube part, in any projection plane of the calibrated coordinate system, the intersection lines between the four side surfaces of the frustum all have an inclination angle with the Z-axis. And in the same projection plane, the included angle directions between the intersection lines of any two side surfaces of the frustum and the Z-axis are different, with one positive inclination angle and one negative inclination angle.

[0040] In this embodiment, the values of the inclination angles are all positive numbers, and here the positive and negative are used to refer to the included angle directions.

[0041] In the first example of the transparent calibration object, the included angle between the upper surface of the inclined part of the transparent calibration object and the horizontal plane is α1, and the included angle between the lower surface of the inclined part of the transparent calibration object and the horizontal plane is α2. Among them, α1 ≤ β, α2 ≤ β; β is the maximum reception angle allowed by any spectral confocal sensor.

[0042] Select three mutually perpendicular edges in the horizontal part as the three coordinate axes of the calibrated coordinate system respectively, and use the intersection point of the three mutually perpendicular edges as the origin of the calibrated coordinate system.

[0043] In the first example of the transparent calibration object, take the intersection point of the upper surface, the left surface and the rear surface of the horizontal part as the origin, and take two mutually perpendicular edges on the upper surface as the X-axis and the Y-axis respectively, and the Z-axis is perpendicular to the upper surface.

[0044] In this embodiment, the direction of change from the rear surface to the front surface is the positive direction of the X-axis, the direction of change from the left surface to the right surface is the positive direction of the Y-axis, and the direction of change from the lower surface to the upper surface is the positive direction of the Z-axis.

[0045] Preferably, as Figure 3 shown, the second example of the transparent calibration object is proposed in this application.

[0046] On the basis of the first example, symmetrically along the X-axis direction with the bottom surface of the frustum, the shape of the transparent calibration object of the second example is obtained.

[0047] Among them, in the second example, there is a horizontal part on each of the left and right sides of the transparent calibration object, and the middle part is an inclined part.

[0048] Preferably, the components of each part of the transparent calibration object in the second example can be an integral structure or a split structure.

[0049] Preferably, the example content of the transparent calibration object provided in this application is only for example reference.

[0050] Preferably, in the inclined portion of the transparent calibration object provided in the present application, the inclination angles between the two opposite inclined surfaces and the calibration coordinate system XOY plane can both be the positive Z-axis angle or the negative Z-axis angle. However, the inclination angles between the two opposite inclined surfaces and the calibration coordinate system are different.

[0051] Preferably, in addition to the above trapezoid or combined body, the inclined portion of the transparent calibration object can also be a cone or a curved surface body composed of any curved surface, etc.

[0052] Each line spectral confocal sensor scans the object to be measured in turn, and obtains at least one spectral image corresponding to each position on any surface of the object to be measured; based on the spectral images obtained by each line spectral confocal sensor at any position of the object to be measured, the measured thickness of the current position of the object to be measured scanned by the line spectral confocal sensor is obtained; based on the installation position relationship of the line spectral confocal sensor and the spectral image of the current position, the position thickness corresponding to the current position is calculated; if the difference between the measured thickness and the position thickness falls within the threshold range, the interior of the current position of the object to be measured is uniform; otherwise, it is non-uniform.

[0053] Among them, the measured thickness is the first thickness or the average thickness.

[0054] The specific calculation process is as follows: Based on the spectral image of any position of the object to be measured obtained by any line spectral confocal sensor, the first measurement distance and the second measurement distance corresponding to the first peak wavelength and the second peak wavelength respectively, and the refractive index of the object to be measured, calculate the compensated distance corresponding to the second peak wavelength; use the difference between the compensated distance and the first measurement distance as the first thickness; use the first thickness as the measured thickness.

[0055] Calculate the first thickness of each line spectral confocal sensor scanning the current position of the object to be measured in turn, and use the average value of the first thickness as the average thickness; use the average thickness as the measured thickness. Embodiment 1

[0056] In this embodiment, taking the example that one line spectral confocal sensor is respectively arranged on the upper surface and the lower surface of the object to be measured, the detection method is specifically described.

[0057] Since the optical axes of the line spectral confocal sensors above and below the transparent material cannot be absolutely symmetrical, there are position deviations and angle deviations between the spectral confocal sensors above and below the transparent material, resulting in inaccurate detection of the uniformity inside the transparent material.

[0058] Therefore, before detecting the uniformity inside the object to be measured, the positions of the line spectral confocal sensors are first calibrated, as follows: As Figure 4 shown, a transparent calibration object with a known thickness is used to calibrate the positions of each line spectral confocal sensor, including: Adjust the installation positions of the line spectral confocal sensors so that the X - axes of the sensor coordinate systems corresponding to the line spectral confocal sensors are parallel to each other and are respectively parallel to the X - axis of the calibration coordinate system; the Y - axes of each sensor coordinate system are parallel to each other, and the Z - axes of each sensor coordinate system are parallel to each other; Each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral image in the first direction at each position on any surface of the transparent calibration object; the transparent calibration object rotates 90 degrees around the Z - axis direction of the calibration coordinate system, and each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral image in the second direction at each position on any surface of the transparent calibration object; Based on the spectral images, calculate the scanning thickness of each line spectral confocal sensor scanning the current position respectively; Determine the reference position, and based on the scanning thickness of each line spectral confocal sensor scanning any position and the shape of the transparent calibration object, calculate the offset of each line spectral confocal sensor in the current scanning direction; the current scanning direction includes the first direction and the second direction, and the direction of the scanning line of the projection of each line spectral confocal sensor on the surface of the transparent calibration object is perpendicular to the current scanning direction; Based on the offset of each line spectral confocal sensor in the current scanning direction, construct the scanning line trajectory model of each line spectral confocal sensor to match the coordinate relationship between the line spectral confocal sensors and calibrate the positions of each line spectral confocal sensor.

[0059] This embodiment takes Figure 2 the shown transparent calibration object as an example to specifically illustrate the calibration process of the line spectral confocal sensor.

[0060] Adjust the installation angles of the two spectral confocal sensors and construct the three - dimensional coordinate systems after the installation of the two spectral confocal sensors respectively.

[0061] As Figure 5 shown, for the spectral confocal sensor above the transparent calibration object, take the length direction of the light - emitting port as the X1 - axis, the optical axis direction of the spectral confocal sensor above as the Z1 - axis, the direction perpendicular to the X1O1Z plane as the Y1 - axis, and the center along the length direction of the light - emitting port as the origin O1 to construct the first sensor coordinate system.

[0062] For the spectral confocal sensor below the transparent calibration object, take the length direction of the light - emitting port as the X2 - axis, the optical axis direction of the spectral confocal sensor below as the Z2 - axis, the direction perpendicular to the X2O2Z2 plane as the Y2 - axis, and the center along the length direction of the light - emitting port as the origin O2 to construct the second sensor coordinate system.

[0063] The X - axes of the first sensor coordinate system and the second sensor coordinate system are parallel to each other, the Y - axes are parallel to each other, the Z - axes are parallel to each other, and the X - axes are respectively parallel to the X - axis of the calibration coordinate system.

[0064] Each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral image in the first direction at each position on any surface of the transparent calibration object.

[0065] The transparent calibration object rotates 90 degrees around the Z-axis direction of the calibration coordinate system. Each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral image in the second direction at each position on any surface of the transparent calibration object.

[0066] Based on the spectral images, calculate the scanning thickness of each line spectral confocal sensor scanning the current position respectively.

[0067] Specifically, it includes: based on the spectral image obtained by any line spectral confocal sensor scanning any position of the transparent calibration object, obtain the first measurement height and the second measurement height corresponding to the first peak wavelength and the second peak wavelength in the spectral image respectively, calculate the compensated height corresponding to the second peak wavelength, and use the difference between the compensated height and the first measurement height as the scanning thickness.

[0068] In this embodiment, the abscissa of the spectral image is the wavelength λ, and the ordinate is the light intensity.

[0069] In any spectral image, sort in the order of the light intensity corresponding to each peak wavelength from large to small, and select the wavelength corresponding to the highest light intensity as the first peak wavelength λ1(x,y) s , and the wavelength corresponding to the second highest light intensity as the second peak wavelength λ2(x,y) s . Based on the first peak wavelength and the second peak wavelength, obtain the corresponding first measurement height d λ1 (x,y) s and the second measurement height d λ2 (x,y) s .

[0070] Among them, the measurement height corresponding to each peak wavelength is the measurement height of the dispersion lens group of the line spectral confocal sensor in the propagation medium where it is located at this peak wavelength.

[0071] Among them, (x,y) represents the scanning position of the transparent calibration object corresponding to this spectral image; the subscript s represents the serial number of the line spectral confocal sensor.

[0072] The line spectral confocal sensor s includes a spectral confocal sensor 1 above the object to be measured (transparent calibration object) and a spectral confocal sensor 2 below the object to be measured (transparent calibration object).

[0073] Such as Figure 6As shown, according to the imaging principle of the line spectral confocal sensor, since the incident light enters the object to be measured (transparent calibration object) from the external environment, the incident light refracts inside the object to be measured (transparent calibration object), causing a change in the focusing distance corresponding to the incident light of this wavelength. That is, the wavelength deviates from the known linear relationship with the theoretical focusing distance (the measurement height corresponding to any peak wavelength), thereby affecting the accuracy of measurement calculation.

[0074] This embodiment proposes to compensate the measurement height corresponding to the second peak wavelength to obtain the compensated height of the second peak wavelength.

[0075] The compensated height corresponding to the second peak wavelength includes: in the spectrogram obtained by scanning any position of the transparent calibration object with any line spectral confocal sensor, the first measurement height and the second measurement height corresponding to the first peak wavelength and the second peak wavelength respectively, as well as the first included angle and the second included angle of the second peak wavelength; correct the second measurement height to obtain the compensated height corresponding to the second peak wavelength.

[0076] The compensated height 'd corresponding to the second peak wavelength λ2 (x,y) s =d λ2 (x,y) s +D[(tan δ1 / tan δ2)-1] In the formula, d λ2 (x,y) s is the second measurement height, representing the measurement height of the second peak wavelength λ2(x,y) s in the propagation medium of the dispersion lens group of the line spectral confocal sensor s.

[0077] δ1 is the included angle between the incident light of the second peak wavelength λ2(x,y) s and the optical axis of the line spectral confocal sensor s, that is, the first included angle of the second peak wavelength; δ2 is the included angle between the light ray after refraction of the incident light of the second peak wavelength λ2(x,y) s by the transparent calibration object and the optical axis of the line spectral confocal sensor s, that is, the second included angle of the second peak wavelength.

[0078] D represents the perpendicular distance along the optical axis of the line spectral confocal sensor s from the intersection point Q1 of the extension line of the incident light of the second peak wavelength λ2(x,y) s and the optical axis of the line spectral confocal sensor s to the intersection point Q2 of the incident light of the second peak wavelength λ2(x,y) s and the surface of the transparent calibration object; where the surface of the transparent calibration object is the surface of the transparent calibration object close to the line spectral confocal sensor.

[0079] In this embodiment, the difference between the second measurement height and the first measurement height in the spectrogram is approximated to the vertical distance D, that is, D≈d λ2 (x,y) s -d λ1 (x,y) s 。

[0080] At this time, calculate the scanning thickness Z corresponding to the spectrogram s (x,y), where s represents the serial number of the line spectral confocal sensor.

[0081] Preferably, Z s (x,y)='d λ2 (x,y) s -d λ1 (x,y) s 。

[0082] Perform the above calculations on each spectrogram to obtain the scanning thickness corresponding to any position of the transparent calibration object scanned by each line spectral confocal sensor.

[0083] Since two line spectral confocal sensors respectively establish their corresponding three-dimensional coordinate systems, after the calculation of the above scanning thickness, their corresponding coordinates are not universal, and the relationship between the scanning thicknesses calculated by the two line spectral confocal sensors cannot be established. Therefore, it is necessary to implement the conversion of the two line spectral confocal sensors to verify the consistency of the scanning thickness calculation results at the same position of the transparent calibration object to determine the accuracy of the detection.

[0084] Determine the reference position, and calculate the offset of each line spectral confocal sensor in the current scanning direction based on the scanning thickness of any position scanned by each line spectral confocal sensor and the shape of the transparent calibration object. The current scanning direction includes the first direction and the second direction, and the direction of the scanning line projected by each line spectral confocal sensor on the surface of the transparent calibration object is perpendicular to the current scanning direction.

[0085] Specifically, it includes: extracting the spectrograms with the same scanning line positions of each line spectral confocal sensor, calculating the scanning thickness corresponding to each spectrogram with the same scanning line position, and calculating the optical axis direction deviation of each line spectral confocal sensor relative to the reference position based on the first measurement height corresponding to the first peak wavelength in each spectrogram with the same scanning line position and the installation position relationship of the line spectral confocal sensors; calculating the offset of each line spectral confocal sensor in the current scanning direction based on the optical axis direction deviation and the shape of the transparent calibration object.

[0086] In this embodiment, the current scanning direction is expressed in the same way as the coordinate axis direction of the calibration coordinate system.

[0087] Preferably, in this embodiment, the line spectral confocal sensor located above the transparent calibration object is the line spectral confocal sensor 1, i.e., s = 1; the line spectral confocal sensor located below the transparent calibration object is the line spectral confocal sensor 2, i.e., s = 2.

[0088] The line spectral confocal sensor 1 and the line spectral confocal sensor 2 scan at any position of the transparent calibration object respectively to obtain two spectral images. As Figure 7 shown, the projection direction (scanning line direction) of the scanning line of the line spectral sensor is the X direction (the direction of the X axis of the calibration coordinate system), then the scanning direction (current scanning direction) of the spectral confocal sensor is the Y direction (the direction of the Y axis of the calibration coordinate system).

[0089] To distinguish the representations of the positions of the transparent calibration object in the two sensor coordinate systems, the subscript i is added to the position coordinates corresponding to the line spectral confocal sensor 1, and the subscript j is added to the position coordinates corresponding to the line spectral confocal sensor 2.

[0090] That is, the position coordinates in the first coordinate system corresponding to the line spectral confocal sensor 1 are represented as (x i , y i ), and the position coordinates in the second coordinate system corresponding to the line spectral confocal sensor 2 are represented as (x j , y j ).

[0091] The first measurement height d λ1 (x i , y i )1 corresponding to the first peak wavelength in the spectral image obtained by the line spectral confocal sensor 1, and the first measurement height d λ1 (x j , y j )2 corresponding to the first peak wavelength in the spectral image obtained by the line spectral confocal sensor 2.

[0092] According to the spectral image obtained by the line spectral confocal sensor 1, calculate the scanning thickness Z1(x i , y i ); according to the spectral image obtained by the line spectral confocal sensor 2, calculate the scanning thickness Z2(x j , y j ).

[0093] The same position of the scanning lines is the same position on the scanning lines projected on the surface of the transparent calibration object by each line spectral confocal sensor. For example, the central position of the scanning line of each line spectral confocal sensor is the same position of the scanning lines, or other positions on the scanning lines.

[0094] In this embodiment, at any point position (x i , y i), select the first measurement height d corresponding to the first peak wavelength in its corresponding spectrogram λ1 (x i , y i )1; Assume that the coordinates of the spectral confocal sensor 2 at the same position on the scanning line are (x j , y j ).

[0095] If taking the position of the line spectral confocal sensor 1 as the reference.

[0096] Analyze the deviation amount (optical axis direction deviation amount) E = G - d along the optical axis direction when the two line spectral confocal sensors are at the same position on the scanning line λ1 (x i , y i )1 - d λ1 (x j , y j )2 - Z1(x i , y i ).

[0097] Among them, G is the vertical distance between the two line spectral confocal sensors, which is fixed and unchanged.

[0098] As Figure 8 shown, the offset amount △ of the two line spectral confocal sensors in the current scanning direction (taking the Y - direction offset amount calculation as an example here) 当前扫描方向 = E / tan α2.

[0099] When △ 当前扫描方向 < 0, it indicates that the starting point of the scanning line of the line spectral confocal sensor 2 is on the left side of the starting point of the scanning line of the spectral confocal sensor 1; when △ 当前扫描方向 > 0, it indicates that the starting point of the scanning line of the line spectral confocal sensor 2 is on the right side of the starting point of the scanning line of the spectral confocal sensor 1.

[0100] The current scanning direction includes a first direction and a second direction. Among them, the first direction is the X - direction (the direction of the X - axis of the calibration coordinate system), then the second direction is the Y - direction (the direction of the Y - axis of the calibration coordinate system), or the first direction is the Y - direction, then the second direction is the X - direction. Since this application sets two scans of the transparent calibration object, this application does not limit the order of the scanning directions.

[0101] In addition, due to the relative rotation of the transparent calibration object and the line spectral confocal sensor during the second scan. If the transparent calibration object is rotated without changing the direction of the coordinate axes of the sensor coordinate system, the two scanning directions are the same, but the calculation results respectively represent the X - direction offset amount and the Y - direction offset amount.

[0102] Then the offset amount △ in the current scanning direction 当前扫描方向Including the offset ΔX in the X direction and the offset ΔY in the Y direction.

[0103] Preferably, if the position of the line spectral confocal sensor 2 is used as a reference, when the two line spectral confocal sensors are at the same position on the scanning line, the calculation formula for the deviation amount of the optical axis direction can also be expressed as E = G - d λ1 (x i , y i )1 - d λ1 (x j , y j )2 - Z2(x i , y i ).

[0104] Then the offset Δ 当前扫描方向 of the two line spectral confocal sensors in the current scanning direction = E / tan α1.

[0105] Furthermore, a calibration coordinate system corresponding to the transparent calibration object can be established. Taking the calibration coordinate system as the reference coordinate system, the offset ΔX in the X direction and the offset ΔY in the Y direction of the first coordinate system relative to the calibration coordinate system, as well as the offset ΔX in the X direction and the offset ΔY in the Y direction of the second coordinate system relative to the calibration coordinate system, can be calculated respectively.

[0106] Based on the offset of each line spectral confocal sensor in the current scanning direction, a scanning line trajectory model of each line spectral confocal sensor is constructed to match the coordinate relationship between the line spectral confocal sensors and calibrate the position of each line spectral confocal sensor.

[0107] After obtaining the offset of the coordinate positions in the coordinate systems respectively corresponding to the two line spectral confocal sensors, the relationship between the position coordinates of the two sensor coordinate systems on the calibration coordinate system XOY plane can be established to calibrate the position of the line spectral confocal sensor and ensure the accuracy of detection.

[0108] In the calibration coordinate system XOY plane, if the current scanning direction is the Y direction.

[0109] The dynamic scanning line trajectory model of the line spectral confocal sensor 1 in the current scanning direction is: g(t, y i ) = y i - v i t; g(t, x i ) = x i ; where t is the scanning time and v i is the scanning speed of the line spectral confocal sensor 1.

[0110] The dynamic scanning line trajectory model of the line spectral confocal sensor 2 in the current scanning direction is: f(t, y j ) = y j - vj t;f(t,x j )=x j ; Where t is the scan time, v j is the scanning speed of the line spectrum confocal sensor 2.

[0111] Since there is an offset in the current scanning direction between the line spectrum confocal sensor 2 and the line spectrum confocal sensor 1, including the offset in the X direction △X and the offset in the Y direction △Y, the relationship between the coordinates of the line spectrum confocal sensor 2 and the coordinates of the line spectrum confocal sensor 1 is: j= x i +△X,y j= y i +△Y.

[0112] Then the dynamic scanning line trajectory model of the line spectrum confocal sensor 2 is: f(t,y j )=y j -v j t=y i +△Y--v j t;f(t,x j )=x j= x i +△X.

[0113] If the scanning position of the line spectrum confocal sensor 1 at time t1 and the scanning position of the line spectrum confocal sensor 2 at time t2 are the same position of the transparent calibration object, then: g(t1,y i )=f(t2,y j );g(t1,x i )=f(t2,x j ).

[0114] In the above formula, in order to distinguish the representation of the position of the transparent calibration object in the two sensor coordinate systems, the position coordinate corresponding to the line spectral confocal sensor 1 is added with a subscript i, and the position coordinate corresponding to the line spectral confocal sensor 2 is added with a subscript j.

[0115] By establishing the above matching relationship, the coordinates of the two line spectrum confocal sensors in the same XOY plane are aligned one by one, and the positions of the two line spectrum confocal sensors are calibrated to extract two spectrum images of the two line spectrum confocal sensors at the same position.

[0116] After completing the above calibration process, each line spectrum confocal sensor scans the object to be measured in sequence to obtain at least one spectrum image corresponding to each position on any surface of the object to be measured.

[0117] The two spectral confocal sensors detect the objects to be detected alternately or sequentially one by one to eliminate mutual interference between the detection data of the two spectral confocal sensors.

[0118] Based on any line confocal sensor, obtain the spectral image of any position of the object to be measured, screen the first peak wavelength and the second peak wavelength in the spectral image, calculate the measurement distance corresponding to each peak wavelength and the compensated distance corresponding to the second peak wavelength, so as to obtain the first thickness of the current position of the object to be measured scanned by this line confocal sensor.

[0119] In the spectral image of the object to be measured, the screening process of the first and second peak wavelengths is the same as that in the spectral image of the transparent calibration object, which will not be elaborated here.

[0120] To distinguish the calculation results of the spectral images of the object to be measured and the transparent calibration object, take the measurement heights of the dispersion lens groups of the line confocal sensor corresponding to the first and second peak wavelengths in the propagation medium where they are located in the spectral image of the object to be measured as the measurement distances. That is, in any spectral image of the object to be measured, the first and second peak wavelengths respectively correspond to the first measurement distance h λ1 (x,y) s , the second measurement distance h λ2 (x,y) s , and the subscript s represents the serial number of the line confocal sensor.

[0121] As Figure 9 shown, considering that the incident light corresponding to the second peak wavelength enters different media, causing the incident light to refract, there is a deviation between the second measurement distance and the actual distance in the corresponding spectral image. Therefore, the second measurement distance is compensated.

[0122] Based on the refractive index n1 of the propagation medium where the dispersion objective lens group of the line confocal sensor is located, the refractive index n2 of the object to be measured, and the incident angle ψ of the incident light corresponding to the second peak wavelength in the propagation medium where the dispersion objective lens group is located, calculate the compensated distance 'h λ2 (x,y) s , and the calculation formula is as follows:

[0123] Then the first thickness H s (x,y) of the current position of the object to be measured scanned by this line confocal sensor = 'h λ2 (x,y) s -h λ1 (x,y) s .

[0124] Calculate the first thickness of the current position of the object to be measured scanned by each line confocal sensor in turn.

[0125] In this embodiment, only two line spectral confocal sensors are provided to obtain the first thickness H1(x,y) corresponding to the line spectral confocal sensor 1 and the first thickness H2(x,y) corresponding to the line spectral confocal sensor 2.

[0126] The average value of the first thicknesses is used as the average thickness .

[0127] Based on the installation position relationship of the line spectral confocal sensors and the spectral map at the current position, the position thickness corresponding to the current position is calculated.

[0128] In this embodiment, based on the two spectral maps obtained by the two line spectral confocal sensors at the same position of the object to be measured, the first peak wavelength corresponding to the first measurement distance h λ1 (x,y)1, h λ1 (x,y)2 is obtained respectively. According to the installation position relationship of the line spectral confocal sensors, it can be known that the position thickness 'H = G - h λ1 (x,y)1 - h λ1 (x,y)2 corresponding to the current position.

[0129] In the formula, G is the distance between the two line spectral confocal sensors.

[0130] Based on the above calculation results, if the difference between the measured thickness and the position thickness falls within the threshold range, the interior of the current position of the object to be measured is uniform; otherwise, it is non-uniform.

[0131] Among them, the first thickness is used as the measured thickness, or the average thickness is used as the measured thickness.

[0132] Preferably, the threshold range is the product of the unit error range allowed under the unit height and the thickness. Among them, the unit error range is formulated according to the actual needs of the user and / or the physical and chemical properties of the object to be measured and / or the actual use environment, and the present application does not make specific limitations. Embodiment 2

[0133] On the basis of Embodiment 1, for the calculation of the offset in the current scanning direction, another implementation method is proposed, including: extracting the spectral maps with the same position of the scanning lines of each line spectral confocal sensor, calculating the scanning thickness corresponding to each spectral map with the same position of the scanning lines, and calculating the offset of each line spectral confocal sensor in the current scanning direction based on the reference position and the shape of the transparent calibration object.

[0134] According to the calibration process described in Embodiment 1, the scanning thickness Z s (x,y) at any position obtained by scanning with the line spectral confocal sensor is obtained in the same way, where s represents the serial number of the line spectral confocal sensor.

[0135] Taking the setting of two line spectral confocal sensors as an example, at the same position of the scanning lines of the two line spectral confocal sensors, spectral maps at the same position of the scanning lines are respectively obtained.

[0136] Taking the first measurement height and the second measurement height corresponding to the first peak wavelength and the second peak wavelength in any one of the spectral maps respectively, calculate the scanning thickness of the line spectral confocal sensor; that is, obtain Z1(x i , y i ) corresponding to the line spectral confocal sensor 1 and Z2(x j , y j ).

[0137] Then the offset Δ 当前扫描方向 of the two line spectral confocal sensors in the current scanning direction is calculated as follows: Δ 当前扫描方向 = [Z2(x j , y j ) - Z1(x i , y i )] / (tan α1 + tan α2).

[0138] In the formula, α1 is the angle between the upper surface of the calibration object and the horizontal plane (the calibration coordinate system XOY plane), and α2 is the angle between the lower surface of the calibration object and the horizontal plane; both α1 and α2 are not zero, and α1 ≤ β, α2 ≤ β; β is the maximum incident angle allowed by any spectral confocal sensor. If the surface tilt angle (the angle between the inclined plane and the horizontal plane) of the transparent calibration object is greater than the maximum incident angle, the spectrometer cannot receive the reflected light.

[0139] When Δ 当前扫描方向 < 0, it indicates that the starting point of the scanning line of the line spectral confocal sensor 2 is located on the left side of the starting point of the scanning line of the spectral confocal sensor 1; when Δ 当前扫描方向 > 0, it indicates that the starting point of the scanning line of the line spectral confocal sensor 2 is located on the right side of the starting point of the scanning line of the spectral confocal sensor 1.

[0140] In this embodiment, the current scanning direction is expressed in the same direction as the coordinate axis of the calibration coordinate system. The current scanning direction includes a first direction and a second direction. Among them, if the first direction is the X direction (the X - axis direction of the calibration coordinate system), then the second direction is the Y direction (the Y - axis direction of the calibration coordinate system), or if the first direction is the Y direction, then the second direction is the X direction. Then the offset Δ 当前扫描方向 of the current scanning direction includes the offset ΔX in the X direction and the offset ΔY in the Y direction.

[0141] The scanning line direction of the projection of each line spectral confocal sensor on the surface of the transparent calibration object is perpendicular to the current scanning direction. For example, if the projection direction (scanning line direction) of the scanning line of the line spectral sensor is the X direction (the direction of the X axis of the calibration coordinate system), then the scanning direction (current scanning direction) of the spectral confocal sensor is the Y direction (the direction of the Y axis of the calibration coordinate system). Embodiment 3

[0142] Based on the detection method described in the above embodiments, it is necessary to first adjust the position of the line spectral confocal sensor so that the coordinate systems of the line spectral confocal sensors satisfy that the X axes are parallel to each other, the Y axes are parallel to each other, the Z axes are parallel to each other, and the Z axis is parallel to the optical axis of the spectral confocal sensor, and then calibrate the position of the line spectral confocal sensor, and further detect the internal uniformity of the object to be measured.

[0143] As Figure 10 As shown, the present application proposes a calibration method that does not require pre-adjusting the position of the line spectral confocal sensor, making the calibration of the line spectral confocal sensor more universal. Specifically, it includes: Establish a sensor coordinate system corresponding to each line spectral confocal sensor and a calibration coordinate system corresponding to the transparent calibration object; Each line spectral confocal sensor scans the transparent calibration object in turn to obtain at least one spectral image corresponding to each position on any surface of the transparent calibration object; Based on the relative movement between the transparent calibration object and the line spectral confocal sensor, obtain the offset of each sensor coordinate system and the calibration coordinate system in the current scanning direction, and the relative rotation angle between each sensor coordinate system and the calibration coordinate system; Based on the offset and relative rotation angle in the current scanning direction, transform each sensor coordinate system to calibrate the position of each line spectral confocal sensor.

[0144] As Figure 11 As shown, in this embodiment, taking the example that a line spectral confocal sensor is respectively arranged on the upper surface and the lower surface of the transparent calibration object, the calibration process is described.

[0145] Establish a sensor coordinate system, which includes a first sensor coordinate system and a second sensor coordinate system.

[0146] For the spectral confocal sensor above the object to be measured, taking the length direction of the light outlet as the X1 axis, the optical axis direction of the spectral confocal sensor above as the Z1 axis, the direction perpendicular to the X1O1Z1 plane as the Y1 axis, and the center along the length direction of the light outlet as the origin O1, construct the first sensor coordinate system.

[0147] For the spectral confocal sensor below the analyte, with the length direction of the light exit opening as the X2 axis, the optical axis direction of the spectral confocal sensor below as the Z2 axis, the direction perpendicular to the X2O2Z2 plane as the Y2 axis, and the center along the length direction of the light exit opening as the origin O2, a second sensor coordinate system is constructed.

[0148] As Figure 2 shown, in the first example of the transparent calibration object, taking the intersection of the upper surface, left surface, and rear surface of the horizontal part as the origin, and taking two mutually perpendicular edges on the upper surface as the X axis and Y axis respectively, the Z axis is perpendicular to the upper surface.

[0149] In this embodiment, the positive direction of the X axis is the direction from the rear surface to the front surface, the positive direction of the Y axis is the direction from the left surface to the right surface, and the positive direction of the Z axis is the direction from the lower surface to the upper surface.

[0150] Since the transparent calibration object of the present application includes a horizontal part with at least two opposite and parallel planes and an inclined part with at least two opposite and non-parallel inclined planes; wherein, any inclined plane has an inclined angle with the XOY plane of the calibration coordinate system, and any inclined angle does not exceed the maximum acceptance angle allowed by any line spectral confocal sensor, so that when any line spectral confocal sensor scans the transparent calibration object, the optical axis directions of scanning the horizontal part and the inclined part are not the same, that is, the sensor coordinate system changes.

[0151] At this time, for the same position of the transparent calibration object, the position coordinates corresponding to the sensor coordinate system and the calibration coordinate system are not the same. Therefore, by scanning the transparent calibration object, the offset △ of any sensor coordinate system relative to the calibration coordinate system in the current scanning direction can be obtained. 当前扫描方向 [[ID=...]] .

[0152] When any line spectral confocal sensor scans the transparent calibration object along the X direction (the X-axis direction of the calibration coordinate system) and the Y direction (the Y-axis direction of the calibration coordinate system) respectively, the offset △x in the X direction can be calculated. s and the offset △y in the Y direction. s . The subscript s represents the serial number of the current line spectral confocal sensor.

[0153] Based on the offset of any sensor coordinate system relative to the calibration coordinate system, calculate the translated coordinates ('x s , 'y s , 'z s ) of any position (x s , y s , z s ) of the transparent calibration object, as follows:

[0154] Among them, G sIt represents the vertical distance between the origin of the sensor coordinate system of the line spectral confocal sensor s and the origin of the calibration coordinate system. If the line spectral confocal sensor is set in the positive direction of the Z axis of the calibration coordinate system, then γ = 1; if the line spectral confocal sensor is set in the negative direction of the Z axis of the calibration coordinate system, then γ = -1.

[0155] In this embodiment, the vertical distance between the origin O1 of the first coordinate system of the line spectral confocal sensor 1 on the upper surface of the transparent calibration object and the origin O of the calibration coordinate system is G1, and the vertical distance between the origin O2 of the second coordinate system of the line spectral confocal sensor 2 on the lower surface of the transparent calibration object and the origin O of the calibration coordinate system is G2.

[0156] G1 + G2 = G, where G is the vertical distance between the two line spectral confocal sensors.

[0157] Furthermore, it can also be set as the relative movement in other two mutually perpendicular directions.

[0158] Calculate the rotation angles of the sensor coordinate system relative to the calibration coordinate system around each axis in sequence and perform transformations respectively. The specific transformation steps are as follows: Take the line spectral confocal sensor 1 on the upper surface of the transparent calibration object as an example.

[0159] Based on the X-direction offset Δx1 and Y-direction offset Δy1 of the first sensor coordinate system relative to the calibration coordinate system; then the coordinates ('x1, 'y1, 'z1) after translation of any position (x1, y1, z1) of the transparent calibration object are as follows:

[0160] When rotating around the X axis, the coordinate points on the X axis of the calibration coordinate system where the line spectral confocal sensor 1 scans the horizontal part of the transparent calibration object change; it is known that the length of the horizontal part of the transparent calibration object on the X axis is L1, while the length of the punctuation coordinate system X axis actually obtained by the line spectral confocal sensor scanning the horizontal part of the transparent calibration object is L2.

[0161] When the first sensor coordinate system rotates around the X axis relative to the calibration coordinate system, the rotation angle θx1 = arccos(L1 / L2).

[0162] The transformed coordinates are:

[0163] In the formula, when the rotation direction around the X axis is counterclockwise, σ = -1; when the rotation direction around the X axis is clockwise, σ = 1.

[0164] When rotating about the Y-axis, the coordinate points of the horizontal part of the transparent calibration object scanned by the line spectral confocal sensor 1 change on the Z-axis of the calibration coordinate system. The value of the coordinate point of the horizontal part of the transparent calibration object on the Z-axis of the calibration coordinate system is d1, while the value of the coordinate point of the horizontal part of the transparent calibration object scanned by the line spectral confocal sensor on the Z-axis of the calibration coordinate system is d2.

[0165] When the first sensor coordinate system after the X-axis rotation change rotates about the Y-axis relative to the calibration coordinate system, the rotation angle θy1 = arccos(d1 / d2).

[0166] The transformed coordinates are:

[0167] In the formula, when the rotation direction about the Y-axis is counterclockwise, σ = -1; when the rotation direction about the Y-axis is clockwise, σ = 1.

[0168] When rotating about the Z-axis, the coordinate points of the horizontal part of the transparent calibration object scanned by the line spectral confocal sensor 1 change on the Y-axis of the calibration coordinate system; the value of the coordinate point of the horizontal part of the transparent calibration object on the Y-axis of the calibration coordinate system is L3, while the value of the coordinate point of the horizontal part of the transparent calibration object scanned by the line spectral confocal sensor on the Y-axis of the calibration coordinate system is L4.

[0169] When the first sensor coordinate system after the Y-axis rotation change rotates about the Z-axis relative to the calibration coordinate system, the rotation angle θz1 = arccos(L3 / L4).

[0170] The transformed coordinates are:

[0171] In the formula, when the rotation direction about the Z-axis is counterclockwise, σ = -1; when the rotation direction about the Y-axis is clockwise, σ = 1.

[0172] Through the above transformation process, the first sensor coordinate system is converted into the calibration coordinate system.

[0173] Similarly, based on the X-direction offset Δx2 and Y-direction offset Δy2 of the second sensor coordinate system relative to the calibration coordinate system; after translating and rotating any position (x2, y2, z2) of the transparent calibration object, the coordinates ('''x2, '''y2, '''z2) can be obtained, that is, the second sensor coordinate system is transformed into the calibration coordinate system.

[0174] The position calibration of the line spectral confocal sensors on the upper and lower surfaces of the transparent calibration object is completed.

[0175] Furthermore, taking any sensor coordinate as a reference, through translating and rotating other sensor coordinate systems and the calibration coordinate system, position calibration can be achieved.

[0176] Furthermore, the shape of the transparent calibration object can also change, thereby changing the magnitude of the rotation angle.

[0177] After completing the above calibration process, each line spectral confocal sensor sequentially scans the object to be measured, and obtains at least one spectral image corresponding to each position on any surface of the object to be measured. Based on the spectral images corresponding to the object to be measured, by analyzing and calculating the first thickness and the position thickness of each line spectral confocal sensor scanning the current position of the object to be measured, it is determined whether the interior of the object to be measured is uniform.

[0178] The calculation of the first thickness and the position thickness is the same as that described in Embodiment 1, and the determination and analysis of whether the interior of the object to be measured is uniform are also the same as those described in Embodiment 1; therefore, no further elaboration will be provided here. Embodiment 4

[0179] As Figure 12 shown, on the basis of the above embodiment, if it is determined that the interior of the object to be measured is not uniform, the analysis of the refractive index of the object to be measured is increased to improve the accuracy of the determination result and avoid misjudgment caused by the refraction of incident light.

[0180] Specifically, if the difference between the measured thickness at the current position and the position thickness does not fall within the threshold range, then based on the position thickness and the first measurement distance and the second measurement distance corresponding to the first peak wavelength and the second peak wavelength in the spectral image corresponding to the current position, the new refractive index 'n2 of the object to be measured is calculated, and the calculation formula is as follows:

[0181] In the formula, n1 is the refractive index of the propagation medium where the dispersion objective lens group of the line spectral confocal sensor is located; ψ is the incident angle of the incident light corresponding to the second peak wavelength in the propagation medium where the dispersion objective lens group is located; the first and second peak wavelengths in any spectral image respectively correspond to the first measurement distance h λ1 (x,y) s 、the second measurement distance h λ2 (x,y) s ; 'H is the position thickness.

[0182] In this embodiment, based on the two spectral images obtained by two line spectral confocal sensors at the same position of the object to be measured, the first measurement distance h λ1 (x,y)1, h λ1 (x,y)2 corresponding to the first peak wavelength are respectively obtained. According to the installation position relationship of the line spectral confocal sensors, it can be known that the position thickness 'H corresponding to the current position = G - h λ1 (x,y)1 - h λ1 (x,y)2.

[0183] In the formula, G is the distance between the two line spectral confocal sensors.

[0184] Based on the new refractive index of the object to be measured, calculate the newly compensated distance corresponding to the second peak wavelength:

[0185] Further simplification gives:

[0186] Based on the newly compensated distance and the first measured distance, calculate the new measured thickness. If the difference between the new measured thickness and the position thickness falls within the threshold range, the interior of the object to be measured at the current position is uniform, and update the refractive index of the object to be measured to the new refractive index; otherwise, it is non-uniform.

[0187] Specifically, it includes the following two methods: Method 1: Based on the newly compensated distance and the first measured distance, calculate the new first thickness: 'H s (x,y) = 'h λ2 (x,y) s -h λ1 (x,y) s Take the new first thickness as the new measured thickness. If the differences between the new first thickness and the position thickness all fall within the threshold range, the interior of the object to be measured at the current position is uniform, and update the refractive index of the object to be measured to the new refractive index. Otherwise, it is non-uniform.

[0188] Method 2: Furthermore, it is also possible to calculate the new first thickness of each line spectroscopic confocal sensor scanning the current position of the object to be measured in sequence, and take the average value of the new first thicknesses as the new average thickness; take the new average thickness as the new measured thickness.

[0189] If the difference between the new average thickness and the position thickness falls within the threshold range, the interior of the object to be measured at the current position is uniform, and update the refractive index of the object to be measured to the new refractive index. Otherwise, it is non-uniform.

[0190] This application adds Example 4 to exclude the situation where the internal uniformity of the object to be measured cannot be determined due to inaccurate refractive index, and ensures the accuracy of the detection result.

[0191] On the other hand, based on the same inventive concept, as Figure 13 shown, this application proposes a detection device for implementing the above method, specifically including: At least two line spectroscopic confocal sensors, which are respectively arranged on any two opposite surfaces of the object to be measured for scanning the object to be measured. Among them, any two opposite surfaces refer to the upper surface and the lower surface of the object to be measured, or the left surface and the right surface of the object to be measured, or the front surface and the back surface of the object to be measured.

[0192] A spectrometer, opposite to the reflecting surface of the line spectrum confocal sensor, is used to acquire and analyze the wavelength distribution of the reflected light of the object to be measured and generate a spectrogram.

[0193] A host computer acquires the spectrogram and implements the detection method described in the above embodiments.

[0194] It further includes: A support mechanism, including: a first support mechanism for fixing the installation position of the line spectrum confocal sensor; a second support mechanism for fixing the installation position of the object to be measured.

[0195] Wherein, the first support mechanism and the second support mechanism can be an integral structure or be separately arranged.

[0196] It further includes: A rotating mechanism, connected to the second support mechanism, rotates the object to be measured and the second support mechanism by 90° around the Z axis of the calibration coordinate system, and is used to realize the offset detection in mutually perpendicular directions.

[0197] Wherein, the support mechanism and the rotating mechanism can be an integral structure or a split structure.

[0198] Based on the same inventive concept, the present application also proposes a computer-readable storage medium, including a computer program, and when the computer program is executed by a processor, the detection method described above is realized.

[0199] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0200] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting transparency uniformity, characterized in that, At least one line spectral confocal sensor is respectively arranged on any two opposite surfaces of the object to be measured made of a transparent material; the method includes: Using a transparent calibration object with a known thickness to calibrate the positions of each line spectral confocal sensor; The transparent calibration object includes a horizontal part having at least two opposite and parallel planes and an inclined part having at least two opposite and non-parallel inclined planes; wherein, any inclined plane has an inclined angle with the calibration coordinate system XOY plane, and any inclined angle does not exceed the maximum reception angle allowed by any line spectral confocal sensor; Each line spectral confocal sensor scans the object to be measured in sequence to obtain at least one spectral image corresponding to each position on any surface of the object to be measured; based on the spectral images obtained by each line spectral confocal sensor at any position of the object to be measured, obtain the measured thickness of the current position of the object to be measured scanned by this line spectral confocal sensor; based on the installation position relationship of the line spectral confocal sensor and the spectral image of the current position, calculate the position thickness corresponding to the current position; If the difference between the measured thickness and the position thickness falls within the threshold range, the interior of the current position of the object to be measured is uniform; otherwise, it is non-uniform.

2. The transparent uniformity detection method according to claim 1, characterized in that Based on the first measurement distance and the second measurement distance corresponding to the first peak wavelength and the second peak wavelength respectively in the spectral image of any position of the object to be measured obtained by any line spectral confocal sensor, and the refractive index of the object to be measured, calculate the compensated distance corresponding to the second peak wavelength; use the difference between the compensated distance and the first measurement distance as the first thickness; Use the first thickness as the measured thickness.

3. The transparent uniformity detection method according to claim 2, wherein It further includes: Calculate the first thickness of each line spectral confocal sensor scanning the current position of the object to be measured in sequence, and use the average value of the first thickness as the average thickness; Use the average thickness as the measured thickness.

4. The transparent uniformity detection method according to claim 1, wherein Using a transparent calibration object with a known thickness to calibrate the positions of each line spectral confocal sensor includes: Adjust the installation positions of the line spectral confocal sensors so that the X axes of the sensor coordinate systems corresponding to the line spectral confocal sensors are parallel to each other and are respectively parallel to the X axis of the calibration coordinate system; the Y axes of each sensor coordinate system are parallel to each other, and the Z axes of each sensor coordinate system are parallel to each other; Each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral image in the first direction at each position on any surface of the transparent calibration object; the transparent calibration object rotates 90 degrees around the Z axis direction of the calibration coordinate system, and each line spectral confocal sensor scans the transparent calibration object in sequence to obtain at least one spectral image in the second direction at each position on any surface of the transparent calibration object; Based on the spectral images, calculate the scanning thickness of each line spectral confocal sensor scanning the current position respectively; Determine the reference position, and based on the scanning thickness of each line spectral confocal sensor scanning any position and the shape of the transparent calibration object, calculate the offset of each line spectral confocal sensor in the current scanning direction; the current scanning direction includes the first direction and the second direction, and the direction of the scanning line projected by each line spectral confocal sensor on the surface of the transparent calibration object is perpendicular to the current scanning direction; Based on the offset of each line spectral confocal sensor in the current scanning direction, a scanning line trajectory model of each line spectral confocal sensor is constructed to match the coordinate relationship between the line spectral confocal sensors, and the position of each line spectral confocal sensor is calibrated.

5. The transparent uniformity detection method according to claim 4, wherein Scanning thickness, including: Based on the spectral map obtained by scanning any position of a transparent calibration object with any line spectral confocal sensor, the first measurement height and the second measurement height corresponding to the first peak wavelength and the second peak wavelength in the spectral map are obtained, and the compensated height corresponding to the second peak wavelength is calculated. The difference between the compensated height and the first measurement height is used as the scanning thickness.

6. The transparent uniformity detection method according to claim 5, wherein The compensated height corresponding to the second peak wavelength includes: based on the spectral map obtained by scanning any position of a transparent calibration object with any line spectral confocal sensor, the first measurement height and the second measurement height corresponding to the first peak wavelength and the second peak wavelength, as well as the first angle and the second angle of the second peak wavelength; the second measurement height is corrected to obtain the compensated height corresponding to the second peak wavelength.

7. The transparent uniformity detection method according to claim 4, characterized in that, The offset of each line spectral confocal sensor in the current scanning direction includes: Extract the spectral maps with the same scanning line position of each line spectral confocal sensor, calculate the scanning thickness corresponding to each spectral map with the same scanning line position, and based on the first measurement height corresponding to the first peak wavelength in each spectral map with the same scanning line position and the installation position relationship of the line spectral confocal sensors, calculate the optical axis direction deviation of each line spectral confocal sensor relative to the reference position; based on the optical axis direction deviation and the shape of the transparent calibration object, calculate the offset of each line spectral confocal sensor in the current scanning direction.

8. The transparent uniformity detection method according to claim 4, wherein The offset of each line spectral confocal sensor in the current scanning direction includes: Extract the spectral maps with the same scanning line position of each line spectral confocal sensor, calculate the scanning thickness corresponding to each spectral map with the same scanning line position, and based on the reference position and the shape of the transparent calibration object, calculate the offset of each line spectral confocal sensor in the current scanning direction.

9. The transparent uniformity detection method according to claim 1, characterized in that, Using a transparent calibration object with a known thickness to calibrate the position of each line spectral confocal sensor, including: Establish a sensor coordinate system corresponding to each line spectral confocal sensor and a calibration coordinate system corresponding to the transparent calibration object; Each line spectral confocal sensor scans the transparent calibration object in turn to obtain at least one spectral map corresponding to each position on any surface of the transparent calibration object; Based on the relative movement between the transparent calibration object and the line spectral confocal sensor, obtain the offset of each sensor coordinate system and the calibration coordinate system in the current scanning direction, and the relative rotation angle between each sensor coordinate system and the calibration coordinate system; Based on the offset and relative rotation angle in the current scanning direction, transform each sensor coordinate system to calibrate the position of each line spectral confocal sensor.

10. The transparent uniformity detection method according to claim 2 or 3, characterized in that, It also includes: If the difference between the measured thickness at the current position and the position thickness does not fall within the threshold range, then based on the position thickness and the first measurement distance and the second measurement distance corresponding to the first peak wavelength and the second peak wavelength in the spectral diagram corresponding to the current position, calculate the new refractive index of the object to be measured; based on the new refractive index of the object to be measured, calculate the newly compensated distance corresponding to the second peak wavelength, and based on the first measurement distance, calculate the new measured thickness; If the difference between the new measured thickness and the position thickness falls within the threshold range, then the interior of the current position of the object to be measured is uniform, and update the refractive index of the object to be measured to the new refractive index; otherwise, it is non-uniform.

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