Method and device for measuring glass depth

Abstract

The present invention provides a method and device for measuring glass depth, addressing the problem of measuring the refractive index and glass depth of glass using a prism and camera. By observing the path of a laser on flat glass and the path of the laser reflection image from the flat glass, combined with the slope of the laser, and based on a known sample data sequence [KY, RY, EY], an interpolation formula is used to determine the refractive index and glass thickness of the glass to be identified. The present invention has a simple structure, convenient observation, and is easy to use.

Description

Technical Field

[0001] The invention relates to a method for measuring architectural glass, and in particular to a method and device for measuring the depth of glass. Background Art

[0002] Currently, there are two main types of architectural glass: soda-lime-silica glass and borosilicate glass. Glass of different materials and thicknesses has different performance and costs. To inspect existing glass, it's necessary to measure the material and thickness. Because different materials have different refractive indices, measuring the refractive index can reveal the material. Methods for measuring the refractive index of glass include total reflection, V-prism, minimum deviation angle, and autocollimation.

[0003] In patent application number 201410206058.1 - Device and method for measuring glass thickness using linear frequency modulated multi-beam laser heterodyne second harmonic method, the thickness is obtained by measuring the difference frequency of the reflected light from the front and back surfaces of the glass, ignoring the influence of the glass refractive index on light propagation, and the calculation model gives little consideration to the path of light in the glass.

[0004] In patent application number 201510160594.7 - Surface Plasmon Resonance Transparent Liquid Refractive Index Detection System and Detection Method, the refractive index is detected using the total reflection angle, with little consideration given to the path of light in the glass.

[0005] In patent application No. 201780058952.0 - Stress measurement device for tempered glass, stress measurement method for tempered glass, manufacturing method for tempered glass, tempered glass, the optical path is taken into consideration, but there is a polarization element in the optical path, and the air prism incident surface of the laser is in an inclined state.

[0006] In patent application number 202011371090 - A device and method for measuring birefringence, the refractive index is measured using the total reflection angle instead of observing the path of the laser in the prism.

[0007] For the identification of installed glass, the total reflection angle method is usually used, but there is no way to measure the thickness of the glass. Summary of the Invention

[0008] The present invention provides a method and device for measuring glass depth, which are used to solve the problem of measuring the glass refractive index and glass depth of glass using a prism and a camera. The technical solution is as follows:

[0009] A method for measuring the depth of glass comprises the following steps:

[0010] S1: Place the prism above the glass, and the laser emits laser light, which passes through the incident surface of the prism and enters the flat glass to be tested;

[0011] S2: After the laser passes through the glass, it reaches the other side of the glass and is observed using a camera. The refractive index of the glass is set to R and the thickness is set to T.

[0012] S3: Observe the point P1 where the laser passes through the interface between the prism and the glass, the path L1 inside the glass, and the path L2 where the laser is reflected on the opposite side of the glass;

[0013] S4: Calculate the intersection point P2 of the two straight lines of path L1 and path L2. According to the slope K of path L1, the distance DL between point P1 and point P2, and the data sequence of the sample [KY, RY, EY], calculate the refractive index R and thickness T of the glass, where KY represents the slope of the sample, RY represents the refractive index of the sample, and EY represents the proportional relationship between the distance P12 between the two intersection points of the sample and the thickness of the sample.

[0014] Furthermore, in step S1, the prism is a trapezoidal prism, including a laser incident surface, a surface where the laser is emitted to the glass, and a camera observation surface, which can observe the point P1 where the laser passes through the interface between the prism and the glass, the path L1 in the glass, and the path L2 where the laser is reflected on the opposite side of the glass.

[0015] Furthermore, step S4 includes the following steps:

[0016] S11: Establish a coordinate axis, with the upper left point of the image captured by the observation camera as the coordinate origin, the x-axis from top to bottom, and the y-axis from left to right;

[0017] S12: Calculate the path L1 of the laser through the interface between the prism and the glass at point P1 (x1, y1). The equation of the line for L1 is y = A1 + K * X. Calculate the path L2 of the laser reflected from the opposite side of the glass. The equation of the line for L2 is Y = A2 + A2 * X. Where A1 and A2 are intercepts, and K and A2 are slopes.

[0018] S13: Calculate the intersection point P2 (x2, y2) of the two straight lines of path L1 and path L2;

[0019] S14: Calculate the distance DL between points P1 and P2;

[0020] S15: Compare the slope K and DL with the sample data sequence, find the slopes K1 and K2 of the two samples closest to K, set a+b=1, a*K1+b*K2=K;

[0021] S16: The refractive indices corresponding to the slopes K1 and K2 are R1 and R2, respectively. The corresponding R and E are obtained using the interpolation formula as follows:

[0022] R=a*R1+b*R2, E=a*E1+b*E2, where R is the refractive index of the glass, and E is the proportional relationship between the distance DL between points P1 and P2 and the glass thickness T. The thickness of the glass is obtained according to DL=E*T.

[0023] Furthermore, in step S4, the data sequence of the sample is obtained by measurement, including the following steps:

[0024] S21: Prepare multiple samples with known refractive index and thickness. The refractive index of each sample is different, and the path of the laser in the sample is different. The images captured by the camera show that the path of the laser in different samples is different.

[0025] S22: Following steps S1 to S3, the point P1 (x3, y3) where the laser passes through the interface between the prism and the sample is obtained, the path L1 in the glass, the linear equation of which is y=A10+A11*X, the path L2 where the laser is reflected from the opposite side of the glass, the linear equation of which is Y=A20+A21*X, and the intersection point P2 (x3, y3) of the paths L1 and L2 is calculated.

[0026] S23: Calculate the distance P12 between point P1 (x3, y3) and the intersection point P2 (x3, y3), P12 = sqrt[(x3-x4)*(x3-x4)+(y3-y4)*(y3-y4)];

[0027] S24: Calculate the relationship E between the distance P12 and the sample thickness TY, E = P12 / TY;

[0028] S25: List the data of multiple samples and compile them into a sample data sequence [KY, RY, EY].

[0029] Furthermore, in step S4, the device needs to be calibrated before measuring a sample, and after calibration, it can continuously measure other samples.

[0030] Furthermore, in step S14, the distance DL between the points P1 and P2 is DL=sqrt[(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)].

[0031] A device for measuring the depth of glass includes a PDA and a main frame connected by an angle adjustment hinge. A laser and an industrial camera are provided inside the main frame. The camera is mounted in the middle of the main frame via a camera mount. The laser is fixedly mounted on the lower right end of the main frame via a laser mount. Reflectors are respectively provided at the upper right end, upper left end, and lower left end of the main frame. The bottom of the main frame is a base for fixedly mounting a prism. Laser light from the laser passes through three reflectors in sequence to reach the prism, and then passes through the prism and enters the glass to be measured that is in contact with the prism. The camera is connected to the PDA via a data cable, and the collected image is transmitted to the PAD for data processing.

[0032] The PDA is provided with a built-in battery and a circuit control board. The circuit control board is connected to a power button, a Type C interface and a power status indicator light. The built-in battery supplies power to the circuit control board, the laser and the industrial camera.

[0033] The front end of the camera is provided with a lens, and the lens is provided with a filter.

[0034] A lens and an aperture are provided between the laser and the reflector. The light beam emitted by the laser is expanded and aligned by the lens to become parallel light, and then passes through the aperture to allow the laser with high light intensity density in the center to pass through, thereby reducing the diameter of the light column.

[0035] The method and device for measuring glass depth identify the glass refractive index and glass depth by observing the path of the laser on the flat glass and the path of the laser reflection image from the flat glass. The invention has a simple structure, convenient observation, and easy use. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the optical path of the method for measuring the depth of glass;

[0037] Figure 2 is a schematic diagram of the distance DL between the point P1 and the point P2;

[0038] Figure 3 is the light path of sample 1;

[0039] Figure 4 is the light path of sample 2;

[0040] Figure 5 is the ray path of sample three;

[0041] Figure 6 is a schematic diagram of the angle of refraction;

[0042] Figure 7 is a schematic diagram of the device for measuring the depth of glass;

[0043] Figure 8 yes Figure 7 Schematic diagram of the AA section. DETAILED DESCRIPTION

[0044] The present invention provides a method for measuring the depth of glass, comprising the following steps:

[0045] S1: If Figure 1 As shown, a prism 42 is placed above a glass 43, and a laser 41 emits laser light, which enters the flat glass 43 to be tested through the incident surface of the prism 42;

[0046] The laser 41 is located above the prism. The prism's shape ensures a laser entrance surface, a laser exit surface on the glass, and a camera viewing surface. The laser's incident angle cannot be zero, otherwise the incident and transmitted light will form a line segment. It also cannot be too large to prevent the laser from being totally reflected at the prism-glass interface.

[0047] The prism 42 is preferably a trapezoidal prism, with the inclined surface being non-parallel to the camera optical axis and at a certain angle. When the inclined surface is perpendicular to the camera optical axis, the focusing effect is better and clearer. The laser incident surface is the side surface of the trapezoidal prism, and the surface where the laser is emitted to the glass is the bottom surface of the trapezoidal prism. The camera observation surface can capture the position where the laser passes through the prism, and the inclined surface of the trapezoidal prism can be selected.

[0048] S2: After the laser passes through the glass 43, it reaches the other side of the glass 43 and is observed by the camera 44 on the camera observation surface. The refractive index of the glass 43 is set to R and the thickness is set to T.

[0049] S3: Use the camera 44 to observe through the prism 42 at a certain angle. You can see the point P1 (coordinates are x1, y1) where the laser passes through the interface between the prism 42 and the glass 43, and the path L1 in the glass 43. The straight line equation is y=A1+K*X. The path L2 where the laser is reflected on the opposite side of the glass 43 has a straight line equation of Y=A2+A2*X; among them, A1 and A2 are intercepts, K and A2 represent slopes, and the entire path is observed by the camera 44.

[0050] S4: Calculate the intersection point P2 (coordinates are x2, y2) of the acquisition path L1 and path L2 by using the two straight line intersection formula. After obtaining the coordinates of point P1 and point P2 on the image and the straight line equations of path L1 and path L2, as shown in the following example: Figure 2 As shown, the slope K of path L1 and the distance DL between point P1 and point P2 can be obtained, DL = sqrt[(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)]. Finally, the refractive index R and thickness T are calculated by K and DL.

[0051] The process of obtaining the refractive index R and thickness T is specifically:

[0052] S11: Establish a coordinate system with the upper left point of the image captured by the observation camera as the origin, the x-axis running from top to bottom, and the y-axis running from left to right. Measure the observed coordinates of the intersection point P1 in the image, where the laser light in the prism intersects the prism-air interface.

[0053] S12: Calculate the path L1 of the laser through the interface between the prism and the glass at point P1 (x1, y1). The equation of the line for L1 is y = A1 + K * X. Calculate the path L2 of the laser reflected from the opposite side of the glass. The equation of the line for L2 is Y = A2 + A2 * X. Where A1 and A2 are intercepts, and K and A2 are slopes.

[0054] S13: Calculate the intersection point P2 (x2, y2) of the two straight lines of path L1 and path L2;

[0055] S14: Calculate the distance DL between points P1 and P2, DL = sqrt[(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)].

[0056] S15: Compare the slope K and DL with the sample data sequence, find the slopes K1 and K2 of the two samples closest to K, set a+b=1, a*K1+b*K2=K; solve this linear equation to obtain a and b.

[0057] S16: The refractive indices corresponding to the slopes K1 and K2 are R1 and R2, respectively. The corresponding R and E are obtained using the interpolation formula as follows:

[0058] R=a*R1+b*R2, E=a*E1+b*E2, where R is the refractive index of the glass, and E is the proportional relationship between the distance DL between points P1 and P2 and the glass thickness T. The thickness of the glass is obtained according to DL=E*T.

[0059] The data sequence of the sample is obtained by measurement, such as Figures 3 to 5 As shown, multiple samples with known refractive index R and thickness T are measured to obtain the propagation path of the laser in the glass. Due to the different refractive indices of the samples, the paths of the laser in the samples are different. Through the images captured by the camera, it can be seen from the corresponding photos that the paths of the laser in different samples are different.

[0060] It is known that the refractive indices of the three samples are r1, r2 and r3 respectively. Figure 1As shown in the diagram, we can identify in turn the point P1 (coordinates are x1, y1) where the laser passes through the interface between the prism 42 and the glass 43, the path L1 in the glass 3 (the linear equation is y=A10+A11*X), the path L2 (the linear equation is Y=A20+A21*X) where the laser is reflected on the opposite side of the glass 3, and the intersection point P2 (coordinates are x2, y2) of the path L1 and the path L2, where A10 and A20 are intercepts, and A11 and A21 represent slopes.

[0061] Observe the slope K on the image, the distance P12 between the observation coordinates of the intersection point P2 of the laser in the glass sample and the glass-air interface on the image and the observation coordinates of the intersection point P1 of the laser in the measurement prism and the prism-air interface on the image, and P12 / TY to obtain the relationship E between the observation distance and thickness, where TY represents the sample thickness. For N sample measurements, corresponding N data sequences [K, R, E] can be obtained.

[0062] The device needs to be calibrated before measuring a sample. After calibration, it can measure other samples continuously. Known samples are prefabricated samples with known thickness and refractive index.

[0063] For the refractive index of glass, according to the refraction formula N a sina=N b sinb, we know that in N a When , sina, and sinb are known, N can be determined b That is, given the prism refractive index N a , the refractive index N of the glass can also be calculated when the incident angle of light on the prism-glass interface is a and the propagation angle of light in the prism is b b .

[0064] If the positions of the observation point, prism, and glass are fixed, the angle of incidence of light at the prism-glass interface can be determined based on the observed slope of the light propagation path in the prism, and the propagation angle of light in the glass can be determined based on the observed slope of the light propagation path in the glass.

[0065] like Figure 4 As shown, a device for measuring the depth of glass includes a PDA 3 and a main frame 7 connected by an angle adjustment hinge 21. The main frame 7 is internally provided with a laser 11 and an industrial camera 28. The industrial camera 28 is located in the middle of the main frame 7, and the laser 11 is located on the right side of the main frame 7. A bracket 20 is provided at the upper end of the main frame 7. The bracket 20 is fixedly connected to the bottom of the angle adjustment hinge 21. The other end of the angle adjustment hinge 21 is fixedly connected to the PDA 3.

[0066] The PDA 3 is provided with a shell, a built-in battery 23, and a circuit control board 6. The shell is provided with an on / off button 1 connected to the circuit control board 6, a Type C interface 2, and a power status indicator light 4. The shell includes a PDA front shell 25, a PDA back shell 22, and is provided with a measurement trigger switch 15. A battery pressure plate 24 for installing the built-in battery 23 is provided inside the shell.

[0067] The main frame 7 includes a fixed housing, which includes a front shell 26 and a rear shell 19. The fixed housing houses a laser 11 and an industrial camera 28. The camera 28 is secured within a camera mount 29, which is mounted in the middle of the fixed housing via a lock nut 31. A lens 27 is located at the front of the camera 28, which has the filter 30 located at the front end. The lens 27 allows the camera to observe the optical path below.

[0068] The laser 11 is fixed in the laser holder 10, which is fixed to the lower right end of the fixed housing via a locknut 12. The front end of the laser 11 is provided with a lens 13 and an aperture 14. In order to reduce the size of the device, a multiple mirror folding optical path layout is adopted to make the structure compact. The four corners of the fixed housing are respectively provided with three groups of mirrors and prisms 18. The three groups of mirrors include a first reflector 17, a second reflector 5, and a third reflector 8. The reflectors are fixed by a reflector holder, such as the first reflector 17 is mounted on the upper right end of the fixed housing via a first reflector holder 16.

[0069] The optical path of the laser 11 passes upward through the first reflector 17 , and the reflected light reaches the second reflector 5 to the left. After being further reflected by the second reflector 5 , the light reaches the third reflector 8 downward, and then enters the prism after being reflected by the third reflector 8 .

[0070] The bottom of the main frame 7 is a base 9 for fixing the prism. The bottom surface of the prism coincides with the bottom surface of the device. When the device is attached to the upper surface of the glass, the prism is also attached to the glass.

[0071] When using:

[0072] S31: Press the power button 1 to turn on the PDA 3 of the device, and then the laser 11 is powered by the built-in battery 23;

[0073] S32: A diaphragm 14 is installed between the lens 13 and the reflector;

[0074] S33: The light beam emitted by the laser 11 is expanded and collimated by the lens 13, becoming parallel light. Then, the aperture 14 is used to block most of the light, allowing the laser beam with high light intensity density in the center to pass through. This can reduce the diameter of the light column and enhance the resolution of the optical system.

[0075] S34: The bottom of the device is attached to the upper surface of the glass. At this time, the prism is attached to the glass. After being reflected by multiple mirrors, the laser enters the prism 18 through the air-prism surface, then enters the glass through the prism-glass interface, propagates into the glass, finds the glass-air interface, and is reflected at the glass-air interface.

[0076] S35: Arranging the industrial camera 28 and the short-focus lens 27 at a set angle to observe the change in the light propagation angle caused by the refraction of the laser at the prism-glass interface;

[0077] In order to enhance the anti-interference ability, a filter 30 is added in front of the industrial camera;

[0078] S36: Using the portable PDA 3 to process the image, identify the path L1 of the laser light in the glass, as well as the coordinates and slope K of the laser light at the prism-glass intersection point P1 and the laser light at the glass-air interface intersection point P2 on the image; and calculate the distance DL between points P1 and P2.

[0079] S37: Press the measurement trigger switch 15 to obtain the measurement result;

[0080] Among them, the portable PDA 3 stores a data sequence of samples. According to the slope K, two sample data that are respectively greater than K and less than K are selected in the data sequence. Using step S16, the refractive index and thickness of the glass to be tested can be obtained according to the interpolation calculation. It can be seen that through this method, the calculation process can be greatly simplified and it is convenient to use. The PDA 3 is a computing device equipped with a processing chip, and the processing chip adopts the Kirin series or ARM with data processing capabilities.

[0081] S38: Press and hold the power button 1 to turn off the device. The device can charge the built-in battery 23 through the Type C port 2.

[0082] The method and device for measuring glass depth identify the glass refractive index and glass depth by observing the path of the laser on the flat glass and the path of the laser reflection image from the flat glass. The device has a simple structure, convenient observation, and is easy to use.

Claims

1. A method for measuring the depth of glass, comprising the following steps: S1: Place the prism above the glass, and the laser emits laser light, which passes through the incident surface of the prism and enters the flat glass to be tested; S2: After the laser passes through the glass, it reaches the other side of the glass and is observed using a camera. The refractive index of the glass is set to R and the thickness is set to T. S3: Observe the point P1 where the laser passes through the interface between the prism and the glass, the path L1 inside the glass, and the path L2 where the laser is reflected on the opposite side of the glass; S4: Calculate the intersection point P2 of the two straight lines of path L1 and path L2. According to the slope K of path L1, the distance DL between points P1 and P2, and the data sequence [KY, RY, EY] of the sample, calculate the refractive index R and thickness T of the glass, where: KY represents the slope of the sample, RY represents the refractive index of the sample, and EY represents the proportional relationship between the distance P12 between the two intersection points of the sample and the sample thickness; The following steps are involved: S11: Establish a coordinate axis, with the upper left point of the image captured by the observation camera as the coordinate origin, the x-axis from top to bottom, and the y-axis from left to right; S12: Calculate the path L1 of the laser through the interface between the prism and the glass at point P1 (x1, y1). The equation of the line for L1 is y = A1 + K * X. Calculate the path L2 of the laser reflected from the opposite side of the glass. The equation of the line for L2 is Y = A2 + A3 * X. A1 and A2 are intercepts, and K and A3 represent slopes. S13: Calculate the intersection point P2 (x2, y2) of the two straight lines of path L1 and path L2; S14: Calculate the distance DL between points P1 and P2; S15: Compare the slope K and DL with the sample data sequence [KY, RY, EY], find the slopes K1 and K2 of the two samples closest to K, set a+b=1, a*K1+b*K2=K; S16: The refractive indices corresponding to the slopes K1 and K2 are R1 and R2, respectively. The corresponding R and E are obtained using the interpolation formula as follows: R=a*R1+b*R2, E=a*E1+b*E2, where R is the refractive index of the glass, and E is the proportional relationship between the distance DL between points P1 and P2 and the glass thickness T. The thickness of the glass is obtained according to DL=E*T.

2. The method for measuring glass depth according to claim 1, wherein: In step S1, the prism is a trapezoidal prism, which includes a laser incident surface, a surface where the laser is emitted to the glass, and a camera observation surface, which can observe the point P1 where the laser passes through the interface between the prism and the glass, the path L1 in the glass, and the path L2 where the laser is reflected on the opposite side of the glass.

3. The method for measuring glass depth according to claim 1, wherein: In step S4, the data sequence of the sample is obtained by measurement, including the following steps: S21: Prepare multiple samples with known refractive index and thickness. The refractive index of each sample is different, and the path of the laser in the sample is different. The images captured by the camera show that the path of the laser in different samples is different. S22: Following steps S1 to S3, the point P1 (x3, y3) where the laser passes through the interface between the prism and the sample is obtained, the path L1 in the glass, the linear equation of which is y=A10+A11*X, the path L2 where the laser is reflected from the opposite side of the glass, the linear equation of which is Y=A20+A21*X, and the intersection point P2 (x3, y3) of the paths L1 and L2 is calculated. S23: Calculate the distance P12 between point P1 (x3, y3) and the intersection point P2 (x3, y3), P12 = sqrt[(x3-x4)*(x3-x4)+(y3-y4)*(y3-y4)]; S24: Calculate the relationship E between the distance P12 and the sample thickness TY, E = P12 / TY; S25: List the data of multiple samples and compile them into a sample data sequence [KY, RY, EY].

4. The method for measuring glass depth according to claim 3, wherein: In step S4, the device needs to be calibrated before measuring a sample, and after calibration, it can continuously measure other samples.

5. The method for measuring glass depth according to claim 3, wherein: In step S14, the distance DL between the points P1 and P2 is DL=sqrt[(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)].

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