CN107131847B - Measuring device and method applicable to surface shape detection of 3D curved glass - Google Patents
Measuring device and method applicable to surface shape detection of 3D curved glass Download PDFInfo
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
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Abstract
The invention discloses a measuring device and a measuring method for detecting the surface shape of 3D curved glass, wherein the measuring device comprises a box body, a surface light source, a CCD left camera, a CCD right camera, a supporting mechanism and a two-dimensional lifting workbench, the two-dimensional lifting workbench is positioned below the CCD left camera and the CCD right camera and fixedly connected to the bottom surface of the box body, and the 3D curved glass is clamped on the two-dimensional lifting workbench. The measuring principle steps comprise: 1) A digital phase shift method; 2) Phase unwrapping; 3) Waveform recovery and object three-dimensional modeling, and finally recovering the surface shape data of the measured piece through calculation. The invention adopts the surface light source of projection structure light, has stronger practicability and universality, is easy to industrialize, has high measurement precision, is not only suitable for measuring the 3D curved glass, but also can measure the mirror surface material with high reflection characteristic, and has the advantages of simple steps, easy operation, large measurement dynamic range, strong anti-interference capability and the like.
Description
Technical Field
The invention belongs to the technical field of optical precision measurement, and particularly relates to a measuring device and method applicable to surface shape detection of 3D curved glass.
Background
The three-star mobile phone adopts the mobile phone glass back cover to replace the traditional metal shell, wherein the 3D curved surface glass cover plate becomes a bright spot, the appearance and excellent hand feeling of the high-color value of the three-star mobile phone become new favor of consumers rapidly, the three-star mobile phone gradually becomes a hot spot for the domestic manufacturer to race and pursue, the three-star mobile phone becomes market trend, and currently, brand manufacturers such as China, millet, OPPO, vivo, leshi and the like also adopt the glass cover plate technology.
The 3D curved glass is mainly applied to a protective screen and a rear cover of an intelligent terminal product, and compared with the traditional 2D or 2.5D glass, the 3D curved glass has the characteristics of light weight, transparency, cleanliness, fingerprint resistance, dizziness resistance and the like, and the appearance performance is more novel and superior. The heat dissipation performance, the glossiness and the wear resistance are more advantageous, meanwhile, the curved design is matched with the radian of the palm, so that the heat dissipation device meets the requirements of human engineering, and excellent touch feeling can be brought. With the continuous growth of the market of intelligent terminal products and the change of the electronic consumer market on the aesthetic appearance and touch hand feeling requirements of the products, the 3D curved glass has very wide market space.
The surface morphology of the 3D glass is accurately measured, particularly the arc (R angle) of the edge of the 3D glass is measured, the change and the defect of the 3D glass in the processing process can be accurately identified, the processing method is convenient to control and improve, and the method has important significance for researching the relation between the geometric characteristics of the surface and the service performance and improving the quality of the processed surface and the performance of products. At present, aiming at the detection of transparent glass, the detection method is not more, the existing contact type measurement method is low in measurement speed and easy to scratch the measurement surface, and data distortion is caused to complex surface-shaped parts. The non-contact mirror detection method mainly comprises a contour measurement method, an interferometer measurement method, a three-coordinate measurement method and the like, but all three methods have own limitations. The contour measurement method has the defects of low sampling density, long detection time and the like, and cannot meet the engineering detection requirement; the interferometer measurement method needs to be carried out on a reference mirror which is not smaller than the size of the detected element, and the high-precision reference mirror has the advantages of high processing difficulty, high manufacturing cost, corresponding compensation element design and small dynamic range; the three-coordinate measuring method has low precision, relatively long measuring time, generally can only be used in a rough detection stage, and has limited measuring precision.
Disclosure of Invention
Aiming at the defects of the existing 3D glass detection technology, the invention provides a measuring device and a measuring method which can be applied to the surface shape detection of 3D curved glass, and the basic principle is that structural light is projected by a surface light source, 3D glass to be detected is shot by a CCD camera, and the structural light is reflected by the surface of an object to be detected to form a modulated image; then, a phase unwrapping algorithm is carried out through a digital phase shift technology to obtain a phase diagram of the modulated image, and a one-to-one correspondence between pixel coordinates of the area light source and pixel coordinates of the camera is found out; converting the distribution of the phases into the distribution of the position coordinates by combining the parameters calibrated by the camera, and corresponding the phase calibration information with the space position information; and finally, establishing phase change amount and surface shape gradient information of the object to be detected, namely slope distribution in X and Y directions by utilizing a light three-dimensional deflection technology, and realizing three-dimensional surface shape reconstruction by iterative integration along the slope directions. The method has the advantages of wide application, simple structure, low cost, easy operation, large measurement dynamic range, high measurement accuracy, strong anti-interference capability and the like.
In order to solve the technical problems, the invention adopts the following technical scheme:
measuring device that can be applied to 3D curved surface glass shape of face and detect, its characterized in that: the CCD left camera and the CCD right camera are movably connected to the inside of the box through the supporting mechanism, the supporting mechanism comprises a horizontal guide rod and a vertical guide rod, a first positioning plate is arranged on the inner side face of the box, the vertical guide rod is fixedly connected to the first positioning plate through a first triangular connecting block, two ends of the horizontal guide rod are connected with the vertical guide rod through rectangular connecting blocks, the CCD left camera and the CCD right camera are movably connected to the horizontal guide rod, the two-dimensional lifting workbench is positioned below the CCD left camera and the CCD right camera and is fixedly connected to the bottom face of the box, and 3D curved glass is clamped on the two-dimensional lifting workbench; the structured light measuring device is characterized in that a structured light source projects structured light from a surface light source, the structured light is radiated onto 3D curved glass at a certain angle, the 3D curved glass is placed on a two-dimensional lifting workbench which can be lifted, so that different visual angles can be conveniently adjusted, two CCD cameras form a certain angle with each other, and as much structured light as possible is displayed on the 3D glass to be measured and is acquired by the CCD cameras by adjusting the positions of the CCD cameras and the workbench.
Further, the area light source is obliquely embedded on the inner side surface of the box body, and the area light source is obliquely arranged at a certain angle, so that the space occupancy rate of the box body can be reduced by the design mode, and the oblique polishing mode is more beneficial to projecting structural light to the edge of the 3D glass, so that the measurement of the R angle of the edge is facilitated.
Further, the horizontal guide rod is mutually perpendicular to the vertical guide rod, so that the CCD left camera and the CCD right camera can be flexibly adjusted to the proper positions, the projection of structural light on the surface of a measured object as much as possible during photographing is ensured, the measuring error can be reduced, and the measuring precision is improved.
Further, CCD left side camera and CCD right side camera all include second triangle connecting block and CCD camera, are provided with the locating hole on the second triangle connecting block, and the locating hole is with horizontal guide arm assorted, is provided with the backup pad on the second triangle connecting block, is connected with the limiting plate perpendicularly in the backup pad, and the CCD camera clamping is on the limiting plate, and the CCD camera can remove along the horizontal guide arm under the effect of second triangle connecting block, can take a picture to the 3D curved surface glass of different positions and visual angle, convenient to use is nimble.
Further, two-dimensional elevating platform includes work platform and base, be provided with high adjustment mechanism on work platform's the bottom surface, be provided with first support and the second support that is parallel to each other and cross arrangement between work platform and the base, first support is located the inboard of second support, the center department of two first supports and two second supports passes through the connecting axle to be connected, all pass through upper junction plate fixed connection between the bottom surface of two first supports and between the bottom surface of two second supports, all pass through lower connecting plate fixed connection between the top surface of two first supports and between the top surface of two second supports, through the design of first support and second support, stability in the upper junction plate and lower connecting plate have not only improved the intensity of first support and second support connection, prevent to appear rocking, moreover, work platform's impact force at the in-process of falling has been reduced.
Further, the height adjusting mechanism comprises a handle and a fastening nut, the handle is connected with the second positioning plate through the fastening nut, the second positioning plate is fixedly connected to the lower portion of the working platform, the height position of the working platform can be adjusted through rotating the handle, and positioning can be performed through fastening screws.
The measuring device is a testing system capable of testing the high-reflection mirror surface, and has the advantages of being simple in structure, large in dynamic range, high in measuring accuracy, high in detection speed, strong in anti-interference performance, low in cost, easy to operate and the like.
The measuring method of the measuring device for detecting the surface shape of the 3D curved glass is characterized by comprising the following steps of:
1) Digital phase shift method
In the measuring device, structural light is projected on a surface light source and irradiates on the surface of a measured sample, and the light intensity of deformed stripes reflected by a mirror to be measured and imaged by a camera is described by the following equation:
wherein a (x, y) is the background light intensity; b (x, y) is amplitude modulation;is the required phase distribution; i (x, y) is the light intensity detected by the CCD camera; delta (t) is an additional phase shift over time, the phase difference of adjacent phase shift patterns is +.>The acquired images are respectively marked as I 1 ,I 2 ,……I n . By phase->The value of (2) can be used for obtaining the area light source pixel point corresponding to the CCD camera pixel point, and each acquired actual image I is obtained according to the least square method pn With other ideal images I n The sum of squares of the differences between them takes a minimum value
The phase to be measured is as follows:
2) Phase unwrapping
For the phase unwrapping of the one-dimensional space, the phase unwrapping process adds an integer multiple of 2pi to the wrapped phase in the calculation, the process determines a translation function p (i) of the integer multiple of unknown 2pi, when the recorded interferogram meets the nyquist criterion, at least two pixels are arranged in each fringe period, and the unwrapping concrete recursion is performed according to the following formula:
the unwrapping process starts from a position of the wavefront close to the center of the interferogram, and the whole calculation is performed from inside to outside, so P is set start ＝0；
3) Waveform recovery and object three-dimensional modeling, and finally recovering surface shape data of measured piece through calculation
For the phase shift method, the phase information of each sampling point on the surface is used for obtaining the slope information of each point according to the basic principle of a stripe reflection method by the geometrical relation of the system, the three-dimensional surface shape integral reconstruction process is used for integrating the surface gradient [ p (x, y), q (x, y) ] to obtain the surface shape information of the optical surface, in ideal case, the wave surface is subjected to trapezoidal integration,
z＝∫(g x d x +g y d y ) (5)
the 3D surface shape of the glass surface can be recovered through integration and repeated iteration.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
1. the measuring device is composed of a surface light source for projecting structured light, 2 CCD cameras and some auxiliary profile devices, has low hardware price and convenient measuring process, and has strong practicability and universality;
2. the measuring device has the advantages of simple structure, easy industrialization and high measuring precision, is not only suitable for measuring 3D curved glass, but also can measure mirror materials with high reflection characteristics;
3. the measuring method has the advantages of simple measuring steps, easy operation, high measuring precision, large measuring dynamic range, strong anti-interference capability and the like.
Drawings
The invention is further described below with reference to the accompanying drawings:
FIG. 1 is a diagram showing the effect of a measuring device and a measuring method for detecting the surface shape of a 3D curved glass;
FIG. 2 is a schematic view of the internal structure of the present invention;
FIG. 3 is an enlarged view of a portion of the portion I of FIG. 2;
FIG. 4 is a schematic diagram of the structure of a CCD left camera and a CCD right camera according to the present invention;
FIG. 5 is a front view of FIG. 4;
FIG. 6 is a schematic diagram of a two-dimensional lifting table according to the present invention;
FIG. 7 is a measurement flow chart of an embodiment of the present invention;
FIG. 8 is an intensity graph of the measurement results of the present invention;
FIG. 9 is a graph of curvature of the measurement results of the present invention;
FIG. 10 is a three-dimensional plot of the surface shape of the measurement results of the present invention;
FIG. 11 is a 2D cross-sectional view of the measurement results of the present invention;
fig. 12 is a schematic diagram of a dual camera restoration measurement in accordance with the present invention.
In the figure: 1-a box body; 2-area light source; 3-CCD left camera; 4-CCD right camera; 5-a supporting mechanism; 6-a two-dimensional lifting workbench; 7-3D curved glass; 8-a horizontal guide rod; 9-vertical guide rods; 10-rectangular connecting blocks; 11-a first triangular connection block; 12-a first positioning plate; 13-a second triangular connection block; 14-supporting plates; 15-CCD camera; 16-limiting plates; 17-positioning holes; 18-a working platform; 19-a base; 20-a first scaffold; 21-a second bracket; 22-an upper connecting plate; 23-a lower connecting plate; 24-connecting shaft; 25-a second positioning plate; 26-handle; 27-tightening the nut.
Detailed Description
As shown in fig. 1 to 11, the measuring device for detecting the surface shape of the 3D curved glass comprises a box body 1, a surface light source 2, a CCD left camera 3, a CCD right camera 4, a supporting mechanism 5 and a two-dimensional lifting workbench 6, wherein the surface light source 2 is obliquely embedded on the inner side surface of the box body 1, and the surface light source 2 is obliquely inclined at a certain angle.
The CCD left camera 3 and the CCD right camera 4 are movably connected in the box body 1 through the supporting mechanism 5, the supporting mechanism 5 comprises a horizontal guide rod 8 and a vertical guide rod 9, the horizontal guide rod 8 and the vertical guide rod 9 are mutually perpendicular, the CCD left camera 3 and the CCD right camera 4 can be flexibly adjusted to be at proper positions, as much as possible of structured light is projected onto the surface of a measured object during photographing is guaranteed, the measuring error can be reduced, the measuring precision is improved, a first positioning plate 12 is arranged on the inner side surface of the box body 1, the vertical guide rod 9 is fixedly connected on the first positioning plate 12 through a first triangular connecting block 11, two ends of the horizontal guide rod 8 are connected with the vertical guide rod 9 through rectangular connecting blocks 10, the CCD left camera 3 and the CCD right camera 4 are movably connected on the horizontal guide rod 8, the CCD left camera 3 and the CCD right camera 4 comprise a second triangular connecting block 13 and a CCD camera 15, a positioning hole 17 is formed in the second triangular connecting block 13, the positioning hole 17 is matched with the horizontal guide rod 8, a limiting plate 14 is arranged on the second triangular connecting block 13, a limiting plate 16 is vertically connected on the supporting plate 14, the two ends of the CCD right camera 4 are movably connected on the first triangular connecting block 15 and the second triangular connecting block 15 can not be clamped on the curved surface of the CCD right camera 3 and the CCD right camera 4, and the CCD right camera 4 can be flexibly clamped along the curved surface of the horizontal guide rod 8, and the curved surface can be conveniently clamped by the curved surface of the CCD connecting block 3.
The two-dimensional lifting workbench 6 is positioned below the CCD left camera 3 and the CCD right camera 4 and is fixedly connected to the bottom surface of the box body 1, 3D curved glass 7 is clamped on the two-dimensional lifting workbench 6, the two-dimensional lifting workbench 6 comprises a workbench 18 and a base 19, a height adjusting mechanism is arranged on the bottom surface of the workbench 18, a first support 20 and a second support 21 which are mutually parallel and are arranged in a crossed manner are arranged between the workbench 18 and the base 19, the first support 20 is positioned on the inner side of the second support 21, the centers of the two first supports 20 and the two second supports 21 are connected through a connecting shaft 24, the bottom surfaces of the two first supports 20 and the bottom surfaces of the two second supports 21 are fixedly connected through an upper connecting plate 22, the top surfaces of the two first supports 20 and the top surfaces of the two second supports 21 are fixedly connected through a lower connecting plate 23, the design of the first supports 20 and the second supports 21 improves the stability of the workbench 18 in the up-down moving process, the upper connecting plate 22 and the lower connecting plate 23 not only improve the strength of the first supports 20 and the second supports 21, but also prevent the handle from being connected with the handle 26, namely, the handle can be positioned at the position of the handle 26 through the handle 25, and the handle can be fixedly connected through the positioning mechanism, and the height of the handle 25 can be fixedly connected through the handle 25; the structured light measuring device is characterized in that a light source of the structured light measuring device projects structured light from a surface light source 2, the structured light irradiates onto 3D curved glass 7 at a certain angle, the 3D curved glass 7 is placed on a two-dimensional lifting workbench 6 which can be lifted, the angles of the CCD cameras 15 and the workbench are respectively adjusted through two CCD cameras 15 which are at certain angles, and as much structured light as possible irradiates on the 3D glass at different positions and visual angles.
The measuring device is a testing system capable of testing the high-reflection mirror surface, and has the advantages of being simple in structure, large in dynamic range, high in measuring accuracy, high in detection speed, strong in anti-interference performance, low in cost, easy to operate and the like.
The measuring method of the measuring device for detecting the surface shape of the 3D curved glass comprises the following steps:
1) Digital phase shift method
In the measuring device, structural light is projected on a surface light source and irradiates on the surface of a measured sample, and the light intensity of deformed stripes reflected by a mirror to be measured and imaged by a camera is described by the following equation:
wherein a (x, y) is the background light intensity; b (x, y) is amplitude modulation;is the required phase distribution; i (x, y) is the light intensity detected by the CCD camera 15; delta (t) is an additional phase shift over time, the phase difference of adjacent phase shift patterns is +.>The acquired images are respectively marked as I 1 ,I 2 ,……I n . By phase->The surface light source pixel point corresponding to the CCD camera 15 pixel point can be obtained, and each acquired actual image I is obtained according to the least square method pn With other ideal images I n The sum of squares of the differences between them takes a minimum value
The phase to be measured is as follows:
2) Phase unwrapping
For the phase unwrapping of the one-dimensional space, the phase unwrapping process adds an integer multiple of 2pi to the wrapped phase in the calculation, the process determines a translation function p (i) of the integer multiple of unknown 2pi, when the recorded interferogram meets the nyquist criterion, at least two pixels are arranged in each fringe period, and the unwrapping concrete recursion is performed according to the following formula:
the unwrapping process starts from a position of the wavefront close to the center of the interferogram, and the whole calculation is performed from inside to outside, so P is set start ＝0；
3) Waveform recovery and object three-dimensional modeling, and finally recovering surface shape data of measured piece through calculation
For the phase shift method, the phase information of each sampling point on the surface is used for obtaining the slope information of each point according to the basic principle of a stripe reflection method by the geometrical relation of the system, the three-dimensional surface shape integral reconstruction process is used for integrating the surface gradient [ p (x, y), q (x, y) ] to obtain the surface shape information of the optical surface, in ideal case, the wave surface is subjected to trapezoidal integration,
z＝∫(g x d x +g y d y ) (5)
the 3D surface shape of the glass surface can be recovered through integration and repeated iteration.
The measuring method is characterized in that according to the functional relation between the normal line (or x, y syncrata) at the mirror surface sampling point and the optical center coordinate of the aperture camera, the area light source pixel point coordinate for lighting the measured mirror surface sampling point and the mirror surface sampling point coordinate, a better initial value is provided by assuming a predicted surface shape, and finally the slope and the surface shape of the measured mirror surface are obtained by iteration according to the functional relation, wherein the functional relation between the slope and the surface shape is expressed by the following formula (6):
wherein x is m And y m Is the coordinates of the surface to be measured, and can be obtained from the geometric measurement of the measuring device; x is x camera And y camera The coordinates of the CCD camera 15 can be obtained from the geometric measurement of the measuring device; x is x screen And y screen Is the coordinates of the bright spot of the surface light source, and can be calculated by a digital phase shift technology and a phase unwrapping algorithm; z m2screen And z m2camera The z-coordinate differences between the mirror and the surface light source, the mirror and the CCD camera 15, respectively; d, d m2screen And d m2camera The distances between the mirror and the surface light source, the mirror and the CCD camera 15, respectively; z m2screen 、z m2camera And d m2camera Can be obtained from geometric measurements and calibrations.
In equation (6), due to the slope w x (x m ,y m )、w y (x m ,y m ) Is the surface profile w (x m ,y m ) Therefore, a better initial value is needed to calculate the slope, and an ideal surface shape or other measurement method can be used to obtain the shape to provide a better initial shape estimate, denoted as w 0 (x m ,y m ) Will w 0 (x m ,y m ) Instead of w (x) in formula (6) m ,y m ) Thus obtaining (x) m ,y m ) The data of the x and y directional inclinations at the position, and the surface shape w obtained by slope calculation 1 (x m ,y m ) Instead of w (x) in formula (6) m ,y m ) And further obtaining another set of slopes, and similarly, calculating the slopes and the surface shapes through repeated iteration. The formula adopts a method of recovering single-camera, but the measuring device adopts a method of measuring left and right double-camera, the two single-camera iteratively calculates the slope and the surface shape respectively through the method, and then the two single-camera adopts a picture fusion technologyAnd iterating until the whole surface shape is output. This single-dual camera combined approach has the advantage that the field of view can be increased, i.e. the measurement range is increased, and more complex surface shapes can be measured.
For measurement of three-dimensional surface shapes, a measurement method of single camera restoration is utilized, firstly, a predicted surface shape needs to be determined, if the difference between the predicted surface shape and the measured surface shape is large, program convergence is slow, precision and running speed can be greatly influenced, meanwhile, the requirement on geometric calibration precision in the calibration process is high, and the measurement precision of a selected reference plane can directly influence a final measurement result.
The method for measuring the restoration of the double camera is adopted, the measuring visual field is small, the effective area of the measurement is the common intersection area of the visual field of the two camera, and the method directly scans the whole surface shape, has large data volume and low program running speed, and can not measure and restore the complex surface shape. The two-camera stereo deflection technique is briefly described below, as shown in fig. 12.
Principle of dual camera measurement: and respectively measuring by using a double camera, and obtaining the specific positions of the incident light direction and the observation point on the surface light source corresponding to each pixel of the camera after measurement. However, for a single camera, the normal vector of the real reflecting surface cannot be determined due to the uncertainty of the height, but the normal vector corresponding to different heights can be calculated, and the measurement method of the two cameras is also based on the principle. Only on a plane with a real height, the two normal vectors can be overlapped, and the normal vector distribution on the plane can be obtained by measuring the directions of incident light rays corresponding to different pixel points, so that the slope distribution of the object surface can be obtained.
Aiming at the problems of the scheme, the scheme provides a method for combining single-double cameras based on binocular vision and digital phase shift technology. Firstly, acquiring height information of 20 points of an intersection area by using a double camera, then fitting an initial surface shape to serve as a reference surface of a measured surface shape, then performing slope iterative computation until three-dimensional surface shape information of a measured piece is output by using the initial surface shape input of a single camera, and thus, the running speed of a program is greatly improved.
Advantages of the method using a single-dual camera combination: 1. the measurement view field is large; 2. the operation speed is greatly improved; 3. the calibration requirement on hardware is greatly reduced; 4. the measurement can be performed on complex profiles.
The working principle of the invention is as follows:
1) Adopting a surface light source and projecting structural light;
2) The method comprises the steps that structured light projected by a surface light source irradiates on 3D curved glass at a certain angle, the 3D curved glass is placed on a liftable two-dimensional lifting workbench, after the surface light source irradiates on an object to be measured, the object to be measured is reflected by the surface of the object to be measured and imaged on two CCD cameras, the height of a workbench is adjusted to further adjust the position of the 3D glass and the position of the CCD cameras, left and right cameras are respectively installed at a certain angle, and the positions of the CCD cameras and the workbench are adjusted to enable as much structured light as possible to be displayed on the 3D glass to be measured and acquired by the CCD cameras;
3) The method comprises the steps that a modulated image formed by reflecting structured light on the surface of an object to be detected is obtained through a digital phase shift technology and a phase unwrapping algorithm, a phase diagram of the modulated image is obtained, and a one-to-one correspondence between pixel coordinates of a surface light source and pixel coordinates of a camera is found; converting the distribution of the phases into the distribution of the position coordinates by combining the parameters calibrated by the camera, and corresponding the phase calibration information with the space position information; and finally, establishing phase change amount and surface shape gradient information of the object to be measured by utilizing a light three-dimensional deflection technology.
4) By using a restoration method combining a single camera and a double camera, the known gradient information is integrated in an iterative way along the slope direction, so that the surface shape can be reconstructed, and the surface shape of the 3D glass is restored.
The above is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions or modifications made on the basis of the present invention to achieve substantially the same technical effects are included in the scope of the present invention.
Claims (6)
1. Measuring device that can be applied to 3D curved surface glass shape of face and detect, its characterized in that: the device comprises a box body, a liquid crystal LCD display screen, a CCD left camera, a CCD right camera, a supporting mechanism and a two-dimensional lifting workbench, wherein the CCD left camera and the CCD right camera are movably connected to the inside of the box body through the supporting mechanism, the supporting mechanism comprises a horizontal guide rod and a vertical guide rod, a first locating plate is arranged on the inner side surface of the box body, the vertical guide rod is fixedly connected to the first locating plate through a first triangular connecting block, two ends of the horizontal guide rod are connected with the vertical guide rod through rectangular connecting blocks, the CCD left camera and the CCD right camera are movably connected to the horizontal guide rod, the two-dimensional lifting workbench is positioned below the CCD left camera and below the CCD right camera and is fixedly connected to the bottom surface of the box body, and 3D curved glass is clamped on the two-dimensional lifting workbench;
when the measurement is carried out based on the measuring device, the method comprises the following steps,
1) Digital phase shift method
In the measuring device, the projection structure light on the screen of the LCD display irradiates the surface of the sample to be measured, and the light intensity of deformed stripes reflected by the mirror to be measured and imaged by the camera is described by the following equation:
wherein a (x, y) is the background light intensity; b (x, y) is amplitude modulationIs the required phase distribution; i (x, y) is the light intensity detected by the CCD camera; delta (t) is an additional phase shift over time, the phase difference of adjacent phase shift patterns is +.>The acquired images are respectively marked as I1, 12 and … … In; by phase->The value of (2) can be obtained, the liquid crystal LCD display screen pixel point corresponding to the CCD camera pixel point is obtained, the square sum of the difference between each acquired actual image Ipn and other ideal images In is taken as the minimum value according to the least square method,
the phase to be measured is as follows:
2) Phase unwrapping
For the phase unwrapping of the one-dimensional space, the phase unwrapping process adds an integer multiple of 2pi to the wrapped phase in the calculation, the process determines a translation function p (i) of the integer multiple of unknown 2pi, when the recorded interferogram meets the nyquist criterion, at least two pixels are arranged in each fringe period, and the unwrapping concrete recursion is performed according to the following formula:
the unwrapping process starts from a position of the wavefront close to the centre of the interferogram, and the whole calculation is performed from inside to outside, so pstart=0 is set;
3) Waveform recovery and object three-dimensional modeling, and finally recovering surface shape data of measured piece through calculation
For the phase shift method, the phase information of each sampling point on the surface is used for obtaining the slope information of each point according to the basic principle of a stripe reflection method by the geometrical relation of the system, the three-dimensional surface shape integral reconstruction process is used for integrating the surface gradient [ p (x, y), q (x, y) ] to obtain the surface shape information of the optical surface, and the trapezoidal integration is carried out on the wave surface;
recovering the 3D surface shape of the glass surface through integration and repeated iteration;
the measuring method is to provide a better initial value according to the function relation between the normal line of the mirror surface sampling point and the optical center coordinate of the pinhole camera, the screen pixel point coordinate of the illuminated mirror surface sampling point and the mirror surface sampling point coordinate, then presume the predicted surface shape, and finally calculate the slope and the surface shape of the mirror surface to be measured according to the function relation iteration, wherein the function relation between the slope and the surface shape is as follows:
wherein x is m And y m Is the coordinates of the surface to be measured, and can be obtained from the geometric measurement of the measuring device; x is x camera And y camera The CCD camera coordinates can be obtained from the geometric measurement of the measuring device; x is x screen And y screen The coordinates of the bright spots on the screen of the liquid crystal LCD display can be calculated by a digital phase shift technology and a phase unwrapping algorithm; z m2screen And z m2camera The z coordinate differences between the mirror and the liquid crystal LCD display screen, the mirror and the CCD camera, respectively; d, d m2screen And d m2camera The distances between the mirror and the liquid crystal LCD display screen, the mirror and the CCD camera, respectively; z m2screen 、z m2camera And d m2camera From the geometric measurement and calibration;
slope w x (x m ，y m )、w y (x m ，y m ) Is the surface profile w (x m ，y m ) Provides an initial profile w during computation 0 (x m ，y m ) Instead of w (x) m ，y m ) Calculating the slope and the surface shape through repeated iteration;
the CCD left camera and the CCD right camera respectively calculate the slope and the surface shape through the method, and then iterate for a plurality of times through the technology of picture fusion until the whole surface shape is output;
the method comprises the steps of firstly collecting height information of 20 points of an intersection area by using a double camera, then fitting an initial surface shape to serve as a reference surface of a measured surface shape, then serving as initial surface shape input of a single camera, and performing slope iterative calculation until three-dimensional surface shape information of a measured piece is output.
2. The measuring device for detecting the surface shape of the 3D curved glass according to claim 1, wherein the measuring device comprises: the LCD screen is obliquely embedded on the inner side surface of the box body.
3. The measuring device for detecting the surface shape of the 3D curved glass according to claim 1, wherein the measuring device comprises: the horizontal guide rod is perpendicular to the vertical guide rod.
4. The measuring device for detecting the surface shape of the 3D curved glass according to claim 1, wherein the measuring device comprises: the CCD left camera with the CCD right camera all includes second triangle connecting block and CCD camera, be provided with the locating hole on the second triangle connecting block, the locating hole with horizontal guide arm phase-match, be provided with the backup pad on the second triangle connecting block, be connected with the limiting plate perpendicularly in the backup pad, the CCD camera clamping is in on the limiting plate.
5. The measuring device for detecting the surface shape of the 3D curved glass according to claim 1, wherein the measuring device comprises: the two-dimensional lifting workbench comprises a workbench and a base, wherein a height adjusting mechanism is arranged on the bottom surface of the workbench, a first support and a second support which are parallel to each other and are arranged in a crossing manner are arranged between the workbench and the base, the first support is located on the inner side of the second support, the two first supports and the two centers of the second supports are connected through connecting shafts, the two first supports are fixedly connected with the two second supports through upper connecting plates, and the two first supports are fixedly connected with the two second supports through lower connecting plates.
6. The measuring device for detecting the surface shape of the 3D curved glass according to claim 5, wherein: the height adjusting mechanism comprises a handle and a fastening nut, wherein the handle is connected with a second positioning plate through the fastening nut, and the second positioning plate is fixedly connected below the working platform.
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