TWI844569B - System and method for measuring a surface in contoured glass sheets - Google Patents

Abstract

An optical inspection system is provided for an ultraviolet laser and associated optics forming a planar laser sheet directed to a glass sheet. The planar laser sheet intersects a surface of the glass sheet thereby causing the surface of the glass sheet to fluoresce and form a visible wavelength line on the surface. A camera has an image sensor for detecting the visible wavelength line. A control system is configured to receive image data indicative of the visible wavelength line, analyze and triangulate the data to determine a series of coordinates associated with the line, and create a three-dimensional map of the surface of the glass sheet as a function of the series of coordinates. Methods for using an optical inspection system, for gauging a surface using an optical inspection system, and for providing optical reflectance information for a surface using an optical inspection system are also provided.

Description

System and method for measuring the surface of a curved glass sheet

Various specific embodiments relate to systems and methods for measuring the surface of a curved glass sheet.

Manufacturers of glass sheets are interested in measuring and evaluating the surface of glass sheets, particularly glass sheets formed into various curved shapes for use as automotive windshields, backlites, and sidelites. The manufacturer may want to determine whether the glass sheet is within predetermined specifications for gauging. The manufacturer may also want to measure and evaluate the amount of reflected optical distortion of the formed sheet as perceived by a human observer, such as an outside observer or an operator or passenger in a vehicle, where the glass may be installed as a windshield, backlites, or sidelites, or the like. For example, gauging specifications and reflection distortion thresholds are becoming increasingly stringent as automotive applications increase the use of technologies such as head-up displays. Manufacturers also want to identify small marks or other defects that are visible on the surface of formed glass sheets.

In one embodiment, an optical inspection system is provided with an ultraviolet laser and associated optical components that form a planer laser sheet directed toward a glass sheet. The planer laser sheet intersects the surface of the glass sheet thereby causing the surface of the glass sheet to fluoresce and form visible light wavelengths on the surface. A camera has an image sensor for detecting visible light wavelengths across at least a portion of a width of the sheet. The control system is configured to (i) receive image data representing the visible light wavelength line from the camera, (ii) analyze the data from the camera to determine first and second coordinates in a coordinate series associated with the line, (iii) triangulate a third coordinate each associated with the first and second coordinates in the coordinate series, and (iv) create a three-dimensional map of the surface of the glass sheet as a function of the coordinate series.

In another specific embodiment, a method of using an optical detection system is provided. A planar laser cut page is formed from an ultraviolet laser and related optical components and directed to a surface of a glass sheet. The surface of the glass sheet is excited at an intersection of the planar laser cut page and the surface to form a visible light wavelength line on the surface of the glass sheet. The visible light wavelength line is imaged using a camera. Determining first and second coordinates associated with the visible light wavelength line in a coordinate series is by analyzing imaging data from the camera. In the coordinate series associated with the visible light wavelength line, a third coordinate associated with each of the first and second coordinates is determined by triangulation. A three-dimensional graph of the surface of the glass sheet as a function of the coordinate series is established.

In another specific embodiment, a method for measuring a surface using an optical detection system is provided. A data set including a set of coordinates corresponding to a position on a surface of a glass sheet is calculated by triangulating a position of a fluorescent line imaged on the surface using a camera, wherein the fluorescent line is established at an intersection of a planar laser cut from an ultraviolet laser and the surface. A three-dimensional graph of the surface is established as a function of a series of data sets. An invariant index is calculated by comparing the data set to a gauge model of the surface. The invariant index is output.

In another embodiment, a method is provided for providing optical reflectance information of a surface using an optical detection system. A data set comprising a set of coordinates corresponding to a position on a surface of a glass sheet is calculated by triangulating a position of a fluorescent line imaged on the surface using a camera, wherein the fluorescent line is established at an intersection of a planar laser cut from an ultraviolet laser and the surface. A three-dimensional map of the surface is established as a function of a series of data sets. Denoising the three-dimensional map of the surface. An invariant index is calculated by comparing the data set from the denoised map to an optical reflectance specification specified for the surface of the glass sheet G. The invariant index is output.

10: Optical detection system, detection system, system

12:Conveyor

14:Optical system, system

16: Control system, computer

18: Position sensor

20: User interface and display screen

50:Laser

52: Laser beam

54:Optical components

55: Beam shaper

56: First lens

57: Additional focusing lens

58: Second lens

60: Plane laser cutting, laser cutting

62: First surface

64: Second surface

66: path, laser beam, line

68: Original radiation, radiation, line

70: Radiant light

72, 72A, 72B: Camera

73A, 73B: Area

80: Computer, control system

82: Image processor unit

100: Model line

200:Methods

202-220: Steps

250: Area

300:Methods

302-310: Steps

350:Methods

352-362: Steps

B: Bounding box

C: Calibration diagram

D: Dataset

D1, D2: distance

G: Glass sheet, glass panel

L: Line

M1, M2: two matrices or point clouds

M1*, M2*: sub-matrices

M3: Final matrix or point cloud

λ ₁ , λ ₂ : wavelength

FIG. 1 schematically illustrates a specific embodiment of a glass sheet detection system according to a specific embodiment; FIG. 2 schematically illustrates an optical system used with the detection system of FIG. 1 according to a specific embodiment; FIG. 3 is a graph illustrating the optical transmittance of a glass sheet used in the systems of FIG. 1 and FIG. 2; FIG. 4 schematically illustrates another optical system used with the detection system of FIG. 1; FIG. 5 schematically illustrates another optical system used with the detection system of FIG. 1; FIG. 6 is a flow chart According to a specific embodiment, a method for measuring the surface of a glass sheet using the system of FIG. 1, FIG. 2, FIG. 4 and FIG. 5 is illustrated; FIG. 7 illustrates a portion of a visible spectrum image of the surface of a glass sheet obtained using the system of FIG. 2; FIGS. 8A and 8B schematically illustrate the optical detection system of FIG. 1 to FIG. 2 for use in triangulating a third coordinate; FIG. 9 schematically illustrates a data adjustment step sequence (data alignment) of a multi-camera system used with the method of FIG. 7 according to a specific embodiment. alignment step sequence); FIG. 10 is a flowchart illustrating a method for measuring a surface using a surface map determined from the method of FIG. 6; FIG. 11A and FIG. 11B are representative system outputs displayed to a user when determining using the method of FIG. 10; FIG. 12 is a flowchart illustrating a method for modeling and determining the optical reflectivity and distortion of a surface using a surface map determined from the method of FIG. 6; and FIG. 13 is a representative system output displayed to a user when determining using the method of FIG. 12.

As requested, several detailed specific embodiments of the present disclosure are provided herein; however, it should be understood that the specific embodiments disclosed are only embodiments and may be embodied in different and alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to illustrate the details of a particular component. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but rather merely as a representative basis for teaching those skilled in the art to use the present disclosure in various ways.

It is evident that any circuit or other electronic device disclosed herein may include any number of microprocessors, integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read-only memory (ROM), electronically programmable read-only memory (EPROM), electronically erasable programmable read-only memory (EEPROM), or other suitable variants thereof) and software that work together to perform the operation(s) disclosed herein. In addition, any one or more of the electronic devices disclosed herein may be configured to execute a computer program embodied in a non-transitory computer-readable medium and programmed to execute any number of functions disclosed herein.

FIG. 1 illustrates an online glass sheet optical inspection system 10. The inspection system 10 includes a conveyor 12 for conveying a glass sheet G in a first direction substantially parallel to a first dimension of the glass sheet. In the illustrated embodiment, the curved glass sheet G is a substantially rectangular vehicle windshield or rear shield having a first dimension that is a relatively smaller dimension (and may alternatively be referred to as a height) and a second relatively larger dimension (alternatively referred to as a width). The glass sheet G has a thickness in a third dimension that is less than the width and the height. The glass sheet G is bent relative to one or more axes of curvature that are substantially parallel to the first direction. In other embodiments, the glass sheet G may have other axes of curvature, or be provided as a flat or substantially flat sheet.

The conveyor 12 may be a single conveyor that is solely dedicated to transporting the glass sheet G through the inspection system 10, which may be configured and/or operated as a stand-alone optical inspection system. In other embodiments, the conveyor 12 may be one of a series of conveyors that transport the glass sheet through various process workstations, such as heating, shaping, and annealing or tempering workstations found in typical automotive, architectural, and/or solar glass sheet manufacturing systems. In order to process the glass in the manner described, the conveyor of the glass sheet G may be provided by various technologies such as rollers, air cushions, or belt conveyors, positioners, and robotic arms. It should also be understood that each of the plurality of conveyors may be independently controlled to move the glass sheet at high speed through different processing workstations to effectively control the flow and processing of the glass sheet in the system 10.

Alternatively, the detection system 10 may be provided as a separate independent system or device without a conveyor. The detection system 10 may also be provided with a fixture for the glass panel G, wherein the detection system 10 is configured to be translatable relative to the panel G, such as an optical system 14 mounted on a conveyor system. The detection system 10 may be provided with a glass panel G and an optical system 14 fixed to each other, wherein the optical system has a plurality of optical elements configured to scan the surface of the glass panel G.

The inspection system 10 has an optical system 14 for identifying and measuring the surface of the glass sheet, and can be further used to gauge the sheet, identify and measure small defects in the sheet, and/or measure reflected optical distortion. Refer to Figure 2 for a detailed description of the optical system 14.

In general, the optical system 14 includes a laser or other light source having a wavelength selected at least in part based on the optical properties of the glass sheet G. Light from the light source is directed by the optical system 14 to the glass sheet G. In one embodiment, the light source is selected to have a wavelength λ ₁ in a harmonic narrow band that is opaque or substantially non-transmissive to the glass sheet G. The light source is also selected so that the wavelength λ ₁ of the light source can induce or cause the surface of the glass sheet G to emit light at a wavelength λ ₂ that is different from the wavelength λ 2 of the light source. For example, the light source is also selected so that the wavelength λ ₁ of the light source can induce or cause the surface of the glass sheet G to fluoresce or emit light at a wavelength λ ₂ that is longer than the wavelength λ ₁ of the light source.

The optical system 14 has at least one camera or other detector for detecting light emitted from the glass sheet G. The optical system 14 also includes various optical elements to control and guide the light from the light source to the glass sheet G and from the glass sheet G to the detector.

The optical system 14 has at least one computer and/or control unit, which includes at least one processor, which is programmed to execute logic to control the optical system including the light source and the detector, obtain data from the detector of each glass sheet, analyze the data of the glass sheet, and provide information related to the surface shape, reflected optical distortion, or other surface information or defects of the glass sheet. The computer can be integrated with the control system 16 of the detection system 10, as shown, or can be provided as a separate device that communicates with the control system 16.

The optical system 14 thus provides a non-contact inspection system for quickly acquiring detailed data corresponding to the surface of the glass sheet G and analyzing the acquired surface data to evaluate and report the surface shape of the glass sheet G and properties related to the optical characteristics of the glass sheet G, particularly, the glass sheet G transported on the conveyor 12 between or after bending, cooling or other processing operations.

The detection system 10 includes a programmable control unit or control system 16, which is specifically described as a computer in this embodiment. The computer 16 can communicate with or be integrated with the computer of the optical system 14. The computer 16 includes at least one processor that is programmed to detect the glass sheet as it advances on the conveyor and control the motor(s) to control the movement and speed of the conveyor 12.

The conveyor 12 moves the glass sheet G along a path or in a direction, shown here as the y direction, through the optical system 14. The conveyor 12 is moved using one or more motors and support rollers or other devices.

The inspection system 10 has one or more position sensors 18 to determine the position and timing of the conveyor 12 to analyze the glass sheet G using the optical system 14 as the glass sheet G moves through the system 10. The position sensor(s) 18 may be provided by a digital encoder, an optical encoder, or the like. The speed of the conveyor 12 and the speed of the glass sheet G may be selected to allow sufficient residence time for light from the light source of the optical system 14 on an area of the surface of the glass sheet G to cause the surface to fluoresce, while maintaining straight-line travel of the glass sheet G. In one embodiment, the conveyor 12 moves continuously at a speed of 0.1 to 0.2 m/s, or moves at a rate coordinated with the optical system 14 to obtain data based on a specified movement of the glass panel G, such as a movement in the range of 1 to 4 mm. In a further embodiment, the movement of the conveyor 12 enables the glass panel G to be detected within a time frame of about 10 to 15 seconds. In another embodiment, the conveyor is continuously moved at a speed of 0.01 m/s or more to obtain data based on a movement of the glass panel G of about 5 mm or less. The acquisition of data from the glass sheet can be based on the changing movement of the glass panel G corresponding to the grid size, and can be less than 5 mm, less than 2 mm, about 1 mm, or another value. In another embodiment, the speed of the conveyor can be increased to obtain data based on a movement of the glass panel G of more than about 5 mm, for example, with a grid size of more than 5 mm, or more than 10 mm. When the speed of the conveyor is reduced, the time to scan the panel G increases, and can be about a few seconds, tens of seconds, or a few minutes, for example, two minutes. For glass panels G with complex surface contours, the time to scan the panel may also increase, as the use of smaller grid sizes may require increased resolution. The position sensor 18 can be used as an input to the optical system 14 to determine the timing of data acquisition, such as as a trigger for a camera.

The detection system 10 may be provided with additional sensors, such as photoelectric sensors or the like, which communicate with the control system 16 to determine that the glass sheet G is in the proper position on the conveyor 12, or has advanced to the optical system 14. The computer 16 then communicates with the optical system 14 to activate the system 14 and begin measuring the surface of the glass sheet G. In other embodiments, the optical system 14 may continue to operate and begin to acquire and process data related to the glass sheet G in response to the system 14 detector recording an appropriate signal indicating that the light source has begun to interact with the glass sheet G.

Please refer to Figures 2 to 4 for a detailed description of the optical system 14 according to various specific embodiments. In the disclosed specific embodiment, the light source is provided by a laser 50, which can be a diode laser. The laser 50 can be packaged as a diode laser with an appropriate base and lens to provide a collimated beam, and a heat sink can also be provided. In other specific embodiments, the laser 50 can be provided by another laser or a combination of lasers, which are configured to provide laser light of a desired wavelength at a desired laser intensity and other beam parameters. In a further specific embodiment, the light source can be provided as an ultraviolet light source, which has associated filters and optical elements to provide a light sheet directed to the glass sheet G. In a further specific embodiment, the system 14 can be provided with more than one laser 50.

Based on the intended use of the glass sheet G formed of sodium calcium silicate glass, the laser 50 is selected to have a wavelength in the ultraviolet range and a laser output transmittance of, for example, less than 5% or 2% at a specific wavelength that is opaque or non-transmissive to the glass sheet G or substantially non-transmissive to the glass sheet G. In the disclosed embodiment, the laser 50 is provided by a pulsed diode solid-state laser that is tuned to output light having a central wavelength λ _1. The central wavelength may be selected to correspond to the opacity or non-transmissivity of the glass sheet G and may be a non-visible wavelength and is also selected to induce fluorescence or luminescence on the surface of the glass sheet G. The central wavelength may be less than 350 nanometers and, in one embodiment, 266 nanometers in the ultraviolet range are provided.

In one embodiment, the laser has a power output of 150 microjoules at 15 kHz. In further embodiments, lasers 50 with other power outputs and repetition rates may be provided, and lasers with 500-100 microjoules and 1 kHz or more at a center wavelength of 266 nanometers are contemplated. Systems 10, 14 may be configured to measure glass sheets G within a specified time period, for example, approximately 10 seconds per sheet, although other times may be contemplated based on sheet size and desired resolution of the model. Of course, other wavelengths may be selected based on the composition of glass sheets G.

FIG3 illustrates a curve of the transmittance of sodium calcium silicate glass relative to the wavelength of the incident light. As can be seen from the figure, the transmittance of the glass sheet G decreases sharply as the wavelength of the incident light decreases and is close to an opaque material. The wavelength of the laser 50 is also plotted on the graph, and it is shown that the glass sheet G is opaque at this wavelength. For the glass sheet G having another material composition, the laser 50 tuned to another wavelength can be selected for use in the optical detection system 10 so that the selected wavelength does not transmit through the glass sheet G and induces luminescence or fluorescence in the glass sheet G.

Referring again to FIG. 2 , a plurality of optical elements 54 are provided downstream of the laser 50 to interact with the laser beam, shape and direct the laser beam toward the glass sheet G. The optical elements 54 may include one or more beam shapers, lenses, reflectors and the like. In the disclosed embodiment, a beam shaper 55 is provided to improve the uniformity of the laser intensity by converting the collimated Gaussian beam profile of the laser beam into a collimated flat-top profile beam with a more uniform intensity distribution and without internal laser focusing, thereby resulting in an increase in the uniformity of the laser line intensity on the surface of the glass sheet G. A first lens 56 is provided to form a planar laser sheet from the laser beam 52. In the disclosed embodiment, the first lens 56 is a cylindrical plano-concave lens, and its focal length is selected based on the positioning of the laser 50 relative to the conveyor and the glass sheet, or the distance D1 from the laser 50 to the glass sheet G. In order to further focus the planar laser cut page, a second lens 58 may also be provided. In the disclosed embodiment, the second lens 58 may be a cylindrical plano-concave lens to further focus the planar laser cut page. An additional focusing lens 57 may be provided to narrow and focus the laser cut page. Although the second lens 58 is shown after or downstream of the first lens 56, in other embodiments, the positioning of the lenses 56, 57, 58 may be changed or reversed so that the second lens 58 is before the first lens 56. Based on the opacity of the material forming the glass sheet G, lenses 56, 57, 58 are used to form a focused plane laser cutting page 60 directed to the first surface 62 of the glass sheet G at a harmonic center wavelength λ ₁ of 266 nanometers. In the illustrated embodiment, the optical elements 56, 57, 58 are each provided by an f=-8 mm plano-concave cylindrical lens, an f=1000 mm plano-convex cylindrical focusing lens, and an f=-25 mm plano-concave cylindrical lens. The optical element 54 cooperates to form a planar laser cutting page with a beam width of 1 to 2 mm on the surface of the glass sheet G. In another embodiment, the optical elements can have different focal lengths, and the focal length and lens selection can be based in part on the size of the panel G. In other embodiments, additional optical elements such as filters, choppers, and the like may be installed between the laser 50 and the glass sheet G.

Alternatively or in addition, other optical elements such as Powell lenses may be used to provide a more uniform distribution of laser intensity on the planar laser sheet. Furthermore, although one laser 50 is illustrated in FIGS. 2-4 , in other embodiments, the system 14 may be provided with more than one laser 50. For example, the system 14 may have two lasers 50 directed to different regions of the glass sheet G, or the beams may be aligned to form a common sheet on the glass sheet G. The intensity of the laser sheet may vary, for example, with the distribution of the laser sheet from one laser, and multiple lasers may be used to provide a more uniform intensity on the surface of the glass sheet G, or to provide fluorescent light for multiple cameras, respectively.

The glass sheet G has first and second surfaces 62, 64 forming the first and second sides of the glass sheet G. The first and second surfaces 62, 64 are separated from each other by the thickness of the glass sheet G. Since the wavelength _λ1 of the laser cutting page 60 is opaque or substantially non-transmissive to the glass sheet G, the laser cutting page 60 interacts with the first surface 62 without traveling through the glass sheet G or to the second surface 64, and thus excites the glass sheet G only at the first surface 62. The thickness of the glass sheet G, i.e., the distance between the first and second surfaces 62, 64, can vary, and in some embodiments, is greater than 1.2 mm or greater than 1.6 mm, and in a non-limiting embodiment, falls within the range of 1.6 to 25 mm.

The planar laser cutting page 60 can be oriented so that it extends transversely or in the x-direction to the belt. The laser cutting page 60 interacts with the first surface 62 of the glass sheet G along a path 66 (or the intersection of the laser cutting page 60 and the first surface 62 of the glass sheet G). For a planar glass sheet G, the path 66 is a straight line. For a curved glass sheet G, the path 66 can change with the curvature of the glass sheet G along the surface 62 as the laser cutting page 60 interacts with the curved surface.

Laser cutting 60 excites the material of glass sheet G at first surface 62 and causes luminescence at first surface 62. Glass sheet G fluoresces along excited laser line 66 to emit wavelength λ ₂ longer than λ _1. In this embodiment, radiated light 70 from glass sheet G has a wavelength λ ₂ in the visible range or in the near ultraviolet range and appears as line 68 along surface 62 and excited line 66.

The radiation 70 is detected by a detector such as a camera 72. The camera may be provided with a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. In the present embodiment and as shown in FIG2 , the detector 72 is provided with a CMOS sensor and is positioned so as to image the full width of the glass sheet G, or the glass sheet in the x-direction. In the illustrated embodiment, the camera is provided by a CMOS sensor camera having 5496x3672 pixels, in one embodiment it is arranged at a region of interest having 5496x1836 or 5496x1000 pixels, or in another embodiment, a CMOS sensor having 5120x5120 pixels. The control of various camera settings may be based on laser parameters, conveyor speed, and other system factors, and these camera settings include lens focal length, aperture, gain, and exposure time. In one embodiment, the camera uses a fixed lens, such as a 16 mm or 25 mm lens, and is set to an aperture of f2.4 or higher for increased depth of field, and uses an exposure time of 15-20 milliseconds and a gain of 2-15 dB. In another embodiment, the camera settings may use another exposure time, such as between 10 milliseconds and 300 milliseconds or more, and the gain may also be set to another value between 2 and 30 dB. In other embodiments, the camera 72 may be positioned to photograph only selected areas of the glass sheet G. In a further embodiment, the detector may be configured as another light detector or light sensing element. In a further embodiment, an additional optical element such as a filter may be provided between the glass sheet G and the detector 72 to further improve the signal-to-noise ratio.

In other embodiments and as shown in FIGS. 4-5 , more than one camera 72 may be used with the optical system 14. FIGS. 4-5 are schematic diagrams and do not illustrate various components of the system 14, such as optical elements, controllers, etc. In FIG. 4 , a pair of cameras 72A, 72B are located on one side of the laser cut page 60. Each camera 72A, 72B photographs an area 73A, 73B of the glass sheet G, and the areas overlap each other by, for example, about 10 centimeters. By using more than one camera in the system of FIG. 3 , the final surface image of the surface of the glass sheet G can reduce errors introduced by optical distortion due to the longer focal length of each camera. In addition, the optical system 14 using two or more cameras can also provide higher resolution imaging for the glass surface, such as increasing the pixels per unit surface area of the glass sheet G, and improving accuracy and sensitivity when the camera is physically closer to the glass sheet G.

In FIG. 5 , a pair of cameras 72A, 72B are provided, with the laser cutter 60 positioned between the cameras 72A, 72B. Each camera 72A, 72B photographs an area 73A, 73B of the glass sheet G, and the areas overlap each other by, for example, about 10 centimeters. By using more than one camera in the system of FIG. 3 , the final surface image of the surface of the glass sheet G can reduce errors introduced by optical distortion. In addition, the cameras 72A, 72B are positioned to photograph a glass sheet G with a high degree of curvature, for example, when one camera 72A has an obstructed view to the left of the surface of the glass sheet G in FIG. 4 or has a small angle of incidence or a grazing angle. In another embodiment, the system 14 may have more than two cameras. For example, it is conceivable that four cameras 72 may be installed, two on each side of the laser cutting page 60, and the areas of all four cameras overlap each other. In other embodiments, there may be more than four cameras 72.

Referring again to FIG. 2 , the laser 50 and the camera 72 communicate with at least one computer 80 in the control unit. The computer 80 may be connected to or integrated with the control system 16 or the detection system 10 . The computer 80 has an image processor unit 82 and is also connected to a memory. The computer 80 may receive information from the control system 16 and the position sensor to determine when to send a trigger signal to the camera(s) 72 of FIG. 2 and FIG. 4 to FIG. 5 . For example, based on a 1-4 mm corresponding movement of the glass sheet G, the camera(s) may acquire data at a frame rate of up to 80 fps, or up to 160 fps.

Computer 80 receives image data from camera 72. Computer 80 uses the data from the image to form a matrix or point cloud, such as associating cells in the matrix with locations on glass sheet surface 62, or associating arrays of points in the point cloud with locations on glass sheet surface 62. The image data may be provided as a series of grayscale values, where each value is between 0 and 255, if based on an 8-bit grayscale. In other embodiments, the image data may be provided as a series of RGB signals each corresponding to a red, green, and blue block or color component as detected by a camera sensor, may be provided based on different color spaces and color models, or may be provided as another cell value. Further details of data acquisition and pre-cloud and post-cloud data processing are provided below with reference to FIGS. 6 to 13.

The flowchart of FIG6 is a method 200 for determining a three-dimensional image of the surface of a glass sheet G using an optical detection system according to a specific embodiment. In various specific embodiments, the method 200 can be used with the systems 10 and 14 of FIGS. 1 to 2 and 4 to 5, respectively, and according to various specific embodiments, several steps can be rearranged or omitted, or additional steps can be added.

In step 202, a first wavelength, such as an ultraviolet wavelength, is selected based on the transmittance of the glass sheet, wherein the first wavelength is selected to be substantially non-transmissive through the glass sheet. In step 204, a planar optical section is formed with the first wavelength, for example, using an ultraviolet laser.

In step 206, calibrate the optical system 14. Calibrate the camera(s) and the laser(s) individually. Provide a checkerboard chart or other known planar calibration surface instead of the glass sheet G and approximately at the middle z-distance of the glass sheet G, or in the middle of defining a bounding box for the camera(s). The bounding box for the cameras is defined as a three-dimensional space that allows for sufficient vertical depth or depth of field to include the upper and lower boundaries of the glass sheet G while ignoring any underlying fixture support surfaces. In one embodiment, the bounding box has a depth of approximately 10-15 cm, although other dimensions are contemplated based on the details of the component.

The position of the calibration map is thus known and provides the basis for the global coordinate system of the bounding box. Calibration of the camera is based on the stationary calibration map and selection of camera settings including focus, exposure, aperture, gain and the like.

The laser is also calibrated. For lasers oriented with the laser page extending along the z axis or in the x-z plane, the camera(s) detect the position of the laser page relative to the calibration map and relate this position to the global coordinate system. For lasers not in the x-z plane, additional calibration steps are required to provide the laser page position to the global coordinate system. Laser settings including intensity and frequency are selected. Later reference is made to the determination of the z coordinate of the surface in step 214, using camera and laser calibration relative to the calibration map and the global coordinate system.

In step 208, for example, a related optical element is used to guide the plane light cutting page to the glass sheet, and the surface of the glass sheet is excited so that it radiates light at a second wavelength, such as a visible light wavelength, along a path at the intersection of the plane light cutting page and the surface of the glass sheet facing the light source.

In step 210, a series of data representing a series of visible wavelength lines is measured or detected using one or more cameras, where each camera photographs a region of interest of the glass sheet G. For an optical system 14 with a single camera system, the camera 72 can detect each line detected in the region of interest across the panel or on the panel. For an optical system 14 with a multi-camera system, each camera 72 can be pointed at overlapping individual regions of interest of the glass sheet G and detect each line within the region of interest.

In step 212, each visible light wavelength line is processed and analyzed to determine a first and second coordinate in a coordinate series associated with each line, such as (x, y) coordinates, and the coordinates are stored in a matrix or point cloud associated with the camera.

Computer 80 processes the image using image processor unit 82. FIG. 7 provides a representative example image and associated schematic overlays based on the image processing described below.

The computer 80 and the image processor 82 may process the image to reduce noise, for example, by applying a threshold to the image, normalizing the image, transforming the image using a fast Fourier transform, and the like. In one embodiment, the image is filtered using a median filter for removing noise, including speckle noise. The need for a noise removal step may increase as the camera gain setting increases.

The computer 80 and image processor 82 select a line width region in the image based on the indicated line width size input and the minimum intensity. By selecting the line width region, the reduced area of the image is used in the processing and determining coordinates in subsequent steps. For example, the indicated line width can be selected as a nominal value with a tolerance factor. In one embodiment, a nominal line width between 3-10 pixels is selected, and a tolerance between 1-5 pixels is selected. In another embodiment, a nominal line width between 4-6 pixels is selected, and a tolerance between 2-3 pixels is selected. In yet another embodiment, an indicated line width with a minimum width of one pixel is selected. Intensity is also selected as an input and can be based in part on the expected intensity of the fluorescence at the relevant frame rate, and excludes pixels that contain background noise that is not necessarily included. In various embodiments, the minimum intensity is selected on a grayscale of 5/255, 10/255, 20/255, 30/255, or another value. Region 250 in Figure 7 is an embodiment of a selected line width region.

When the glass sheet G is transparent to visible light emitted at the second wavelength _λ2 and the light emitted from the surface 62 can pass through and/or reflect from the other surface 64, experiments have shown that any reflection from the rear surface 64 has a very low signal and can be discarded as noise. For example, the reflection of the radiation line 68 on the rear surface 64 has a gray level of about 5/255 in the acquired image, while the gray level of the primary emission line 68 is about 20 to 100/255, so that the reflection signal can be regarded as noise. In addition, based on the position of the reflected line in the image and the spacing from the primary visible line, the reflected line can be excluded or outside the range of the selected line width area 250 so that it is no longer considered in data processing. In the event that a reflection line is sufficiently close to radiation line 68 that it cannot be desirably excluded using linewidth region 250, the reflection line may be included in the data processing; however, the data processing is not significantly affected due to the low signal of the reflection line. Alternatively and in the presence of a second reflection line, the data processing may select the fluorescing line to take into account camera geometry, the position of the lines based on the panel, the higher brightness of the fluorescence line than the reflection line, and other factors. The data processing may further receive input regarding the material of panel G. For example, an image of tin-side float glass may be expected to have a reflection line, while an image of air-side float glass may not have a reflection line.

Computer 80 and image processor 82 determine or calculate points on the model line based on the image data and the gray level of the pixels in the visible light fluorescence. From the example image, it can be seen that the surface 62 radiates light extending across multiple pixels in the y direction in the area 250. Similarly, computer 80 calculates the points for the model line as a series of coordinates or (x, y) data sets based on the gray level of the pixels. For example, the points calculated for the model line 100 are overlaid on Figure 4.

In one embodiment, the computer and image processor may average groups of adjacent pixels to find each point and (x, y) data set as the estimated center of the model line, and may provide a (x, y) data set for each pixel in the image in the x direction. In other embodiments, the computer and image processor may perform a weighted average of the pixels to find each point and (x, y) data set as the estimated center of the line. The computer and image processor may calculate the points and (x, y) data sets using a distribution function of the pixel values, such as a Gaussian distribution, mean or median width, or other mathematical function. The computer and image processor may alternatively use known commercially available image library processing tools or software to use the pixel data to determine the values for the data sets.

The computer 80 then inputs the series of (x, y) data sets in the relevant cells of the matrix, or in the point cloud. The data sets may include a series of coordinates from the model line as determined from the image. Each data set may include (x, y) values for the position of the surface 62 of the glass sheet G in the x-y plane, which collectively define the model line 100 and are linked to the global coordinate system.

The matrix can also be populated to a linescan image, where each row in the matrix is populated with coordinates from the model lines from each glass sheet G image, and subsequent images populate subsequent rows. Similarly, a point cloud can be constructed from sequential images of glass sheet G. In one embodiment, the matrix can have a cell and a set of coordinates associated with each pixel from the image in the x direction. In other embodiments, the matrix can have a cell and a set of coordinates associated with multiple adjacent pixels, causing the computer to perform an averaging step or the like before entering the data. In some embodiments, the matrix or point cloud can be thinned, for example, by removing multiples of n in the collected data set.

In step 214, a third coordinate, such as a (z) coordinate, is triangulated using the position of the laser, the position of the camera, and the first and second coordinates and stored in a matrix or point cloud. The computer 80 then calculates a z value for each (x, y) coordinate set that is associated with the z-position of that coordinate set on the surface 62 of the glass sheet G. The z value calculation uses the (x, y) values from each cell of the coordinate set and the positioning of the laser and camera from the detection system 10 in a triangulation calculation as described below in connection with FIGS. 8A-8B. The computer enters the (z) value for the associated cell in the matrix with the corresponding (x, y) coordinate to complete a map of the surface 62. When processing the image in step 212, the computer and imaging program can calculate the (z) value of each coordinate set, or after the entire glass sheet has been imaged, the (z) value of all data sets in the matrix or point cloud can be calculated.

The views of FIG. 8A-8B illustrate the triangulation of the third (z) coordinate associated with the first and second (x, y) coordinates in the data set D in the coordinate series of each line calculated from the image shown in FIG. 4. The laser 50 and camera 72 can be fixed to each other, and the laser beam and the resulting planar laser cut page are also fixed, so that the glass sheet G translates or moves in the direction y relative to the optical system 14 and through the planar laser cut page. Because the positions of the laser cut page and camera are calibrated and linked to the global coordinate system, the z coordinate can be calculated.

The side schematic diagram of FIG8A illustrates the optical system 14 with calibration map C overlying the glass sheet G, and also illustrates the bounding box B. The reference of the laser cut page 60 is relative to the calibration map C and the global coordinate system. Similarly, each pixel in the camera is referenced to the calibration map C and the global coordinate system, so that each pixel has an associated vector in (x, y, z) space. The (x, y) coordinates for data set D can be determined using step 212 described above and tied to the global coordinate system based on the schematic diagram shown in FIG8B. Then, referring to the schematic diagram of FIG8A and using triangulation techniques, using the intersection of the laser cut page 60 and the associated pixel vector, comparing the pixel and vector to the intersection of the calibration map C, the z coordinate for data set D in the global coordinate system can be calculated. Thus, the z value of each (x, y) coordinate in the coordinate series along the line can be calculated, and the control system 80 then inputs this z coordinate into a matrix cell or point cloud, where the (x, y) value of each point in the line already exists.

In step 216, a three-dimensional map of the surface of the glass sheet as a function of the coordinate series is then created from the matrix or point cloud for each of the series of visible light wavelengths of the glass sheet G in the camera.

The steps indicated by region 218 are performed for each camera with data from each camera. For a single camera system, step 216 produces a final matrix or point cloud of the surface of glass panel G.

For a multi-camera system, an additional step 220 is provided to combine matrices or point clouds from different cameras into a single matrix or point cloud representing the glass sheet G. FIG. 9 schematically illustrates a subroutine used in step 220 to align multiple matrices or point clouds, for example, using the dual camera system illustrated in FIG. 4 . For a dual camera system as shown in FIG. 5 or a system with many cameras, the subroutine used to align multiple matrices or point clouds is similar and will be understood by those of ordinary skill in the art based on the method 200 as described herein and the embodiment of FIG. 9 .

FIG9 schematically illustrates step 220 of method 200. Computer 80 is loaded with two matrices or point clouds M1, M2 obtained from scanning glass G by two cameras 72A, 72B, respectively. In other embodiments, more than two matrices or point clouds may be combined using techniques similar to those described herein. As can be seen from FIG9A, when the fields of view of cameras 72A, 72B overlap, matrices M1, M2 overlap. In addition, while the system has been calibrated using at least one point in the calibration map located in each camera region 73A, 73B, and preferably such regions overlap to a certain extent, when matrices M1, M2 overlap, there may be a small degree of deviation between points in the overlapping segments. To form the final matrix representing the surface of the glass sheet G, the computer processes the matrices M1, M2 to resolve the deviations. In one embodiment, the deviations resolved can be as small as about one thousandth of an inch. In addition, the deviations can be different in the overlapping areas.

In FIG. 9B , the computer moves one or both of the matrices or point clouds M1, M2. In one embodiment, the computer 80 uses a rigid transformation to move one of the matrices so that it is translated and/or rotated relative to the other matrix so that the two overlapping regions are aligned with each other as shown and errors or misalignments are reduced.

In FIG. 9C , the computer 80 then creates a final matrix or point cloud M3 for the glass sheet G. In one embodiment, the computer removes points of overlap from one or the other matrix. In another embodiment, and as shown, the computer uses a line L associated with the common calibration points of the matrices and fills the final matrix on one side of the line L with points from one matrix as a sub-matrix M1*, and fills the final matrix on the other side of the line L with points from the other matrix as a sub-matrix M2*.

When the laser light does not pass through the glass sheet G, only the surface 62 facing the detection system emits light. Similarly, the matrix with the coordinate series provides a three-dimensional high-resolution mathematical model of the surface 62 of the glass sheet G through the (x, y, z) coordinate series. In one embodiment, the matrix provides a mathematical model with more than one million coordinate sets for the glass sheet G. For example, the model may have a point density of 1,000,000 coordinate sets per square meter of the sheet surface 62, or about one coordinate set per square millimeter of the sheet surface 62.

In the embodiment mentioned in describing FIGS. 1-2 , the glass sheet G moves on a conveyor relative to the optical system 14. In this scenario, the laser 50 and the camera 72 are fixed relative to each other, and the glass sheet G passes underneath. In another embodiment, the glass sheet G can be fixed, and the laser beam emitted from the laser 50 can be scanned across the first surface 62 of the glass sheet G using a one-axis or two-axis mirror galvanometer or the like. In this scenario, in order to determine the angle associated with the distance D1, D2 associated with the position along the line 66, 68 along which the glass sheet moves, the computer 80 also receives an input representing the beam steering angle provided by the galvanometer.

In a further embodiment, the optical detection system 10 can be used to detect the second surface 64 of the glass sheet G and establish a corresponding three-dimensional matrix or point cloud representing the surface 64 of the glass sheet G.

The matrix or point cloud of the glass sheet G provides a high-resolution three-dimensional image of the surface of the glass sheet G. The coordinates in the matrix can be used to compare the mathematical model of the glass sheet G to determine whether the shape of the glass sheet is within the specification of the shape, such as the curvature. In addition, the coordinates in the matrix can be used to compare the mathematical model of the glass sheet G to determine whether the surface of the glass sheet G is within the specification or standard of the optical reflectivity of the surface.

The matrix and the resulting model can be used with the system 10 to provide specifications for the glass sheet G as a pass/fail detection system to correct for process drift or prevent the system 10 from deviating from specifications to establish an optical reflectivity model for the glass sheet G.

Computer(s) 16, 80 may be programmed to present information associated with the three-dimensional map from the matrix in graphical (e.g., color-coded image) and/or statistical form. In various embodiments, statistics for the glass sheet or predefined regions of the glass sheet may be derived and reported, including z-distance, standard deviation, and other surface shaping or optical reflectivity indicators.

The optical system 14 may also include a glass piece component identifier, which may be provided by the camera 72 or another element, to identify the glass piece as one of a set of known component shapes stored in the memory of the computer 80, wherein each known component has an associated shape standard, and an optical reflectivity standard for comparison to the map in the matrix. The systems 10, 14 may be programmed by the user to graphically and/or numerically display various optical or shape markers of the glass piece G detected by the optical system 14, for example, via a user interface and display screen 20, including markers that are most relevant to industry standards, or other markers that are considered relevant in the industry to analyze the optical reflectivity quality of the formed and manufactured glass piece. The system 10 may also be programmed to display the location of small defects identified by the optical system 14.

Selected data output by the disclosed in-line optical inspection systems 10, 14 may also be provided as input to control logic for an associated glass sheet heating, bending and tempering system (or automotive windshield manufacturing system) to allow the controller(s) of one or more workstations of the glass sheet system to modify operating parameters based on optical data developed from previously processed glass sheets.

The flowchart of FIG. 10 illustrates a method 300 for measuring a component such as a glass sheet G using a matrix or point cloud of the surface of the glass sheet as determined by computer 80 using optical system 14. In various specific embodiments, steps of method 300 may be omitted or rearranged, or additional steps may be provided.

In step 302, a matrix or point cloud of the surface of the glass sheet G determined using the optical system and method 200 as described above is input into the processor unit by the computer 80. The matrix may represent the entire first surface of the glass sheet G, or may include only a data set of a selected surface area of the glass sheet G.

In step 304, the computer 80 determines the appropriate specification model for the glass piece G. The specification model may be provided using a computer-aided design (CAD) model and/or data, or other mathematical model or representation of size or shape. The computer may determine the correct specification model to use from one of several models of glass pieces G of various shapes and/or sizes stored in memory. The computer 80 then causes the selected specification model to be input into a processor.

In step 306, the computer 80 determines the glass sheet invariant index data compared to the standard model. In one embodiment, the computer may determine the z-distance of the data set or the surface of the glass sheet G compared to the standard model. The computer may calculate the normal vector distance from each data set or the surface of the glass sheet G to the standard model. Alternatively, the computer may calculate the vertical distance or z-distance from each data set or the surface of the glass sheet G to the standard model.

The computer may be configured to measure the entire glass sheet G with reference to the matrix or point cloud. In other embodiments, the computer may measure only selected area(s) or portion(s) of the glass sheet G or have additional measurement points in specified areas, such as peripheral areas, or areas intended for optical use such as heads-up displays or cameras or other sensors. In one embodiment, the computer uses a selected area of the glass sheet G to simulate a contact measurement method.

In further embodiments, and as shown in the optional block 308 illustrated in dashed lines, the computer may perform a calculation or subroutine on a neighborhood of a plurality of points to provide a post-processed surface data point or data set for determining an invariant indicator. In one embodiment, the computer performs interpolation, averaging, or another mathematical function, such as thresholding or the like, on the neighboring points or data sets to calculate a post-processed data set of the neighborhood. This may provide improved specifications and invariant indicators by excluding outlier datasets caused by surface dust, etc.

In other embodiments, the computer may determine the standard deviation of the z-distance, or another invariant metric of the surface and the glass sheet G, such as calculating the radius of curvature, or other shape measurement metrics. These invariant metrics may be input into the measurement matrix or point cloud of the glass sheet G.

In step 310, the computer 80 outputs information related to the gauge of the surface, including any invariant indices, such as a gauge matrix. The computer may further analyze the information in the gauge matrix to determine whether one or more indices exceed a critical value. The computer may additionally provide information related to the gauge to a user, for example, via a color-coded map of the glass sheet or via numerical values or other representations, such as a table. The computer may additionally provide information from the gauge to a process step of the glass sheet G as part of a control feedback loop.

Figures 11A and 11B illustrate representative embodiments of outputs from method 300 displayed to a user. Figure 11A illustrates a simplified point map of glass sheet G or a region of glass sheet G and provides a representative embodiment of system output. Gauge points have been associated with listed invariant indicators, such as differential values based on normal, perpendicular or other distances from gauge values. If the differential value exceeds a specified critical value or is outside of an allowable tolerance, a flag may be added to facilitate user understanding. In the illustrated embodiment, the values correspond to the normal perpendicular distance from the gauge model and are in millimeters, however other units are contemplated. In addition, underlined values fall outside of a critical value or margin and are flagged to the user.

FIG. 11B illustrates a map of a glass sheet G or a region of a glass sheet G, where different shading corresponds to different differential value ranges based on the normal, perpendicular or other distance from the gauge value, and provides another representative embodiment of the system output. If the differential value exceeds the specified critical value or is outside the allowable tolerance, a flag can be added to make it easy for the user to understand. Based on the intended use and requirements of the sheet, the tolerance or critical value of different panel areas can be set to different values. For the illustrated embodiment, the differentials are in millimeters, but other units are also conceivable.

Method 300 provides non-contact measurement for surfaces and glass sheets G, which allows for on-line monitoring and inspection of components, and allows for quick and convenient measurement of a range of different components, or the use of multiple measurement models. In addition, non-contact measurement via method 300 provides for reducing the time and costs associated with measuring components, because measurement models can be easily created, changed or updated using CAD data, and precise measurement measurement tools that require contact measurement for component-specific measurement are not required.

The flowchart of FIG. 12 illustrates a method 350 for determining and modeling the optical reflectivity of a component such as a glass sheet G using a matrix or point cloud of the surface of the glass sheet as determined by a computer 80 using an optical system 14. In various embodiments, the steps in method 300 may be omitted or rearranged, or additional steps may be provided.

In step 352, the matrix or point cloud of the surface of the glass sheet G as determined using the optical system and method 200 described above is input into the processor unit by the computer 80. The matrix may represent the entire first surface of the glass sheet G, or may only include a data set of a selected surface area of the glass sheet G.

At step 354, the computer 80 performs post-processing operation(s) on the matrix or point cloud. In one embodiment, the computer 80 modifies or denoises the matrix or point cloud to remove certain points or artifacts from the point cloud. For example, the computer 80 may remove or modify points in the point cloud that are adjacent to the edge of the panel G or within a specified distance, such as 1 to 2 mm, to remove points that have edge effects or deviations in the measured position, such as caused by beam steering effects, and/or deviations introduced by the calculated line center based on the width of the laser line or visible light combined with the panel edge not being perpendicular to the line or sheet. In addition, visible light and fluorescent light may appear immediately outside of the panel G and may be caused by, for example, grinding of the panel or other parameters that cause light spread, thereby generating additional artifact points in the point cloud or matrix. In one embodiment, these inaccurate or artifact points form a curve with a curvature sign opposite to that of the adjacent panel G, or form a knee of the curve between the inaccurate or artifact point and the adjacent panel G, so that the computer 80 may use the inflection point or inflection point as a boundary to truncate or delete these points from the point cloud or matrix. Although the description of this de-noising step involves de-noising a point cloud created when measuring the surface of the glass sheet G using visible fluorescence from laser cutting, the de-noising step can also be applied to other viewing and measurement systems used to de-noise edge effects.

The computer 80 also performs a denoising algorithm on the point cloud or matrix at step 354. According to one embodiment, denoising can be provided by averaging the normal vectors in a neighborhood of the data set, and then using the average normal vector to update the data set to create a post-processed data set that matches the normal changes. In a non-limiting embodiment, the point cloud composed of the data sets has a triangular mesh with each data set as a vertex. In other embodiments, other mesh shapes can be used. The normal vector is calculated for each mesh triangle. Diverging normal vectors can represent noise in the point cloud, while convergent normal vectors can represent a smoother surface of the point cloud. The point cloud is smoothed by averaging or otherwise mathematically combining the normal vectors of neighborhoods or groups of mesh triangles, where such neighborhoods may be defined as meshes that share common vertices or share common edge(s). Each averaged normal vector is used to adjust the coordinates of the associated vertex to create a post-processed vertex or data set in a post-processed de-noised point cloud or matrix. In other embodiments, other denoising algorithms may be provided and may be based on mathematical algorithms related to surface reshaping techniques, such as those described in the following literature: "A signal processing approach to fair surface design" by Gabriel Taubin, published in the SIGGRAPH '95 Proceedings of the 22nd annual conference; "Mesh Smoothing via Mean and Median Filtering Applied to Face Normals" by Hirokazu Yagou et al., published in the GMP '02 Proceedings of the Geometric Modeling and Processing-Theory and Applications (GMP'02); "Bilateral mesh denoising" by Shachar Fleishman et al., published in the SIGGRAPH '03 ACM SIGGRAPH 2003 Papers; and "Non-iterative, feature-preserving mesh denoising" by Thouis R. Jones et al., published in the SIGGRAPH '03 ACM SIGGRAPH 2003 Papers. "smoothing".

According to another non-limiting embodiment, the computer 80 performs a denoising algorithm on the point cloud or matrix that uses a moving least squares method to smooth and interpolate the data. According to the present disclosure and for a given data point in the point cloud, the computer 80 least squares fits a number of neighboring points in the point cloud to a function. In one embodiment, the function may be a polynomial. The post-processed data point is determined by moving the original given point in the point cloud to the determined polynomial surface. The computer 80 iterates the denoising of the point cloud to create a post-processed denoised point cloud or matrix. Examples of moving least squares methods and their surface applications can be found in Lancaster, Peter, and Kes Salkauskas, "Surfaces generated by moving least squares methods", Mathematics of computation 37.155 (1981): 141-158; and Alexa, Marc et al., "Computing and rendering point set surfaces", IEEE Transactions on visualization and computer graphics 9.1 (2003): 3-15.

In step 356, the computer 80 determines or calculates one or more invariant indicators of the surface or one or more selected regions of the surface from the post-processed data set of the de-noised matrix or point cloud. The invariant indicators may include horizontal curvature, vertical curvature, radius of curvature, principal curvature, Gaussian curvature, mean curvature, derivatives or rates of change of one or more of these curvatures, diopters or optical power indicators, and the like.

At step 358, the computer may determine whether an invariant metric representing the optical reflectivity of the surface is within an optical reflectivity specification specified for the surface of the glass sheet G or a region of the surface. The computer may compare one or more of the invariant metrics to a corresponding design metric for the glass sheet G. For example, the optical reflectivity specification may be a standard or thresholded invariant metric for the glass sheet G. In one embodiment, the specification includes a metric such as a calculated curvature from a computer-aided engineering (CAE) model or other model data for the glass sheet G. The computer may compare the invariant metric to a critical value, or create a color-coded map or other visual output to indicate whether the glass sheet or a region of the glass sheet is within a predetermined specification, or compare the surface to a predetermined specification. In further embodiments, the computer may use a mathematical function of more than one invariant to provide an optical reflectance score or other readout for comparison to a specification that weights or otherwise incorporates different invariants and surface areas as it relates to optical reflectance.

In step 360, and in some embodiments, the computer 80 determines or calculates variable indices of the glass sheet G. In one embodiment, the computer 80 creates a simulated reflective grid, zebra stripe, or other image for a simulated visual appearance of optical reflectivity and any distortion. The computer algorithm used to create the simulated reflective image may use techniques such as ray tracing using post-processed vertices in a de-noising matrix and normal vectors calculated from each post-processed vertex. For example and referring to the use of ray tracing, a ray from a post-processed vertex in a de-noised point cloud hits a virtual camera at an angle to the normal vector at a pixel, and since the angle of incidence equals the angle of reflection, the ray from the same post-processed vertex on the point cloud is therefore known and the intersection with the virtual grid can be determined. Using the pixels on the virtual camera and the points on the virtual grid, a reflection image of, for example, a reflection grid or zebra board can be constructed since they correspond one-to-one. The algorithm used by the computer to simulate the reflection grid or zebra board can be tuned or calibrated using the real reflection image of the same grid or zebra board with the angle of incidence, camera settings, etc. as used in the algorithm. In yet another embodiment, the computer may combine, for example, a series of simulated grids or simulated zebra strips acquired at different angles of incidence to provide a video or flipbook of the zebra strips for visual display to a user to simulate scanning the zebra strips from varying positions relative to the zebra strips.

In step 362, the computer 80 outputs information related to the simulated optical reflectivity and distortion of the surface, including any variable or invariant indicators, invariant data or a visual representation or mapping of a simulated zebra strip, or other calculations or simulations. In one embodiment, the computer 80 displays the information on a display screen or other user interface. FIG. 13 illustrates a representative embodiment of a simulated reflected optical image of a grid plate constructed using methods 200, 350 as described herein. The computer may additionally provide this information to the process steps of the glass sheet G as part of a control feedback loop.

Method 350 provides for non-contact detection and determination of the optical reflectivity and any distortion of the surface of the glass sheet G, which allows for online monitoring and inspection of components, and allows for quick and convenient inspection of a range of different components. In addition, non-contact optical reflection inspection via method 350 provides for reducing the time and expense associated with inspecting components, and additionally provides a non-subjective indicator for determining whether a component has passed specification.

In other embodiments, and depending on the manufacturing technology used to form the glass sheet, the first and second surfaces 62, 64 may emit light of different wavelengths in response to activation from the laser 50. In one embodiment, the glass sheet G is formed using a float glass process and has a higher concentration of tin on one surface than the other surface. In this scenario, the surface with the higher concentration of tin fluoresces at a different intensity and/or wavelength than the other surface, and the detection system can further be used to identify one side of the sheet from the other side based on the different intensity and/or wavelength _λ2 of the emitted light. For example, in the case of a glass sheet having a first surface having a higher concentration of tin than a second surface, the first surface may fluoresce at a different intensity and/or wavelength than the second surface, and further, the first surface fluoresces at a higher intensity and/or shorter wavelength than the second surface. In addition, the control unit and computer 80 can modify the intensity of the laser 50 based on the surface of the glass sheet facing the laser, and/or adjust camera settings, such as gain or image processing settings. For example, for a glass sheet having a higher concentration of tin on a first surface than on a second surface, the laser intensity on the first surface can be reduced compared to the second surface, for example to prevent oversaturation of the camera sensor. Alternatively or additionally, the gain of the second surface can be increased, or the second surface may require additional image processing steps for de-noising.

In addition, for example, in order to be used with a larger glass sheet G, reduce scanning time, or increase measurement accuracy, the system 10 may be provided with more than one optical system 14.

Using a system 14 with a light source that is not transmissive to the glass sheet G, measurements of the surface of the glass sheet G can be provided while avoiding the problems caused by other systems that interrogate the glass sheet using visible light and the combined scattering and reflectivity from both the front and back surfaces 62, 64. Likewise, by making the light emitted from the glass sheet G in the visible spectrum, the measurement is simplified so that a UV sensor is not required.

In further embodiments, the optical system can be used to form a three-dimensional surface image of an object other than the glass sheet G. In a limited embodiment, an optical system having a laser emitting light at another wavelength, such as visible light wavelengths, can be used to scan an object having a diffuse surface. The optical system uses one or more cameras (s) as described above to determine a three-dimensional surface image of the diffuse surface.

Although various embodiments of the present disclosure are described above, it is not intended that these specific embodiments describe all possible forms of the present invention. Instead, the terms used in the patent specification are descriptive rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. In addition, the features of various implementations of specific embodiments can be combined to form other specific embodiments.

10: Optical detection system, detection system, system

12:Conveyor

14:Optical system, system

16: Control system, computer

18: Position sensor

20: User interface and display screen

G: Glass sheet, glass panel

λ 1, λ 2: wavelength

Claims (20)

An optical detection system (10) comprises: an ultraviolet laser (50) and associated optical components (54) which form a planar laser cutting page (60) directed toward a glass sheet (G), wherein the planar laser cutting page (60) intersects a surface (62) of the glass sheet (G), thereby causing the surface (62) of the glass sheet (G) to fluoresce and form a visible light wavelength line (68) on the surface (62); a first camera (72A) having a first image sensor for detecting the visible light across a first portion (73A) of the width of the glass sheet (G); a first camera (72A) having a second image sensor for detecting the visible light wavelength (68) across a second portion (73B) of the width of the glass sheet (G), the first portion (73A) being different from the second portion (73B) so that the first camera (72A) and the second camera (72B) have separate fields of view on the surface (62) of the glass sheet (G); and a control system (16) configured to: (i) receive an image representing the visible light wavelength (68) from the first camera (72A); (ii) analyzing the image data from the first camera (72A) to determine a first coordinate and a second coordinate in a first coordinate series associated with the visible light wavelength (68); (iii) triangulating a third coordinate in the first coordinate series associated with each of the first coordinate and the second coordinate; (iv) creating a first three-dimensional map (M1) of the surface (62) of the glass sheet (G) as a function of the first coordinate series; (v) receiving image data representing the visible light wavelength (68) from the second camera (72B); (v i) analyzing the image data from the second camera (72B) to determine a first coordinate and a second coordinate in a second coordinate series associated with the visible light wavelength (68); (vii) triangulating a third coordinate in the second coordinate series associated with each of the first coordinate and the second coordinate; (viii) establishing a second three-dimensional map (M2) of the surface (62) of the glass sheet (G) as a function of the second coordinate series; and (ix) using the first three-dimensional map (M1) and the second three-dimensional map (M2) to form a combined map (M3). An optical detection system (10) as claimed in claim 1, wherein the control system (16) is further configured to use a rigid transformation to move the first three-dimensional image (M1) relative to the second three-dimensional image (M2) so that the first three-dimensional image (M1) is aligned with the second three-dimensional image (M2), and then remove the coordinate series from the overlapping field of view of one of the first three-dimensional image (M1) and the second three-dimensional image (M2) to form the combined image (M3). As in claim 1, the optical detection system (10), wherein the first camera (72A) and the second camera (72B) are fixed on one side of the planar laser cutting page (60). An optical detection system (10) as claimed in claim 1, wherein the planar laser cutting page (60) is positioned between the first camera (72A) and the second camera (72B). The optical detection system (10) of claim 1 further comprises: a third camera having a third image sensor for detecting the visible light wavelength (68) across a third portion of the width of the glass sheet (G); and a fourth camera having a fourth image sensor for detecting the visible light wavelength (68) across a fourth portion of the width of the glass sheet (G); wherein the first camera (72A), the second camera (72B), the third camera and the fourth camera have respective fields of view on the surface (62) of the glass sheet (G). The optical detection system (10) of claim 1 further comprises: a conveyor configured to translate at least one of the glass sheet (G) and the laser (50) relative to the other; wherein the laser (50), the planar laser cutting sheet (60) and the cameras (72A, 72B) are fixed relative to each other; wherein the control system (16) is further configured to receive a series of data representing a series of visible light wavelength lines (68) from each camera (72A, 72B) when measuring across the glass sheet (G), each line in the series of visible light wavelength lines (68) corresponding to a wavelength along a different position of the surface (62) of the glass sheet (G); and wherein the control system (16) is further configured to: analyze each line in the series of visible light wavelength lines (68) to determine a first coordinate and a second coordinate in a coordinate series associated therewith, triangulate a third coordinate associated with each of the first coordinate and the second coordinate in each of the coordinate series, and establish three-dimensional maps (M1, M2, M3) of the surface (62) of the glass sheet (G) from each of the coordinate series associated with each camera (72A, 72B). The optical detection system (10) of claim 1, wherein the control system (16) is further configured to use a predetermined line width region (250) to analyze the image data from each camera (72A, 72B) to determine the first coordinate and the second coordinate in each coordinate series associated with the visible light wavelength (68), wherein the first coordinate and the second coordinate in each coordinate series fall within the line width region (250). As in claim 7, the optical detection system (10), wherein the line width region (250) is a function of a number of pixels and/or a grayscale threshold value. The optical detection system (10) of claim 1, wherein the surface (62) of the glass sheet (G) is a first surface (62); wherein the glass sheet (G) has a second surface (64) opposite to the first surface (62); and wherein the control system (16) is further configured to adjust the intensity of the laser (50) in response to one of the first surface (62) and the second surface (64) containing a higher concentration of tin than the other of the first surface (62) and the second surface (64). The optical detection system (10) of claim 9, wherein the control system (16) is further configured to operate the laser (50) at a lower intensity when the first surface (62) contains a higher concentration of tin. The optical detection system (10) of claim 1, wherein the control system (16) is further configured to use the combination map (M3) of the surface (62) to determine a simulated optical reflectivity of the surface (62). The optical detection system (10) of claim 11 further comprises a display communicating with the control system (16); wherein the control system (16) is further configured to output a graph of invariant data and/or a simulated reflected optical image of one of a grid plate and a zebra plate to the display. The optical inspection system (10) of claim 1, wherein the control system (16) is further configured to use the combination map (M3) of the surface (62) to measure the glass sheet (G). The optical detection system (10) of claim 1, wherein the control system (16) is further configured to denoise the combined image (M3) by: gridding the first coordinate series and the second coordinate series in the combined image (M3); averaging the normal vectors of the grid neighbors; and adjusting a coordinate position in the first coordinate series and the second coordinate series to establish a series of post-processed coordinates in the combined image (M3). The optical detection system (10) of claim 1, wherein the control system (16) is further configured to denoise the combined image (M3) by removing a plurality of points adjacent to an edge of the three-dimensional image using one of an inflection point and a zigzag point. A method for using an optical detection system (10) includes: forming a planar laser cutting page (60) from an ultraviolet laser (50) and related optical components (54) and directing the planar laser cutting page (60) toward a surface (62) of a glass sheet (G); exciting the surface (62) of the glass sheet (G) at an intersection of the planar laser cutting page (60) and the surface (62) to form a visible light wavelength line (68) on the surface (62) of the glass sheet (G); using a first camera A first camera (72A) and a second camera (72B) are used to photograph the visible light wavelength (68), the first camera (72A) and the second camera (72B) each photograph a relatively individual portion (73A, 73B) of the surface (62) of the glass sheet (G), and have individual fields of view on the surface (62) of the glass sheet (G); by analyzing the imaging data from the first camera (72A), a first coordinate series associated with the visible light wavelength (68) is determined a first coordinate and a second coordinate in the first coordinate series associated with the visible light wavelength (68); determining a third coordinate associated with each of the first coordinate and the second coordinate in the first coordinate series associated with the visible light wavelength (68) by triangulation; determining a first coordinate and a second coordinate in a second coordinate series associated with the visible light wavelength (68) by analyzing imaging data from the second camera (72B); determining the second coordinate associated with the visible light wavelength (68) by triangulation A third coordinate in the series associated with each of the first coordinate and the second coordinate; establishing a first three-dimensional graph (M1) of the surface (62) of the glass sheet (G) as a function of the first coordinate series; establishing a second three-dimensional graph (M2) of the surface (62) of the glass sheet (G) as a function of the second coordinate series; and combining the first three-dimensional graph (M1) and the second three-dimensional graph (M2) to form a combined graph (M3) of the surface (62) of the glass sheet (G). The method of claim 16 further comprises: moving the glass sheet (G) relative to the laser (50), the planar laser cutting page (60) and the cameras (72A, 72B); and when the glass sheet (G) moves relative to the planar laser cutting page (60), using the first camera (72A) to capture a first series of visible light wavelengths; when the glass sheet (G) moves relative to the planar laser cutting page (60), When the page (60) moves, the second camera (72B) is used to shoot a second series of visible light wavelengths; wherein the first three-dimensional map (M1) of the surface (62) is established as a function of the first coordinate series in the first series of visible light wavelengths; wherein the second three-dimensional map (M2) of the surface (62) is established as a function of the second coordinate series in the second series of visible light wavelengths. The method of claim 16 further comprises: using a set of coordinates in the combined graph (M3) to compare with a gauge model of the surface (62) to calculate an invariant index of the glass sheet (G); and outputting the invariant index to provide gauge information of the glass sheet (G). The method of claim 16 further comprises: denoising the combined image (M3) of the surface (62); calculating an invariant index of the glass sheet (G) by comparing at least one set of coordinates from the combined image (M3) with an optical reflectance specification of the surface (62) specified for the glass sheet (G); and outputting the invariant index to provide optical reflectance information of the surface (62). The method of claim 19 further comprises: constructing a simulated reflected optical image of one of a grid plate and a zebra plate by ray tracing the data set from the denoised combined image (M3); and outputting the simulated reflected optical image.