Systems and methods for inspecting structures using laser ultrasound - Patents.com

Abstract

To provide a nondestructive testing method of a structure such as an aircraft and a vehicle using laser ultrasound.SOLUTION: A method for testing a structure includes steps of: identifying a three-dimensional position of a surface of the structure relative to a reference frame; transmitting laser light from an output of a transmitter onto the surface of the structure to form ultrasound waves in the structure and to detect a response to the ultrasound waves; based on the three-dimensional position of the surface, moving the laser light over the structure along a scan path so that the output of the transmitter is located at a constant offset distance from the surface and that the laser light, transmitted from the output of the transmitter, is directed onto the surface at a constant angle of projection; and based on the response to the ultrasound waves, determining whether an inconsistency is present in the structure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates generally to non-destructive testing, and more particularly, to non-destructive testing of structures using laser ultrasound. [Background technology]

[0002] When manufacturing aircraft, vehicles, and other structures, inspection of parts used to form these structures is often performed to determine whether these parts have the proper parameters and characteristics for desired function and performance. Additionally, structures and / or parts may be inspected as part of normal maintenance. Non-destructive testing is generally used to evaluate the characteristics of a part without altering the ability of the part to be used for the desired function. Examples of non-destructive testing include ultrasonic testing, eddy current testing, x-ray testing, and visual testing.

[0003] Ultrasonic testing is often used to perform inspections of aircraft parts made from composite materials. Ultrasonic testing involves transmitting acoustic waves (i.e., sound waves) through the test object and detecting the response to the acoustic waves. This response is analyzed to determine if any inconsistencies exist within the test object.

[0004] Ultrasonic testing is typically performed using a transducer. The transducer is configured to transmit acoustic waves into the test object and detect the response to the acoustic waves. Typically, the transducer is coupled to the surface of the test object by placing the transducer in physical contact with the test object. Often, a coupling medium, such as water, oil, aqueous gel, or some other liquid, is used to reduce the acoustic impedance between the transducer and the test object. However, in many cases, coupling the transducer to the surface of the test object can be difficult and complicated. For example, when the test object has a non-constant shape, a non-flat surface, or other non-flat features, it can be difficult and complicated to couple the transducer to the test object to ensure that sound enters the test object in a desired direction (e.g., perpendicular to the surface). Furthermore, in some cases, it can be difficult and complicated to include a coupling medium. Furthermore, in some cases, the use of a coupling medium may simply not be desirable for certain types of test objects.

[0005] Laser ultrasonic testing is an example of non-destructive testing that overcomes the difficulty and complexity of physically coupling a transducer to a test object by enabling the test object to be inspected without the need for physical contact with the test object. Typically, laser ultrasonic testing uses a laser beam to generate ultrasound waves within the test object and a separate laser beam to detect the response to the ultrasound waves and generate data about the test object. However, in many cases, inspecting a test object using a single channel laser (e.g., a single transmitting and receiving laser) is too time-consuming in practical implementations. To address this issue, an array of lasers may be used. However, the size, weight, and cost of high-energy lasers typically used in laser ultrasonic testing make the use of an array of lasers impractical. To address this issue, an array of low-energy lasers may be used. However, using low-energy lasers to generate useful data, especially when the test object has a non-constant shape, requires maintaining proper alignment and separation distances throughout the scanning process of the array of lasers. Maintaining proper alignment and separation distances is often difficult and can require complex mechanical control systems to maintain laser-to-part alignment, which can significantly slow the scan speed of the laser ultrasonic testing system.

[0006] Accordingly, those skilled in the art continue to conduct research and development efforts in the field of laser ultrasonic inspection. Summary of the Invention

[0007] In one embodiment, a disclosed method for testing a structure using laser ultrasound includes the steps of: (1) determining a three-dimensional location of a surface of the structure relative to a reference frame, (2) transmitting laser light from a transmitter output to the surface of the structure to generate ultrasound waves within the structure and detecting a response to the ultrasound waves, (3) based on the three-dimensional location of the surface, moving the laser light along a scan path over the structure such that the transmitter output is located at a constant offset distance from the surface and the laser light transmitted from the transmitter output is directed at the surface at a constant projection angle, and (4) determining whether an inconsistency exists within the structure based on the response to the ultrasound waves.

[0008] In one embodiment, a disclosed laser ultrasonic testing system includes a laser source configured to emit a laser light, and a transmitter optically coupled to the laser source and configured to transmit the laser light from an output of the transmitter to a surface of the structure. The laser light is configured to generate ultrasonic waves within the structure and detect a response to the ultrasonic waves. The laser ultrasonic testing system further includes a movement mechanism coupled to the transmitter and configured to move the transmitter relative to the structure. The laser ultrasonic testing system further includes a computer. The computer is configured to identify a three-dimensional position of the surface relative to a reference frame. The computer is further configured to control the movement mechanism to move the laser light over the structure along a scan path, and based on the three-dimensional position of the surface, the output of the transmitter is located at a fixed distance from the surface and the laser light transmitted from the output of the transmitter is directed to the surface at a fixed projection angle. The computer is further configured to determine whether an inconsistency exists in the structure based on the response to the ultrasonic waves.

[0009] Other embodiments of the disclosed systems and methods will become apparent from the following detailed description, the accompanying drawings, and the appended claims. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic perspective view of an embodiment of an aircraft; [Diagram 2] FIG. 1 is a schematic block diagram of an embodiment of a test environment. [Diagram 3] 1 is a schematic perspective view of an example of a structure that can be tested using laser ultrasound; [Figure 4] FIG. 1 is a schematic diagram of an example testing environment. [Diagram 5] 1 is a schematic diagram of an example of a pattern of laser light transmitted onto a surface of a structure. [Figure 6] 1 is a schematic diagram of an example of a pattern of laser light transmitted onto a surface of a structure. [Figure 7] FIG. 1 is a schematic block diagram of a portion of an embodiment of a laser ultrasonic testing system. [Figure 8] 1 is a schematic diagram of an example of a laser light being transmitted onto a surface of a structure to form an ultrasonic wave within the structure. [Figure 9] 1 is a schematic diagram of an example of a laser light being transmitted onto a surface of a structure to detect a response to ultrasound. [Figure 10] FIG. 1 is a schematic diagram of a portion of an embodiment of a laser ultrasonic testing system. [Figure 11] FIG. 1 is a flow diagram of an embodiment of a method for testing a structure using laser ultrasound. [Figure 12] 1 is a schematic diagram of an example of a three-dimensional position of a surface of a structure relative to a reference frame; [Figure 13] 1 is a schematic diagram of an example of a three-dimensional position of a surface of a structure relative to a reference frame; [Figure 14] 1 is a schematic diagram of an example of a pattern of laser light transmitted onto a surface of a structure. [Figure 15] 1 is a schematic diagram of an example of a pattern of laser light transmitted onto a surface of a structure. [Figure 16] 1 is a schematic diagram of an example of a pattern of laser light transmitted along a scan path and onto a surface of a structure. [Figure 17]1 is a schematic diagram of an example of a pattern of laser light transmitted along a scan path and onto a surface of a structure. [Figure 18] FIG. 1 illustrates a flow diagram of an exemplary aircraft production and service method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following detailed description refers to the accompanying drawings, which illustrate specific embodiments and / or examples described by the present disclosure. Other embodiments and / or examples having different structures and operations do not depart from the scope of the present disclosure. Like reference numbers may represent the same features, elements, or components in different drawings.

[0012] Illustrative, but non-exhaustive, examples of the presently disclosed subject matter are provided below that may, but are not necessarily, claimed.

[0013] 1 is an example embodiment of an aircraft 1200. In the example embodiment, aircraft 1200 is a fixed-wing aircraft. Aircraft 1200 includes an airframe 1202, a number of high-level systems 1204, and an interior 1206. Examples of high-level systems 1204 include one or more of a propulsion system 1208, an electrical system 1210, a hydraulic system 1212, an environmental system 1214, and a communication system 1216. In other examples, aircraft 1200 may include any number of other types of systems.

[0014] In one example, aircraft 1200 includes an airframe 1202. Airframe 1202 forms a fuselage 1218. Fuselage 1218 defines an interior 1206 of aircraft 1200. Interior 1206 may include a passenger cabin and / or a cargo hold. Fuselage 1218 is the main body of aircraft 1200 and includes any suitable central structure configured to hold a crew member, one or more passengers, and / or cargo. In the illustrative example, fuselage 1218 is an elongated, generally cylindrical fuselage.

[0015] The fuselage 1218 includes a nose section 1222 at the forward end of the aircraft 1200 and a tail section 1224 at the aft end of the aircraft 1200. As used herein, the terms "forward" and "aft" have their ordinary meanings known to those skilled in the art and refer to positions relative to the direction of motion of the aircraft 1200. The tail section 1224 further includes a vertical stabilizer 1226 and at least one horizontal stabilizer 1228.

[0016] The aircraft 1200 further includes a pair of wings 1220 (individually referred to as wings 1220). The wings 1220 are each coupled to the fuselage 1218. The wings 1220 include any suitable airfoil structure configured to provide lift to the aircraft 1200. In an exemplary embodiment, the wings 1220 are elongated structures extending from a lower portion of the fuselage 1218 and resemble swept-back wings with a tapered planform. In other embodiments, the wings 1220 are straight or delta shaped. In still other embodiments, the wings 1220 are trapezoidal, regular, elliptical, semi-elliptical, or other configurations known in the art.

[0017] In the exemplary embodiment, propulsion system 1208 includes turbofan engines mounted to wings 1220, for example, by a pylon. In one embodiment, each engine is housed in a nacelle that includes an inlet and a nozzle. In other embodiments, the engines may be mounted to fuselage 1218 or other aircraft structure, such as tail section 1224. In various other embodiments, propulsion system 1208 may include more or fewer engines, and other types of engines (e.g., turboprop engines) may be used.

[0018] Aircraft 1200 may further include various flight control surfaces. Flight control surfaces include any aerodynamic device used to adjust and control the flight and aerodynamic characteristics of aircraft 1200. Examples of flight control surfaces include flaps located at the trailing ends of wings 1220, elevators located at the trailing ends of horizontal stabilizers 1228, rudder located at the trailing end of vertical stabilizers 1226, and other control surfaces such as tip flaps, ailerons, and spoilers.

[0019] In one embodiment, the aircraft 1200 includes various structural members that form the airframe 1202, fuselage 1218, wings 1220, vertical stabilizer 1226, horizontal stabilizer 1228, and other structures of the aircraft 1200. Examples of structural members include skin panels, stringers, spars, ribs, and other types of components. These structural members are connected together by any one of a variety of methods, including, but not limited to, connecting with various fasteners, co-curing, structurally bonding (e.g., adhesive bonding), or integrally molded.

[0020] Aircraft 1200 is an example of an aircraft having composite structures that may be inspected by a laser ultrasonic inspection system. For example, composite skin panels, composite stringers, and other composite structures may be inspected using a laser ultrasonic testing system.

[0021] 2 illustrates an example of a testing environment 100. Testing environment 100 is an example of an environment in which a laser ultrasonic inspection system 102 is used for testing a structure 200. In various embodiments, structure 200 includes any article or object that may be tested using laser ultrasonic testing system 102.

[0022] As used herein, the terms and phrases "test," "testing," and similar terms as they relate to the testing of structure 200 refer to non-destructive testing (NDT), non-destructive investigation (NDE), non-destructive inspection (NDI), non-destructive evaluation (NDE), and other analytical techniques used to inspect and / or evaluate the properties of a structure, material, or component without permanently altering or damaging the article being tested.

[0023] In one embodiment, the laser ultrasonic testing system 102 includes a laser source 104. The laser source 104 is configured to emit a laser light 106. The laser ultrasonic testing system 102 further includes a transmitter / receiver, generally referred to herein as a transmitter 108. The transmitter 108 is optically coupled to the laser source 104. The transmitter 108 is configured to transmit the laser light 106 from an output 110 of the transmitter 108 to a surface 202 of the structure 200. During an ultrasonic testing operation, the laser light 106 takes the form of a transmitted laser light and a received laser light. The laser light 106 (e.g., the transmitted laser light) is configured to form or otherwise generate an ultrasonic wave 204 within the structure 200. The laser light 106 (e.g., the received laser light) is configured to detect a response 206 to the ultrasonic wave 204.

[0024] The laser ultrasonic testing system 102 further includes a movement mechanism 112. The movement mechanism 112 is coupled to the transmitter 108. The movement mechanism 112 is configured to move the transmitter 108 relative to the structure 200.

[0025] The laser ultrasonic testing system 102 further includes a computer 114. The computer 114 is configured to determine a three-dimensional position 208 of the surface 202 relative to a reference frame 118. Based on the three-dimensional position 208 of the surface 202, the computer 114 is further configured to control the moving mechanism 112 to move the laser light 106 over the structure 200 along a scan path 116, where the output 110 of the transmitter 108 is located at a fixed distance from the surface 202, and the laser light 106 transmitted from the output 110 of the transmitter 108 is directed toward the surface 202 at a fixed projection angle. The computer 114 is further configured to determine whether an inconsistency 212 exists in the structure 200 based on the response 206 to the ultrasonic waves 204.

[0026] As used herein, the term "surface," as it relates to surface 202 of structure 200, has its ordinary meaning well known to those of ordinary skill in the art and includes any portion of the exterior surface of structure 200 through which laser light 106 is transmitted during an ultrasonic testing operation.

[0027] As used herein, reference frame 118 is a reference coordinate system defined relative to test environment 100. In one embodiment, reference frame 118 is a three-dimensional Cartesian coordinate system defined by an X-axis, a Y-axis, and a Z-axis. In alternative embodiments, reference frame 118 may utilize other coordinate systems, such as a polar coordinate system.

[0028] As used herein, a three-dimensional position, such as with respect to a three-dimensional position 208 of a surface 202 of a structure 200, is represented by the three-dimensional coordinates of a point located within a reference coordinate system, such as the coordinate system of a reference frame. In one embodiment, the three-dimensional position 208 takes the form of the XYZ coordinates of a point on the surface 202 within the reference frame 118.

[0029] As used herein, inconsistencies 212 include, but are not limited to, unwanted levels or porosity, delamination, or other undesired features or characteristics within the structure 200.

[0030] The structure 200 may include or be formed from a number of materials 244. As used herein, a "number of" items means one or more items. Thus, the number of materials 244 may include one or more materials.

[0031] In one embodiment, structure 200 is a composite structure and materials 244 are composite materials. In other words, a composite structure includes or is formed from composite materials. Generally, composite structures are rigid and lightweight and are made by combining two or more functional composite materials. In other embodiments, materials 244 may further include metal materials, plastic materials, or other suitable types of materials.

[0032] In one embodiment, composite materials include a matrix material and a reinforcing material. In one embodiment, the matrix material takes the form of a thermosetting resin (e.g., epoxy), a thermoplastic polymer (polyester, vinyl ester, nylon, etc.), or other type of matrix material. In one embodiment, the reinforcing material takes the form of fibers (e.g., fiberglass, carbon fiber, aramid fiber, etc.), or other type of reinforcing material. The fibers may be unidirectional or may take the form of a woven or non-woven fabric or non-woven fabric.

[0033] In one embodiment, structure 200 is a laminated structure. A laminated structure includes or is formed from a number of layers. In one embodiment, one or more of the layers includes or is formed from a number of composite materials.

[0034] Structure 200 may take any number of forms. In one example, structure 200 is a portion (e.g., a structural member) of aircraft 1200 ( FIG. 1 ) or is a portion of the structure of aircraft 1200. In one example, structure 200 is a composite portion of aircraft 1200, such as fuselage 1218, wing 1220, vertical stabilizer 1226, horizontal stabilizer 1228, or other structure of aircraft 1200. In one example, structure 200 is one or more composite structural members forming at least one of fuselage 1218, wing 1220, vertical stabilizer 1226, horizontal stabilizer 1228, or another structure of aircraft 1200 (such as a skin panel, a stringer, a spar, a rib, a wing box, a stiffener, or other type of part).

[0035] The present disclosure recognizes that composite structures are beneficially used in aircraft to reduce the weight of the aircraft, which in turn improves performance characteristics such as payload capacity and fuel efficiency, and further provides extended service lives for various components of the aircraft.

[0036] In the manufacture of composite structures, layers of composite material are typically laid up on a tool. The layers may include fibers in the form of sheets. The sheets may take the form of fabrics, tapes, tows, or other suitable forms. In some cases, resin may be infused or pre-impregnated into the sheets. These types of sheets are commonly referred to as prepregs. Various layers of prepregs may be laid up in various orientations, and different numbers of layers may be used depending on the performance requirements of the composite structure being manufactured.

[0037] The present disclosure further recognizes that inconsistencies may be introduced into a composite structure during its manufacture or during its use. The spacing of the layers that make up the composite structure may make the composite structure more difficult to inspect for inconsistencies in some locations or of some types than desired. Furthermore, some inconsistencies may not be detectable using conventional non-destructive inspection techniques.

[0038] Further, the present disclosure recognizes that inspecting composite structures with non-constant shapes may be more difficult than desired. Generally, to generate accurate and useful information from laser ultrasonic testing, the position of the laser beam transmitter relative to the object being tested must be controlled so that the distance the laser beam travels (e.g., the offset distance between the transmitter output and the surface of the object) and the angle of impact of the laser beam with the surface are constant throughout the scanning process. This position control is particularly important when low energy lasers are used for laser ultrasonic testing. Such position control is not overly difficult when there is little or no variation in the shape of the surface along one or more major axes of the object. However, when the shape of the surface of an object varies along all major axes of the object, maintaining the proper alignment and separation distance may be more difficult than desired, and complex mechanical controls, complex laser controls, or manual presetting may be required at each position to maintain the orientation of the laser relative to the surface.

[0039] 3 is an example embodiment of a structure 200. In the example embodiment, structure 200 is a stiffener 214 (such as a stringer or spar of wing 1220), a vertical stabilizer 1226, or a horizontal stabilizer 1228 of aircraft 1200 ( FIG. 1 ). Any portion of a surface 202 of structure 200, or any one of a number of points 222 ( FIG. 2 ) on surface 202 of structure 200, has a corresponding three-dimensional position 208 relative to structural reference frame 210.

[0040] As used herein, structural reference frame 210 is a reference coordinate system defined relative to points on structure 200 and rigid points relative to structure 200. In one embodiment, structural reference frame 210 is a three-dimensional Cartesian coordinate system defined by X, Y, and Z axes, e.g., aligned with the principal axes of structure 200.

[0041] In one embodiment, the structural reference frame 210 forms the reference frame 118 of the test environment 100. In one embodiment, the structural reference frame 210 is transformed for alignment with the test environment reference frame 118. As used herein, the terms "transform," "transformed," "transformation," and similar terms relating to the transformation of a reference frame refer to a three-dimensional rotation and / or translation in which one reference frame is substantially aligned with another reference frame, or in which the orthogonal axes of one coordinate system are substantially aligned with the orthogonal axes of another coordinate system.

[0042] In one embodiment, structure 200 has an irregular shape along each of its major axes. As used herein, the term "primary axes" refers to orthogonal axes of an item. In one embodiment, the primary axes of structure 200 include a first axis 216, a second axis 218 that is perpendicular to first axis 216, and a third axis 220 that is perpendicular to first axis 216 and second axis 218. In an exemplary embodiment, first axis 216 is formed along a length dimension (e.g., longitudinal axis) of structure 200, second axis 218 is formed along a width dimension (e.g., transverse axis) of structure 200, and third axis 220 is formed along a thickness or depth dimension of structure 200. Thus, in an exemplary embodiment, a change in the contour or shape of surface 202 is represented by a change in surface 202 along third axis 220.

[0043] In one embodiment, due to the irregular shape of structure 200, three-dimensional position 208 of surface 202 relative to structural reference frame 210 varies along each of the major axes of structure 200 and along each of the major dimensions (e.g., length, width, and thickness) of structure 200. In other words, the contour of surface 202 varies when viewed from a YZ plane of structural reference frame 210 (an imaginary plane defined by the Y and Z axes of structural reference frame 210) and / or when viewed from an XZ plane of structural reference frame 210 (an imaginary plane defined by the X and Z axes of structural reference frame 210).

[0044] In one embodiment, the contour of surface 202 relative to structural reference frame 210 is defined by the three-dimensional location 208 of each of a plurality of points 222 on surface 202. Each of the points 222 on surface 202 has a corresponding three-dimensional location 208 that is distinct from any other of the points 222 of surface 202. In one embodiment, each of the three-dimensional locations 208 of points 222 has XYZ coordinates relative to structural reference frame 210, and thus further has XYZ coordinates relative to reference frame 118 of test environment 100.

[0045] In an example embodiment, a first point 224 on surface 202 has a corresponding first three-dimensional location 208, a second point 226 on surface 202 has a corresponding second three-dimensional location 208, a third point 228 on surface 202 has a corresponding third three-dimensional location 208, a fourth point 230 on surface 202 has a corresponding fourth three-dimensional location 208, etc. The corresponding three-dimensional locations 208 of each of the first point 224, second point 226, third point 228, and fourth point 230 are different.

[0046] More specifically, in the exemplary embodiment, first point 224 and second point 226 have the same X coordinate (e.g., the same location along the X axis of structural reference frame 210). First point 224 and second point 226 have different Y coordinates (e.g., different locations along the Y axis of structural reference frame 210). First point 224, third point 228, and fourth point 230 have the same Y coordinate (e.g., the same location along the Y axis of structural reference frame 210). First point 224, third point 228, and fourth point 230 have different X coordinates (e.g., the same location along the X axis of structural reference frame 210). First point 224, second point 226, third point 228, and fourth point 230 have different Z coordinates (e.g., different locations along the Z axis of structural reference frame 210).

[0047] 4 illustrates an example of a testing environment 100 in which the disclosed laser ultrasonic testing system 102 is used to test a structure 200. In an exemplary embodiment, the structure 200 is a portion of an aircraft and includes a skin panel 232, such as a composite skin panel, and a stiffener 214, such as a composite stringer. In one embodiment, the stiffener 214 is permanently connected to the skin panel 232. By way of example, the stiffener 214 may be connected to the skin panel 232 by various types of fasteners (not shown), the stiffener 214 may be co-cured with the skin panel 232, the stiffener 214 may be structurally bonded (e.g., adhesively bonded) to the skin panel 232, or a combination thereof. Although the exemplary embodiment of structure 200 includes only one stiffener 214 coupled to skin panel 232, in other embodiments, additional stiffeners 214 (e.g., additional stringers) or other types of stiffeners 214 (e.g., girders) may be coupled to skin panel 232.

[0048] The movement mechanism 112 is configured to move or otherwise manipulate the transmitter 108 relative to the structure 200 such that the laser light 106 emitted from the output 110 of the transmitter 108 is directed (e.g., scanned or moved on or across the surface 202 of the structure 200) along a scan path 116 along the surface 202 of the structure 200. In various embodiments, the movement mechanism 112 may be implemented using a number of different types of systems.

[0049] In one embodiment, the movement mechanism 112 includes or takes the form of a robot 122. The robot 122 may be, for example, a scanning robot arm configured to move the transmitter 108 about a number of axes relative to the structure 200. In one embodiment, the robot 122 includes a base, one or more arms, and one or more actuators (e.g., servo motors) operable to move the various arms. It should be noted that the robot 122 may include a greater or lesser number of arms and / or different types of members such that any desired range of rotational and / or translational movement of the transmitter 108 can be provided. In other embodiments, the movement mechanism 112 may include a gantry robot, or other suitable type of motion system.

[0050] In one embodiment, the transmitter 108 takes the form of or is incorporated into the end effector 128. The end effector 128 is removably coupled to the robot 122. The robot 122 is configured to move the end effector 128 relative to the structure 200.

[0051] The laser source 104 is configured to emit a laser light 106. In one embodiment, in a first stage of a laser ultrasonic testing operation, the laser light 106 has an energy configured to move an ultrasonic wave through the structure 200. As used herein, ultrasonic waves 204 are acoustic or sound waves formed in the structure 200 by the laser light 106. In a second stage of the testing operation, the laser light 106 has an energy configured to not produce an acoustic wave in the structure 200 and configured to detect a response to the laser light 106. The response contains information that is used to identify a response to the ultrasonic wave 204 in the structure 200.

[0052] In one embodiment, the laser ultrasonic testing system 102 further includes a detector 126. The detector 126 is configured to detect the laser energy and generate data 132 (FIG. 2). In one embodiment, the detector 126 includes a number of detectors. In one embodiment, the detector 126 includes a number of photodetectors. In one embodiment, when the laser light 106 encounters an ultrasonic wave 204 in the structure 200, the return path of the laser light 106 may be altered. The detector 126 is configured to detect this alteration.

[0053] In one embodiment, data 132 is used to determine information 252 about structure 200. Information 252 may include, but is not limited to, a thickness of structure 200, a material composition of structure 200 (e.g., material 244), an indication of whether there are any undesirable inconsistencies 212 on and / or within structure 200, and / or other types of information.

[0054] In some embodiments, the data 132 generated by the detector 126 includes multiple data points. Generally, increasing the number of data points included in the data 132 provides a higher signal-to-noise ratio using currently available signal processing techniques. In one embodiment, the number of data points in the data 132 can be increased by increasing the speed at which the laser beam 106 scans the structure 200, by scanning the same area of ​​the surface 202 multiple times, by arranging the laser beam 106 in a pattern or array of spots on the surface 202, or a combination thereof.

[0055] In one embodiment, the laser source 104 and the detector 126 are separate components of the laser ultrasonic testing system 102. In one embodiment, the laser source 104 and the detector 126 are combined as a single component of the laser ultrasonic testing system 102. In one embodiment, one or both of the laser source 104 and the detector 126 form part of the transmitter 108 and / or are integrated into the end effector 128. In one embodiment, one or both of the laser source 104 and the detector 126 are separate from the transmitter 108 and / or separate from the end effector 128.

[0056] In one embodiment, the laser source 104 and the detector 126 are optically coupled to the transmitter 108 via an optical communication link 130, as shown in Figure 4. In one embodiment, the optical communication link 130 includes a number of optical fibers.

[0057] The computer 114 is configured to control the operation of the laser ultrasonic testing system 102. The computer 114 is further configured to analyze the data 132 generated by the laser ultrasonic testing system 102. In one embodiment, the computer system 114 is one or more computers. When more than one computer is present, the computers may be in communication with each other through a communications medium, such as a network.

[0058] In one embodiment, the computer 114 includes a controller 138 ( FIG. 2 ) (e.g., a controller implemented within a computer). The controller 138 is configured to control the operation of the movement mechanism 112 (e.g., the robot 122), the laser source 104, the detector 126, and other components of the laser ultrasonic testing system 102. In various embodiments, the controller 138 is implemented using hardware, software, or a combination of hardware and software. When software is employed, the operations performed may be embodied in the form of program code or instructions stored in a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium) configured to be executed by a processor. When hardware is employed, the hardware may include circuitry operative to perform the operations.

[0059] In various embodiments, the hardware may take the form of a circuit system, an integrated circuit, an application specific integrated circuit (ASIC), a programmable logic device, or any other suitable type of hardware configured to perform a number of operations. In the case of a programmable logic device, the device is configured to perform a number of operations. The device may be later reconfigured or may be permanently configured to perform a number of operations. Examples of programmable logic devices include, for example, a programmable logic array, a programmable array logic, a field programmable logic array, a field programmable gate array (FPGA), and other suitable hardware devices.

[0060] In one embodiment, computer 114 is communicatively coupled to movement mechanism 112, laser source 104, and detector 126 via data communication link 134. In one embodiment, data communication link 134 includes a number of wired connections, a number of wireless connections, or a combination thereof. Computer 114 is configured to send operation commands for movement mechanism 112, laser source 104, and detector 126 via data communication link 134. Computer 114 is further configured to receive data 132 (FIG. 2) from detector 126 via data communication link 134.

[0061] In one embodiment, the computer 114 further includes a processor (FIG. 2). In one embodiment, the processor 140 is configured to execute program codes or instructions stored in the internal memory 142, an external memory (not shown), or a combination thereof. The processor 140 may take the form of any logical processing unit, such as one or more of a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), other suitable logical processors, or a combination thereof. The internal memory 142 may take the form of any data storage unit, such as one or more of a read only memory (ROM), a random access memory (RAM), a solid state memory, a volatile or non-volatile storage device, other suitable data storage, or a combination thereof. The processor 140 is configured to analyze the data 132 generated by the detector 126 from the response detected by the transmitter 108. This analysis may include an indication of whether or not a number of inconsistencies 212 are present in the structure 200.

[0062] Additionally, computer 114 further includes a number of input / output (I / O) devices 144 (FIG. 2). For example, I / O devices 144 may include, but are not limited to, a keypad, a keyboard, a touch-sensitive display screen, a liquid crystal display (LCD) screen, a microphone, a speaker, a communication port, or any combination thereof. Computer 114 is configured to generate information indicative of whether a number of inconsistencies 212 are present in structure 200. This information may take a variety of different forms, such as an alert, a report, an image, other suitable information based on an ultrasonic examination of structure 200, or a combination thereof.

[0063] In one embodiment, the alert may indicate whether or not there is an inconsistency 212. The alert may be displayed on a display device coupled to the computer 114.

[0064] In one embodiment, the image may be displayed on a display device of computer 114. The image may be an image of part or all of structure 200 with a graphic indicator if inconsistency 212 is present in structure 200. The graphic indicator may be displayed at a location within the image that corresponds to the location where inconsistency 212 was detected in structure 200. In another embodiment, if inconsistency 212 is not present, a graphic indicator may be displayed to indicate that inconsistency 212 is not present.

[0065] In one embodiment, the report may identify any inconsistencies 212 in the structure 200. The report may also include other information, such as the location of the inconsistency, the type of inconsistency, the size of the inconsistency, and other suitable types of information.

[0066] In one embodiment, the pose of the movement mechanism 112 (e.g., robot 122) and the pose of the transmitter 108 (e.g., end effector 128) may be known to or ascertainable by the computer 114. As used herein, the term "pose" as it relates to the pose of the transmitter 108 refers to the position and / or orientation of an item relative to a frame of reference. In one embodiment, the movement mechanism 112 may include one or more sensors (e.g., encoders, reed switches, position sensors, contact switches, accelerometers, etc.) or other devices positioned and configured to sense, measure, or determine information indicative of the current position, velocity, acceleration, and / or orientation of the transmitter 108 relative to the frame of reference 118.

[0067] In one embodiment, the transmitter 108 includes a transmitter reference frame 136. As used herein, the transmitter reference frame 136 is a reference coordinate system defined relative to points on the transmitter 108 and points rigid relative to the transmitter 108. In one embodiment, the transmitter reference frame 136 is a three-dimensional Cartesian coordinate system defined by an X-axis, a Y-axis, and a Z-axis.

[0068] In one embodiment, the computer 114 receives information from various sensors or devices and / or actuators that indicate the position and / or orientation of the motion mechanism 112 relative to the reference frame 118. The computer 114 then computationally determines the attitude of the transmitter 108 relative to the reference frame 118, for example, by performing a transformation of the transmitter reference frame 136 relative to the reference frame 118.

[0069] 4 and 5, the transmitter 108 is configured to transmit the laser light 106 to the surface 202 of the structure 200 in the form of a pattern 120. The pattern 120 of the laser light 106 is a number of areas on the surface 202 of the structure 200 where the laser light 106 is applied. These areas may be circular, elliptical, rectangular, diagonal, or have any other shape depending on the projection angle of the laser light 106 on the surface 202. In one embodiment, the laser light 106 takes the form of a number of laser beams and the pattern 120 of the laser light 106 is formed by a number of laser beams of the laser light 106, also referred to as an array of laser beams. In one embodiment, the laser light 106 takes the form of a number of arrays of laser beams and the pattern 120 of the laser light 106 is formed by a number of arrays of the laser beams of the laser light 106. In one embodiment, the number of arrays of laser beams are aligned with each other. In one embodiment, at least one of the multiple arrays of laser beams is offset or staggered with respect to at least another of the multiple arrays of laser beams.

[0070] 5, pattern 120 takes the form of a plurality of spots 172 arranged in a linear pattern formed by laser beam 106. In one embodiment, each of the plurality of spots 172 is formed by a corresponding one of the plurality of laser beams of laser beam 106.

[0071] In one example, the linear distance between the centers of adjacent spots in the plurality of spots 172 is about 0.08 inches (80 mils or 2 millimeters). Such spacing of the plurality of spots 172 allows for the collection of data 132 characterizing a point on the surface 202 every 0.08 inches. In one example, increasing the density of the spots 172 formed by the plurality of laser beams of laser light 106 (e.g., by decreasing the linear distance between the centers of adjacent spots in the plurality of spots 172 and / or by increasing the number of spots 172 over the length of the pattern 120) can increase the number of data points in the data 132. In one example, the pattern 120 of laser light 106 has a sufficient density (e.g., has a sufficient number of spots 172 over the length of the pattern 120) to allow for characterization of smaller features of the structure 200. In one embodiment, increasing the density of spots 172 formed by multiple laser beams of laser light 106 reduces the number of times an area of ​​surface 202 needs to be scanned, thereby increasing the scanning speed of the laser ultrasonic testing system 102.

[0072] In one embodiment, the pattern 120 is or takes the form of a line 124. The line 124 is defined by a linear arrangement of spots 172 formed by the laser light 106. In one embodiment, the pattern 120 is a straight line. In other words, the transmitter 108 is configured to transmit the pattern 120 of the laser light 106 onto the surface 202 of the structure 200 in the form of a straight line. In one embodiment, the line 124 is a continuous line. In another embodiment, the line 124 is a discontinuous line.

[0073] In another embodiment, the pattern 120 takes the form of a single spot 172 formed by the laser light 106 .

[0074] Generally, ultrasonic testing of structure 200 using a line pattern rather than a single point allows for more rapid testing of structure 200.

[0075] In other embodiments, the pattern 120 may have a shape similar to a rectangle or other suitable shape.

[0076] In one example, the pattern 120 has a first (e.g., major) linear dimension 174 and a second (e.g., minor) linear dimension 176. The first linear dimension 174 defines a length dimension of the pattern 120 formed by the plurality of spots 172. In one example, the number of spots 172 of the array of laser beams of the laser light 106 across the first linear dimension 174 of the pattern 120 defines a density of the pattern 120. The second linear dimension 176 defines a width dimension of the pattern 120 formed by the spot size of the spots 172.

[0077] In one embodiment, first linear dimension 174 of pattern 120 is about 6 inches (152 millimeters) or less. In one embodiment, first linear dimension 174 of pattern 120 is about 2 inches (50 millimeters) or less. In one embodiment, first linear dimension 174 of pattern 120 is about 1 inch (25 millimeters) or less.

[0078] In one embodiment, each spot 172 forming pattern 120 has a spot size of about 5 millimeters or less. Thus, in one embodiment, second linear dimension 176 of pattern 120 is about 5 millimeters or less. In one embodiment, each spot 172 forming pattern 120 has a spot size of about 1 millimeter or less. Thus, in one embodiment, second linear dimension 176 of pattern 120 is about 1 millimeter or less.

[0079] 6, the movement mechanism 112 (FIG. 2) operates the transmitter 108 to move the pattern 120 of the laser beam 106 along the scan path 116, e.g., in the direction of the arrow 175 (FIG. 5), across the surface 202 of the structure 200 to scan the structure 200. The position of the pattern 120 (e.g., each spot 172) on the surface 202 of the structure 200 as the laser beam 106 moves along the scan path 116 is indicated by the dashed lines in FIG.

[0080] In one embodiment, one or more of the spots 172 forming the pattern 120 touch or at least partially overlap one or more immediately adjacent spots 172, such that the same area on the surface 202 is covered by more than one spot 172 of the pattern 120 of the laser light 106. In other words, the pattern 120 of the laser light 106 is a continuous line. In one embodiment, one or more of the spots 172 may be spaced apart from an immediately adjacent spot 172 such that a portion on the surface 202 is not covered by a spot 172 of the pattern 120 of the laser light 106. In other words, the pattern 120 of the laser light 106 is a non-continuous line.

[0081] 7, in one embodiment, the laser ultrasonic testing system 102 includes an ultrasonic generator 148. The ultrasonic generator 148 is configured to generate and emit a first laser light 156. The ultrasonic generator 148 is an example of a laser source, such as laser source 104 (FIG. 2). The first laser light 156 is an example of a transmitting laser light or an ultrasound generating laser light, such as laser light 106 (FIG. 2). In one embodiment, the ultrasonic generator 148 includes or takes the form of a laser 186. In one embodiment, the laser 186 is configured to emit the first laser light 156.

[0082] In one embodiment, the first laser light 156 is a coherent light. In one embodiment, the ultrasonic generator 148 is configured to generate coherent light. In other words, the laser 186 is a coherent light source. In one embodiment, the first laser light 156 is or takes the form of a laser beam (a focused beam of coherent light). In one embodiment, the first laser light 156 is or takes the form of a pulsed laser beam. A pulsed laser beam is formed by pulses of laser energy. In other words, a pulsed laser beam is formed by pulses of laser light emitted in the form of a beam.

[0083] In some embodiments, laser 186 is a laser generator, an array of laser diodes, or any other suitable source of coherent light. In one embodiment, laser 186 is a low power or low energy fiber-based laser. In one embodiment, laser 186 is a gas laser. In one embodiment, laser 186 is a carbon dioxide (CO2) laser. In one embodiment, laser 186 is a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser.

[0084] In one embodiment, the ultrasonic generator 148 is configured to generate a first laser beam 156 having a number of first characteristics 166. Each of the first characteristics 166 has a value within a selected range. The range of each of the first characteristics 166 is selected such that the first laser beam 156 is generated such that when the first laser beam 156 encounters the structure 200, a first ultrasonic wave 234 is formed within the structure 200 without causing any undesirable misalignment within the structure 200 outside of the selected tolerance. In some embodiments, the first characteristics 166 include, but are not limited to, a first wavelength, a first pulse repetition rate, a first spot size, a first pulse width, a first energy per pulse, a first intensity, and other first characteristics.

[0085] In one embodiment, the laser ultrasonic testing system 102 includes a receiver 150. The ultrasonic receiver 150 is configured to generate and emit a second laser light 158. The ultrasonic receiver 150 is an example of a laser source and detector combination, such as the laser source 104 and detector 126 (FIG. 2). The second laser light 158 ​​is an example of a receiving laser light or an ultrasonic detection laser light, such as the laser light 106 (FIG. 2). In one embodiment, the ultrasonic receiver 150 includes or takes the form of an interferometer 164. In one embodiment, the interferometer 164 is configured to emit the second laser light 158.

[0086] In one embodiment, the second laser light 158 ​​is a coherent light. In one embodiment, the ultrasound receiver 150 is configured to generate a coherent light. In other words, the interferometer 164 is a coherent light source. In one embodiment, the second laser light 158 ​​is or takes the form of a laser beam (a focused beam of coherent light). In one embodiment, the second laser light 158 ​​is or takes the form of a pulsed laser beam. A pulsed laser beam is formed by pulses of laser energy. In other words, a pulsed laser beam is formed by pulses of laser light emitted in the form of a beam.

[0087] In some embodiments, interferometer 164 includes a laser generator, an array of laser diodes, or any other suitable source of coherent light. In one embodiment, interferometer 164 is a low power or low energy fiber-based laser. In one embodiment, interferometer 164 includes a gas laser. In one embodiment, interferometer 164 includes a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser.

[0088] In one embodiment, the ultrasonic receiver 150 is configured to generate the second laser light 158 ​​having a number of second characteristics 168. Each of the second characteristics 168 has a value within a selected range. The range of each of the second characteristics 168 is selected such that the second laser light 158 ​​is generated such that when the second laser light 158 ​​encounters the structure 200, no ultrasonic waves are generated within the structure 200. In some embodiments, the second characteristics 168 include, but are not limited to, a second wavelength, a second pulse repetition rate, a second spot size, a second pulse width, a second energy per pulse, a second intensity, and other second characteristics.

[0089] In some embodiments, at least a portion of the first characteristic 166 of the first laser light 156 and the second characteristic 168 of the second laser light 158 ​​are different.

[0090] In one example, the wavelength of the laser light 106 may be selected based on the material 244 forming the structure 200, the thickness of the structure 200, and other suitable factors. In one example, a wavelength may be selected for the first laser light 156 to increase absorption of energy from the first laser light 156 when the first laser light 156 is transmitted to the surface 202 of the structure 200. For example, when the structure 200 is formed from one or more composite materials, the wavelength selected for the first laser light 156 may be from about 300 millimeters to about 30,000 millimeters.

[0091] The pulse repetition rate is the rate at which pulses of laser energy are fired to form the pulsed laser beam. The pulse repetition rate may be described in terms of frequency. In one embodiment, the ultrasonic generator 148 is configured to generate the pulsed laser beam such that the pulsed laser beam has a pulse repetition rate between about 10,000 Hertz (Hz) and about 500,000 Hertz (Hz). A pulse repetition rate within this range may be considered high. In one embodiment, the selection range of the pulse repetition rate is selected such that the pulse repetition rate is high enough to allow the rate at which the pulsed laser beam moves along the structure 200 to be within a selected tolerance. In particular, a high value of the pulse repetition rate allows the rate at which the pulsed laser beam scans the structure 200 to be similarly high. In other words, as the pulse repetition rate increases, the scanning speed may also increase.

[0092] The spot size is the size of the area on the surface of the structure 200 illuminated by the laser light 106, such as a pulsed laser beam. In one embodiment, the laser ultrasonic testing system 102 is configured to generate the laser light 106, such as in the form of a pulsed laser beam, such that the spot size is less than about 1 millimeter.

[0093] In one embodiment, a pulse width, or pulse length, may be selected for the first laser light 156 to generate a desired frequency for the first ultrasonic wave 234. In one embodiment, a pulse width of about 1 nanosecond to about 200 nanoseconds may be selected for the first laser light 156 used to generate the first ultrasonic wave 234. In one embodiment, a pulse width of about 50 microseconds to about 100 microseconds may be selected for the second laser light 158 ​​used to detect the second ultrasonic wave 238 in the first response 236. In general, the pulse width of the first laser light 156 is selected so that the first laser light 156 illuminates the surface 202 for a time long enough for an ultrasonic pulse of the ultrasonic wave to make a complete round trip through the structure 200.

[0094] The energy per pulse may be the amount of energy contained within each pulse of laser energy forming the laser beam 106. In one embodiment, the first laser beam 156, such as a pulsed laser beam, is generated such that each pulse is within a range selected to enable the formation of the first ultrasonic waves 234 within the structure 200 without causing numerous misalignments within the structure 200 outside of a selected tolerance. In one embodiment, the ultrasonic generator 148 is configured to generate the first laser beam 156, such as a pulsed laser beam, such that the energy per pulse is within a range of about 1 microjoule to about 10,000 microjoules.

[0095] In one example, the intensity may be selected based on the amount of energy desired to be transmitted to the structure 200 by the first laser beam 156 encountering the surface 202 of the structure 200. The intensity may be selected for the first laser beam 156 to result in a desired level of first ultrasound waves 234 when the first laser beam 156 is transmitted to the surface 202 of the structure 200. The intensity may be selected for the first laser beam 156 and the second laser beam 158 to reduce or avoid damage to the surface 202 of the structure 200. Depending on the values ​​selected for the pulse length and spot size, the intensity may further vary.

[0096] In some embodiments, a combination of spot size and energy per pulse can be used to generate an optical fluence within a desired range. As used herein, the term "fluence" refers to the energy transmitted through a unit area. In one embodiment, the laser light 106, such as a pulsed laser beam, can be generated such that the optical fluence per pulse ranges between about 0.1 millijoules per square centimeter to about 1000 millijoules per square centimeter. The value within this range selected for the optical fluence per pulse can be selected such that the pulsed laser beam does not cause any inconsistencies on and / or within the composite structure 200 outside of a selected tolerance.

[0097] In some embodiments, the speed at which the laser light 106 scans the structure 200 can be increased by increasing the number of spots 172 (e.g., increasing the intensity of the pattern 120) on the corresponding area of ​​the surface 202 being scanned. As a result, the data 132 generated when the laser light 106 has a denser pattern 120 and a higher repetition rate can have a higher signal-to-noise ratio than when the laser light 106 has a less dense pattern 120 and a lower repetition rate. Generally, a higher pulse repetition rate increases the number of times a point or area on the surface 202 is illuminated by the laser light 106. The data points of response from multiple points of the laser light 106 on the same point or area on the surface 202 can be averaged to have a higher signal-to-noise ratio.

[0098] Although particular values ​​are specified for the first characteristic 166 and / or the second characteristic 168, these values ​​are presented for illustrative purposes and are not intended to limit other values ​​that may be used. The selection of the first characteristic 166 and / or the second characteristic 168 may vary depending on the corresponding light source, the materials in the structure 200, and other factors.

[0099] In one embodiment, the ultrasonic generator 148 is optically coupled to the transmitter 108. The transmitter 108 is configured to transmit a first laser light 156 from an output 110 of the transmitter 108 to the surface 202 of the structure 200 in a first pattern 160. The first pattern 160 of the first laser light 156 is a plurality of areas where the first laser light 156 is applied on the surface 202. The first pattern 160 is an example of the pattern 120 (FIG. 2). In one embodiment, the first pattern 160 takes the form of lines 124 (FIG. 2).

[0100] In one embodiment, the ultrasonic receiver 150 is optically coupled to the transmitter 108. The transmitter 108 is configured to transmit a second laser light 158 ​​from an output 110 of the transmitter 108 to the surface 202 of the structure 200 in a second pattern 162. The second pattern 162 of the second laser light 158 ​​is a plurality of areas where the second laser light 158 ​​is projected onto the surface 202. The second pattern 162 is an example of the pattern 120 (FIG. 2). In one embodiment, the second pattern 162 takes the form of lines 124 (FIG. 2).

[0101] In some embodiments, the second pattern 162 of the second laser beam 158 is substantially aligned with the first pattern 160 of the first laser beam 156. In one embodiment, the lines 124 of the first laser beam 156 and the lines 124 of the second laser beam 158 are substantially aligned and / or cover substantially the same area on the surface 202 of the structure 200.

[0102] 8, in one embodiment, when the first laser beam 156 encounters the structure 200, the first laser beam 156 is configured to generate, form, or otherwise induce a first ultrasonic wave 234 within the structure 200. In other words, when the first laser beam 156 is transmitted to the surface 202 of the structure 200, a first ultrasonic wave 234 may be generated. The energy within the first laser beam 156 induces a thermoelastic expansion within the structure 200. The thermoelastic expansion results in the first ultrasonic wave 234 within the structure 200. The first ultrasonic wave 234 is an example of an ultrasonic wave 204 (FIG. 2).

[0103] In one example, the first ultrasonic wave 234 has a frequency of about 20 kilohertz (kHz) to about 10 megahertz (MHz), depending on the particular implementation, for example. For example, the frequency of the first ultrasonic wave 234 may depend on the material 244 ( FIG. 2 ) used to form the structure 200, the pulse width of the laser excitation, and other suitable factors.

[0104] 9, in one embodiment, the first ultrasonic wave 234 is configured to generate a first response 236. In other words, the first response 236 is a feedback generated by the first ultrasonic wave 234. In one embodiment, the first response 236 includes a second ultrasonic wave 238 that occurs as a result of scattering, reflection, modulation, and other changes to the first acoustic wave 234 (FIG. 8) traveling within the structure 200. In other words, the first response 236 is formed from the second ultrasonic wave 238 that occurs as a response to the first ultrasonic wave 234. The second ultrasonic wave 238 is an example of the ultrasonic wave 204 (FIG. 2). The first response 236 is an example of the response 206 (FIG. 2).

[0105] In one embodiment, the first response 236 is detected by transmitting a second laser light 158 ​​to the surface 202 of the structure 200 and detecting a second response 240 to the second laser light 158. In one embodiment, the second response 240 is a third laser light 242 that is detected by the first response 236. The third laser light 242 is a portion of the second laser light 158 ​​that is reflected from the surface 202. For example, a second ultrasonic wave 238 (e.g., the first response 236) caused by the first ultrasonic wave 234 traveling within the structure 200 reaches the surface 202 of the structure 200 and generates or forms a mechanical vibration on the surface 202. The mechanical vibration is detected. The second response 240 is an example of the response 206 (FIG. 2).

[0106] In one embodiment, the first response 236 is detected using an ultrasonic receiver 150. The ultrasonic receiver 150 transmits a second laser light 158 ​​(e.g., a reference laser light) and detects mechanical vibrations on the surface 202 as a second response 240. In one embodiment, upon detecting the second response 240, the ultrasonic receiver 150 transmits data 132 to the computer 114 (FIG. 2). The computer 114 uses the data 132 to generate information indicative of whether the inconsistency 212 is present in the structure 200.

[0107] In an exemplary embodiment, the laser ultrasonic testing system 102 is used to test portions of the structure 200 where the surface 202 of the structure 200 has a varying contour shape. The laser ultrasonic testing system 102 is also used to test portions of the structure 200 where non-planar features are present. The non-planar features may include, but are not limited to, at least one of radii, edges, grooves, and other non-planar features.

[0108] 8 and 9, during a laser ultrasonic testing operation, the output 110 of the transmitter 108 is positioned at a predetermined offset distance relative to the surface 202 of the structure 200. As the first laser beam 156 and the second laser beam 158 move along the scan path 116 (FIG. 2) across the surface 202 of the structure 200, the output 110 of the transmitter 108 is maintained at a substantially constant offset distance 180 relative to the surface 202.

[0109] In one example, the offset distance 180 refers to the linear distance between the surface 202 of the structure 200 and the output 110 of the transmitter 108. In other words, the offset distance 180 represents the distance the laser light 106 travels from the transmitter 108 to the surface 202 within an acceptable error. In one example, the offset distance 180 between the output 110 of the transmitter 108 and the surface 202 of the structure 200 is between about 9 millimeters and about 11 millimeters. In one embodiment, the offset distance 180 is about 10 millimeters. Other offset distances 180 may be used when positioning the output 110 of the transmitter 108 depending on the particular implementation. As the first laser light 156 and the second laser light 158 ​​travel along the scan path 116 (FIG. 2) and across the surface 202 of the structure 200, the output 110 of the transmitter 108 is maintained at a substantially constant offset distance 180 relative to the surface 202 of the structure 200.

[0110] During a laser ultrasonic testing operation, each transmission of the first laser beam 156 and the second laser beam 158 from the output 110 of the transmitter 108 is oriented at a predetermined projection angle 182 with respect to a frame of reference (such as the frame of reference 118 of the test environment 100, the transmitter frame of reference 136, or the structure frame of reference 210). As the first laser beam 156 and the second laser beam 158 move along the scan path 116 (FIG. 2) and across the surface 202 of the structure 200, the first laser beam 156 and the second laser beam 158, respectively, are maintained at a substantially constant projection angle 182 with respect to the corresponding frame of reference.

[0111] As used herein, projection angle 182 refers to the angular orientation of laser beam 106 (e.g., first laser beam 156 and second laser beam 158) relative to a corresponding reference frame, which achieves a desired angle of impact 184 between laser beam 106 and surface 202 of structure 200 within an acceptable tolerance. In one example, angle of impact 184 is between about 88 degrees and about 92 degrees. In one embodiment, angle of impact 184 is about 90 degrees.

[0112] 10, in one embodiment, the transmitter 108 further includes a transmitter housing 146. In one embodiment, the transmitter housing 146 includes a frame or some other type of physical structure. The transmitter housing 146 is shown in dashed lines in FIG. 10. In one embodiment, the transmitter housing 146 takes the form of an end effector 128 and is configured to couple to the robot 122 (FIG. 4).

[0113] In an exemplary embodiment, the ultrasonic generator 148 and the ultrasonic receiver 150 are associated with the transmitter 108. The ultrasonic generator 148 is configured to optically transmit the laser light 106 (e.g., a first laser light 156) to the transmitter 108. The ultrasonic receiver 150 is configured to optically transmit the laser light 106 (e.g., a second laser light 158) to the transmitter 108. The ultrasonic receiver 150 is further configured to detect a response 206 ( FIG. 2 ) to the ultrasonic waves 204.

[0114] In one embodiment, the laser ultrasonic testing system 102 includes a first array of optical fibers 152. The first array of optical fibers 152 includes a plurality of optical fibers arranged in an array. The optical fibers of the first array of optical fibers 152 may be implemented using any type of optical fiber configured to carry light within the optical fiber. Any number of optical fibers and / or other types of arrays may be used for the first array of optical fibers 152.

[0115] The first array of optical fibers 152 optically couples together the ultrasonic generator 148 and the transmitter 108. The first array of optical fibers 152 is configured to receive the first laser light 156 from the ultrasonic generator 148 and transmit the first laser light 156 from the output 110 of the transmitter 108 in the form of a first pattern 160 to the surface 202 of the structure 200. The first laser light 156 from the first array of optical fibers 152 is configured to cause excitation within the structure 200. In other words, the first laser light 156 from the first array of optical fibers 152 is configured to generate a first ultrasonic wave 234 within the structure 200.

[0116] In one embodiment, the laser ultrasonic testing system 102 includes a second array of optical fibers 154. The second array of optical fibers 154 includes a plurality of optical fibers arranged in an array. The optical fibers of the second array of optical fibers 154 may be implemented using any type of optical fiber configured to carry light within the optical fiber. Any number of optical fibers and / or other types of arrays may be used for the second array of optical fibers 154.

[0117] A second array of optical fibers 154 optically couples together the ultrasonic receiver 150 and the transmitter 108. The second array of optical fibers 154 is configured to receive the second laser light 158 ​​from the ultrasonic receiver 150 and transmit the second laser light 158 ​​from the output 110 of the transmitter 108 in a second pattern 162 to the surface 202 of the structure 200. The second array of optical fibers 154 is configured to receive (e.g., detect) a second response 240 ( FIG. 9 ) to the second laser light 158. The second laser light 158 ​​is not configured to generate ultrasonic waves within the structure 200. Instead, the second laser light 158 ​​is configured to reflect, scatter, or interact with the surface 202 of the structure 200, the air surrounding the surface 202 of the structure 200, or both, such that a portion of the second laser light 158 ​​(e.g., the third laser light 178) that reflects back to the second array of optical fibers 154 and is received by the second array can be affected by the second ultrasonic waves 238 in the first reaction 236 that reach the surface 202 of the structure 200.

[0118] In some embodiments, there is an overlap in time between the first pattern 160 and the second pattern 162 transmitted to the surface 202. This overlap allows the second array of optical fibers 154 to be used to monitor the first response 236, either simultaneously or prior to generating the first ultrasonic waves 234.

[0119] In other embodiments, each optical fiber in the first array of optical fibers 152 may transmit the first laser light 156 sequentially, rather than simultaneously. Additionally, groups of optical fibers in the first array of optical fibers 152 may transmit the first laser light 156 sequentially. The second laser light 158 ​​may be transmitted in a similar manner as the second array of optical fibers 154. In other embodiments, the first laser light 156 and the second laser light 158 ​​may be transmitted using different phases, wavelengths, or both.

[0120] In some embodiments, mechanisms such as delay lines and delay circuits separate the laser sources in the ultrasonic generator 148 and / or the ultrasonic receiver 150. These mechanisms can reduce crosstalk in the optical fibers that results in a first laser light 156 in the first array of optical fibers 152 and a second laser light 158 ​​in the second array of optical fibers 154 exiting one optical fiber and entering another optical fiber. In other words, different phases, wavelengths, timing, or any combination thereof may be used to reduce crosstalk between the optical fibers in the first array of optical fibers 152 and the second array of optical fibers 154.

[0121] In one embodiment, the transmitter 108 further includes a number of optical elements 170 configured to direct and / or modify the transmission of the first laser light 156 and the second laser light 158 ​​from the output 110 of the transmitter 108 to the surface 202 of the structure 200. Additionally, the optical elements 170 may further direct the second response 240 (e.g., the third laser light 178) to the second array of optical fibers 154. In some embodiments, the optical elements 170 include at least one of a lens, a mirror, a diffractive optical element, a polarizer, a wave plate, a periodically-poled Lithium niobate crystal, or other suitable optical element.

[0122] In one embodiment, the optical elements 170 are configured to shape the first laser beam 156 that is transmitted from the first array of optical fibers 152 to form the first pattern 160. Similarly, the optical elements 170 are configured to shape the second laser beam 158 that is transmitted from the second array of optical fibers 154 to form the second pattern 162. In some embodiments, the optical elements 170 may be used to change the deflection of the first laser beam 156 and / or the second laser beam 158, the color of the first laser beam 156 and / or the second laser beam 158, and other parameters of the first laser beam 156 and / or the second laser beam 158.

[0123] In one embodiment, the optical element 170 includes a cylinder lens 188. The cylinder lens 188 is configured to cause the first laser light 156 transmitted by the first array of optical fibers 152 to form a linear beam. In other words, the cylinder lens 188 is configured to shape the first laser light 156. In one embodiment, the cylinder lens 188 is configured to cause the first laser light 156 to form the first pattern 160 on the surface 202 of the structure 200 as a continuous line. In one embodiment, the cylinder lens 188 may function to cause the first pattern 160 of the first laser light 156 to have an intensity with a Gaussian profile. In one embodiment, the Gaussian profile is in the X and Y directions relative to a plane on the surface 202 of the structure 200.

[0124] In one embodiment, the first array of optical fibers 152 are spaced apart such that the first pattern 160 illuminates a pattern of discrete areas on the surface 202 of the structure 200. In one embodiment, the first array of optical fibers 152 and / or the optical elements 170 are configured to transmit the first laser light 156 from the output 110 of the transmitter 108 as a first array of laser beams, such as a first array of pulsed laser beams.

[0125] In one embodiment, first pattern 160 takes the form of lines 124 (FIG. 4). In one embodiment, first pattern 160 is formed from the intersection or overlap of a laser beam on surface 202 of structure 200.

[0126] In one embodiment, the second array of optical fibers 154 is spaced apart such that the second pattern 162 illuminates a pattern of individual areas on the surface 202 of the structure 200. In one embodiment, the second array of optical fibers 154 and / or the optical elements 170 are configured to transmit the second laser light 158 ​​from the output 110 of the transmitter 108 as a second array of laser beams, such as a second array of pulsed laser beams.

[0127] In one embodiment, second pattern 162 takes the form of lines 124 (FIG. 4). In one embodiment, second pattern 162 is formed from the crosstalk or overlap of a second array of laser beams on surface 202 of structure 200.

[0128] In one embodiment, the optical element 170 includes a number of mirrors 190 configured to manipulate the direction in which the first array of laser beams of the first laser beam 156 and / or the second array of laser beams of the second laser beam 158 travel to reach the surface 202 of the structure 200. The mirrors 190 are further configured to control the direction in which the third laser beam 178 of the second reaction 240 travels.

[0129] In one embodiment, the optical fibers of the first array of optical fibers 152 may be grouped and covered to form a fiber bundle 192. In one embodiment, an end of the fiber bundle 192 is optically coupled to a collimator 194. In one embodiment, the collimator 194 is optically coupled to the laser 186. In one embodiment, the first laser light 156 is transmitted through the collimator 194. The collimator 194 is configured to make the first laser light 156 coherent.

[0130] In another embodiment, the ultrasonic generator 148 includes a number of collimators 194. In one embodiment, each optical fiber of the first array of optical fibers 152 is optically coupled to a corresponding one of the plurality of collimators 194.

[0131] In one embodiment, the interferometer 164 is a hardware device and is configured to determine information from the third laser light 178 that forms the second response 240 ( FIG. 9 ). In one embodiment, the interferometer 164 may include a number of interferometers. The information determined by the interferometer 164 may include, for example, displacement, deflection, surface flow velocity, and other information that may be used to determine the second response 240 detected by the second array of optical fibers 154 that receive the third laser light 178 in the second response 240.

[0132] In one embodiment, the ultrasound receiver 150 further includes a number of collimators 196. In one embodiment, each of the optical fibers of the second array of optical fibers 154 is optically coupled to a corresponding one of the collimators 196. In one embodiment, the collimators 196 may be implemented using a variety of different types of collimators. For example, the collimators 196 may be selected from at least one of an aspheric lens collimator, a spherical lens collimator, a grin lens collimator, or any other suitable type of collimator. The collimators 196 are configured to make the second laser light 158 ​​coherent.

[0133] In one embodiment, the third laser light 242 in the second response 240 is received or detected at one end of the second array of optical fibers 154 and transmitted through the second array of optical fibers 154 in a direction opposite to the transmission of the second laser light 158. In one embodiment, the opposite end of the second array of optical fibers 154 is coupled to an interferometer 164. In this embodiment, the interferometer 164 is the source of the second laser light 158 ​​and receives the second response 240.

[0134] This disclosure recognizes that in order to maintain a substantially constant offset distance 180 and projection angle 182 of the laser beam 106 as it moves along the scan path 116 across the surface 202 of the structure 200, it is necessary to know the contour shape of the surface 202 and / or the three-dimensional position 208 of the surface 202 relative to the reference frame 118.

[0135] 2 , in one embodiment, the computer 114 is configured to utilize the three-dimensional point cloud data 248 to determine three-dimensional positions 208 of the plurality of points 222 on the surface 202 of the structure 200. In one embodiment, the three-dimensional positions 208 of the plurality of points 222 on the surface 202 are determined relative to the structural reference frame 210. In one embodiment, the computer 114 is further configured to position the three-dimensional positions 208 of the plurality of points 222 on the surface 202 relative to the reference frame 118. In one embodiment, the computer 114 is configured to perform a transformation operation on the structural reference frame 210, for example by executing instructions or implementing a software tool, such that the structural reference frame 210 is aligned with the reference frame 118 and the three-dimensional positions 208 of the plurality of points 222 on the surface 202 are positioned relative to the reference frame 118.

[0136] In various embodiments, the three-dimensional point cloud data 248 representing the surface 202 of the structure 200 is generated by any one of a variety of methods. In one embodiment, the computer 114 is configured to extract the three-dimensional point cloud data 248 representing the surface 202 of the structure 200 from the three-dimensional model 246 of the structure 200. In one embodiment, based on the three-dimensional point cloud data 248 of the surface 202, the computer 114 is further configured to determine three-dimensional positions 208 of the plurality of points 222 on the surface 202 relative to the reference frame 118.

[0137] In various embodiments, three-dimensional model 246 of structure 200 is generated by any one of a variety of different methods. In one embodiment, three-dimensional model 246 is generated using a computer-aided design (CAD) tool or software implemented on a computer (such as processor 140 of computer 114 or another computer system).

[0138] In one embodiment, the three-dimensional model 246 is generated using a number of images 250. In various embodiments, the images 250 of the structure 200 are generated by any one of a variety of different methods. In one embodiment, the laser ultrasonic testing system 102 is configured to acquire the images 250 of the structure 200. In one embodiment, the images 250 are acquired before the start of an ultrasonic testing operation. In one embodiment, the images 250 are acquired during the performance of an ultrasonic testing operation, for example, as the laser beam 106 moves across the surface 202 to scan the structure 200.

[0139] In one embodiment, the laser ultrasonic testing system 102 includes a sensor 198. The sensor 198 is configured to acquire an image 250 of the structure 200. In one embodiment, the computer 114 is configured to generate a three-dimensional model 246 of the structure 200 from the image 250 of the structure 200. In another embodiment, the computer 114 is configured to extract three-dimensional point cloud data 248 representing the surface 202 of the structure 200 directly from the image 250 of the structure 200, for example, by executing instructions or implementing a software tool.

[0140] In one embodiment, the sensor 198 includes a sensor housing. The sensor housing may include a frame or some other type of physical structure. In one embodiment, the sensor 198 takes the form of a part of the end effector 128 or is otherwise configured to be coupled to the transmitter 108 or the robot 122 (FIG. 4).

[0141] Sensor 198 may include any one of a variety of types of image acquisition systems. In one embodiment, sensor 198 may include or take the form of a type of stereo vision system. In one embodiment, sensor 198 may include or take the form of a type of structured light system. In one embodiment, sensor 198 may include or take the form of a three-dimensional laser scanner or other type of laser measurement system.

[0142] In one embodiment, the sensor 198 includes a number of cameras configured to capture the images 250 in the form of a number of two-dimensional images.

[0143] In one embodiment, sensor 198 includes a number of light sources. The light sources are configured to illuminate a portion of surface 202 of structure 200. In one embodiment, the light sources are configured to transmit structured light to surface 202 of structure 200. The cameras are configured to capture a number of images 250 of surface 202 and the structured light reflected from surface 202.

[0144] In one embodiment, the processor 140 of the computer 114 is configured to receive the number of images 250, e.g., by executing instructions or implementing a software tool, and determine changes in the contour of the surface 202 of the structure 200 based on one or more image processing operations. In one embodiment, the image processing operations are performed using a software tool implemented in a computer (e.g., the processor 140 of the computer 114 or another computer system).

[0145] Determining the contour of the surface 202 of the structure 200 may be accomplished by any other suitable optical means. In one embodiment, the sensor 198 includes or takes the form of a laser measurement device that uses a point cloud method to measure a number of points 222 of the surface 202 in three-dimensional space. The three-dimensional position 208 or contour of the surface 202 of the structure 200 is extracted from the three-dimensional point cloud data 248. In one embodiment, the points 222 are each measured with a laser range finder. In one embodiment, the sensor 198 includes or takes the form of a profilometer that uses a laser line scan to measure the shape of the surface 202 of the structure 200. The laser line scan system generates a two-dimensional shape of the surface 202 along a line.

[0146] Positioning the laser beam 106 on the surface 202 during scanning may include, for example, moving the transmitter 108 using a motion mechanism 112 relative to the structure 200 to move the laser beam 106 along a scan path 116. In some embodiments, the scan path 116 is a dynamically calculated path generated using input from the sensor 198, a pre-planned path based on a three-dimensional model 246 (e.g., a CAD description) of the structure 200, or a combination of the two. This disclosure recognizes that a physical structure, particularly a composite structure, may differ from the CAD description of the structure.

[0147] 11, there is further disclosed an exemplary method 1000 for testing a structure using laser ultrasound. For example, the disclosed method 1000 may be used to test a structure 200 using a laser ultrasonic testing system 102.

[0148] In one embodiment, the method 1000 includes determining a three-dimensional position 208 of a surface 202 of a structure 200 relative to a reference frame 118 (block 1002 ).

[0149] In one embodiment, the method 1000 includes transmitting laser light 106 from an output 110 of a transmitter 108 to a surface 202 of a structure 200, forming ultrasonic waves 204 within the structure 200, and detecting a response 206 to the ultrasonic waves 204 (block 1004).

[0150] In one embodiment, the method 1000 includes a step of moving the laser light 106 over the structure 200 along a scan path 116 based on a three-dimensional position 208 of the surface 202 such that the output 110 of the transmitter 108 is located at a constant offset distance 108 from the surface 202 and the laser light 106 transmitted from the output 110 of the transmitter 108 is directed toward the surface 202 at a constant projection angle 182 (block 1006).

[0151] In one embodiment, the method 1000 includes determining whether an inconsistency 212 exists in the structure 200 based on the response 206 to the ultrasound wave 204 (Block 1008).

[0152] 12 and 13, in one embodiment, each of the plurality of points 222 on the surface 202 has a corresponding three-dimensional position 208 relative to the reference frame 118. The three-dimensional positions 208 include XYZ coordinates in the reference frame 118. The Z coordinate of one of the plurality of points 222 on the surface 202 is different from the Z coordinate of another of the plurality of points 222 on the surface 202.

[0153] In one embodiment, as shown in FIG. 12, a first point 224 (e.g., a first point of the plurality of points 222) has a first XYZ coordinate, and a second point 226 (e.g., a second point of the plurality of points 222) has a second XYZ coordinate. The first point 224 has a first Z coordinate (Z1), and the second point 226 has a second Z coordinate (Z2). The first Z coordinate (Z1) and the second Z coordinate (Z2) are different. A difference value 256 between the first Z coordinate (Z1) and the second Z coordinate (Z2) represents a change in the contour of the surface 202 along the Y axis between the first Y coordinate (Y1) and the second Y coordinate (Y2) in the YZ plane of the reference frame 118.

[0154] 13, a first point 224 (e.g., a first point of the plurality of points 222) has a first XYZ coordinate, a third point 228 (e.g., a second point of the plurality of points 222) has a second XYZ coordinate, and a fourth point 230 has a third XYZ coordinate. The first point 224 has a first Z coordinate (Z1), the third point 228 has a second Z coordinate (Z2), and the fourth point 230 has a third Z coordinate (Z3). The first Z coordinate (Z1), the second Z coordinate (Z2), and the third Z coordinate (Z3) are different. The difference value 256 between the first Z coordinate (Z1) and the second Z coordinate (Z2) represents a change in the contour of the surface 202 along the X axis between the first X coordinate (X1) and the second X coordinate (X2) in the XZ plane of the reference frame 118. The difference value 256 between the second Z coordinate (Z2) and the third Z coordinate (Z3) represents a change in the contour of the surface 202 along the X axis between the second X coordinate (X2) and the third X coordinate (X3) in the XZ plane of the reference frame 118. The difference value 256 between the first Z coordinate (Z1) and the third Z coordinate (Z3) represents a change in the contour of the surface 202 along the X axis between the first X coordinate (X1) and the third X coordinate (X3) in the XZ plane of the reference frame 118.

[0155] Referring to FIG. 11, in one embodiment, a method 1000 includes forming laser light 106 transmitted from an output 110 of a transmitter 108 into a pattern 120 on a surface 202 of a structure 200 (block 1010).

[0156] In one embodiment, the method 1000 includes a step of positioning the pattern 120 on the surface 202 such that a difference value 256 of the Z coordinates of any two of a plurality of points 222 on the surface 202 that are located comprehensively within the pattern 120 of the laser light 106 is less than or equal to a threshold value 254 (block 1012).

[0157] In one embodiment, according to method 1000, threshold 254 is equal to or less than approximately one-eighth of an inch (3 millimeters). In other embodiments, threshold 254 may be greater than one-eighth of an inch. Threshold 254 may depend on various factors, such as the type of material 244 of structure 200, the type of laser source 104 used to generate laser light 106, the characteristics of laser light 106, and other factors.

[0158] In general, the threshold 254 represents a maximum allowable difference value 256 that describes the change in the contour of the surface 202 (e.g., the slope of the surface 202) over a distance such that the laser light 106 in the form of the pattern 120 of the laser light 106 may be accurately used to generate data 132 characterizing the structure 200. For example, if the condition of the difference value 256 of any two of the plurality of points 222, located collectively within the pattern 120 of the laser light 106, exceeds the threshold 254, the offset distance 180 and / or the projection angle 182 may not remain constant for the laser light 106 over the pattern 120 of the laser light 106.

[0159] In one embodiment, according to method 1000 , pattern 120 of laser light 106 takes the form of lines 124 of laser light 106 .

[0160] In one embodiment, the method 1000 includes a step of identifying a first point of the plurality of points 222 on the surface 202 and a second point of the plurality of points 222 on the surface 202, wherein a difference value 256 of the Z coordinates in the reference frame 118 of any two of the plurality of points 222 on the surface 202 that are located comprehensively along a straight line 258 extending between the first point of the plurality of points 222 and the second point of the plurality of points 222 is less than or equal to a threshold value 254.

[0161] In one embodiment, the method 1000 includes aligning the line 124 of the laser light 106 with a straight line 258 extending between a first point of the plurality of points 222 and a second point of the plurality of points 222.

[0162] 14, in one embodiment, a straight line 258 is generated extending between the first point 224 (e.g., the first point of the plurality of points 222) and the second point 226 (e.g., the second point of the plurality of points 222). In this embodiment, the difference value 256 of the Z coordinates of any two of the plurality of points 222 located inclusively along the straight line 258 extending between the first point 224 and the second point 226 exceeds the threshold value 254. Thus, the line 124 of the laser light 106 will not be aligned with the straight line 258 extending between the first point 224 and the second point 226 to scan the structure 200. In one embodiment, a straight line 258 is generated extending between the first point 224 (e.g., the first point of the plurality of points 222) and the fourth point 230 (e.g., the second point of the plurality of points 222). In this embodiment, the difference value 256 of the Z coordinates of any two of the plurality of points 222 located inclusively along the straight line 258 extending between the first point 224 and the fourth point 230 exceeds the threshold value 254. Thus, the line 124 of the laser light 106 will not be aligned with the straight line 258 extending between the first point 224 and the fourth point 230 to scan the structure 200. In one embodiment, a straight line 258 extending between the first point 224 (e.g., the first point of the plurality of points 222) and the third point 228 (e.g., the second point of the plurality of points 222) is generated. In this embodiment, the difference value 256 of the Z coordinates of any two of the plurality of points 222 located inclusively along the straight line 258 extending between the first point 224 and the third point 228 is less than or equal to the threshold value 254. Thus, the line 124 of the laser light 106 will be aligned with the straight line 258 extending between the first point 224 and the third point 228 to scan the structure 200 .

[0163] In one embodiment, the method 1000 includes focusing the line 124 of the laser light 106 globally between a first point of the plurality of points 222 and a second point of the plurality of points 222 .

[0164] In one embodiment, the line 124 can be sized, for example, by setting and / or adjusting the first linear dimension 174 of the pattern 120 of the laser light 106 so that the first linear dimension 174 of the pattern 120 of the laser light 106 is equal to or less than a linear dimension of a straight line 258 extending between a first point of the plurality of points 222 and a second point of the plurality of points 222 (e.g., a straight line 258 extending between the first point 224 and the third point 228).

[0165] In one embodiment, the method 1000 includes a step of identifying a third point of the plurality of points 222 on the surface 202 and a fourth point of the plurality of points 222 on the surface 202, wherein a difference value 256 of the Z coordinates in the reference frame 118 of any two of the plurality of points 222 on the surface 202, located comprehensively along a second straight line 260 extending between the third point of the plurality of points 222 and the fourth point of the plurality of points 222, is less than or equal to a threshold value 256.

[0166] Referring to FIG. 11 , in one embodiment, the method 1000 includes selecting a scan path 116 of the laser light 106 between a straight line 258 extending between a first point of the plurality of points 222 and a second point of the plurality of points 222 and a second straight line 260 extending between a third point of the plurality of points 222 and a fourth point of the plurality of points 222 (block 1014).

[0167] In one embodiment, the method 1000 includes moving the line 124 of the laser light 106 across the surface 202 along the scan path 116 .

[0168] In one embodiment, the method 1000 includes aligning the line 124 of the laser light 106 with a second straight line 260 extending between a third point of the plurality of points 222 and a fourth point of the plurality of points 222.

[0169] 15, in one embodiment, a second straight line 260 is generated extending between a fifth point 262 (e.g., a third point of the plurality of points 222) on the surface 202 and a sixth point 264 (e.g., a fourth point of the plurality of points 222) on the surface 202. In this embodiment, the difference value 256 of the Z coordinates of any two of the plurality of points 222 located inclusively along the second straight line 260 extending between the fifth point 262 and the sixth point 264 is less than or equal to the threshold value 254. Thus, to further scan the structure 200, the line 124 of the laser light 106 will move across the surface 202 along the scan path 116 such that the line 124 of the laser light 106 is aligned with the second straight line 260 extending between the fifth point 262 and the sixth point 264.

[0170] In one embodiment, the computer 114 is configured to generate the scan path 116, for example, by executing instructions or implementing a software tool. In one embodiment, the processor 114 of the computer 114 is configured to calculate the scan path 116, for example, by executing instructions or implementing a software tool. In one embodiment, the processor 114 is configured to calculate a vector of the scan path 116 relative to the reference frame 118, for example, by executing instructions or implementing a software tool. In one embodiment, the scan path 116 is determined based at least in part on the calculated difference values ​​256 of the plurality of points 222 on the surface 202 using the three-dimensional positions 208 of the plurality of points 222, the first linear dimension 174 of the pattern 120 of the laser light 106, the predetermined offset distance 180, the predetermined projection angle 182, and other factors.

[0171] The scan path 116 along which the laser light 106 travels to adequately test the structure 200 is generally predetermined. In one embodiment, a preliminary scan path is generated based on the type of structure 200. The final scan path 116 is generated by adjusting the preliminary scan path based on a three-dimensional model 246 (e.g., a CAD description) of the structure 200, the real-time part geometry generated by the sensor 198, the size and / or density of the pattern 120 of the laser light 106, the spacing of the laser ultrasonic elements, the maximum speed allowed by the physics of ultrasonic waves (e.g., the time it takes for sound to travel through the part), and other factors.

[0172] 11 , in one embodiment, the method 1000 includes adjusting the attitude of the transmitter 108 such that the output 110 of the transmitter 108 is located at a constant offset distance 180 from the surface 202 and the laser light 106 transmitted from the output 110 of the transmitter 108 is directed toward the surface 202 at a constant projection angle 182 as the line 124 of the laser light 106 moves across the surface 202 along the scan path 116 between a straight line 258 extending between a first point of the plurality of points 222 and a second point of the plurality of points 222 and a second straight line 260 extending between a third point of the plurality of points 222 and a fourth point of the plurality of points 222 (block 1016).

[0173] In one embodiment, the computer 114 is configured, for example, by executing instructions or implementing a software tool, to ascertain the orientation of the transmitter 108 relative to the frame of reference 118 of the test environment 100. In one embodiment, the processor 140 is configured, for example, by executing instructions or implementing a software tool, to calculate a difference in the position and / or orientation of the transmit frame of reference 136 relative to the frame of reference 118 and / or the structure frame of reference 210, and determine the orientation of the transmitter 108 based on the position and / or orientation of the transmit frame of reference 136 within the frame of reference 118. In one embodiment, the processor 140 is configured, for example, by executing instructions or implementing a software tool, to calculate an appropriate orientation of the transmitter 108 as the transmitter 108 moves relative to the surface 202 of the structure 200, thereby maintaining a constant offset distance 180 and a constant projection angle 182 as the line 124 of the laser light 106 moves along the scan path 116. In one embodiment, the controller 138 is configured to control the motion of the moving mechanism 112 and adjust the attitude of the transmitter 108 as the line 124 of the laser light 106 moves along the scan path 116 .

[0174] 15 , in one embodiment, according to method 1000, structure 200 includes or takes the form of stiffener 214. Stiffener 214 is a component of aircraft 1200 ( FIG. 1 ). Stiffener 214 includes a first axis 216. A straight line 258 extending between a first point of plurality of points 222 and a second point of plurality of points 222 and a second straight line 260 extending between a third point of plurality of points 222 and a fourth point of plurality of points 222 are each oriented parallel to first axis 216 of stiffener 214.

[0175] 16, in one embodiment, according to the method 1000, the scan path 116 of the laser beam 106 is perpendicular to the first axis 216 of the stiffener 214. In one embodiment, the scan path 116 extends from one end of the stiffener 214 to an opposite end of the stiffener 214 and traverses the stiffener 214 perpendicular to the first axis 216. In FIG. 16, the line 124 of the laser beam 106 at various successive positions on the surface 202 as the line 124 moves along the scan path 116 is shown in dashed lines. The scan path 116 is selected such that the line 124 of the laser beam 106 traverses back and forth across the stiffener 214. In one embodiment, the scan path 116 is selected such that the line 124 of the laser beam 106 covers a portion of the surface 202 or the same area on the surface 202 more than once as the line 124 of the laser beam 106 moves along the scan path 116. In one embodiment, when the line 124 of laser beam 106 reaches the outer edge of the scan path 116 (e.g., near the side of the stiffener 214), the line 124 of laser beam 106 is moved along the first axis 216 by an index 266. The index 266 is selected such that as the line 124 of laser beam 106 moves along the scan path 116, the line 124 of laser beam 106 covers a portion of the surface 202 or the same area on the surface 202 more than once.

[0176] 17, in one embodiment, according to the method 1000, the scan path 116 of the laser beam 106 is oblique to the first axis 216 of the stiffener 214. In one embodiment, the scan path 116 extends from one end of the stiffener 214 to the opposite end of the stiffener 214 and traverses the stiffener 214 obliquely to the first axis 216. In FIG. 17, the line 124 of the laser beam 106 at various successive positions on the surface 202 as the line 124 moves along the scan path 116 is shown in dashed lines. The scan path 116 is selected such that the line 124 of the laser beam 106 traverses back and forth across the stiffener 214. In one embodiment, the scan path 116 is selected such that the line 124 of the laser beam 106 covers a portion of the surface 202 or the same area on the surface 202 more than once as the line 124 of the laser beam 106 moves along the scan path 116.

[0177] In one embodiment, the method 1000 includes simulating a scan path 116 of the laser light 106 as the line 124 of the laser light 106 moves across the surface 202 of the structure 200, based on a three-dimensional model 246 of the surface 202, such that a difference value 256 of the Z coordinates of any two of a plurality of points 222 on the surface 202 that are located comprehensively within the line 124 of the laser light 106 is less than or equal to a threshold value 254.

[0178] In one embodiment, the simulation of the scan path 116 is generated using a software tool that allows for simulation of a robot path in relation to a three-dimensional model 246 of the structure 200 .

[0179] Thus, the laser ultrasonic testing system 102 and method 1000 disclosed herein may enable rapid, non-destructive testing of a variety of different cross-sectional and / or surface contour shapes.

[0180] Embodiments of the system 102 and method 1000 disclosed herein may find use in a variety of potential applications, particularly in the transportation industry, including, for example, aerospace applications. Referring now to Figures 1 and 18, embodiments of the system 102 and method 1000 may be used in connection with an aircraft manufacturing and service method 1100 shown in the flow diagram of Figure 18, as well as the aircraft 1200 shown in Figure 1. Aircraft applications of the disclosed embodiments may include use in the system 102 for ultrasonic testing of composite structures of the aircraft 1200.

[0181] As shown in FIG. 18 , during pre-production, the example method 1100 may include specification and design of the aircraft 1200 (block 1102) and material procurement (block 1104). During production of the aircraft 1200, component and subassembly manufacturing (block 1106) and system integration (block 1108) of the aircraft 1200 may occur. The aircraft 1200 may then undergo certification and delivery (block 1110) and be placed into service (block 1112). The disclosed system 102 and method 1000 may form part of component and subassembly manufacturing (block 1106) and / or system integration (block 1108). Routine maintenance and upkeep may include modification, reconfiguration, refurbishing, etc., of one or more systems of the aircraft 1200.

[0182] Each process of the example method may be performed or implemented by a system integrator, a third party, and / or an operator (e.g., a customer). For purposes of this specification, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors, a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers, and an operator may be an airline, a leasing company, a military entity, a service organization, etc.

[0183] The embodiments of the system 102 and method 1000 shown or described herein may be utilized during any one or more stages of the manufacturing and service method 1100 illustrated in the flow diagram illustrated in FIG. 18. For example, components or subassemblies corresponding to the manufacturing of components and subassemblies (block 1106) may be made or manufactured in a similar manner as components or subassemblies manufactured during the operation of the aircraft 1200 (block 1112). Additionally, one or more embodiments of the system 102, method 1000, or combinations thereof may be utilized during system integration (block 1108) and certification and delivery (block 1110). Similarly, one or more embodiments of the system 102, method 1000, or combinations thereof may be utilized during the operation of the aircraft 1200 (block 1112) and during the maintenance and service (block 1114) stages, for example, but not limited to.

[0184] The example embodiment of aircraft 1200 ( FIG. 1 ) is provided for illustrative purposes and is not intended to suggest architectural limitations to the manner in which various examples may be implemented. For example, while aircraft 1200 is shown as a commercial passenger aircraft, in other examples, aircraft 1200 may be other types of aircraft, such as a private passenger aircraft, a cargo aircraft, a rotorcraft, an unmanned aerial vehicle, or any other suitable type of aircraft.

[0185] Although exemplary embodiments of the disclosed system 102 and method 1000 are described with respect to an aircraft, other embodiments may be applied to other types of platforms. The platform may be, for example, a mobile platform, a fixed platform, a land structure, a water structure, or a space structure. More specifically, the platform may be a surface ship, a tank, a personnel carrier, a train, a spacecraft, a space station, a satellite, a submarine, an automobile, a manufacturing facility, a building, and other suitable platforms.

[0186] Additionally, embodiments of the disclosed system 102 and method 1000 may be applied to other types of composite structures. For example, composite structures other than platforms may be inspected using a laser ultrasound inspection system. The composite structures other than platforms may include medical devices, prosthetic limbs, or any other desired products.

[0187] Reference herein to an "example" means that one or more features, structures, elements, components, properties, and / or operational steps described in connection with the example are included in at least one embodiment and / or implementation of the subject matter disclosed herein. Thus, the phrases "one example," "another example," and similar phrases throughout this disclosure may, but do not necessarily, refer to the same example. Moreover, subject matter characterizing any one example may, but does not necessarily, include subject matter characterizing any other example.

[0188] In this specification, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is not in fact capable of performing the particular function without any modification, but rather may perform the particular function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured" to perform a particular function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the particular function. In this specification, the phrase "configured to" refers to the existing characteristics of a system, device, structure, article, element, component, or hardware that enable the system, device, structure, article, element, component, or hardware to perform a particular function without further modification. For the purposes of this disclosure, a system, device, structure, article, element, component, or hardware that is described as "configured" to perform a particular function may additionally or alternatively be described as "adapted to" and / or "operative to" perform the function.

[0189] Unless otherwise indicated, terms such as "first," "second," and the like are used herein merely as labels and are not intended to impose any sequential, positional, or hierarchical requirements on the items they refer to. Furthermore, reference to a "second" item does not require or preclude the presence of a smaller number item (e.g., the "first" item) and / or a larger number item (e.g., the "third" item).

[0190] As used herein, "coupled," "coupling," and similar terms refer to two or more elements that are coupled, joined, fastened, connected, in communication, or otherwise associated with one another (e.g., mechanically, electrically, fluidly, optically, electromagnetically). In various embodiments, these elements may be directly or indirectly associated. As an example, element A may be directly associated with element B. As another example, element A may be indirectly associated with element B, e.g., through another element C. It will be understood that not all associations between the various disclosed elements are necessarily depicted. As such, other connections than those shown in the figures may exist.

[0191] As used herein, the term "approximately" refers to a condition, amount, or value that is close to, but not necessarily close to, a given condition, amount, or value that still performs a desired function or achieves a desired result. For example, the term "approximately" can refer to an amount or value that is within ranges of less than 10%, less than 5%, less than 1%, less than 0.1%, and less than 0.01% of the given amount or value.

[0192] The term "substantially" in this specification may include the meanings of "exactly" and "similar", which means to the extent that it can be recognized as being exact. The term "substantially" may be quantified as a difference of + / -5% from the exact or actual value, which is for illustrative purposes only and is not a limiting example. For example, the phrase "A is substantially the same as B" may include a condition where A is exactly the same as B or A is within a difference of + / -5% of the value of B (or vice versa).

[0193] In the above-mentioned FIG. 2 and FIG. 7, when solid lines are present connecting various elements and / or components, these solid lines may represent mechanical, electrical, fluid, optical, electromagnetic, and other connections, and / or combinations thereof. It will be understood that not all relationships between various elements disclosed are necessarily represented. Thus, connections other than those depicted in the block diagrams may exist. When dashed lines are present connecting blocks representing various elements and / or components, these dashed lines represent connections similar in function and purpose to those represented by the solid lines. However, the connections represented by dashed lines may be either selectively provided or related to alternative embodiments of the present disclosure. Similarly, when dashed elements and / or components are present, they represent alternative embodiments of the present disclosure. One or more elements shown with solid and / or dashed lines may be omitted from a particular embodiment without departing from the scope of the present disclosure. When environmental elements are present, they are represented with dotted lines. Virtual (fictitious) elements may also be shown for clarity. Those skilled in the art will appreciate that some of the features shown in Figures 2 and 7 may be combined in various ways without necessarily including other features described in Figures 2 and 7, other figures, and / or the accompanying disclosure, even if such combination or combinations are not expressly set forth herein. Similarly, additional features, not limited to the examples presented, may be combined with some or all of the features shown and described herein.

[0194] In the above-mentioned FIG. 11 and FIG. 18, the blocks may represent steps and / or portions thereof, and the lines connecting various blocks do not suggest any particular order or dependency of the steps or portions thereof. The blocks shown with dashed lines represent alternative steps and / or portions thereof. When dashed lines connect various blocks, the dashed lines represent alternative dependencies of the steps or portions thereof. It will be understood that not all dependencies between the various disclosed steps are necessarily represented. FIG. 11 and FIG. 18, which describe the steps of the disclosed method presented herein, and the accompanying disclosure, should not be construed as necessarily dictating the order in which the steps should be performed. Rather, while an exemplary order is shown, it will be understood that the order of the steps can be modified, where appropriate. Thus, the illustrated steps may be modified, added, and / or omitted, and certain steps may be performed in a different order or simultaneously. Moreover, one skilled in the art will understand that it is not necessary to perform all the steps described.

[0195] In addition, the disclosure includes the embodiments described in the paragraphs listed below.

[0196] A1 A method (1000) for testing a structure (200) using laser ultrasound, comprising: determining a three-dimensional position (208) of a surface (202) of the structure (200) relative to a reference frame (118); transmitting laser light (106) from an output (110) of a transmitter (108) to the surface (202) of the structure (200) to generate ultrasonic waves (204) within the structure (200); detecting a response (206) to the ultrasonic waves (204); and detecting a response (206) to the ultrasonic waves (204) based on the three-dimensional position (208) of the surface (202) of the structure (200). a scanning path (116) for moving the laser light (106) over the structure (200) such that the output (110) of the transmitter (108) is located at a constant offset distance (180) from the surface (202) and such that the laser light (106) transmitted from the output (110) of the transmitter (108) is directed toward the surface (202) at a constant projection angle (182); and determining whether an inconsistency (212) exists within the structure (200) based on the response (206) to the ultrasonic waves (204).

[0197] A2 A method (1000) according to A1, wherein each of a plurality of points (222) on the surface (202) has a corresponding three-dimensional position (208) relative to the reference frame (118), the three-dimensional position (208) comprising X, Y and Z coordinates in the reference frame (118), and wherein a Z coordinate of one of the plurality of points (222) on the surface (202) differs from a Z coordinate of another one of the plurality of points (222) on the surface (202).

[0198] A3 The method (1000) according to A2, further comprising forming the laser light (106) transmitted from the output section (110) of the transmitter (108) into a pattern (120) on the surface (202) of the structure (200), and positioning the pattern (120) on the surface (202) such that a difference value (256) of Z coordinates of any two of the plurality of points (222) on the surface (202) that are located comprehensively within the pattern (120) of the laser light (106) is less than or equal to a threshold value (254).

[0199] A4 The method (1000) of A3, wherein the threshold (254) is equal to or less than one-eighth of an inch.

[0200] A5 The method (1000) of A3 or A4, wherein the pattern (120) of the laser light (106) is in the form of lines (124) of the laser light (106).

[0201] A6 identifying a first point of the plurality of points (222) on the surface (202) and a second point of the plurality of points (222) on the surface (202), wherein a difference value (256) of Z coordinates in the reference frame (118) of any two of the plurality of points (222) on the surface (202), which are located inclusively along a straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222), is less than or equal to the threshold value (254); and aligning the line (124) of the laser light (106) with the straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222).

[0202] A7 identifying a third point of the plurality of points (222) on the surface (202) and a fourth point of the plurality of points (222) on the surface (202), wherein a difference value (256) of a Z coordinate in the reference frame (118) between any two of the plurality of points (222) on the surface (202), which are located inclusively along a second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222), is less than or equal to the threshold value (254); and a second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222); moving the line (124) of the laser beam (106) along the scan path (116) across the surface (202); and aligning the line (124) of the laser (186) light with the second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222).

[0203] A8 20. The method (1000) of claim 19, further comprising: adjusting an attitude of the transmitter (108) such that the output (110) of the transmitter (108) is located at a constant offset distance (180) from the surface (202) and such that the laser light (106) transmitted from the output (110) of the transmitter (108) is directed toward the surface (202) at a constant projection angle (182).

[0204] A9 A method (1000) according to A7, wherein the structure (200) comprises a stiffener (214) of an aircraft (1200), the stiffener (214) comprising a first axis (216), and the straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222), and the second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222), are each oriented parallel to the first axis (216) of the stiffener (214).

[0205] A10 The method (1000) according to A9, wherein the scanning path (116) of the laser beam (106) is perpendicular to the first axis (216) of the reinforcement material (214).

[0206] A11 The method (1000) according to A9, wherein the scanning path (116) of the laser beam (106) is oblique to the first axis (216) of the reinforcement material (214).

[0207] A12 The method (1000) of A5 further comprises providing three-dimensional point cloud data (248) of the surface (202) of the structure (200), determining three-dimensional positions (208) of the plurality of points (222) on the surface (202) relative to a structural reference frame (210) based on the three-dimensional point cloud data (248) of the surface (202), and aligning the structural reference frame (210) with the reference frame (118).

[0208] A13 The method (1000) of A12, further comprising providing a three-dimensional model (246) of the structure (200) and extracting the three-dimensional point cloud data (248) of the surface (202) from the three-dimensional model (246) of the structure (200).

[0209] A14 The method (1000) of A13, further comprising obtaining an image (250) of the structure (200) and generating the three-dimensional model (246) of the structure (200) from the image (250) of the structure (200).

[0210] A15 The method (1000) according to A13 or A14, further comprising simulating the scan path (116) of the laser beam (106) as the line (124) of the laser beam (106) moves across the surface (202) of the structure (200) based on the three-dimensional model (246) of the surface (202) such that a difference value (256) of Z coordinates of any two of the plurality of points (222) on the surface (202) that are located comprehensively within the line (124) of the laser beam (106) is less than or equal to the threshold value (254).

[0211] B1 A laser ultrasound inspection system (102) comprising: a laser source (104) configured to emit a laser light (106); a transmitter (108) optically coupled to the laser source (104) and configured to transmit the laser light (106) from an output (110) of the transmitter (108 to a surface (202) of a structure (200), the laser light (106) forming ultrasonic waves (204) within the structure (200) and configured to detect a response (206) to the ultrasonic waves (204); a movement mechanism (112) coupled to the transmitter (108) and configured to move the transmitter (108) relative to the structure (200); and a computer (114) configured to move the transmitter (108) relative to the structure (200) and to detect the surface (202) relative to a reference frame (118). and controlling the moving mechanism (112) to move the laser light (106) over the structure (200) along a scan path (116), wherein, based on the three-dimensional position (208) of the surface (202), the output (110) of the transmitter (108) is positioned at a constant distance (180) from the surface (202) and the laser light (106) transmitted from the output (110) of the transmitter (108) is directed toward the surface (202) at a constant projection angle (182), and a computer (114) configured to determine whether an inconsistency (212) exists within the structure (200) based on the response (206) to the ultrasonic waves (204).

[0212] B2 The laser ultrasound inspection system (102) of claim 1, wherein the transmitter (108) is configured to transmit the laser light (106) in the form of a pattern (120) onto the surface (202) of the structure (200), and the pattern (120) of the laser light (106) is positioned on the surface (202) such that a difference value (256) of Z coordinates of any two of a plurality of points (222) on the surface (202) that are located comprehensively within the pattern (120) of the laser light (106) is less than or equal to a threshold value (254).

[0213] B3 The laser ultrasound inspection system (102) of B2, wherein the computer (114) is further configured to extract three-dimensional point cloud data (248) of the surface (202) from the three-dimensional model (246) of the structure (200), and to identify the three-dimensional positions (208) of the multiple points (222) on the surface (202) relative to the reference frame (118) based on the three-dimensional point cloud data (248) of the surface (202).

[0214] B4 The laser ultrasound inspection system (102) of B3, further comprising a sensor (198) configured to acquire an image (250) of the structure (200), and the computer (114) is further configured to generate the three-dimensional model (246) of the structure (200) from the image (250) of the structure (200).

[0215] B5 The laser ultrasound inspection system (102) of B3 or B4, wherein based on the three-dimensional point cloud data (248) of the surface (202), the computer (114) is further configured to select the scan path (116) of the laser light (106) such that as the pattern (120) of the laser light (106) moves across the surface (202) of the structure (200), a difference value (256) of Z coordinates of any two of the plurality of points (222) on the surface (202) that are located comprehensively within the pattern (120) of the laser light (106) is less than or equal to the threshold value (254).

[0216] While various embodiments of the disclosed system and method have been shown and described, modifications will occur to those skilled in the art upon reading this specification, and the application includes such modifications and is limited only by the scope of the claims.

Claims

1. 1. A method (1000) for testing a structure (200) using laser ultrasound, comprising: determining a three-dimensional position (208) of a surface (202) of said structure (200) relative to a reference frame (118), said reference frame being a reference coordinate system defined relative to a test environment (100) in which said structure is to be tested; transmitting laser light (106) in the form of a line (124) from an output (110) of a transmitter (108) onto the surface (202) of the structure (200) to form an ultrasonic wave (204) within the structure (200) and detect a response (206) to the ultrasonic wave (204); wherein each of a plurality of points (222) on the surface (202) has a corresponding three-dimensional position (208) relative to the reference frame (118); the three-dimensional position (208) indicating XYZ coordinates in the reference frame (118); and a Z coordinate of one of the plurality of points (222) on the surface (202) differs from a Z coordinate of another one of the plurality of points (222) on the surface (202); forming the laser light (106) transmitted from the output (110) of the transmitter (108) into a pattern (120) on the surface (202) of the structure (200); positioning the pattern (120) on the surface (202) such that a difference value (256) between Z coordinates of any two of the plurality of points (222) on the surface (202) that are located comprehensively within the pattern (120) of the laser light (106) is less than or equal to a threshold value (254); based on the three-dimensional position (208) of the surface (202), moving the laser beam (106) over the structure (200) along a scan path (116) such that the output (110) of the transmitter (108) is located at a constant offset distance (180) from the surface (202) and such that the laser beam (106) transmitted from the output (110) of the transmitter (108) is directed toward the surface (202) at a constant projection angle (182); determining whether an inconsistency (212) exists within the structure (200) based on the response (206) to the ultrasound (204); The method (1000) includes:

2. The method (1000) of claim 1, wherein the threshold (254) is equal to or less than one-eighth of an inch.

3. identifying a first point of the plurality of points (222) on the surface (202) and a second point of the plurality of points (222) on the surface (202), wherein a difference value (256) of Z coordinates in the reference frame (118) of any two of the plurality of points (222) on the surface (202), which are located inclusively along a straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222), is less than or equal to the threshold value (254); aligning the line (124) of the laser light (106) with the straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222); The method of claim 1 , further comprising:

4. identifying a third point of the plurality of points (222) on the surface (202) and a fourth point of the plurality of points (222) on the surface (202), wherein a difference value (256) of Z coordinates in the reference frame (118) of any two of the plurality of points (222) on the surface (202), which are located inclusively along a second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222), is less than or equal to the threshold value (254); selecting the scan path (116) of the laser beam (106) between the straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222) and the second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222); moving the line (124) of the laser beam (106) across the surface (202) along the scan path (116); aligning the line (124) of light from the laser (186) with the second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222); The method of claim 3 , further comprising:

5. 5. The method of claim 4, further comprising adjusting an orientation of the transmitter (108) as the line of light (124) of the laser (186) moves along the scan path (116) across the surface (202) between the straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222) and the second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222), such that the output (110) of the transmitter (108) is located a constant offset distance (180) from the surface (202) and such that the laser light (106) transmitted from the output (110) of the transmitter (108) is directed towards the surface (202) at a constant projection angle (182).

6. the structure (200) includes a stiffener (214) for the aircraft (1200); The stiffener (214) includes a first axis (216); 5. The method (1000) of claim 4, wherein the straight line (258) extending between the first point of the plurality of points (222) and the second point of the plurality of points (222), and the second straight line (260) extending between the third point of the plurality of points (222) and the fourth point of the plurality of points (222), are each oriented parallel to the first axis (216) of the stiffener (214).

7. The method (1000) of claim 6, wherein the scan path (116) of the laser light (106) is perpendicular to the first axis (216) of the stiffener (214).

8. The method (1000) of claim 6, wherein the scan path (116) of the laser beam (106) is oblique to the first axis (216) of the stiffener (214).

9. determining a three-dimensional position (208) of a surface (202) of the structure (200) relative to the reference frame (118); providing three-dimensional point cloud data (248) of the surface (202) of the structure (200); determining the three-dimensional positions (208) of the plurality of points (222) on the surface (202) relative to a structural reference frame (210) based on the three-dimensional point cloud data (248) of the surface (202); transforming the three-dimensional positions (208) of the points (222) on the surface (202) relative to the structural reference frame (210) to three-dimensional positions (208) relative to the reference frame (118); The method (1000) of any one of claims 1 to 8, comprising:

10. providing the three-dimensional point cloud data (248) provides a three-dimensional model (246) of the structure (200); and extracting the three-dimensional point cloud data (248) of the surface (202) from the three-dimensional model (246) of the structure (200).

11. 1. A laser ultrasound inspection system (102), comprising: A laser source (104) configured to emit laser light (106); a transmitter (108) optically coupled to the laser source (104) and configured to transmit the laser light (106) in the form of a line (124) from an output (110) of the transmitter (108) to a surface (202) of a structure (200), the laser light (106) forming an ultrasonic wave (204) within the structure (200) and configured to detect a response (206) to the ultrasonic wave (204); a movement mechanism (112) coupled to the transmitter (108) and configured to move the transmitter (108) relative to the structure (200); and A computer (114), determining a three-dimensional position (208) of said surface (202) relative to a reference frame (118), said reference frame being a reference coordinate system defined relative to a test environment (100) in which said structure is to be tested; controlling the moving mechanism (112) to move the laser light (106) over the structure (200) along a scan path (116), wherein, based on the three-dimensional position (208) of the surface (202), the output (110) of the transmitter (108) is positioned at a constant distance (180) from the surface (202) and the laser light (106) transmitted from the output (110) of the transmitter (108) is directed toward the surface (202) at a constant projection angle (182); a computer (114) configured to determine whether an inconsistency (212) exists in the structure (200) based on the response (206) to the ultrasound (204); Equipped with the transmitter (108) is configured to project the laser light (106) in the form of a pattern (120) onto the surface (202) of the structure (200), and to position the pattern (120) of the laser light (106) on the surface (202) such that a difference value (256) between Z coordinates of any two of a plurality of points (222) on the surface (202) that are located comprehensively within the pattern (120) of the laser light (106) is less than or equal to a threshold value (254); each of a plurality of points (222) on the surface (202) having a corresponding three-dimensional position (208) relative to the reference frame (118); the three-dimensional position (208) indicating XYZ coordinates in the reference frame (118); and A laser ultrasonic inspection system (102), wherein a Z coordinate of one of the plurality of points (222) on the surface (202) is different from a Z coordinate of another one of the plurality of points (222) on the surface (202).

12. The computer (114), extracting three-dimensional point cloud data (248) of the surface (202) from a three-dimensional model (246) of the structure (200); and 12. The laser ultrasound inspection system (102) of claim 11, further configured to determine the three-dimensional positions (208) of the plurality of points (222) on the surface (202) relative to the reference frame (118) based on the three-dimensional point cloud data (248) of the surface (202).

13. 13. The laser ultrasonic inspection system (102) of claim 12, further comprising a sensor (198) configured to acquire an image (250) of the structure (200), and the computer (114) is further configured to generate the three-dimensional model (246) of the structure (200) from the image (250) of the structure (200).

14. 14. The laser ultrasonic inspection system (102) of claim 12 or 13, wherein based on the three-dimensional point cloud data (248) of the surface (202), the computer (114) is further configured to select the scan path (116) of the laser light (106) such that as the pattern (120) of the laser light (106) moves across the surface (202) of the structure (200), a difference value (256) of Z coordinates of any two of the plurality of points (222) on the surface (202) that are located comprehensively within the pattern (120) of the laser light (106) is less than or equal to a threshold value (254).

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