Inspection system and method

Abstract

An inspection system includes one or more processors and an infrared (IR) camera operably coupled to the one or more processors. The one or more processors control a microwave transmitter to sequentially transmit microwaves having different frequencies within a specified frequency range into an object during a first frequency sweep. The IR camera generates thermal image data of the object after heating the object by each of the different frequencies of the microwaves. The one or more processors analyze the thermal image data and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range. The one or more processors also analyze selected thermal image data of the object in response to heating of the object by the selected frequency of the microwaves to detect elements in the object.

Description

Technical Field

[0001] The subject matter described in this article relates to non-destructive object inspection. Background Art

[0002] Microwave enhanced thermography, or microwave thermography, involves directing a high energy microwave signal from a microwave source onto the surface of an area of ​​interest to heat the area of ​​interest. An infrared (IR) camera generates thermal image data of the resulting heating, which can be analyzed for indications of sub-surface elements within the area of ​​interest. Sub-surface elements (e.g., defects in a test object) can be detected based on the characteristics of the temperature distribution along the surface as depicted in the thermal image data. For example, microwaves impinging upon a sub-surface element may be absorbed, reflected, or scattered differently than microwaves adjacent to the sub-surface element, such that the sub-surface element may experience a different heating rate attributable to the microwaves compared to adjacent areas of the object. This heating variation may be represented by a temperature distribution depicted in the thermal image data, such that the temperature distribution can be analyzed to detect the presence of, and potentially also identify, the sub-surface element.

[0003] The ability and efficiency of using microwave thermographic imaging for detecting sub-surface elements (e.g., defects) in an object is reduced for thicker object structures relative to thin object structures. For example, due to the material properties of the object and the characteristics of the microwaves, some microwaves may not penetrate the full depth of the area of ​​interest. Even for microwaves that do penetrate the full depth, the depth can cause degraded resolution, which can reduce accuracy by causing false detection and / or misidentification of sub-surface elements. The depth can also cause slower processing times due in part to interference and slower heat transfer rates through the object. Radiating microwaves toward the object at a greater energy level is an inaccurate and inefficient means of attempting to improve the accuracy and efficiency of inspecting thick object structures. Summary of the invention

[0004] In one or more embodiments, an inspection system is provided, which includes one or more processors and an infrared (IR) camera operably coupled to the one or more processors. The one or more processors are configured to couple with a microwave transmitter and control the microwave transmitter to sequentially transmit microwaves having different frequencies within a specified frequency range into the object during a first sweep of the object. The IR camera is configured to generate thermal image data of the object after heating the object by each of the different frequencies of the microwaves during the first sweep. The one or more processors are configured to analyze the thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the object compared to one or more other frequencies in the specified frequency range. The one or more processors are also configured to analyze the selected thermal image data of the object in response to the heating of the object by the selected frequency of the microwaves to detect elements in the object.

[0005] In one or more embodiments, a method is provided, the method comprising performing a first frequency sweep of a microwave transmitter over one or more portions of an object. During the first frequency sweep, the microwave transmitter sequentially emits microwaves having a plurality of different frequencies within a specified frequency range into the object at each of the one or more portions. The method comprises generating thermal image data of each of the one or more portions of the object via an infrared (IR) camera after heating by microwaves having different frequencies during the first frequency sweep. The method comprises determining, for each of the one or more portions of the object by analyzing the thermal image data, a corresponding selected frequency within the specified frequency range. The microwaves having the selected frequency provide greater heating to the corresponding portion than one or more other frequencies in the specified frequency range. The method further comprises analyzing selected thermal image data of each of the one or more portions generated by the IR camera when heated by microwaves having the corresponding selected frequency to detect a thermal signature representing an element in the object. The selected thermal image data is a subset of the thermal image data generated during the first frequency sweep, or is generated during a subsequent second frequency sweep of the microwave transmitter over the one or more portions of the object.

[0006] In one or more embodiments, an inspection system is provided, which includes a microwave transmitter, one or more processors, and an infrared (IR) camera. The one or more processors are operably coupled to the microwave transmitter and the IR camera. The one or more processors are configured to control the microwave transmitter to transmit microwaves into a plurality of different parts of the object during a first frequency sweep of the object and during a subsequent second frequency sweep of the object. The IR camera is configured to generate thermal image data of each of the parts of the object after the parts are heated by microwaves during the first frequency sweep and during the second frequency sweep. During the first frequency sweep, the one or more processors are configured to control the microwave transmitter to sequentially transmit microwaves having a plurality of different frequencies within a specified frequency range into each of the plurality of parts, so that microwaves having a first frequency within a specified frequency range are emitted into a first part of the part during a first time period, and microwaves having a second frequency within a specified frequency range are emitted into the first part during a second time period after the first time period. The one or more processors are configured to analyze the thermal image data generated by the IR camera during the first frequency sweep, so as to determine, for each of the parts of the object, a corresponding selected frequency within the specified frequency range that provides greater heating to the corresponding part of the object compared to other frequencies of the microwaves emitted into the corresponding part. During the second frequency sweep, the one or more processors are configured to control the microwave emitter to emit only microwaves having the respective selected frequencies into each corresponding portion of the object.

[0007] The present invention provides a set of technical solutions, as follows.

[0008] Technical Solution 1. An inspection system, comprising:

[0009] one or more processors configured to be coupled to a microwave transmitter and to control the microwave transmitter to sequentially transmit microwaves having different frequencies within a specified frequency range into the object during a first frequency sweep of the object; and

[0010] an infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data of the object after heating the object by each of the different frequencies of microwaves during the first frequency sweep,

[0011] wherein the one or more processors are configured to analyze the thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range, and

[0012] Wherein the one or more processors are further configured to analyze selected thermal image data of the object in response to heating of the object by the selected frequency of microwaves to detect elements in the object.

[0013] Technical Solution 2. An inspection system as described in any of the foregoing technical solutions, wherein the selected thermal image data is a subset of the thermal image data generated during the first frequency sweep, or is generated during a subsequent second frequency sweep of the microwave transmitter over the object.

[0014] Technical Solution 3. The inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to detect the element in the object by identifying a thermal signature in the selected thermal image data that represents a type of the element.

[0015] Technical Solution 4. The inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to control the microwave transmitter to transmit the microwaves having the different frequencies into a common portion of the object at different times.

[0016] Technical Solution 5. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to control the microwave transmitter to transmit the microwaves having the different frequencies into each of a plurality of different parts of the object during the first frequency sweep of the microwave transmitter.

[0017] Technical Solution 6. An inspection system as described in any of the preceding technical solutions, wherein the selected frequency is a first selected frequency corresponding to a first part of the plurality of different parts of the object, and wherein

[0018] The IR camera is configured to generate thermal image data of the second portion of the object after heating the second portion by each of the different frequencies of microwaves during the first frequency sweep, and

[0019] The one or more processors are configured to analyze the thermal image data of the second portion and determine a second selected frequency within the specified frequency range corresponding to the second portion, the second selected frequency providing greater heating to the second portion compared to one or more other frequencies in the specified frequency range.

[0020] Technical Solution 7. An inspection system as described in any of the above technical solutions, wherein, before analyzing the selected thermal image data, the one or more processors are configured to control the microwave transmitter to perform a second frequency sweep over the object so that the microwave transmitter transmits only microwaves having the selected frequency into the object, and

[0021] The IR camera is configured to generate the selected thermal image data of the object after heating by the microwaves during the second frequency sweep.

[0022] Technical Solution 8. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are further configured to control the microwave transmitter to transmit microwaves having a plurality of different power levels into the object during the first frequency sweep of the object.

[0023] Technical Solution 9. An inspection system as described in any of the foregoing technical solutions, wherein the IR shooting device is configured to generate thermal image data of the object after heating the object by each of the different frequencies of the microwaves at each of the different power levels during the first frequency sweep.

[0024] Technical Solution 10. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to control the microwave transmitter to emit microwaves, wherein the microwaves penetrate a surface coating on the object, wherein the surface coating is thicker than one inch.

[0025] Technical Solution 11. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to determine the selected frequency for the object based on which frequency of the microwaves within the specified frequency range provides maximum heating of the object.

[0026] Technical Solution 12. The inspection system as described in any of the above technical solutions further includes a drone, wherein the microwave transmitter and the IR camera are installed on the drone.

[0027] Technical Solution 13. A method comprising:

[0028] performing a first frequency sweep of a microwave launcher over one or more portions of the object, wherein during the first frequency sweep, the microwave launcher sequentially launches microwaves having a plurality of different frequencies within a specified frequency range into the object at each of the one or more portions;

[0029] generating thermal image data of each of the one or more portions of the object via an infrared (IR) camera after heating by the microwaves having the different frequencies during the first frequency sweep;

[0030] determining, by analyzing the thermal image data, for each of the one or more portions of the object, a corresponding selected frequency within the specified frequency range, wherein microwaves having the selected frequency provide greater heating of the corresponding portion than one or more other frequencies in the specified frequency range; and

[0031] analyzing selected thermal image data of each of the one or more portions generated by the IR camera when heated by microwaves having a corresponding selected frequency to detect a thermal signature representative of elements in the object, and

[0032] The selected thermal image data is a subset of the thermal image data generated during the first sweep or during a subsequent second sweep of the microwave transmitter over the one or more portions of the object.

[0033] Technical Solution 14. A method as described in any of the foregoing technical solutions, wherein the microwaves having the different frequencies are emitted sequentially by the microwave emitter, so that microwaves having a first frequency within the specified frequency range are emitted into a first part of the one or more parts during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first part during a second time period after the first time period.

[0034] Technical Solution 15. A method as described in any of the above technical solutions, wherein, before analyzing the selected thermal image data, the method further comprises performing the second frequency sweep of the microwave transmitter over the one or more parts of the object, wherein during the second frequency sweep, the microwave transmitter transmits only microwaves having the corresponding selected frequency into each corresponding part of the object, and

[0035] The selected thermal image data of each of the one or more portions of the object is generated via the IR camera after heating by the microwaves during the second frequency sweep.

[0036] Technical Solution 16. A method as described in any of the preceding technical solutions, wherein determining the corresponding selected frequency for each of the one or more parts of the object includes determining which frequency of the microwaves within the specified frequency range provides greater heating to the corresponding part compared to all the other frequencies of the microwaves in the specified frequency range.

[0037] Technical Solution 17. The method as described in any of the preceding technical solutions, wherein the corresponding selected frequency for each of the one or more parts of the object is also determined based on the penetration depth of the microwaves emitted into the object.

[0038] Technical Solution 18. A method as described in any of the preceding technical solutions, wherein, during the first frequency sweep, the microwave transmitter is also controlled to sequentially transmit microwaves having a plurality of different power levels into each of the one or more portions of the object.

[0039] Technical Solution 19. An inspection system comprising:

[0040] Microwave transmitters;

[0041] one or more processors operably coupled to the microwave emitter and configured to control the microwave emitter to emit microwaves into a plurality of different portions of the object during a first sweep of the object and during a subsequent second sweep of the object; and

[0042] an infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data of each of the portions of the object after heating the portions by the microwaves during a first frequency sweep and during a second frequency sweep,

[0043] wherein during the first frequency sweep, the one or more processors are configured to control the microwave transmitter to sequentially transmit microwaves having a plurality of different frequencies within a specified frequency range into each of the plurality of sections, so that microwaves having a first frequency within the specified frequency range are transmitted into a first section of the sections during a first time period, and microwaves having a second frequency within the specified frequency range are transmitted into the first section during a second time period after the first time period,

[0044] wherein the one or more processors are configured to analyze the thermal image data generated by the IR camera during the first frequency sweep to determine, for each of the portions of the object, a respective selected frequency within the specified frequency range that provides greater heating of the corresponding portion of the object than other frequencies of microwaves emitted into the corresponding portion, and

[0045] During the second frequency sweep, the one or more processors are configured to control the microwave transmitter to transmit only microwaves having the corresponding selected frequency into each corresponding portion of the object.

[0046] Technical Solution 20. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to analyze the thermal image data generated by the IR camera during the second frequency sweep to detect a thermal signature representing an element in the object.

[0047] Technical Solution 21. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to mechanically guide the microwave emitter during the first frequency sweep so as to emit the microwave into each of the multiple parts of the object.

[0048] Technical solution 22. An inspection system as described in any of the preceding technical solutions, wherein the one or more processors are configured to electrically guide the microwave transmitter using a phased array antenna system during the first frequency sweep so as to transmit the microwave into each of the multiple parts of the object. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The inventive subject matter will be better understood from the following description of non-limiting embodiments read with reference to the accompanying drawings, in which:

[0050] Figure 1 FIG. 1 illustrates an inspection system according to an embodiment;

[0051] Figure 2 illustrates an object to be inspected by an inspection system according to an embodiment;

[0052] Figure 3 is a flowchart illustrating a first frequency sweep of a microwave transmitter of an inspection system according to an embodiment;

[0053] Figure 4 is a flowchart illustrating a second frequency sweep of a microwave transmitter of an inspection system according to an embodiment;

[0054] Figure 5 is a flow chart of a method for inspecting an object according to an embodiment;

[0055] Figure 6 A first example use application of the illustration inspection system is shown; and

[0056] Figure 7 A second example use application of the inspection system is illustrated. DETAILED DESCRIPTION

[0057] Embodiments described herein provide inspection systems and methods for nondestructively evaluating the presence of elements (e.g., defects) at or below the surface structure of an object. The disclosed inspection systems and methods utilize microwave enhanced thermographic imaging. For example, the surface structure of an object is heated by non-contact microwave excitation, and an optical sensor (e.g., an infrared (IR) camera) is used to capture the heat distribution or signature resulting from the heating in thermal image data. The elements present can be detected based on the identified characteristics of the thermal signature of the object structure indicating the known type of element. The type of element can be various types of defects, such as air pockets, delamination, cracks, crevices, etc. Microwaves have the ability to penetrate deeply into dielectric materials with very little attenuation, which allows the systems and methods disclosed herein to be used for thicker non-conductive structures (e.g., structural layers with a thickness of up to or greater than one inch). The inspection system and method can be used to detect subsurface elements below the surface of an object. Subsurface elements may not be visible along the surface of the object, so image-based inspection techniques using visible light may not be able to detect subsurface elements. According to one or more embodiments, in addition to subsurface elements, the inspection system and method can also detect surface elements along the surface of the object.

[0058] In the embodiments disclosed herein, the accuracy and efficiency of the inspection process are enhanced by individually tuning the characteristics of the microwaves used to heat each portion of the inspected object, thereby customizing the excitation microwaves for each portion of the object. For example, the corresponding selected microwave frequency can be determined for each portion of the object based on how well microwaves at different frequencies heat the corresponding portion of the object. For example, the rate at which the temperature increases in the corresponding portion of the object may depend on the material properties of the portion (e.g., permittivity, dipole orientation, thermal conductivity, etc.), the structural properties of the portion (e.g., coating thickness, surface uniformity, etc.), and the characteristics of the microwaves (e.g., energy level, frequency, phase, etc.). The thermal image data analyzed for the detection of sub-surface elements is the thermal image data generated in response to the heating of the corresponding portion by only those microwaves having the corresponding selected microwave frequencies. Performing a thermographic imaging inspection of an object based on excitation by microwaves specifically selected for each corresponding portion of the object can provide desired results, such as increased detection accuracy (partially due to enhanced thermal resolution) and reduced energy consumption. For example, energy efficiency can be improved because the process determines the frequencies within a specified range that provide the greatest heating efficiency for each portion of the object, and only microwaves at those selected frequencies are used to heat the object to provide thermal image data for defect analysis. By adjusting to determine the selected frequencies, the energy efficiency of the inspection process can be improved, and / or the total amount of energy consumed can be reduced relative to pre-existing microwave thermography imaging techniques.

[0059] Figure 1An inspection system 100 is shown in accordance with an embodiment. The inspection system 100 uses microwave enhanced thermographic imaging to perform nondestructive evaluation of an object 102 for detecting sub-surface elements 104 within the object 102. The object 102 is Figure 1 1. The inspection system 100 includes a microwave emitter 106, an optical sensor 108, and a controller 110 having one or more processors 112. In one embodiment, the optical sensor 108 is an infrared (IR) camera that senses the intensity of one or more IR wavelengths of light. Alternatively, the optical sensor 108 may sense the intensity of one or more other wavelengths of light.

[0060] Controller 110 is operably coupled to microwave emitter 106 and optical sensor 108 and is configured to control the operation of both devices. For example, controller 110 is communicatively connected to microwave emitter 106 and optical sensor 108 via one or more wired or wireless communication channels. Controller 110 generates control signals, which are transmitted to microwave emitter 106 and optical sensor 108 via the communication channels. Controller 110 includes or represents any processor-based or microprocessor-based system, including systems using microcontrollers, reduced instruction set computers (RISC), application-specific integrated circuits (ASICs), logic circuits, GPUs, FPGAs, and any other circuits or processors capable of performing the functions described herein.

[0061] The microwave emitter 106 (also referred to herein as a transmitter) is connected to a microwave generator 114 or source. For example, the transmitter 106 and the generator 114 may be components of a general microwave device. The microwave generator 114 generates microwaves, which are emitted by the transmitter 106 toward a target area 116 of the object 102. For example, the transmitter 106 may include one or more antennas, lenses, etc., which are used to direct the emission of microwaves toward the target area. The transmitter 106 may be mechanically adjustable and / or electrically adjustable so as to selectively direct the microwave radiation field 122 emitted therefrom toward different target areas. In a non-limiting example, the transmitter 106 may represent a probe that is spaced apart from the microwave generator 114 and mechanically connected to the generator 114 via an electrical cable or cable 118.

[0062] The microwave radiation field 122 emitted by the emitter 106 strikes the surface 120 of the object 102 and penetrates the surface 120 within the target area 116. The target area 116 extends a certain depth below the surface 120 into the interior of the object 102. The microwaves heat the target area 116. In one or more embodiments, the object 102 has a non-metallic outer structure or coating 124 that is inspected by the inspection system 100. For example, the outer structure 124 may have a composition that includes one or more ceramics, polymers, carbon fibers, glass fibers, and / or various other dielectric materials. The microwaves heat the outer structure 124 via volumetric or dielectric loss heating. For example, microwave radiation may cause molecules (e.g., dipoles) in the material of the object 102 to vibrate, which generates heat. The heat is transferred through the material of the object 102 based on the properties of the material (e.g., heat capacity, density, etc.). The optical sensor 108 is used to obtain a temperature change or distribution in the irradiated portion of the object. For example, optical sensor 108 is positioned to have a field of view 125 of surface 120 of object 102 that is aligned with target area 116. Optical sensor 108 generates thermal image data that is representative of thermal energy radiated from surface 120. For example, the data is representative of the intensity of thermal energy received from surface 120 (e.g., thermal energy radiated and / or reflected therefrom). At least some of the thermal energy may be attributable to microwave-induced heating of outer structure 124 of object 102.

[0063] When the outer structure 124 of the object 102 has at least one sub-surface element 104 (e.g., a defect) that has a different density, heat capacity, and / or other properties relative to the surrounding material of the outer structure 124, the sub-surface element 104 transfers heat differently from the surrounding material. These thermal variations caused by the sub-surface element 104 are reflected in the temperature distribution of the thermal image data generated by the optical sensor 108. For example, some specific types of sub-surface elements 104 (e.g., air pockets) may cause corresponding patterns or signatures in the temperature distribution along the surface 120.

[0064] The thermal image data generated by the optical sensor 108 is analyzed by one or more processors 112 of the controller 110 to detect the presence of the sub-surface elements 104. The one or more processors 112 may compare the temperature distribution in the received thermal image data with one or more template distributions stored in the memory device 126. The template distributions may be stored in a database, a lookup table, or the like. For example, each template distribution may be associated with a particular type of sub-surface element (e.g., air pockets, delaminations, cracks, crevices, metallic foreign matter, water, etc.), and the template distribution represents the thermal signature of that sub-surface element. If the temperature distribution in the received thermal image data from the optical sensor 108 has a thermal gradient pattern that matches or corresponds to a thermal signature in one of the template distributions, the one or more processors 112 detect the presence of the sub-surface element in the object. If the temperature distribution in the received thermal image data does not match or correspond to a thermal signature in any of the template distributions, the one or more processors 112 determine that the object does not have a sub-surface element. In the illustrated embodiment, the one or more processors 112 are configured to detect the presence of a sub-surface element 104 within the outer structure 124 of the object 102 based on a thermal signature in the thermal image data corresponding to one of the sub-surface elements of known types.

[0065] The controller 110 is configured to control the operation of the microwave emitter 106, the microwave generator 114, and the optical sensor 108. For example, the controller 110 generates control signals to the microwave generator 114 to control the characteristics or properties of the microwaves generated by the generator 114, such as frequency, phase, power level (e.g., amplitude, energy), etc., including the timing of generating microwaves. The generator 114 can generate microwaves by various mechanisms (e.g., pseudo noise, FM chirp, discrete frequency, etc.). The controller 110 generates control signals to the emitter 106 to aim the microwave radiation field 122. For example, the control signal can automatically mechanically redirect the emitter 106 relative to the object 102 by rotating (e.g., pivoting, rotating, etc.) the emitter 106 around a fixed housing. In another example, the control signal can automatically mechanically move the emitter 106 along the length of the object 102 to radiate different portions thereof. In yet another example, the microwave radiation field 122 can be electronically guided by adjusting the phase of the radio frequency energy emitted by different antenna elements in an array (e.g., a phased array antenna system). Alternatively, the control signal may control movement of a lens or the like of the emitter 106 to enlarge or reduce the coverage area of ​​the microwave radiation field 122. Alternatively, a combination of mechanical and electrical techniques may be used to direct the microwave radiation field 122 at different portions of the object 102 along its length. The controller 110 generates control signals to the optical sensor 108 to control the generation of thermal image data (e.g., the timing at which the optical sensor 108 captures thermal radiation from the object 102 to generate the thermal image data). The control signal to the optical sensor 108 may also redirect and / or reposition the optical sensor 108 relative to the object 102 to control which portion of the object 102 is in the field of view 125 of the optical sensor 108 at a given time.

[0066] The one or more processors 112 of the controller 110 may operate based on programmed instructions stored in the memory device 126 or hardwired into the logic of the processor 112. The memory device 126 may store programmed instructions (i.e., software) that specify the functionality of the controller 110 (e.g., its one or more processors 112). For example, the memory device 126 may store one or more protocols for setting up and operating the inspection system 100 to perform microwave enhanced thermography imaging along one or more portions of the object 102. The memory device 126 may also store information (e.g., the template distribution described above) that is used by the one or more processors 112 to analyze thermal image data for indication of sub-surface elements. The controller 110 may implement the programmed instructions to autonomously operate the inspection system 100.

[0067] Optionally, the controller 110 is operably connected to an input / output (I / O) device 130 and a communication device 132. The I / O device 130 may include a keyboard, a touch screen, etc., which is used to enable an operator (e.g., an individual) to manually input commands. The I / O device 130 may also include a display for displaying output information, such as thermal image data, alarms, notifications, inspection results, etc. generated by the optical sensor 108. The wireless communication device 132 may include circuitry for remote communication. For example, the communication device 132 may provide a network connection that enables remote communication to a remote processing or storage device (e.g., a server) via the Internet, a local area network (LAN), etc. Alternatively, the communication device 132 may be a wireless communication device that includes a transceiver (or a separate transmitter and receiver), an antenna, and associated circuitry for wireless communication.

[0068] The object 102 on which microwave enhanced thermography imaging is performed may be an industrial workpiece in a device, machine, or vehicle. Some non-limiting examples of the object 102 include rotor blades from a rotor assembly (e.g., an airfoil of a wind turbine, a turbine blade from an engine, a turbocharger, etc.) or compressor blades from an engine, a turbocharger, etc. In another non-limiting example, the object 102 may be a surface component of a vehicle, such as a portion of a wing or fuselage of an aircraft. The outer structure 124 of the object 102 may represent a coating, such as a thermal barrier coating. The outer structure 124 may include a non-metallic composite material (the non-metallic composite material includes multiple layers), such as a carbon fiber composite material, a glass fiber composite material, a ceramic matrix composite material, etc. The embodiments disclosed herein can be used to inspect a thicker outer structure 124, where the thickness is up to or exceeds one inch. For example, microwaves can penetrate deeper into non-metallic materials, and the control steps described herein for adjusting microwaves to specific portions of the object can enhance the inspection resolution at such depths.

[0069] Figure 2 An object 102 to be inspected by the inspection system 100 according to an embodiment is illustrated. Figure 2 Object 102 in FIG. 1 is rotor blade 202 . Figure 2 The object 102 shown in FIG. 1 is used to describe the initial stage of the microwave enhanced thermography inspection method according to the embodiment. The inspection method is composed of Figure 1 The initial stage involves virtually dividing the object 102 into one or more parts 204. Figure 2, the blade 202 is divided into three sections 204 along the length of the blade, including a proximal section 204A, a middle section 204B, and a distal section 204C. The middle section 204B is between the proximal section 204A and the distal section 204C along the length. The proximal section 204A is the section 204 closest to the base 206 of the rotor blade 202, which couples the blade 202 to the hub. The sections 204A-C can be divided into areas with equal or similar size and / or length to each other. The division is virtual, so that the sections 204 are determined without any physical contact with the blade 202.

[0070] Although Figure 2 204A-C, but the blade 202 (or other object) can be divided into fewer or more than three parts based on application-specific considerations. In the simplest example, the inspection system 100 can consider the object 102 to have only a single part 204, which may be useful when the material composition and structural composition (e.g., thickness, shape, surface treatment, etc.) of the inspection area of ​​the object 102 are known to be uniform along the area. Increasing the number of parts 204 can improve inspection accuracy, especially for objects 102 that may have varying material composition and / or structural composition along the inspection area. The number of divided parts 204 can be limited to no more than a specified limit (e.g., 10, 20, or 50 parts) to avoid slowdowns caused by excessive processing requirements during the inspection process. Alternatively, rather than being divided in rows side by side along the length, the object 102 can be divided in columns along the width of the object 102, or can be divided in an array of rows and columns. For example, the parts 204 in the array can be virtually tiled on the surface 120 within the area to be inspected.

[0071] Figure 3 3 is a flowchart 300 illustrating a first frequency sweep of the microwave launcher 106 of the inspection system 100 according to an embodiment. During the first frequency sweep, the microwave launcher 106 is controlled by the controller 110 to sequentially and continuously launch microwaves having a plurality of different frequencies within a specified frequency range 302 into each of the portions 204 of the object 102. The flowchart 300 includes a graph 304 that depicts the frequency of microwaves launched by the launcher 106 into the object 102 over time. The vertical axis 306 represents frequency, while the horizontal axis 308 represents time. The launcher 106 launches microwaves sequentially into the three portions 204A, 204B, 204C of the object 102. For example, the launcher 106 launches microwaves into the proximal portion 204A during a first time period between times t0 and t5, and then the proximal portion 204A is launched during a time period from t5 to t6. 10 204B during a subsequent second time period of t 10 to 15As described above, the transmitter 106 can be controlled to sweep across the different portions 204 over time by rotating to redirect the transmitter 106 relative to the object 102, translating to reposition the transmitter 106 relative to the object 102, and / or modifying the electrical characteristics of the microwave radiation field 122 to electrically direct the field 122 to each portion of the different portions 204 over time.

[0072] At each section 204, the transmitter 106 is controlled to sequentially transmit microwaves having different frequencies within the specified frequency range 302. The frequency and other characteristics of the microwaves may be determined by Figure 1 1. The transmitter 106 transmits microwaves with a first frequency 310 toward the proximal portion 204A between time t0 and t1. A second frequency 312 of the microwaves is then directed toward the proximal portion 204A between time t1 and t2. A third frequency 314 is then directed toward the proximal portion 204A, followed by a fourth frequency 316 of the microwaves and then by a fifth frequency 318. All five frequencies 310, 312, 314, 316, 318 are within the specified frequency range 302. In a non-limiting example, the specified frequency range 302 is between 1.0 Ghz and 2.0 GHz. The first to fifth frequencies 310, 312, 314, 316, 318 may be 1.1 GHz, 1.2 GHz, 1.3 GHz, 1.4 GHz, and 1.5 GHz, respectively. Microwaves having five different frequencies 310, 312, 314, 316, 318 are continuously and sequentially emitted at different times into a common portion of the object 102. For example, the emitted microwaves have only one of the frequencies 310, 312, 314, 316, 318 at each given time. The emitter 106 may be controlled to sequentially scan through the frequencies 310, 312, 314, 316, 318 in the specified frequency range 302, as indicated by the step-shaped plot line 319 shown in the graph 304.

[0073] Although Figure 3310, 312, 314, 316, 318 are shown in FIG. 314, but in other embodiments, the emitter 106 may be controlled to emit microwaves having more or less than five different frequencies. For example, the limits of the specified frequency range 302 and the number of discrete frequencies to be measured may be selected based on application-specific factors and considerations. Additional application-specific factors and considerations may include properties such as the length of time each frequency of the microwaves is emitted into the object, the delay or lag timing between the emission of two different frequencies into the same portion of the object, the power level or energy level at which the microwaves are emitted from the emitter 106, etc. For example, the frequency range 302 and / or other characteristics of the microwaves may be selected to enable the microwaves to penetrate into the object 102 to a desired depth. The desired depth may represent the thickness of the outer structure 124 to be inspected.

[0074] After scanning through all the frequencies 310, 312, 314, 316, 318 in the proximal portion 204A, the microwave emitter 106 is controlled to repeat the process for the middle portion 204B and then for the distal portion 204C. For example, at time t5, the emitter 106 is controlled to stop emitting microwaves into the proximal portion 204A and start emitting microwaves into the middle portion 204B. The microwave generator 114 provides the same step-wise progression of the five frequencies 310, 312, 314, 316, 318 for the middle and distal portions 204B as for the proximal portion 204A. Therefore, each of the five frequencies 310, 312, 314, 316, 318 of the microwaves is sequentially emitted into each of the different portions 204A-C of the object 102.

[0075] The optical sensor 108 is controlled to generate thermal image data for each of the portions 204A-C of the object 102 after the portions 204A-C are heated by the microwaves during the first frequency sweep. For example, the optical sensor 108 is controlled to generate thermal image data indicating heating of the object 102 caused by each of the different frequencies 310, 312, 314, 316, 318 of the microwaves within each of the different portions 204A-C. The thermal image data may represent a temperature distribution along the surface 120 of the object 102 within the corresponding portion 204. The thermal image data is used by the one or more processors 112 to determine a selected frequency 350 for each of the portions 204A-C of the object 102.

[0076] During the time period from t0 to t5, the optical sensor 108 is positioned and oriented to have a field of view including the proximal portion 204A. At or near time t1 (e.g., within a specified buffer time period and before the transmitter 106 transmits microwaves having the second frequency 312), the optical sensor 108 generates thermal image data 320 associated with the first frequency 310. The thermal image data 320 indicates thermal energy radiated by the proximal portion 204A attributable to the microwaves having the first frequency 310. At or near time t2, the optical sensor 108 generates additional thermal image data 322 associated with the second frequency 312. The optical sensor 108 then generates thermal image data 324, 326, 328 associated with the third, fourth, and fifth frequencies 314, 316, 318, respectively, at or near time t3, t4, and t5. All of the thermal image data 320, 322, 324, 326, 328 depict the same proximal portion 204A of the subject 102, but at different times. The image data 320, 322, 324, 326, 328 represent a collection 352 associated with the proximal portion 204A.

[0077] The differences between the thermal image data 320, 322, 324, 326, 328 in the set 352 may be attributable to variations in the interaction between the microwaves and the object 102. For example, all microwaves may cause the object 102 to heat, but some frequencies of the microwaves may cause the object 102 to heat at different rates and / or to different heating magnitudes than other frequencies.

[0078] After time t5, the optical sensor 108 is repositioned to view the middle portion 204B. The optical sensor 108 generates thermal image data 330 at or near time t6, which indicates thermal energy radiated through the middle portion 204B attributable to heating caused by microwaves having the first frequency 310. The optical sensor 108 generates thermal image data 332 at or near time t7, which indicates thermal energy radiated through the middle portion 204B attributable to heating caused by microwaves having the second frequency 312. Similarly, the optical sensor 108 continues to generate thermal image data 334, 336, and 338 at different times, which indicates heating of the middle portion 204B caused by microwaves having the third, fourth, and fifth frequencies 314, 316, 318, respectively. The thermal image data 330, 332, 334, 336, 338 represent a set 354 associated with the middle portion 204B.

[0079] At time t 10Thereafter, the optical sensor 108 is repositioned to view the distal portion 204C, and the optical sensor 108 is controlled to continuously generate thermal image data indicating radiant heat energy along the distal portion 204C. 11 Thermal image data 340 is generated at or near the distal portion 204C, the thermal image data 340 indicating heating of the distal portion 204C caused by microwaves having the first frequency 310. The optical sensor 108 is controlled to continuously generate thermal image data 342, 346, and 348 at different times, the thermal image data indicating heating of the distal portion 204C caused by microwaves having the second, third, fourth, and fifth frequencies 312, 314, 316, 318, respectively. The thermal image data 340, 342, 344, 346, 348 represent a collection 356 associated with the distal portion 204C.

[0080] Thus, the optical sensor 108 generates a corresponding set of thermal image data for each of the portions 204 of the object 102 to be inspected. Figure 3 302, each of the three sets 352, 354, 356 is analyzed by the one or more processors 112 for determining a corresponding selected frequency 350 within the specified frequency range 302 for each portion 204A-C. The one or more processors 112 are configured to determine the selected frequencies 350 based on how well each of the measured frequencies 310, 312, 314, 316, 318 of the microwaves heats the corresponding portion 204A, 204B, 204C of the object 102. The selected frequency 350 for each portion 204A-C provides greater heating for the corresponding portion than one or more other frequencies in the specified frequency range 302. The selected frequency 350 may be determined as a frequency that provides greater heating for the corresponding portion than all other frequencies in the range 302. For example, the one or more processors 112 may select one of the microwave frequencies 310, 312, 314, 316, 318 for each portion 204 that provides the maximum amount and / or rate of temperature increase (e.g., the steepest temperature gradient) in the allotted time. The temperature increase is determined based on the thermal image data generated by the optical sensor 108.

[0081] For the set 352 associated with the proximal portion 204A, the one or more processors 112 may analyze the thermal image data 320, 322, 324, 326, 328. The one or more processors 112 may subtract adjacent image data to generate a difference image indicating heating attributable to the corresponding frequency of the microwaves. For example, the thermal image data 320 may be subtracted or otherwise compared with a template thermal image of the proximal portion 204A before excitation to determine the rate or degree of heating of the proximal portion 204A caused by the first frequency 310. In a non-limiting example, the processor 112 determines that the thermal image data 328 indicates the maximum degree or rate of heating in the set 352, so the fifth frequency 318 associated with that thermal image data 328 is determined to be the selected frequency 350 of the proximal portion 204A.

[0082] Independent of the analysis of set 352, the one or more processors 112 analyze and compare the thermal image data 330, 332, 334, 336, 338 in set 354 to determine the selected frequency 350 corresponding to the middle portion 204B. The processor 112 also separately analyzes and compares the thermal image data 340, 342, 344, 346, 348 in set 356 to determine the selected frequency 350 corresponding to the distal portion 204C. In a non-limiting example, the processor 112 determines that the thermal image data 332 indicates the maximum degree or rate of heating in the set 354, and the thermal image data 346 indicates the maximum degree or rate of heating in the set 356. Therefore, the second frequency 312 associated with the thermal image data 332 is determined to be the selected frequency 350 for the middle portion 204B, and the fourth frequency 316 associated with the thermal image data 346 is determined to be the selected frequency 350 for the distal portion 204C. Figure 3 The three selected frequencies 350 for the corresponding parts 204A-C are shown in table 360 ​​of FIG. Table 360 ​​indicates that different selected frequencies may be determined for different parts of the same object. For example, the selected frequencies for different parts of the same object may differ due to material changes and / or structural changes between the parts. For example, one part of the outer structure of the object may have a greater number of composite layers and / or a different composition of one or more layers than another part, causing the layers to react to microwaves in different ways.

[0083] Alternatively, the selected frequency 350 for the different portions 204 of the object 102 may be determined based on one or more properties of the excitation microwaves other than frequency. For example, in addition to changing the frequency of the microwaves emitted to each of the portions 204, the emitter 106 may be controlled to sequentially emit microwaves having a plurality of different power levels or energy levels during the first frequency sweep. In a non-limiting example, the emitter 106 emits microwaves having a first frequency 310 and a low power level during a first time period from time t0 to t1, emits microwaves having a first frequency 310 and a medium power level from time t1 to t2, and emits microwaves having a first frequency 310 and a high power level from time t2 to t3. The terms low, medium, and high for power levels are relative terms. Then, the emitter 106 emits microwaves having a second frequency 312 and a low power level from time t3 to t4. Thus, in addition to testing the effects of different frequencies, the inspection system 100 may also test different power levels. In this example, the optical sensor 108 is controlled to generate thermal image data at each of the different frequencies 310, 312, 314, 316, 318 and at each of the three different power levels, thereby producing a collection 352 having 15 individual thermal images instead of 15 individual thermal images. Figure 3 As shown there are only five. Processor 112 determines selected frequency 350 by analyzing 15 thermal images and selecting from among them.

[0084] Figure 4 4 is a flowchart 400 illustrating a second frequency sweep of the microwave launcher 106 of the inspection system 100 according to an embodiment. The flowchart 400 includes a graph 404 depicting the frequency of microwaves emitted by the launcher 106 into the object 102 over time during the second frequency sweep. The microwave launcher 106 is controlled by the controller 110 during the second frequency sweep to emit microwaves having only the selected frequency 350 into each corresponding portion 204 of the object 102. For example, when the launcher 106 is positioned to emit microwaves into the proximal portion 204A, the launcher 106 emits only microwaves having the fifth frequency 318, which represents the selected frequency 350 of the proximal portion 204A. When the launcher 106 subsequently emits microwaves into the middle portion 204B along the frequency sweep, the microwaves directed to the middle portion 204B have only the second frequency 312, which represents the selected frequency 350 of the middle portion 204B. The transmitter 106 will thereafter transmit microwaves having only the fourth frequency 316 to the distal portion 204C because the fourth frequency 316 represents the selected frequency 350 of the distal portion 204C.

[0085] The optical sensor 108 generates selected thermal image data of each portion 204 of the object 102 after being heated by the microwaves during the second frequency sweep. The thermal image data generated during the second frequency sweep is referred to as selected thermal image data because it is based on the heating caused by the corresponding selected frequency 350. For example, the optical sensor 108 is controlled to generate selected thermal image data 410 of the proximal portion 204A at or near time t1. The second frequency sweep is Figure 3 404 occurs after the first frequency sweep described in FIG. 404 , so time t1 in FIG. 404 is Figure 3 The selected thermal image data 410 depicts the temperature distribution along the surface 120 of the object 102 within the proximal portion 204A in response to heating caused by microwaves having a corresponding selected frequency 350 (eg, the fifth frequency 318).

[0086] The optical sensor 108 is controlled to generate selected thermal image data 412 of the middle portion 204B at or near time t2. The selected thermal image data 412 depicts the temperature distribution along the surface 120 of the object 102 within the middle portion 204B in response to heating caused by microwaves having a corresponding selected frequency 350 (e.g., the second frequency 312). The optical sensor 108 is controlled to generate selected thermal image data 414 of the distal portion 204C at or near time t3. The selected thermal image data 414 depicts the temperature distribution along the surface 120 of the object 102 within the distal portion 204C in response to heating caused by microwaves having a corresponding selected frequency 350 (e.g., the fourth frequency 316). Thus, the second frequency sweep is performed using only the selected frequency 350 of the microwaves, which is selected based on the desired heating quality provided by the selected frequency 350. For example, because the selected frequency 350 is tuned to the corresponding portion 204 of the object 102 , exciting the material of the object 102 using the selected frequency 350 may provide enhanced resolution of the interior volume of the object 102 , which enables more accurate detection of sub-surface elements.

[0087] The selected thermal image data 410, 412, 414 generated during the second sweep of the microwave transmitter 106 is communicated to and / or accessed by the one or more processors 112. The processors 112 analyze the selected thermal image data 410, 412, 414 individually to detect sub-surface elements (e.g., Figure 1 The thermal signature of the subsurface element 104) shown in FIG. Figure 1As described, the processor 112 may analyze each of the selected thermal image data 410, 412, 414 by comparing the temperature distribution in each of the selected thermal image data 410, 412, 414 to a stored template distribution associated with different types of sub-surface elements (e.g., air pockets, delaminations, cracks, crevices, metallic foreign matter, water, etc.). If the temperature distribution in the selected thermal image data 410, for example, has a thermal gradient pattern that matches or corresponds to a thermal signature in one of the template distributions, the one or more processors 112 detect the presence of the sub-surface element in the proximal portion 204A of the object 102. If the matching template distribution is associated with a crack, the processor 112 may also identify the detected sub-surface element in the proximal portion 204A as a crack. The processor 112 may separately determine whether the sub-surface element exists in each of the portions 204A-C of the object 102.

[0088] In an alternative embodiment, rather than performing a second sweep of the microwave emitter 106 to emit microwaves into the portions 204A-C of the object 102, the selected thermal image data analyzed by the processor 112 to detect the presence of sub-surface elements can be a subset of the thermal image data generated during the first sweep. Figure 3 , after the processor 112 determines the corresponding selected frequency 350 for each portion 204A-C, the thermal image data generated during the first frequency sweep based on the heating provided by the selected frequency 350 can be used as the selected thermal image data. For example, when the fifth frequency 318 is determined to represent the selected frequency 350 for the proximal portion 204A based on the analysis of the thermal gradient in the thermal image data 328, that thermal image data 328 can be used as the selected thermal image data. The one or more processors 112 can perform a sub-surface element detection analysis on the thermal image data 328. Similarly, the sub-surface element detection analysis can be performed on the thermal image data 332 of the middle portion 204B and the thermal image data 346 of the distal portion 204C. Therefore, sub-surface element detection and selection of the desired microwave characteristics of each portion of the object can be performed on the same image data generated during a single frequency sweep of the object (rather than performing two frequency sweeps).

[0089] Figure 5 is a flow chart 500 of a method for inspecting an object according to an embodiment. The method may be used Figure 1 One or more of the steps of the method may be performed by the controller 110 of the inspection system 100 or one or more processors 112 thereof. Optionally, the method may include Figure 5 Additional steps not shown in Figure 5 Fewer steps than shown Figure 5 Steps different from the steps shown, and / or steps can be followed in accordance with Figure 5The order shown may be executed in a different order.

[0090] At 502, a first frequency sweep of the microwave launcher 106 is performed over one or more portions of the object 102. During the first frequency sweep, the microwave launcher 106 sequentially launches microwaves having a plurality of different frequencies (e.g., frequencies 310, 312, 314, 316, 318) within the specified frequency range 302 into the object at each of the one or more portions 204 (e.g., 204A-C). The different frequency microwaves are sequentially launched by the microwave launcher 106 such that microwaves having a first frequency 310 within the specified frequency range 302 are launched into the first portion 204A of the one or more portions 204 during a first time period, and microwaves having a second frequency 312 within the specified frequency range 302 are launched into the first portion 204A during a second time period after the first time period. Optionally, the microwave launcher 106 may also be controlled to sequentially launch microwaves having a plurality of different power levels into each of the one or more portions 204 of the object 102.

[0091] At 504, after the one or more portions 204 are heated by the microwaves having different frequencies during the first frequency sweep, thermal image data of each of the one or more portions 204 of the object 102 is generated via the optical sensor 108. For example, the optical sensor 108 may capture a plurality of thermal images of the first portion 204A, wherein each thermal image of the first portion 204A represents a temperature distribution caused by heating according to different frequencies of the microwaves within the frequency range 302.

[0092] At 506, for each of the one or more portions 204 of the object 102, a corresponding selected frequency 350 within the designated frequency range 302 is determined by analyzing the thermal image data. Microwaves having the selected frequency 350 provide greater heating of the corresponding portion than one or more other frequencies in the designated frequency range 302. For example, the selected frequency 350 of the microwaves may provide greater heating of the corresponding portion 204 than all other frequencies of the microwaves in the designated frequency range 302. The corresponding selected frequency 350 may optionally also be determined based on a penetration depth of the microwaves emitted into the object 102. For example, only frequencies of microwaves having the ability to penetrate into the object to an expected depth are considered as candidates for representing the selected frequency 350.

[0093] Optionally, the method proceeds to 508 where a second frequency sweep of the microwave emitter 106 is performed over the one or more portions 204 of the object 102. During the second frequency sweep, the microwave emitter 106 emits only microwaves having the respective selected frequencies 350 into each corresponding portion 204 of the object 102. At 510, selected thermal image data (e.g., Figure 4 At 512 , the selected thermal image data for each of the one or more portions 204 is analyzed to detect a thermal signature representative of the sub-surface elements 104 in the object 102 .

[0094] Alternatively, the method proceeds directly from 506 to 512 without performing a second frequency sweep. For example, the selected thermal image data analyzed for sub-surface element detection can be a subset of the thermal image data generated during the first frequency sweep, such as Figure 3 Thermal image data 328 , 332 , 346 are shown in .

[0095] Figure 6 The first example use application of the inspection system 100 is shown. All or at least part of the inspection system 100 is installed on an unmanned aerial vehicle (UAV) or a drone 600. For example, the microwave generator 114 ( Figure 1 ), the transmitter 106 and the optical sensor 108 are all mounted on the UAV 600. The UAV 600 is controlled to move the transmitter 106 and the optical sensor 108 within the proximity of the object to perform a non-contact inspection of the object according to the process described herein. In the illustrated embodiment, the object is an airfoil 602 of a wind turbine (e.g., a windmill) 604. Figure 5 The inspection method described in may include controlling a UAV 600 to fly close to a corresponding airfoil 602 being inspected. The UAV 600 may enable the inspection method to be performed on high or difficult to reach objects, and also on objects in motion (e.g., a rotating wind turbine airfoil 602).

[0096] Figure 7 A second example use application of the inspection system 100 is shown. Figure 7 In the embodiment, all or at least part of the inspection system 100 is mounted on a land-based mobile robotic device 700 (referred to herein as a robot). For example, the microwave generator 114 ( Figure 1), the transmitter 106 and the optical sensor 108 are mounted on the robot 700. The robot 700 is controlled to move along the ground so as to position the transmitter 106 and the optical sensor 108 within the proximity of the object. In the illustrated embodiment, the object is an aircraft 702 (e.g., a wing 704 of the aircraft 702). Figure 5 The inspection method described in may include controlling a robot 700 to drive along a wing 704 being inspected.

[0097] At least one technical effect of the embodiments described herein is the ability to perform more accurate and energy efficient detection of elements (e.g., defects) beneath the surface of an inspected object. Another technical effect is the ability to perform non-contact elemental detection on objects with varying material and / or structural composition and also on thicker outer structures up to or exceeding one inch.

[0098] In one or more embodiments, the inspection system includes one or more processors and an infrared (IR) camera. The one or more processors are configured to couple with a microwave transmitter and control the microwave transmitter to sequentially transmit microwaves having different frequencies within a specified frequency range into the object during a first frequency sweep of the object. The IR camera is operably coupled to the one or more processors and configured to generate thermal image data of the object after heating the object by each of the different frequencies of the microwaves during the first frequency sweep. The one or more processors are configured to analyze the thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the object compared to one or more other frequencies in the specified frequency range. The one or more processors are also configured to analyze the selected thermal image data of the object in response to the heating of the object by the selected frequency of the microwaves to detect elements in the object.

[0099] Optionally, the selected thermal image data is a subset of thermal image data generated during the first sweep, or generated during a subsequent second sweep of the microwave transmitter over the object.

[0100] Optionally, the one or more processors are configured to detect elements in the object by identifying a thermal signature in the selected thermal image data that is representative of a type of element.

[0101] Optionally, the one or more processors are configured to control the microwave emitter to emit microwaves having different frequencies into a common portion of the object at different times.

[0102] Optionally, the one or more processors are configured to control the microwave emitter to emit microwaves having different frequencies into each of the plurality of different portions of the object during a first frequency sweep of the microwave emitter.

[0103] Optionally, the selected frequency is a first selected frequency corresponding to a first portion of the plurality of different portions of the object. The IR camera is configured to generate thermal image data of a second portion of the object after heating the second portion by each of the different frequencies of the microwaves during the first frequency sweep. The one or more processors are configured to analyze the thermal image data of the second portion and determine a second selected frequency corresponding to the second portion within the specified frequency range. The second selected frequency provides greater heating of the second portion than one or more other frequencies in the specified frequency range.

[0104] Optionally, before analyzing the selected thermal image data, the one or more processors are configured to control the microwave emitter to perform a second frequency sweep over the object so that the microwave emitter emits only microwaves having a selected frequency into the object. The IR camera is configured to generate the selected thermal image data of the object after being heated by microwaves during the second frequency sweep.

[0105] Optionally, the one or more processors are further configured to control the microwave emitter to emit microwaves having a plurality of different power levels into the object during a first frequency sweep of the object. Optionally, the IR camera is configured to generate thermal image data of the object after heating the object by each of the different frequencies of the microwaves at each of the different power levels during the first frequency sweep.

[0106] Optionally, the one or more processors are configured to control the microwave emitter to emit microwaves that penetrate a surface coating on the object. The surface coating is thicker than one inch.

[0107] Optionally, the one or more processors are configured to determine the selected frequency for the object based on which frequency of the microwaves within the specified frequency range provides maximum heating of the object.

[0108] Optionally, the inspection system further comprises a drone, and the microwave transmitter and the IR camera are mounted on the drone.

[0109] In one or more embodiments, a method includes performing a first sweep of a microwave transmitter over one or more portions of an object. During the first sweep, the microwave transmitter sequentially transmits microwaves having a plurality of different frequencies within a specified frequency range into the object at each of the one or more portions. The method includes generating thermal image data of each of the one or more portions of the object via an infrared (IR) camera after heating by microwaves having different frequencies during the first sweep. The method also includes determining, for each of the one or more portions of the object by analyzing the thermal image data, a corresponding selected frequency within the specified frequency range. The microwaves having the selected frequency provide greater heating to the corresponding portion than one or more other frequencies in the specified frequency range. The method includes analyzing selected thermal image data of each of the one or more portions generated by the IR camera when heated by microwaves having the corresponding selected frequency to detect a thermal signature representing an element in the object. The selected thermal image data is a subset of the thermal image data generated during the first sweep, or is generated during a subsequent second sweep of the microwave transmitter over the one or more portions of the object.

[0110] Optionally, microwaves having different frequencies are emitted sequentially by the microwave emitter, so that microwaves having a first frequency within a specified frequency range are emitted into a first portion of the one or more portions during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period after the first time period.

[0111] Optionally, before analyzing the selected thermal image data, the method further includes performing a second frequency sweep of the microwave transmitter over the one or more portions of the object. During the second frequency sweep, the microwave transmitter transmits only microwaves having a corresponding selected frequency into each corresponding portion of the object. The method further includes generating selected thermal image data of each of the one or more portions of the object via the IR camera after heating by microwaves during the second frequency sweep.

[0112] Optionally, determining the respective selected frequency for each of the one or more portions of the object comprises determining which frequency of microwaves within the specified frequency range provides greater heating of the corresponding portion than all other frequencies of microwaves in the specified frequency range.

[0113] Optionally, the respective selected frequency for each of the one or more portions of the object is further determined based on a penetration depth of the microwaves emitted into the object.

[0114] Optionally, during the first frequency sweep, the microwave transmitter is further controlled to sequentially transmit microwaves having a plurality of different power levels into each of the one or more portions of the object.

[0115] Optionally, the method further includes installing a microwave transmitter and an IR camera on a drone, and controlling the drone to fly close to the object.

[0116] Optionally, the method further includes installing a microwave transmitter and an IR shooting device on a land-based mobile robotic device, and controlling the land-based mobile robotic device to move close to the object.

[0117] In one or more embodiments, an inspection system includes a microwave transmitter, one or more processors, and an infrared (IR) camera. The one or more processors are operably coupled to the microwave transmitter and configured to control the microwave transmitter to transmit microwaves into a plurality of different portions of the object during a first frequency sweep of the object and during a subsequent second frequency sweep of the object. The IR camera is operably coupled to the one or more processors and configured to generate thermal image data of each portion of the portion of the object after the portion is heated by microwaves during the first frequency sweep and during the second frequency sweep. During the first frequency sweep, the one or more processors are configured to control the microwave transmitter to sequentially transmit microwaves having a plurality of different frequencies within a specified frequency range into each portion of the plurality of portions, so that microwaves having a first frequency within the specified frequency range are emitted into a first portion of the portion during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period after the first time period. The one or more processors are configured to analyze the thermal image data generated by the IR camera during the first frequency sweep so as to determine, for each portion of the portion of the object, a corresponding selected frequency within the specified frequency range that provides greater heating of the corresponding portion of the object compared to other frequencies of the microwaves emitted into the corresponding portion. During the second frequency sweep, the one or more processors are configured to control the microwave emitter to emit only microwaves having the respective selected frequencies into each corresponding portion of the object.

[0118] Optionally, the one or more processors are configured to analyze thermal image data generated by the IR camera during the second sweep to detect thermal signatures representative of elements in the object.

[0119] Optionally, the one or more processors are configured to mechanically direct the microwave launcher during the first frequency sweep to launch microwaves into each of the plurality of portions of the object.

[0120] Optionally, the one or more processors are configured to electrically direct the microwave launcher using the phased array antenna system during the first frequency sweep to launch microwaves into each of the plurality of portions of the object.

[0121] As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding a plurality of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to "one embodiment" of the presently described subject matter are not intended to be understood as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, unless explicitly stated to the contrary, embodiments "comprising" or "having" an element or a plurality of elements having a particular property may include such additional elements not having that property.

[0122] The above description is illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) may be used in combination with each other. In addition, various modifications may be made to adapt specific situations or materials to the teachings of the subject matter described herein without departing from its scope. Although the dimensions and types of materials described herein are intended to define the parameters of the disclosed subject matter, they are by no means restrictive, but exemplary embodiments. Upon reviewing the above description, many other embodiments will be apparent to those skilled in the art. Therefore, the scope of the subject matter described herein should be determined by reference to the appended claims together with the full range of equivalents to which such claims are given. In the appended claims, the terms "including" and "wherein" are used as the plain English equivalents of the corresponding terms "including" and "wherein". In addition, in the following claims, the terms "first", "second", and "third", etc. are used only as labels, and are not intended to impose numerical requirements on their objects. In addition, the limitations of the following claims are not written in a method-plus-function form and are not intended to be based on 35 USC§ 112 (f), unless and until such claim limitations are specifically used with the phrase "components for..." followed by a functional statement lacking further structure.

[0123] This written description uses examples, including the best mode, to disclose several embodiments of the subject matter described herein, and also to enable persons skilled in the art to practice embodiments of the disclosed subject matter, including making and using devices or systems and performing methods. The patentable scope of the subject matter described herein is defined by the claims, and may include other examples that occur to persons skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. An inspection system for non-destructive object inspection, comprising: one or more processors configured to be coupled to a microwave transmitter and to control the microwave transmitter to sequentially transmit microwaves having different frequencies within a specified frequency range into the object during a first frequency sweep of the object; as well as an infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data of the object after heating the object by each of the different frequencies of microwaves during the first frequency sweep, wherein the one or more processors are configured to analyze the thermal image data from the infrared (IR) camera and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range, and wherein the one or more processors are further configured to analyze selected thermal image data of the object to detect elements in the object in response to heating of the object by the selected frequency of microwaves, wherein the one or more processors are configured to control the microwave transmitter to transmit the microwaves having the different frequencies into each of a plurality of different portions of the object during the first frequency sweep of the microwave transmitter, wherein before analyzing the selected thermal image data, the one or more processors are configured to control the microwave emitter to perform a second frequency sweep over the object so that the microwave emitter emits only microwaves having the selected frequency into the object, and The infrared (IR) camera is configured to generate the selected thermal image data of the object after heating by the microwaves during the second frequency sweep.

2. The inspection system according to claim 1, wherein: The selected thermal image data is a subset of the thermal image data generated during the first sweep or during a subsequent second sweep of the microwave transmitter over the object.

3. The inspection system according to claim 1, wherein: The one or more processors are configured to detect the element in the object by identifying a thermal signature in the selected thermal image data that is representative of a type of the element.

4. The inspection system according to claim 1, wherein: The one or more processors are configured to control the microwave emitters to emit the microwaves having the different frequencies into a common portion of the object at different times.

5. The inspection system according to claim 1, wherein: The selected frequency is a first selected frequency corresponding to a first portion of the plurality of different portions of the object, and wherein The infrared (IR) camera is configured to generate thermal image data of the second portion of the object after heating the second portion by each of the different frequencies of the microwaves during the first frequency sweep, and The one or more processors are configured to analyze the thermal image data of the second portion and determine a second selected frequency within the specified frequency range corresponding to the second portion, the second selected frequency providing greater heating to the second portion compared to one or more other frequencies in the specified frequency range.

6. The inspection system of claim 1, wherein: The one or more processors are further configured to control the microwave transmitter to transmit microwaves having a plurality of different power levels into the object during the first frequency sweep of the object.

7. The inspection system of claim 6, wherein: The infrared (IR) camera is configured to generate thermal image data of the object after heating the object by each of the different frequencies of the microwaves at each of the different power levels during the first frequency sweep.

8. The inspection system of claim 1, wherein: The one or more processors are configured to control the microwave emitter to emit microwaves that penetrate a surface coating on the object, the surface coating being thicker than one inch.

9. The inspection system of claim 1, wherein: The one or more processors are configured to determine the selected frequency for the object based on which frequency of microwaves within the specified frequency range provides maximum heating of the object.

10. The inspection system of claim 1, further comprising a drone, wherein the microwave transmitter and the infrared (IR) camera are mounted to the drone.

11. A method for non-destructive object inspection, comprising: performing a first frequency sweep of a microwave launcher over one or more portions of the object, wherein during the first frequency sweep, the microwave launcher sequentially launches microwaves having a plurality of different frequencies within a specified frequency range into the object at each of the one or more portions; generating thermal image data of each of the one or more portions of the object via an infrared (IR) camera after heating by the microwaves having the different frequencies during the first frequency sweep; determining, by analyzing the thermal image data, for each of the one or more portions of the object, a corresponding selected frequency within the designated frequency range, wherein microwaves having the selected frequency provide greater heating of the corresponding portion than one or more other frequencies within the designated frequency range; as well as analyzing selected thermal image data of each of the one or more portions generated by the infrared (IR) camera when heated by microwaves having a corresponding selected frequency to detect a thermal signature representative of elements in the object, and wherein the selected thermal image data is a subset of the thermal image data generated during the first sweep or during a subsequent second sweep of the microwave transmitter over the one or more portions of the object, wherein before analyzing the selected thermal image data, the method further comprises performing a second frequency sweep of the microwave transmitter over the one or more portions of the object, wherein during the second frequency sweep, the microwave transmitter transmits only microwaves having a corresponding selected frequency into each corresponding portion of the object, and generating the selected thermal image data of each of the one or more portions of the object via the infrared (IR) camera after heating by the microwaves during the second frequency sweep, The microwaves having the different frequencies are sequentially emitted by the microwave emitter, so that microwaves having a first frequency within the specified frequency range are emitted into a first part of the one or more parts during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first part during a second time period after the first time period.

12. The method of claim 11, wherein: Determining the respective selected frequency for each of the one or more portions of the object includes determining which frequency of microwaves within the specified frequency range provides greater heating of the corresponding portion than all of the other frequencies of microwaves in the specified frequency range.

13. The method of claim 11, wherein: The respective selected frequency for each of the one or more portions of the object is also determined based on a penetration depth of the microwaves emitted into the object.

14. The method of claim 11, wherein: During the first frequency sweep, the microwave transmitter is also controlled to sequentially transmit microwaves having a plurality of different power levels into each of the one or more portions of the object.

15. An inspection system for non-destructive object inspection, comprising: Microwave transmitters; one or more processors operably coupled to the microwave emitter and configured to control the microwave emitter to emit microwaves into a plurality of portions of the object during a first sweep of the object and during a subsequent second sweep of the object; as well as an infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data of each of the portions of the object after heating the portions by the microwaves during a first frequency sweep and during a second frequency sweep, wherein during the first frequency sweep, the one or more processors are configured to control the microwave transmitter to sequentially transmit microwaves having a plurality of different frequencies within a specified frequency range into each of the plurality of sections, so that microwaves having a first frequency within the specified frequency range are transmitted into a first section of the sections during a first time period, and microwaves having a second frequency within the specified frequency range are transmitted into the first section during a second time period after the first time period, wherein the one or more processors are configured to analyze the thermal image data generated by the infrared (IR) camera during the first frequency sweep to determine, for each of the portions of the object, a corresponding selected frequency within the specified frequency range that provides greater heating of the corresponding portion than other frequencies of microwaves emitted into the corresponding portion of the object, and During the second frequency sweep, the one or more processors are configured to control the microwave transmitter to transmit only microwaves having the corresponding selected frequency into each corresponding portion of the object.

16. The inspection system of claim 15, wherein: The one or more processors are configured to analyze the thermal image data generated by the infrared (IR) camera during the second frequency sweep to detect a thermal signature representative of elements in the object.

17. The inspection system of claim 15, wherein: The one or more processors are configured to mechanically direct the microwave launcher during the first frequency sweep to launch the microwaves into each of the plurality of portions of the object.

18. The inspection system of claim 15, wherein: The one or more processors are configured to electrically direct the microwave launcher using a phased array antenna system during the first frequency sweep to launch the microwaves into each of the plurality of portions of the object.

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