阅读说明：本技术 用于智能材料分析的设备和方法 (Apparatus and method for smart material analysis ) 是由 E.博韦罗 于 2018-05-10 设计创作，主要内容包括：一种使用可移动检查设备检查包括光子材料的结构的方法,包括照射所述结构的一部分,接收从所述结构的所述部分中的光子材料衍射的辐射,根据以下的至少一种确定所述光子材料的变形：i)接收的辐射的强度,ii)接收的辐射的位置和iii)接收的辐射的波长；和确定变形幅度是否高于阈值。如果变形幅度高于阈值,则存储关于所述光子材料的变形的数据；相反,如果变形幅度不高于阈值：停止所述光子材料的位置处的检查并移动所述检查设备以检查所述结构的另一部分。(A method of inspecting a structure comprising a photonic material using a movable inspection apparatus, comprising illuminating a portion of the structure, receiving radiation diffracted from the photonic material in the portion of the structure, determining a deformation of the photonic material from at least one of: i) an intensity of the received radiation, ii) a location of the received radiation and iii) a wavelength of the received radiation; and determining whether the magnitude of the deformation is above a threshold. Storing data about the deformation of the photonic material if the deformation magnitude is above a threshold; conversely, if the magnitude of the deformation is not above the threshold: stopping the inspection at the location of the photonic material and moving the inspection apparatus to inspect another portion of the structure.)

1. A method of inspecting a structure comprising a photonic material using a movable inspection apparatus, the method comprising:

illuminating a portion of the structure;

receiving radiation diffracted from photonic material in the portion of the structure;

determining a deformation of the photonic material from at least one of: i) an intensity of the received radiation, ii) a location of the received radiation and iii) a wavelength of the received radiation; and

determining whether the magnitude of deformation is above a threshold;

if the magnitude of the deformation is above the threshold:

storing data regarding deformation of the photonic material;

if the magnitude of the deformation is not above the threshold:

i) stopping inspection at the location of the photonic material; and

ii) moving the inspection apparatus to inspect another portion of the structure.

2. The method of claim 1, wherein the portion of the photonic material is irradiated with monochromatic radiation and the deformation is determined from the intensity of the received radiation.

3. The method of claim 2, wherein the inspection device comprises a radiation source and a radiation sensor, and the deformation is further determined according to: (i) a wavelength emitted by the radiation source, and (ii) a position of the radiation source relative to the portion of the structure being illuminated, and (iii) a distance between the radiation source and the radiation sensor.

4. The method of claim 1, wherein the portion of the photonic material is irradiated with polychromatic radiation, and the deformation is further determined as a function of a wavelength of the received radiation.

5. The method of claim 4, wherein the photonic material is three-dimensional and the deformation is further determined from a measured wavelength band gap.

6. The method of claim 4, wherein the diffracted radiation is received by a camera sensor.

7. The method of claim 6, wherein the deformation is further determined from a location of a wavelength received at a camera sensor.

8. The method of claim 7, wherein the inspection device includes a radiation source and the deformation is determined from a wavelength of the received radiation and a location of the radiation, wherein the location of the received radiation includes a pixel location of the radiation captured at the camera sensor, wherein the deformation is further determined from: (i) a radiation source position relative to the portion of the structure being illuminated, and (ii) a distance between the radiation source and the camera sensor.

9. The method of claim 6, wherein the camera sensor comprises a plurality of pixel elements that respond to the received radiation by expressing a hue, and wherein the wavelength of the received radiation is determined according to the expressed hue.

10. The method of claim 9, wherein the wavelength is determined as a linear function of the expressed hue.

11. The method of claim 4, wherein the polychromatic radiation is in the visible spectrum.

12. The method of claim 4, wherein at least a portion of the polychromatic radiation is outside the visible spectrum.

13. A computer program product comprising a non-transitory computer-readable medium including program code which, when loaded into a computer, controls the computer to perform the method of claim 1.

14. A movable apparatus for inspecting an object comprising a photonic material, comprising:

a radiation source for illuminating a portion of the structure;

a radiation sensor for receiving radiation diffracted from photonic material in the portion of the structure;

a processor coupled to the sensor and configured to determine a deformation of the photonic material according to at least one of: i) intensity, ii) position and iii) wavelength of the received radiation, and determining whether the magnitude of the deformation is above a threshold; and

a storage medium coupled to the processor;

wherein the processor directs data regarding the deformation of the photonic material to the storage medium if the deformation magnitude is above a threshold; and

wherein if the magnitude of deformation is not above a threshold, the processor stops inspection at the location of the photonic material and sends a signal that causes the inspection device to move and inspect another portion of the structure.

15. The apparatus of claim 14, wherein the radiation source emits monochromatic radiation and the deformation of the photonic material is determined from the intensity of radiation received at the radiation sensor.

16. The apparatus of claim 14, wherein the radiation source emits polychromatic radiation and the deformation of the photonic material is determined according to the wavelength of the received radiation.

17. The apparatus of claim 16, wherein polychromatic wavelengths are in the visible spectrum and the radiation sensor comprises a camera having a plurality of pixel elements with different positions.

18. The device of claim 17, wherein the processor is configured to determine a deformation according to: (i) a wavelength of the received radiation, (ii) a pixel element position of the radiation captured at the camera sensor, (iii) a position of the radiation source relative to the portion of the structure being illuminated, and (iv) a distance between the radiation source and the camera.

19. The device of claim 18, wherein the plurality of pixel elements respond to the received radiation by expressing a hue, and the wavelength of the received radiation is determined according to the expressed hue.

20. The apparatus of claim 14, wherein the photonic material is three-dimensional and the processor is configured to determine the deformation of the photonic material further from a measured wavelength forbidden band.

Technical Field

The present invention relates to embedded smart materials for monitoring and detection, and more particularly to an apparatus and method for smart material analysis.

Background

Pipe and vessel structures used in the oil and gas industry are subject to stresses over time that can build up to create defects in the structure. Unfortunately, it is often difficult to determine whether such structures are subjected to destructive stress until an easily observable defect occurs.

The availability of non-destructive inspection techniques for structural materials such as non-metallic pipes used in pipelines is limited. In most cases, the techniques available to date are either destructive to the material or experimental and unreliable. Even considering current experimental techniques for non-destructive inspection, none of the prior art techniques reliably predicts the formation of defects and is typically only used to detect existing defects.

More specifically, existing building materials and corresponding systems and techniques for inspecting materials are insufficient to detect the presence of stresses, such as tensile or compressive stresses, on or in the material with sufficient accuracy and precision so that defects can be predicted in advance. Currently available techniques for sensing material defects are typically based on single-fiber bragg gratings. These fibers provide one-dimensional information: that is, they can only detect stresses that occur along the length of the fiber, and only detect significant stresses corresponding to materials that have been damaged, with significant cracks and breaks in the structural material.

There is a need for a system and method for detecting perturbations in a structural material that utilizes a photonic material, such as a grating or photonic crystal, as a sensitive element for generating diffraction. In addition, there is a need for systems and methods for detecting perturbations in structural materials that quantify deformation in photonic materials through wavelength changes, or diffraction angle changes from intensity changes. Furthermore, there is a need for a system and method for detecting perturbations that has a sensitivity that can be tuned by selecting the detection wavelength and the corresponding period of the photonic structure material. Additionally, there is a need for systems and methods for detecting disturbances that have multidimensional sensitivity levels.

With respect to these and other considerations, the disclosure herein is set forth.

Disclosure of Invention

According to the present invention, there is provided a method of inspecting a structure comprising a photonic material using a movable inspection apparatus. The method comprises illuminating a portion of the structure, receiving radiation diffracted from a photonic material in the portion of the structure, determining a deformation of the photonic material from at least one of: i) an intensity of the received radiation, ii) a location of the received radiation and iii) a wavelength of the received radiation; and determining whether the magnitude of the deformation is above a threshold. Storing data about the deformation of the photonic material if the deformation magnitude is above a threshold; conversely, if the magnitude of the deformation is not above the threshold: stopping the inspection at the location of the photonic material and moving the inspection apparatus to inspect another portion of the structure.

In some embodiments, the portion of the structure is illuminated with monochromatic radiation, and the deformation is determined from the intensity of the received radiation. The examination apparatus may comprise a radiation source and a radiation sensor, and the deformation may be further determined according to: (i) a wavelength emitted by the radiation source, (ii) a position of the radiation source relative to the portion of the structure being illuminated, and (iii) a distance between the radiation source and the radiation sensor.

In other embodiments, the portion of the structure is illuminated with polychromatic radiation and the deformation is determined as a function of the wavelength of the received radiation. In embodiments where the photonic material is three-dimensional, the deformation is further determined from a measured wavelength bandgap (wavelength stop band).

In some embodiments, the diffracted radiation is received by a camera sensor, and the deformation may be further determined from a location at the camera sensor of the received radiation. The examination apparatus may comprise a radiation source and the deformation may be determined from a wavelength and a position of the received radiation, wherein the position of the received radiation comprises pixel positions of the radiation captured at the camera sensor, wherein the deformation is further determined from: (i) a radiation source position relative to the portion of the structure being illuminated, and (ii) a distance between the radiation source and the camera sensor. In some embodiments, the camera sensor includes a plurality of pixel elements that respond to the received radiation by expressing a hue, and determining a wavelength of the received radiation from the expressed hue. In some embodiments, the polychromatic radiation is in the visible spectrum, while in other embodiments, at least a portion of the polychromatic radiation is outside the visible spectrum.

According to a further aspect of the invention, a computer program product is provided, comprising a non-transitory computer-readable medium comprising program code which, when loaded into a computer, controls the computer to perform the above-mentioned method.

According to a further aspect of the invention, a movable apparatus for inspecting an object comprising a photonic material is provided. The apparatus comprises a radiation source for illuminating a portion of a structure, a radiation sensor for receiving radiation diffracted from a photonic material in the portion of the structure, a processor coupled to the sensor and configured to determine a deformation of the photonic material in accordance with at least one of: i) an intensity of the received radiation, ii) a location of the received radiation and iii) a wavelength of the received radiation, and determining whether a magnitude of the deformation is above a threshold, and a storage medium coupled to the processor. If the magnitude of the deformation is above a threshold, the processor directs data regarding the deformation of the photonic material to a storage medium; conversely, if the magnitude of the deformation is not above the threshold, the processor stops the inspection at the location of the photonic material and sends a signal that causes the inspection device to move and inspect another portion of the structure.

In some embodiments, the radiation source emits monochromatic radiation, and the deformation of the photonic material is determined from the intensity of the radiation received at the radiation sensor. In other embodiments, the radiation source emits polychromatic radiation, and the deformation of the photonic material is further determined according to the wavelength of the received radiation. In some embodiments, the polychromatic wavelength is in the visible spectrum and the radiation sensor comprises a camera having a plurality of pixel elements with different positions. In such embodiments, the processor is configured to determine the deformation according to: (i) a wavelength of the received radiation, (ii) a pixel element location of the radiation captured at the camera sensor, (iii) a location of the radiation source relative to the portion of the photonic material, and (iv) a distance between the radiation source and the camera. The plurality of pixel elements respond to the received radiation by expressing a hue, and the wavelength of the received radiation is determined according to the expressed hue.

In some embodiments, the photonic material is three-dimensional, and the processor is configured to determine the deformation of the photonic material further from the measured wavelength forbidden band.

These and other aspects, features and advantages may be understood from the following description of certain embodiments of the invention and the accompanying drawings and claims.

Drawings

Fig. 1 is a schematic view of an inspection apparatus according to an embodiment of the present invention.

Fig. 2 is a schematic block diagram of components of an inspection apparatus according to an embodiment of the present invention.

Fig. 3 is a perspective view illustrating an angular pattern of inspection according to an embodiment of the present invention.

Fig. 4 is a perspective view illustrating an inspected wavelength pattern according to an embodiment of the present invention.

FIG. 5 is a flow diagram of a method of inspecting a structure containing photonic material, in accordance with an embodiment of the present invention.

Detailed Description

In one or more embodiments, a method of inspecting a structure having embedded "smart" material is provided. The inspection device is positioned to emit radiation onto a portion of the surface of the structure. Radiation diffracted from the smart material embedded in the surface of the structure is detected using a radiation sensor. Depending on the particular inspection mode applied, it is determined whether the portion of the inspected surface has been subjected to a threshold level of deformation (i.e., a length of deformation) based on the characteristics of the detected diffracted light. If the distortion is above a threshold level, the detected sensor data is stored and further analysis is performed. If the deformation is below a threshold level, the device is moved to inspect different portions on the surface of the structure.

To monitor the condition of large structures in the field, such as pipes and storage vessels, smart materials may be embedded or attached to the structure as indicators of the state of the structure. Smart materials include structures that undergo a change in an exponential parameter in response to deformation. An important class of smart materials includes periodic photonic materials, including gratings and photonic crystals. The diffraction pattern transmitted by a photonic material in response to radiation is extremely sensitive to the periodic spacing of its constituent elements. Thus, any deformation or perturbation from normal experienced by the embedded photonic material due to, for example, tensile stress, compressive stress, bending, temperature changes, etc., may be manifested in a corresponding difference in the diffraction pattern of the perturbed structure from normal. The change in the diffraction pattern is proportional to the size of the perturbation and can be measured using an inspection apparatus.

The inspection apparatus may be operated in different inspection modes, such as an angle mode and a wavelength mode. In the angular mode, diffracted radiation is received at the radiation sensor, and the deformation is determined from the variation in intensity at the location where the diffracted beam strikes the sensor, or more specifically, at the location on the sensor. The change in intensity of the pass-through location is used to determine the displacement distance. In the wavelength mode, the wavelength, rather than the intensity, of light received at one or more particular locations on the light sensor is used to quantify the displacement. By selecting the detection wavelength and the corresponding period of the photonic material, the sensitivity of the detection can be adjusted. In one or more embodiments, multiple inspection modes may be combined to help determine the deformation of the structure 102 with embedded photonic material 103, as will be understood from the discussion below.

Fig. 1 shows an exemplary embodiment of an inspection apparatus 100 according to the present invention for inspecting a structure 102 with embedded photonic material 103. The photonic material 103 may (preferably) comprise a diffraction grating, but may also comprise other structures exhibiting a periodic variation of an optical property, such as refractive index. The apparatus 100 includes a housing 105 containing a plurality of components for inspecting the structure, which can be positioned and moved as a unit along the length of the structure 102. For this purpose, the housing 105 may be connected to a vehicle, such as a robot or drone, or the housing may include a drive mechanism and wheels for automatic movement. The housing 105 comprises openings 107 for the radiation source and the detector.

Disposed within housing 105 are radiation sources 110, 115 positioned to direct radiation toward a portion of structure 102. Although two radiation sources are depicted, a single source may be used in some embodiments, and in alternative embodiments, more than two sources may be used. In an exemplary embodiment, radiation source 110 is a laser source (e.g., a collimated beam having, for example, a single wavelength), and radiation source 115 is a diffuse radiation source that emits multiple different wavelengths. Diffuse radiation source 115 may take a variety of forms and may emit radiation over a broad or narrow range of wavelengths in and/or outside the visible spectrum. For example, the diffuse radiation source may be implemented using white LEDs, flash lamps, X-ray emitters or natural ambient radiation. One or more lenses, e.g., 120, may be configured to focus radiation emitted by diffuse radiation source 115 onto structure 102 for inspection.

Radiation received at the photonic material 103 is diffracted and reflected back to the opening 107 of the inspection apparatus. In some embodiments, apparatus 100 includes a reflector 125 (as shown) positioned to receive radiation diffracted from photonic material 103. The reflector 125 and one or more focusing components 128 are oriented to direct and focus incident radiation into the radiation sensor 130. The radiation sensor 130 may be implemented in a variety of ways including a digital camera, an infrared detector, a Charge Coupled Device (CCD) photomultiplier tube, photographic film, and the like. In embodiments where the sensor constitutes a single element, the amplitude or intensity of the sensor output signal is used to determine the displacement. For sensors comprising an array of elements, such as a CCD array, the response of a particular array element (i.e. position) provides information from which displacement can be determined. In the illustrated embodiment, the radiation sensor is coupled to the local processor 140 and transmits the captured sensor data to the local processor 140. In an alternative embodiment, the processor is remotely located and the device includes a wireless communication module (as shown in fig. 2) for transmitting the sensor data to the remote processor.

The inspection device 100 may be arranged with various computer hardware and software components for enabling operation of the inspection device and, more particularly, performing operations related to analysis of information captured by the radiation sensor 130. Fig. 2 is a block diagram depicting exemplary computer hardware and software components of inspection apparatus 100 including processor 140 and circuit board 150. As shown in fig. 2, the circuit board may include a memory 155, a communication interface 160, and a computer-readable storage medium 165 accessible by the processor 140. The processor 140 and/or circuit board 150 may also be coupled to a display 170 for visually outputting information to an operator (user), a user interface 175 for receiving operator inputs, and an audio output 180 for providing audio feedback, as understood by those skilled in the art. As an example, device 100 may emit a visual signal from display 170 or a sound from sound output 180 when a defect or deformation above a certain threshold is encountered. The threshold may be set manually or by default prior to measurement via the user interface 175, which user interface 175 may be a touch screen or a suitable keyboard. While the various components are depicted as being separate from the circuit board 150 or as being part of the circuit board 150, it will be appreciated that the components may be arranged in various configurations without departing from the disclosure herein.

The processor 140 is used to execute software instructions that may be loaded into memory. Processor 140 may be implemented using multiple processors, multiple processor cores, or some other type of processor, as well as distributed processors, which for purposes of this disclosure are collectively referred to as a "processor". The memory 155 is accessible by the processor 140 to enable the processor to receive and execute instructions stored on the memory and/or storage. The memory 155 may be implemented using, for example, Random Access Memory (RAM) or any other suitable volatile or non-volatile computer-readable storage medium. In addition, the memory 155 may be fixed or removable. The storage medium 165 may also take various forms, depending on the particular implementation. For example, the storage medium 165 may comprise one or more components or devices, such as a hard disk drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, or some combination of the above. The storage medium 165 may also be fixed or removable or remote, such as a cloud-based data storage system. The circuit board 150 may also include or be coupled to a power source (not shown) for powering the inspection device.

One or more software modules 185 are encoded in memory 155 and/or storage medium 165. The software modules may include one or more software programs or applications having computer program code or a set of instructions that are executed in the processor 140. Such computer program code or instructions for performing operations and implementing aspects of the systems and methods disclosed herein may be written in any combination of one or more programming languages. When the software modules 185 are stored locally on the processor 140, the processor may interact with a remote-based computing platform via a local or wide area network, preferably wirelessly, to perform calculations or analyses via the communication interface 160.

During execution of the software module 185, the processor 140 is configured to perform various operations related to analysis of the radiation captured by the sensor 130 for detecting and quantifying disturbances in the inspected material as a function of the diffraction pattern, as will be described in more detail below. The program code of the software module 185 and one or more non-transitory computer-readable storage devices (such as memory 155 and/or storage 165) form a computer program product that may be manufactured and/or distributed in accordance with the present disclosure, as will be appreciated by those of ordinary skill in the art. Additionally, information and/or data relating to the configuration and operation of the present devices and methods may also be stored in association with the software modules. Such information may include prescribed settings and parameters, such as expected diffraction patterns, relating to the device and the various materials and photonic materials that may be inspected. Similarly, operating parameters and various operating modes specific to the inspection device (e.g., relative sizes of device components, deformation thresholds, radiation intensities) may also be stored.

According to some embodiments of the invention, the software module 185 includes sub-modules for operating the inspection apparatus and analyzing the data in an angular mode 186, a wavelength mode 187, and a three-dimensional mode 188. Fig. 3 is a schematic perspective view showing an angle inspection mode. As shown in FIG. 3, an embodiment of the inspection apparatus 100 begins inspection as directed by the angle mode sub-module 186 by first illuminating a portion of the substrate 102 with a radiation source 110, the radiation source 110 preferably being a laser (monochromatic) source. The use of a monochromatic light source allows the wavelength to be a fixed parameter in the analysis. In fig. 3, the radiation source 110 emits an activation beam 302 onto the photonic grating 103 of the structure 102. An incident beam 302 is reflected by a single beam 304 and is also diffracted by the grating along several beam paths 306, 308, 310, 312 in different orders. Beams 306 and 308 are at 1 and-1 orders, respectively, and beams 310 and 312 are at 2 and-2 orders. The relationship between the characteristics of the grating 103 and the diffraction parameters is as follows:

d(sinα-sinβ)＝nλ (1)

where d is the distance between the grooves in grating 103, α is the angle of incidence of beam 302, β is the angle of diffraction of a beam 312, which is detected at sensor 130, n is the diffraction order, and λ is the wavelength of the radiation. In this way, given a constant wavelength (λ), order (n) and activation beam angle (α), any change in grating pitch (d) will depend only on the detected diffraction angle (β).

The light beam 312 having the order n-2 is received by the radiation sensor 130. The parameter α is the angle at which the beam 302 is directed relative to the vertical axis and is therefore known from the configuration and position of the radiation source 110. The parameter β may be calculated by taking into account the distance e between the radiation source 110 and the radiation sensor 130, which is also known from the configuration of these components in the device 100 and the distance s between the device 100 and the surface of the structure.

In particular, the formula for β is:

thus, given the wavelength (λ) of the laser, the only unknown in grating equation (1) is the spacing (d) between features. Quantification of this distance provides relative and absolute information about the deformation of the material. This distance is relative and also absolute with respect to the surrounding values, since the values provided are a direct measure of the state of the material in a particular point and not a ratio.

As the spacing between features changes, the value of s in equation (2) also changes in a corresponding manner. The recorded value of s depends on the type of radiation sensor used. In some embodiments where the radiation sensor is a single element, such as an intensity meter, the change in s is captured as a decrease in signal intensity (where the sensor position is calibrated for maximum intensity of zero deformation). The single element sensor does not indicate whether the change in displacement is an extended compression. More preferably, the radiation sensor comprises a plurality of sensitive elements, such as a CCD array. By determining the strength change of a plurality of individual elements, the multi-element sensor can indicate the direction of change (expansion or compression) as well as the magnitude of deformation.

The apparatus 100 may also include a proximity sensor (not shown) to automatically determine the distance e between the radiation source and the surface of the structure.

As described above, in addition to the angular mode, the deformation in the photonic material may also be determined by operating the inspection apparatus in the wavelength mode. In the wavelength mode, the wavelength of diffracted light is a signal for quantifying displacement. In this mode, light having multiple wavelengths (e.g., a polychromatic radiation source such as white light) is directed onto the sample and also diffracted according to grating equation (1). Fig. 4 is a schematic perspective view showing a wavelength inspection mode. Another embodiment of an inspection apparatus 400 is shown in fig. 4. The inspection apparatus comprises a polychromatic light source 410 and a radiation sensor 430, or IR camera, capable of sensing different wavelengths, e.g. ultraviolet or visible light, in the relevant part of the spectrum. The radiation sensor 430 may be an array of individual sensing elements capable of detecting multiple wavelengths simultaneously. As noted above, multiple modes of operation may be combined in certain embodiments, with the determination of distortion as an average of the results returned from each method, as a weighted average, or multiple modes of operation may compare the results for verification of the results, or the results of a particular mode of operation may be selected based on prevailing conditions (e.g., humidity at the time of measurement).

In the solution shown in fig. 4, the illuminated area of the structure surface is covered between angles α 1 and α 2. Each point on the surface being illuminated diffracts radiation in a respective direction, but the radiation sensor 430 collects only a limited range of radiation. The width of the range is determined by the size of the radiation sensor 430 and/or the aperture in the device 400 leading to the sensor. In any case, this range is rather narrow due to the typical geometry of gratings that are typically manufactured. This narrowness is used for detection advantages because a single wavelength can be associated with each pixel or point in the resulting image generated at the radiation sensor 430. The image collected by the sensor is defined by the field of view of the sensor itself, which is defined by dashed lines 422 and 424 in fig. 4. The field of view is further defined by the diffraction angle beta₁＝β₂Defined as γ. As shown in fig. 4, different wavelengths at different locations in the image may correspond to the same displacement d. More specifically, all the radiation collected by the sensor 430 arrives from different angles, from different wavelengths α 1, β 1 to α 2, β 2, resulting from the same displacement d.

Thus, photonic materials with uniform pitch (i.e., no deformation due to tensile or compressive stress) diffract different wavelengths at different angles, and the diffraction angle and detection position in the sensor image vary uniformly with wavelength. The shift will result in a local variation of the diffraction wavelength for a particular angle or a non-uniform variation of the wavelength over the illuminated area. Therefore, in order to quantify this displacement, it is important to consider several parameters: of the most important are the relative position of the illumination spot with respect to the inspection apparatus, and the color (wavelength) detected by the radiation sensor 430.

The position of the pixels of the captured wavelengths in the collected image can be used to accurately determine the position of the illumination spot relative to the device as a whole. For example, the angles α, β of diffraction corresponding to a generic point may be expressed as a function of the coordinates of the pixels corresponding to a particular point in the collected image. The angle α can be calculated according to trigonometric considerations by observing:

in equation (3), tga is the tangent of α, y is the size of the image on the surface of the material, and P_yIs the position of the analysis point measured from the end of the image corresponding to pixel coordinate 0. P_yCan be derived from the pixel p_yThe size of the image on the pixel P and the actual size of the image in length y are calculated as:

by substituting P_yEquation (3) becomes:

similarly, the angle β can be expressed as:

incorporating equations (5) and (6) into grating equation (1), we obtain grating equation (7) for the wavelength mode:

equation (7) is written in a convenient form because it is generally easy to measure the actual size of the image at a distance from the device. However, equation (7) may also be expressed by considering the angle (γ) of image acquisition. First, the distance (y) can be expressed as:

y＝2e·tgγ (8)

in conjunction with equation (8), equation (7) becomes:

equations (7) and (9) provide the exact value of d, which is used to quantify any displacement in the material. Since all parameters are known from the measurement setup and the architecture of the device, the only measurement variable is λ.

The two modes described so far are applicable to a grating with a planar periodicity or any other two-dimensional structure form of the technology. However, the analysis can also be extended to three-dimensional periodic structures. For three-dimensional photonic materials, both angle and wavelength mode analysis are governed by different mechanisms. In three-dimensional photonic crystals, periodic structures are associated with periodic modulation of the dielectric constant. Photonic materials have regions of allowed band and forbidden band for wavelengths in a similar manner to the way semiconductors cross electronic band structures. An approximation of the forbidden band wavelength can be expressed as a combination of a modified version of bragg diffraction law and Snell's law of refraction as follows:

in equation (10), S is a shrinkage factor that accounts for the final shrinkage of the lattice structure during formation, is a parameter of the photonic crystal responsible for the particular forbidden band under consideration, m is the order of diffraction, h, k, and l are miller indices, Φ is the volume fraction of one of the materials making up the lattice, and n₁、n₂Is the refractive index of both materials. If the photonic material is deformed, the parameter a will change. As a result, by monitoring the change in the wavelength of the forbidden band, the deformation of the material can be monitored. In general, changes in the viewing angle in a three-dimensional periodic structure do not affect changes in wavelength as do two-dimensional photonic materials. Typically, there are a range of angles and the wavelength of the forbidden band will be constant. However, once the angle changes by a certain magnitude, another lattice plane and lattice constant act and change the forbidden band.

Measurements can be easily made with the apparatus as described above. The measurement may be performed in a reflective mode (i.e. by receiving a reflected beam from the photonic crystal) or in a transmissive mode. In the reflection mode, the wavelength measured by the radiation sensor will correspond to the wavelength of the forbidden band. In the transmission mode, the measured wavelength will be complementary to the forbidden band. The angle of the incident radiation does not affect the measurement. One useful form of equation (10) for monitoring deformation of three-dimensional photonic materials is:

in other embodiments, the forbidden wavelength can be determined using the absorption spectrum of the structure. For absorption spectroscopy measurements, the measured value of the peak of the band will correspond to the wavelength of the forbidden band rather than the complementary wavelength.

In some embodiments of the method of the present invention in which the camera is implemented as a radiation sensor, the wavelength measurement may be determined using a tone scale of the camera. The hue (H) of the camera pixel can be used as an approximation of the wavelength. For example, in some cameras, the hue may be modeled as 360 radians from red, through yellow, etc., and back to red. As the wavelength in the visible range decreases, the hue increases. Thus, by matching wavelengths in the visible range from about 650nm to 430nm taking into account a limited range of hues, an empirical correspondence can be written as follows:

λ＝650-1.16H (12)

the quantification of the wavelength by the hue (H) is not necessarily precise, but there is a functional ratio between the wavelength and the hue. Therefore, equation (12) has strong empirical characteristics and may require calibration. This level of accuracy of the tone scale is sufficient for applications where local variations of the deformation are more important than the absolute value.

Fig. 5 is a flow diagram of a method 500 of inspecting a structure including a photonic material, in accordance with an embodiment of the present invention. In step 502, the method starts with positioning an inspection apparatus relative to a structure so that the structure can be inspected. Positioning may include many steps to advance or maneuver a robotic crawling machine or drone, or other mechanism on which the detection device may be mounted. In step 504, a portion of a structure comprising a photonic material is illuminated. In step 506, radiation diffracted from the photonic material is received. In a subsequent step 508, the deformation of the photonic material is determined according to one of: i) intensity ii) location and iii) wavelength of the received radiation. In step 510, it is determined whether the magnitude of the deformation is above a threshold. If the deformation is above the threshold, then in step 512, data regarding the deformation of the photonic material is stored. If the deformation is below the threshold, the inspection of the portion of the structure is stopped in step 514 and the inspection device is moved to another portion of the structure in step 516.

Illustrative embodiments and arrangements of the present system and method provide a system and computer implemented method, computer system and computer program product for inspecting intelligent structures. The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments and arrangements. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

It is to be understood that any structural and functional details disclosed herein are not to be interpreted as limiting the system and method, but are instead provided as representative embodiments and/or arrangements teaching one skilled in the art one or more ways to implement the method.

It will be appreciated that although many of the foregoing descriptions have referred to systems and methods for inspecting photonic materials, the methods disclosed herein may similarly deploy other 'smart' structures in scenarios, situations and settings beyond those mentioned. It is to be further understood that any such embodiments and/or deployments are within the scope of the systems and methods described herein.

It should be further understood that throughout the several drawings, like reference numerals indicate like elements, and that not all of the components and/or steps described and illustrated with reference to the drawings are required for all embodiments or arrangements.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The directional terminology used herein is for the purpose of convention and reference only and is not to be construed as limiting. However, it is recognized that these terms may be used with reference to a viewer. No limitation is therefore implied or inferred.

Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.