Patent Description:
Because of the time involved in image processing, manufacturing goals and inspection goals may not be tenable while taking advantage of typical hyperspectroscopy systems and methods. Further, significant computer resources and cameras including complex hyperspectral imaging arrays are required for typical analysis methods. The hyperspectral cameras may also be susceptible to signal noise produced by ambient light and other sources. Other disadvantages may exist.

<CIT>, in accordance with its Abstract, states a spectroscopic system that processes spatially dispersed electromagnetic emissions at a number of wavelengths from a test material. The spectroscopic system includes a converter that generates an electrical signal that is proportional to the intensity of electromagnetic radiation received by the converter. An optical delay circuit is coupled to an input of the converter. The optical delay circuit selectively delays application to the converter of electromagnetic emissions from the test material for at least one wavelength of electromagnetic emissions. A data processing circuit is coupled to an output of the converter. The data processing circuit records the value of the electrical signal from the converter over time so as to measure, contemporaneously, the intensity of electromagnetic emissions at each wavelength as a function of time.

<CIT>, in accordance with its Abstract, states a few-mode fiber having a graded-index core and a surrounding cladding comprising a ledge between the core and the trench, a down-doped trench abutting the ledge, and an undoped cladding region abutting the trench. The fiber's refractive index profile is configured to support <NUM> LP modes for transmission of a spatially-multiplexed optical signal and has optimized maximum differential group delay (MDGD) through a wide range of wavelengths.

<CIT>, in accordance with its Abstract, states a new architecture for implementing a time-resolved Raman spectrometer which is <NUM>-<NUM> orders of magnitude faster than current systems. The system employs a rotating optical switch to time multiplex an input signal through multiple bandpass filters and into a single optical detector which is electrically activated only when the filtered input light pulse is about to impact it. The combination of time-multiplexing the input signal through multiple optical filters and time-sequencing the optical detector enables the device to detect and analyze <NUM>-<NUM> orders of magnitude faster than current designs, processing spectra within milliseconds instead of seconds. The system can process multiple material samples (<NUM>+) simultaneously, instead of sequentially, and its mechanical ruggedness and simplicity enables using the system in harsh physical environments when traditional spectrometers can not be used reliably.

<CIT>, in accordance with its Abstract, states a time correlated single photon counting system having a time to digital converter triggered by a laser fire event detector and the reception of a single photon. The system may be used for chemical agent detection based on Rayleigh scattering using optical time domain reflectometry techniques. The system may also be used for Raman detection using frequency to time transformations.

Disclosed is a method comprising scanning a surface of a composite workpiece, as defined in claim <NUM>, and a spectral sensing system, as defined in claim <NUM>, that resolve or mitigate at least one of the disadvantages mentioned above. The method of the disclosure includes scanning a surface of a composite workpiece with multiple electromagnetic pulses, each of the multiple electromagnetic pulses being associated with a respective location on the surface of the composite workpiece. The method further includes, for each respective location on the surface of the composite workpiece, receiving a response to one of the multiple electromagnetic pulses at a multi-mode fiber, the response including multiple wavelength components, time shifting the multiple wavelength components with respect to each other by passing the response through the multi-mode fiber to produce a wavelength-binned pulse, sampling the wavelength-binned pulse at time intervals corresponding to the multiple wavelength components to determine a set of wavelength intensity levels corresponding to the multiple wavelength components, and identifying a type or condition of material at the respective location on the surface of the composite workpiece based on the set of wavelength intensity levels.

In some embodiments, the method includes generating an image of the surface of the composite workpiece indicating the type or condition of material for each respective location on the surface of the composite workpiece. In some embodiments, the method includes identifying anomalies on the surface of the composite workpiece based on the type or condition of material for each respective locations and superimposing graphical indicators of the anomalies on a visible image of the surface of the composite workpiece. In some embodiments, the method includes synchronizing a modulation period of a source of the multiple electromagnetic pulses with a duration of the wavelength-binned pulse for each respective location. In some embodiments, the method includes spatially dispersing the multiple wavelength components using a diffraction grating system before time shifting the multiple wavelength components, and focusing each of the multiple wavelength components into the multi-mode fiber using a lens. In some embodiments, identifying the type or condition of material at the respective location on the surface of the composite workpiece includes comparing the set of wavelength intensity levels to stored wavelength intensity levels associated with pre-selected types or conditions of material. In some embodiments, the method includes, in response to determining that, for each respective location on the surface of the composite workpiece, the type or condition of material excludes contaminants, adding a new layer to the composite workpiece.

The method of the disclosure, as defined in claim <NUM>, includes receiving, at a multi-mode fiber, a response to an electromagnetic pulse directed to a location on a surface of a composite workpiece, the response including multiple wavelength components. The method further includes time shifting the multiple wavelength components with respect to each other by passing the response through a multi-mode fiber to produce a wavelength-binned pulse. The method also includes sampling the wavelength-binned pulse at time intervals corresponding to the multiple wavelength components to determine a set of wavelength intensity levels corresponding to the response. The method includes identifying a type or condition of material at the location on the surface of the composite workpiece based on the set of wavelength intensity levels.

In some embodiments, the method includes identifying additional types or conditions of material at additional locations on the surface of the composite workpiece using the multi-mode fiber, and generating an image of the surface of the composite workpiece that includes graphical indicators indicating the type or condition of material at the location and indicating the additional types or conditions of material at the additional locations. As defined in claim <NUM>, the method of the disclosure includes synchronizing a modulation period of a source of the electromagnetic pulse with a duration of the wavelength-binned pulse. As also defined in claim <NUM>, the method of the disclosure includes spatially dispersing the multiple wavelength components using a diffraction grating system before time shifting the multiple wavelength components, and focusing each of the multiple wavelength components into the multi-mode fiber using a lens. In some embodiments, identifying the type or condition of material at the location on the surface of the composite includes comparing the set of wavelength intensity levels to stored wavelength intensity levels associated with pre-selected types or conditions of material.

As defined in claim <NUM>, a spectral sensing system according to the disclosure includes a multi-mode fiber configured to receive a response to an electromagnetic pulse directed to a location on a surface of a composite workpiece, the response including multiple wavelength components, and to time shift the multiple wavelength components with respect to each other to produce a wavelength-binned pulse. The system further includes a detector configured to sample the wavelength-binned pulse at time intervals corresponding to the multiple wavelength components to determine a set of wavelength intensity levels corresponding to the multiple wavelength components. The system also includes a processor configured to identify a type or condition of material at the location on the surface of the composite workpiece based on the wavelength intensity levels.

In some embodiments, the processor is further configured to generate an image of the surface of the composite workpiece that indicates the type or condition of material at the location on the surface of the composite workpiece. In some embodiments, the system further includes a source of the electromagnetic pulse, where the source includes a red-green-blue (RGB) laser source, a white light laser source, a light emitting diode source, an arc lamp, or combinations thereof. In some embodiments, a modulation period of the source of the electromagnetic pulse is synchronized with a duration of the wavelength-binned pulse. As defined in claim <NUM>, the system of the disclosure includes a diffraction grating system for spatially dispersing the multiple wavelength components. As also defined in claim <NUM>, the system of the disclosure includes a lens configured to focus the multiple wavelength components into the multi-mode fiber. In some embodiments, the system includes a mirror system configured to scan the surface of the composite workpiece to enable the multi-mode fiber to receive additional responses for identifying types or conditions of material at additional locations on the surface of the composite workpiece using the multi-mode fiber. In some embodiments, the composite workpiece is a pre-preg ply of an aircraft wing.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.

The systems and methods disclosed herein may be applied in a composite component manufacturing environment. In particular, the systems and methods disclosed may be used during the manufacturing of aircraft components, including composite wing structures to provide for in-process non-destructive evaluation of the composite wing structures as they are assembled and before being cured. An example of a manufacturing environment suitable for use with the disclosed systems and methods is described in <CIT> and entitled "Contamination Identification System," the contents of which are herein incorporated by reference in their entirety.

Referring to <FIG> of the present disclosure, an embodiment of a spectral sensing system <NUM> includes an electromagnetic source <NUM> which may be directed to a surface <NUM> of a composite workpiece <NUM>, a mirror system <NUM>, a diffraction grating system <NUM>, a lens <NUM>, a multi-mode fiber <NUM>, a detector <NUM>, a computing system <NUM>, and a display device <NUM>.

The source <NUM> may include any electromagnetic source capable of producing sufficient wavelengths to identify substances of interest on the surface <NUM> of the composite workpiece <NUM>. For example, the source <NUM> may include, but is not limited to, red-green-blue (RGB) laser sources, a white light laser source, a light emitting diode (LED) source, an arc lamp, another type of electromagnetic source, or combinations thereof.

As depicted in <FIG>, the source <NUM> is modulated to emit multiple electromagnetic pulses <NUM>-<NUM>. The source <NUM> may further be configured to scan across the surface <NUM> of the composite workpiece <NUM> in a direction <NUM>. As the source <NUM> scans, each of the electromagnetic pulses <NUM>-<NUM> may reflect off the surface <NUM> at corresponding locations <NUM>-<NUM> on the surface <NUM> of the composite workpiece <NUM>. For example, a first electromagnetic pulse <NUM> may be associated with a first location <NUM>, a second electromagnetic pulse <NUM> may be associated with a second location <NUM>, a third electromagnetic pulse <NUM> may be associated with a third location <NUM>, a fourth electromagnetic pulse <NUM> may be associated with a fourth location <NUM>, and a fifth electromagnetic pulse <NUM> may be associated with a fifth location <NUM>. The methods of spectral sensing are described herein with respect to the first electromagnetic pulse <NUM> and the first location <NUM>, but is should be understood that the described methods may be performed for each of the electromagnetic pulses <NUM>-<NUM> and their corresponding locations <NUM>-<NUM>.

In some embodiments, the composite workpiece <NUM> may include a component of an aircraft. The surface <NUM> may generate a response <NUM> to the first electromagnetic pulse <NUM> at the first location <NUM>, which may be determined based on the reflective, absorptive, and transmissive properties of the surface <NUM>, as well as the properties of any contaminant materials that may be present on the surface <NUM>.

The response <NUM> may be directed through the mirror system <NUM>. The mirror system <NUM> may include any number of mirrors and may be configured to scan the locations <NUM>-<NUM> along with the source <NUM>. Specific examples of a sufficient mirror system are described with reference to <CIT>, which has been incorporated herein.

In some embodiments, the source <NUM> may also be configured to make use of the mirror system <NUM> for scanning across the surface <NUM> of the composite workpiece <NUM>. In both cases, the mirror system <NUM> may be configured to direct the response <NUM> of the electromagnetic pulse <NUM> into the diffraction grating system <NUM> while the electromagnetic pulse <NUM> is directed to the location <NUM>.

The response <NUM> may include multiple wavelength components <NUM>-<NUM>. For example, the response <NUM> may include a first wavelength component <NUM>, a second wavelength component <NUM>, and a third wavelength component <NUM>. While the response <NUM> is depicted as including three wavelength components, persons of ordinary skill in the art understand that wavelength is a continuous parameter, such that the response <NUM> may include any number of wavelength components. Further, the response may include noise, such as from ambient lighting or other sources within a production environment of the composite workpiece <NUM>.

The diffraction grating system <NUM> may include any number of diffraction gratings to spatially disperse the wavelength components <NUM>-<NUM> from each other. The diffraction grating system <NUM> may further function to filter wavelengths that are not used for the spectral sensing. For example, some wavelengths may not be needed to identify materials and contaminants on the surface <NUM> of the composite workpiece <NUM>. These wavelength components may be ignored by the diffraction grating system <NUM> or may otherwise not pass through the diffraction grating system <NUM>. After passing through the diffraction grating system <NUM>, the wavelength components <NUM>-<NUM> of the response <NUM> are spatially dispersed from each other. The lens <NUM> then focusses, according to the disclosure, each of the spatially dispersed wavelength components <NUM>-<NUM> into the multi-mode fiber <NUM> as shown in <FIG> at reference number <NUM>.

The multi-mode fiber <NUM> may be selected based on its modal dispersion properties including its ability to time-shift signals having different wavelengths. In general, multi-mode fibers cause wavelength-dependent time-shifting due to different wavelengths passing through the multi-mode fiber <NUM> at different speeds. While the speed of light is the same for each of the wavelength components, due to differing indices of refraction, the distances travelled by each of the wavelengths through the multi-mode fiber <NUM> differ. As such, the amount of time-shifting that occurs between wavelengths within the multi-mode fiber <NUM> depends on a number of factors including the index of refraction of the multi-mode fiber cladding, the particular wavelengths of interest, a diameter of the multi-mode fiber <NUM>, a length of the multi-mode fiber <NUM>, and other features and properties of the multi-mode fiber <NUM>. In the system <NUM>, each of these features of the multi-mode fiber <NUM> may be selected in order to spread the wavelength components <NUM>-<NUM> as shown in <FIG> at reference number <NUM>.

For example, the multi-mode fiber <NUM> may time-shift the wavelength components <NUM>-<NUM> of the response <NUM> from each other as each of the wavelength components <NUM>-<NUM> pass through the multi-mode fiber <NUM> at a different speed. The result is an expanded wavelength-binned pulse <NUM> that includes each of the wavelength components <NUM>-<NUM> sorted over time.

The detector <NUM> is, according to the disclosure, timed to sample the wavelength components <NUM>-<NUM> separately. For example, as each of the wavelength components <NUM>-<NUM> arrives at the detector <NUM> after a respective interval, the detector <NUM> may sample the arriving wavelength component. In the system <NUM>, the detector <NUM> may include any electromagnetic detector capable of detecting the wavelength components <NUM>-<NUM>. For example, the detector <NUM> may include, but is not limited to, a complementary metal-oxide semiconductor (CMOS) detector, a charge-coupled device (CCD) detector, another type of electromagnetic detector, or combinations thereof.

While some systems may include complex detector arrays for spectral imaging, the detector <NUM> may include fewer, or a single, detector because each of the wavelength components <NUM>-<NUM> arrives at the detector <NUM> at a different time. The modulation of the source <NUM> may be synchronized with the wavelength-binned pulse <NUM> in order to prevent the electromagnetic pulses <NUM>-<NUM> from producing interfering wavelength-binned pulses and to enable the continuous sampling of the detector <NUM> as the surface <NUM> is scanned. The timing and synchronization of the detector <NUM> and the source <NUM> is further described with reference to <FIG>.

Based on the samplings, the detector <NUM> produces a set of wavelength intensity levels <NUM>-<NUM> associated with each of the wavelength components <NUM>-<NUM>. For example, the wavelength intensity level <NUM> may be associated with the wavelength component <NUM>, the wavelength intensity level <NUM> may be associated with the wavelength component <NUM>, and the wavelength intensity level <NUM> may be associated with the wavelength component <NUM>. The set of wavelength intensity levels <NUM>-<NUM> may be collectively referred to as a signature <NUM>.

The signature <NUM> may be analyzed at the computing system <NUM>. For example, the computing system <NUM> may include a processor <NUM> and memory <NUM>. In general the memory <NUM> may include instructions that, when executed by the processor <NUM>, cause the processor <NUM> to identify a type or condition of material at the first location <NUM> based on the set of wavelength intensity levels <NUM>-<NUM>. This process is described in more detail herein with reference to <FIG>.

After a type or condition of material is identified at the first location <NUM>, additional types or conditions of material may be identified at the remaining locations <NUM>-<NUM> using responses to their corresponding electromagnetic pulses <NUM>-<NUM>. As the source <NUM> scans the surface <NUM> of the composite workpiece <NUM>, an image <NUM> may be generated that maps each of the locations <NUM>-<NUM> to a corresponding type or condition of material. The image <NUM> may be sent to the display device <NUM> for view by an operator. The operator may identify contaminants or other anomalies based on the image <NUM>.

In some embodiments, anomalies, which may include contaminants, may be automatically identified by the processor <NUM> based on the image <NUM>. The processor <NUM> may generate another image <NUM> that superimposes graphical indicators of the anomalies on a visible image of the surface <NUM> of the composite workpiece <NUM>. The other image <NUM> may be sent to the display device <NUM> to enable an operator to locate and correct anomalies that exist on the composite workpiece <NUM>. The generation of the images <NUM>, <NUM> is further described with reference to <FIG>.

A benefit of the system <NUM> is that by sorting and binning the wavelength components <NUM>-<NUM> while in a propagating signal before detection by the detector <NUM>, fewer computing resources may be used to perform a spectral analysis on the response <NUM> as compared to systems that do not sort and bin wavelength components before detection. Further, the amount of time devoted to image processing may be greatly reduced, enabling the system <NUM> to be applied to an in-process non-destructive evaluation without substantially slowing down the manufacturing process. Further, because the sorted and binned wavelength components <NUM>-<NUM> reach the detector <NUM> one-at-a-time, only a single detector <NUM> may be employed as compared to other systems that include a full spectral detector array to accumulate sufficient spectral imaging data. Thus, the system <NUM> may be greatly simplified as compared to other spectral analysis systems.

Another benefit of the system <NUM> is that, because the multi-mode fiber <NUM> time-shifts the response <NUM> based on wavelength, noise within the response (e.g., from ambient light or other sources) may be automatically and substantially removed from the binned wavelength components <NUM>-<NUM>. Thus, the system <NUM> may include fewer resources devoted to noise reduction as compared to other spectral analysis system. Other benefits of the system <NUM> may exist.

Referring to <FIG>, a lookup table <NUM> is described. The lookup table <NUM> may be stored at the memory <NUM> and may be used by the processor <NUM> of <FIG> to identify types or conditions of materials based on the wavelength intensity levels <NUM>-<NUM>. In some embodiments, the lookup table <NUM> may be stored at a database separate from the memory <NUM>. As used herein, the lookup table may include any data structure or data system that maps material signatures to types of materials.

The lookup table <NUM> may include stored data corresponding to multiple signatures or sets of wavelength intensity levels <NUM>-<NUM>. Each of the stored sets of wavelength intensity levels <NUM>-<NUM> may correspond to respective types or conditions of material <NUM>-<NUM>. For example, a first set of wavelength intensity levels <NUM> may correspond to a first type or condition of material <NUM>, a second set of wavelength intensity levels <NUM> may correspond to a second type or condition of material <NUM>, a third set of wavelength intensity levels <NUM> may correspond to a third type or condition of material <NUM>, and a fourth set of wavelength intensity levels <NUM> may correspond to a fourth type or condition of material <NUM>.

In the depicted embodiment, the first type or condition of material <NUM> is normal, e.g., a composite material used to construct the composite workpiece <NUM> under normal conditions. The second type or condition of material <NUM> is plastic. The third type or condition of material <NUM> is unknown, e.g., indicating an unknown contamination or condition. The fourth type of material or condition <NUM> is moisture, e.g., a wet condition. While <FIG> only depicts four types of materials or conditions, more or fewer than four may be included in the lookup table <NUM>. Further, plastic materials, unknown materials, and moisture may be considered contaminants while normal materials are part of the normal structure of the composite workpiece <NUM>.

The lookup table <NUM> may be used to compare the set of wavelength intensity levels <NUM>-<NUM> to the stored sets of wavelength intensity levels <NUM>-<NUM>, which may then be mapped to a type of material or condition. For example, the set of wavelength intensity levels <NUM>-<NUM> are mapped to the second type of material or condition <NUM>, or plastic. Each location of the surface <NUM> of the composite workpiece <NUM> may be scanned to determine the type of material or condition. The image <NUM> may be generated and may include graphical indicators, such as shading or color, to indicate the material present at each of the locations. For example, locations that are mapped to plastic materials may be shaded a first shade <NUM> that differs from locations that are mapped to unknown materials, which may be shaded a second shade <NUM>.

In some embodiments, the analysis may be taken further by generating another image <NUM>. The other image <NUM> may include a visual image <NUM> of the surface <NUM> of the composite workpiece <NUM>. Graphical indicators <NUM>, <NUM> may be superimposed on the visual image <NUM> to show an operator the location of anomalies on the composite workpiece <NUM>, enabling the operator to remove the anomalies before continuing a manufacturing process.

Referring to <FIG>, a timing diagram depicts the electromagnetic pulse <NUM> and the electromagnetic pulse <NUM>. The diagram may be conceptualized as traveling from left to right, such that the electromagnetic pulse <NUM> occurs before the electromagnetic pulse <NUM>. In <FIG>, the electromagnetic pulses <NUM>, <NUM> are depicted as a square wave to illustrate the modulation of the source <NUM> of <FIG>. As discussed herein, the source <NUM> may scan the surface <NUM> such that the electromagnetic pulse <NUM> may be directed at the first location <NUM> of the surface <NUM> and the electromagnetic pulse <NUM> may be directed at the second location <NUM> of the surface <NUM>.

Contact between the electromagnetic pulse <NUM> and the surface <NUM> may result in creating the response <NUM>. Likewise, subsequent contact between the electromagnetic pulse <NUM> and the surface <NUM> may results in the response <NUM>. The response <NUM> may include the multiple wavelength components <NUM>-<NUM> and the response <NUM> may also include multiple wavelength components. As depicted in <FIG>, each of the electromagnetic pulses <NUM>, <NUM> and the responses <NUM>, <NUM> may have the same duration <NUM>, which may be less than a modulation period <NUM> of the electromagnetic source <NUM>.

After the response passes through the multi-mode fiber <NUM>, each of the wavelength components <NUM>-<NUM> are time-shifted with respect to each other based on their respective wavelengths to produce the wavelength-binned pulse <NUM>. The individual wavelength components <NUM>-<NUM> are then sampled at intervals specific to the particular wavelength component. For example, the first wavelength component <NUM> may be sampled after a first interval <NUM>, the second wavelength component <NUM> may be sampled after a second interval <NUM>, and the third wavelength component <NUM> may be sampled after a third interval <NUM>. Each of the intervals <NUM>-<NUM> correspond to times when the wavelength components <NUM>-<NUM> will reach the detector <NUM>. Although each of the intervals <NUM>-<NUM> are depicted as extending to the center of each of the wavelength components <NUM>-<NUM>, in other embodiments, the intervals <NUM>-<NUM> may extend to any point within the corresponding wavelength components <NUM>-<NUM>. The response <NUM> also may be passed through the multi-mode fiber <NUM> as well and sampled in a similar manner. Only a first wavelength component <NUM> of the second response <NUM> is depicted in <FIG>.

After being time-shifted, the wavelength-binned pulse <NUM> may have a duration <NUM> that is longer than the duration <NUM> of the response <NUM> due to spreading. The modulation period <NUM> is, according to the disclosure, synchronized with the duration <NUM> of the wavelength-binned pulse <NUM> so that the third wavelength component <NUM> of the wavelength-binned pulse <NUM> does not interfere with the first wavelength component <NUM> associated with the second electromagnetic pulse <NUM>.

It should be noted that the timing depicted in <FIG> is not to scale. Each wavelength component <NUM>-<NUM> may be spread more or less than depicted in the example of <FIG>. Further, as previously stated, more or fewer than three wavelength components may be analyzed as part of the response <NUM>.

A benefit of the timing depicted in <FIG> is that by synchronizing the modulation period <NUM> with the duration <NUM>, the wavelength components <NUM>-<NUM> associate with the first electromagnetic pulse <NUM> may not interfere with the wavelength component <NUM> associated with the second electromagnetic pulse <NUM>. Further, the responses <NUM>, <NUM> may be continuously analyzed without long time periods therebetween. Other benefits and advantages may exist.

Referring to <FIG>, the composite workpiece <NUM> is depicted during a manufacturing stage. In an embodiment, the composite workpiece may be a pre-preg ply of an aircraft component, such as a wing. The composite workpiece <NUM> may include multiple layers <NUM>. After each layer is deposited, it may be inspected for anomalies, including contaminants, before the next layer is deposited. For example, after a layer <NUM> is placed over another layer <NUM>, the surface <NUM> of the composite workpiece <NUM>, including the layer <NUM>, may be inspected by scanning and analyzing each of the locations <NUM>-<NUM> to determine a type or condition of material for each of the locations <NUM>-<NUM> as described herein. After a determination that for each of the locations <NUM>-<NUM>, the type or condition of material excludes contaminants, the layer <NUM> may be placed over the layer <NUM>. In that way, the composite workpiece may be subjected to an in-process inspection during its manufacture.

Referring to <FIG>, an embodiment of a method <NUM> for spectral sensing is depicted. The method <NUM> includes receiving, at a multi-mode fiber, a response to an electromagnetic pulse directed to a location on a surface of a composite workpiece, the response including multiple wavelength components, at <NUM>. For example, the multi-mode fiber <NUM> may receive the response <NUM> to the first electromagnetic pulse <NUM> directed to the first location <NUM> on the surface <NUM> of the composite workpiece <NUM>.

The method <NUM> further includes time shifting the multiple wavelength components with respect to each other by passing the response through a multi-mode fiber to produce a wavelength-binned pulse, at <NUM>. For example, the wavelength components <NUM>-<NUM> may be time shifted with respect to one another to produce the wavelength-binned pulse <NUM>.

The method <NUM> also includes sampling the wavelength-binned pulse at time intervals corresponding to the multiple wavelength components to determine a set of wavelength intensity levels corresponding to the response, at <NUM>. For example, the wavelength-binned pulse <NUM> may be sampled by the detector <NUM> at intervals <NUM>, <NUM>, and <NUM> to determine the set of wavelength intensity levels <NUM>-<NUM>.

The method <NUM> includes identifying a type or condition of material at the location on the surface of the composite workpiece based on the set of wavelength intensity levels, at <NUM>. For example, a type or conditions of material (e.g., one of the types and conditions of material <NUM>-<NUM> may be identified at the first location <NUM> based on the set of wavelength intensity levels <NUM>-<NUM>.

Claim 1:
A method comprising:
scanning a surface (<NUM>) of a composite workpiece (<NUM>) with multiple electromagnetic pulses (<NUM>-<NUM>) emitted by a source (<NUM>), each of the multiple electromagnetic pulses (<NUM>-<NUM>) being associated with a respective location (<NUM>-<NUM>) on the surface of the composite workpiece (<NUM>);
for each respective location (<NUM>-<NUM>) on the surface (<NUM>) of the composite workpiece (<NUM>):
receiving a response (<NUM>) to one of the multiple electromagnetic pulses (<NUM>) at a multi-mode fiber (<NUM>), the response (<NUM>) including multiple wavelength components (<NUM>-<NUM>);
time shifting the multiple wavelength components (<NUM>-<NUM>) with respect to each other by passing the response (<NUM>) through the multi-mode fiber (<NUM>) to produce a wavelength-binned pulse (<NUM>);
sampling the wavelength-binned pulse (<NUM>) at time intervals (<NUM>-<NUM>) corresponding to the multiple wavelength components (<NUM>-<NUM>) to determine a set of wavelength intensity levels (<NUM>-<NUM>) corresponding to the multiple wavelength components (<NUM>-<NUM>);
identifying a type or condition of material (<NUM>, <NUM>, <NUM>, <NUM>) at the respective location (<NUM>) on the surface (<NUM>) of the composite workpiece (<NUM>) based on the set of wavelength intensity levels (<NUM>-<NUM>); whereby the following steps are performed:
spatially dispersing the multiple wavelength components using a diffraction grating system before time shifting the multiple wavelength components;
focusing each of the multiple wavelength components into the multi-mode fiber using a lens; and
synchronizing for each respective location (<NUM>-<NUM>) a modulation period (<NUM>) of the source (<NUM>) of the electromagnetic pulse with a duration (<NUM>) of the wavelength-binned pulse so that the wavelength components (<NUM>-<NUM>) associated with a first electromagnetic pulse (<NUM>) do not interfere with the wavelength component (<NUM>) associated with a second electromagnetic pulse (<NUM>).