Systems and methods for performing truncated-correlation photothermal coherence tomography
First Claim
1. A method of performing photothermal imaging, the method comprising:
- generating an excitation chirped waveform comprising a chirped sequence of pulses;
controlling a laser according to the excitation chirped waveform, such that the laser emits a chirped sequence of laser pulses;
directing the chirped sequence of laser pulses onto a sample;
detecting, with an infrared camera, photothermal radiation emitted from the sample, thereby obtaining time-dependent photothermal signal data for each image pixel of the infrared camera;
generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and whereineach truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses;
cross-correlating the time-dependent photothermal signal data with the truncated chirped waveform, thereby obtaining, for each pixel of the infrared camera, time-dependent cross-correlation data; and
generating image data based on the time-dependent cross-correlation data.
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Abstract
Photothermal imaging systems and methods are disclosed that employ truncated-correlation photothermal coherence tomography (TC-PCT). According to the example methods disclosed herein, photothermal radiation is detected with an infrared camera while exciting a sample with the chirped delivery of incident laser pulses (where the pulses have a fixed width), and time-dependent photothermal signal data is obtained from the infrared camera and processed using a time-evolving filtering method employing cross-correlation truncation. The cross-correlation truncation method results in pulse-compression-linewidth-limited depth-resolved images with axial and lateral resolution well beyond the well-known thermal-diffusion-length-limited, depth-integrated nature of conventional thermographic and thermophotonic modalities. As a consequence, an axially resolved layer-by-layer photothermal image sequence can be obtained, capable of reconstructing three-dimensional visualizations (tomograms) of photothermal features in wide classes of materials. Additional embodiments are disclosed in which the aforementioned systems and methods are adapted to photo-acoustic and acousto-thermal imaging.
21 Citations
19 Claims
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1. A method of performing photothermal imaging, the method comprising:
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generating an excitation chirped waveform comprising a chirped sequence of pulses; controlling a laser according to the excitation chirped waveform, such that the laser emits a chirped sequence of laser pulses; directing the chirped sequence of laser pulses onto a sample; detecting, with an infrared camera, photothermal radiation emitted from the sample, thereby obtaining time-dependent photothermal signal data for each image pixel of the infrared camera; generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and wherein each truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses; cross-correlating the time-dependent photothermal signal data with the truncated chirped waveform, thereby obtaining, for each pixel of the infrared camera, time-dependent cross-correlation data; and generating image data based on the time-dependent cross-correlation data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for performing photothermal imaging, the system comprising:
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a laser; an infrared camera; and computer hardware including processor electronics configured to perform operations comprising; generating an excitation chirped waveform comprising a chirped sequence of pulses; controlling the laser according to the excitation chirped waveform, such that the laser emits a chirped sequence of laser pulses onto a sample; detecting, with the infrared camera, photothermal radiation responsively emitted from the sample, thereby obtaining time-dependent photothermal signal data for each image pixel of the infrared camera; generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and wherein each truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses; cross-correlating the time-dependent photothermal signal data with the truncated chirped waveform, thereby obtaining, for each pixel of the infrared camera, time-dependent cross-correlation data; and generating image data based on the time-dependent cross-correlation data.
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11. A method of performing acousto-thermal imaging, the method comprising:
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generating an excitation chirped waveform comprising a chirped sequence of pulses; controlling a high-frequency ultrasound source according to the excitation chirped waveform, such that the high-frequency ultrasound source emits a chirped sequence of ultrasound pulses; directing the chirped sequence of ultrasound pulses onto a sample; detecting, with an infrared camera, photothermal radiation emitted from the sample, thereby obtaining time-dependent photothermal signal data for each image pixel of the infrared camera; generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and wherein each truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses; cross-correlating the time-dependent photothermal signal data with the truncated chirped waveform, thereby obtaining, for each pixel of the infrared camera, time-dependent cross-correlation data; and generating image data based on the time-dependent cross-correlation data. - View Dependent Claims (12, 13, 14)
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15. A system for performing acousto-thermal imaging, the system comprising:
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a high-frequency ultrasound source; an infrared camera; and computer hardware including processor electronics configured to perform operations comprising; generating an excitation chirped waveform comprising a chirped sequence of pulses; controlling the high-frequency ultrasound source according to the excitation chirped waveform, such that the high-frequency ultrasound source emits a chirped sequence of ultrasound pulses onto a sample; detecting, with the infrared camera, photothermal radiation responsively emitted from the sample, thereby obtaining time-dependent photothermal signal data for each image pixel of the infrared camera; generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and wherein each truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses; cross-correlating the time-dependent photothermal signal data with the truncated chirped waveform, thereby obtaining, for each pixel of the infrared camera, time-dependent cross-correlation data; and generating image data based on the time-dependent cross-correlation data.
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16. A method of performing photo-acoustic imaging, the method comprising:
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generating an excitation chirped waveform comprising a chirped sequence of pulses; controlling a laser according to the excitation chirped waveform, such that the laser emits a chirped sequence of laser pulses; directing the chirped sequence of laser pulses onto a sample; detecting, with an ultrasound array, ultrasound waves emitted from the sample and beamforming the received ultrasound signals to obtain spatially-resolved time-dependent ultrasound signal data from the sample; generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and wherein each truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses; cross-correlating the spatially resolved time-dependent ultrasound signal data with the truncated chirped waveform, thereby obtaining time-dependent cross-correlation data; and generating image data based on the time-dependent cross-correlation data. - View Dependent Claims (17, 18)
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19. A system for performing photo-acoustic imaging, the system comprising:
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a laser; an ultrasound array; and computer hardware including processor electronics configured to perform operations comprising; generating an excitation chirped waveform comprising a chirped sequence of pulses; controlling the laser according to the excitation chirped waveform, such that the laser emits a chirped sequence of laser pulses onto a sample; detecting, with an ultrasound array, ultrasound waves responsively emitted from the sample and beamforming the received ultrasound signals to obtain spatially-resolved time-dependent ultrasound signal data from the sample; generating a truncated chirped waveform comprising a chirped sequence of truncated pulses, wherein each truncated pulse has a pulsewidth less than that of the pulses of the excitation chirped waveform, and wherein each truncated pulse is delayed by a pre-selected time delay relative to a corresponding pulse of the chirped sequence of pulses; cross-correlating the spatially resolved time-dependent ultrasound signal data with the truncated chirped waveform, thereby obtaining time-dependent cross-correlation data; and generating image data based on the time-dependent cross-correlation data.
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Specification