Terahertz time-domain spectral imaging using telecentric beam steering and an f-θ scanning lens: distortion compensation and determination of resolution limits

Harris, Zachery B.; Virk, Arjun; Khani, Mahmoud E.; Arbab, M. Hassan

doi:10.1364/oe.398706

Cited by 33 publications

(28 citation statements)

References 27 publications

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“…In this study, the terahertz time-domain spectroscopy technology was used to evaluate the crystallinity and crystal structure of cellulose [21][22][23], and to compare with two traditional analysis methods of XRD and FT-IR. It was focused on the terahertz absorption peak characteristics of cellulose at low frequency bands in the range of 0.2-3.0 THz, providing a theoretical basis for the application of fiber materials [24].…”

Section: Introductionmentioning

confidence: 99%

Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

et al. 2020

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Crystallinity is an essential indicator for evaluating the quality of fiber materials. Terahertz spectroscopy technology has excellent penetrability, no harmful substances, and commendable detection capability of absorption characteristics. The terahertz spectroscopy technology has great application potential in the field of fiber material research, especially for the characterization of the crystallinity of cellulose. In this work, the absorption peak of wood cellulose, microcrystalline cellulose, wood nano cellulose, and cotton nano cellulose were probed in the terahertz band to calculate the crystallinity, and the result compared with XRD and FT-IR analysis. The vibration model of cellulose molecular motion was obtained by density functional theory. The results showed that the average length of wood cellulose (WC) single fiber was 300 μm. The microcrystalline cellulose (MCC) was bar-like, and the average length was 20 μm. The cotton cellulose nanofiber (C-CNF) was a single fibrous substance with a length of 50 μm, while the wood cellulose nanofiber (W-CNF) was with a length of 250 μm. The crystallinity of cellulose samples in THz was calculated as follows: 73% for WC, 78% for MCC, 85% for W-CNF, and 90% for C-CNF. The crystallinity values were obtained by the three methods which were different to some extent. The absorption peak of the terahertz spectra was most obvious when the samples thickness was 1 mm and mixed mass ratio of the polyethylene and cellulose was 1:1. The degree of crystallinity was proportional to the terahertz absorption coefficients of cellulose, the five-movement models of cellulose molecules corresponded to the five absorption peak positions of cellulose.

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Section: Introductionmentioning

confidence: 99%

Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

et al. 2020

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“…A high-resistivity silicon beam splitter guides the collimated beams toward a mirror mounted on a 2-axis motorized heliostat system, composed of a goniometer and a rotational stage, which raster scans the beam over a custom-made f-θ lens 51 . In a telecentric f-θ scanning system, collimated beams passing through the front focus of an f-θ lens at a deflection angle θ are focused to a true planar surface at a distance f × θ from the optic axis 52 . Therefore, the focused beam remains parallel to the optic axis and has a constant spot-size at the target plane 52 .…”

Section: Thz Time-domain Spectroscopymentioning

confidence: 99%

Supervised machine learning for automatic classification of in vivo burn injuries using the terahertz Portable Handheld Spectral Reflection (PHASR) scanner

Khani

Harris

Osman

et al. 2022

Preprint

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We present an automatic classification strategy for early and accurate assessment of burn injuries using terahertz (THz) time-domain spectroscopic imaging. Burn injuries of different severity grades, representing superficial partial-thickness (SPT), deep partial-thickness (DPT), and full-thickness (FT) wounds, were created by a standardized porcine scald model. THz spectroscopic imaging was performed using our new fiber-coupled Portable HAndheld Spectral Reflection (PHASR) scanner, incorporating a telecentric beam steering configuration and an f-\theta scanning lens. ASynchronous Optical Sampling (ASOPS) in a dual-fiber-laser THz spectrometer with 100 MHz repetition rate enabled high-speed spectroscopic measurements. Given twenty-four different samples composed of ten scald and ten contact burns and four healthy samples, supervised machine learning algorithms using THz-TDS spectra achieved areas under the receiver operating characteristic (ROC) curves of 0.88, 0.93, and 0.93 when differentiating between SPT, DPT, and FT burns, respectively, as determined by independent histological assessments. These results show the potential utility of our new broadband THz PHASR scanner for early and accurate triage of burn injuries.

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“…Vancouver, BC, Canada) in a telecentric configuration 32,33 . The 12×19 mm 2 area can be scanned in approximately two minutes with a depth of focus much greater than the penetration depth of the THz beam 25 . Furthermore, the scanner is "alignment-free" and maintains constant resolution across the entire FOV.…”

Section: Handheld Thz-tdsi Scannermentioning

confidence: 99%

“…A handheld single-line scanner was designed for imaging malignant breast tumors, however, it was restricted to scanning along a single dimension 23 , with a 2 mm by 15 mm field-of-view (FOV). In contrast to these instruments, we have designed and built a handheld, fiber-coupled, two-dimensional THz-TDSI scanner with a maximum FOV of up to 43×27 mm, and have tested its utility in the first in vivo porcine burn study using THz radiation 24,25 .…”

Section: Introductionmentioning

confidence: 99%

In Vivo Assessment of Burn Depth and Wound Healing Using a Handheld Terahertz Hyperspectral Scanner

Osman

Harris

Zhou

et al. 2021

Preprint

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The accuracy of clinical assessment in partial-thickness burn injuries has remained as low as 50-75%. Depending on the depth and environmental factors in the wound, such as reactive oxygen species, inflammation, and autophagy, partial-thickness burns can heal spontaneously or require surgical intervention. In this study, we demonstrate that Terahertz Time-Domain Spectral Imaging (THz-TDSI) is a promising tool for in vivo quantitative assessment of burn injuries. We used a novel handheld THz-TDSI scanner to characterize burn injuries in a porcine scald model with histopathological control. Prior work used THz reflectivity (representation of tissue hydration) as the only source of signal contrast. However, we used the spectral amplitude and the spectral slope of the terahertz electric field to distinguish the different severities of burns, suggesting that the energy loss due to electromagnetic scattering from skin constituents serves an additional metric to quantitatively assess burn injuries. Statistical analysis (n = 40) indicates that THz-TDSI can accurately differentiate between partial-thickness and full-thickness burn injuries (1-way ANOVA, p < 0.05) and monitor the healing process of partial thickness burns. THz-TDSI has the potential to improve burn care outcomes by helping surgeons to make objective decisions for early excision.

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Terahertz time-domain spectral imaging using telecentric beam steering and an f-θ scanning lens: distortion compensation and determination of resolution limits

Cited by 33 publications

References 27 publications

Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

Supervised machine learning for automatic classification of in vivo burn injuries using the terahertz Portable Handheld Spectral Reflection (PHASR) scanner

In Vivo Assessment of Burn Depth and Wound Healing Using a Handheld Terahertz Hyperspectral Scanner

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