Mr. Tom Y. Cheng Profile

Tom Y. Cheng

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Publications (6)

Proceedings Article | 13 March 2024 Presentation

A 256-channel SPAD detector for time-gated fNIRS and DCS

Jonathan Richardson, Tom Cheng, George Jordy, Matthew Stamplis, Ana-Maria Mandrila Vaca, Michael Bradshaw, Erik Duerr, Marco Renna, Mitchell Robinson, Stefan Carp, Maria-Angela Franceschini

Proceedings Volume PC12828, PC128280E (2024) https://doi.org/10.1117/12.3003159

KEYWORDS: Readout integrated circuits, Silicon, Near infrared spectroscopy, Windows, Spectroscopy, Photons, Imaging spectroscopy, Functional imaging, Field programmable gate arrays, Brain

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Proceedings Article | 12 March 2024 Presentation + Paper

Camera selection for speckle contrast optical spectroscopy and validation against diffuse correlation spectroscopy

Tom Cheng, Byungchan Kim, Bernhard Zimmermann, Mitchell Robinson, Marco Renna, Stefan Carp, Maria Angela Franceschini, David Boas, Xiaojun Cheng

Proceedings Volume 12841, 1284105 (2024) https://doi.org/10.1117/12.3000411

KEYWORDS: Diffuse optical spectroscopy, Temperature control, Cerebral blood flow, Fluctuations and noise, Signal intensity, Cameras, Signal to noise ratio, Quantum reading, Speckle, Spectroscopy, Optical spectroscopy, Liquids, Quantum noise, Interference (communication), CMOS cameras

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SPIE Journal Paper | 27 January 2024 Open Access

Comparing the performance potential of speckle contrast optical spectroscopy and diffuse correlation spectroscopy for cerebral blood flow monitoring using Monte Carlo simulations in realistic head geometries

Mitchell Robinson, Tom Cheng, Marco Renna, Melissa Wu, Byungchan Kim, Xiaojun Cheng, David Boas, Maria Angela Franceschini, Stefan Carp

NPh, Vol. 11, Issue 01, 015004, (January 2024) https://doi.org/10.1117/12.10.1117/1.NPh.11.1.015004

KEYWORDS: Speckle, Monte Carlo methods, Sensors, Cameras, Pulsed laser operation, Light sources and illumination, Neurophotonics, Tissues, Signal to noise ratio, Cerebral blood flow

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SignificanceThe non-invasive measurement of cerebral blood flow based on diffuse optical techniques has seen increased interest as a research tool for cerebral perfusion monitoring in critical care and functional brain imaging. Diffuse correlation spectroscopy (DCS) and speckle contrast optical spectroscopy (SCOS) are two such techniques that measure complementary aspects of the fluctuating intensity signal, with DCS quantifying the temporal fluctuations of the signal and SCOS quantifying the spatial blurring of a speckle pattern. With the increasing interest in the use of these techniques, a thorough comparison would inform new adopters of the benefits of each technique.AimWe systematically evaluate the performance of DCS and SCOS for the measurement of cerebral blood flow.ApproachMonte Carlo simulations of dynamic light scattering in an MRI-derived head model were performed. For both DCS and SCOS, estimates of sensitivity to cerebral blood flow changes, coefficient of variation of the measured blood flow, and the contrast-to-noise ratio of the measurement to the cerebral perfusion signal were calculated. By varying complementary aspects of data collection between the two methods, we investigated the performance benefits of different measurement strategies, including altering the number of modes per optical detector, the integration time/fitting time of the speckle measurement, and the laser source delivery strategy.ResultsThrough comparison across these metrics with simulated detectors having realistic noise properties, we determine several guiding principles for the optimization of these techniques and report the performance comparison between the two over a range of measurement properties and tissue geometries. We find that SCOS outperforms DCS in terms of contrast-to-noise ratio for the cerebral blood flow signal in the ideal case simulated here but note that SCOS requires careful experimental calibrations to ensure accurate measurements of cerebral blood flow.ConclusionWe provide design principles by which to evaluate the development of DCS and SCOS systems for their use in the measurement of cerebral blood flow.

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Proceedings Article | 15 June 2023 Presentation

A 256-channel SPAD detector for time-gated fNIRS and DCS

Jonathan Richardson, Tom Cheng, Marco Renna, George Jordy, Matthew Stamplis, Ana-Maria Mandrilla Vacca, Michael Bradshaw, Eric Ringdahl, Brian Aull, Megan Blackwell, Erik Duerr, Mitchell Robinson, Stefan Carp, Maria-Angelica Franceschini

Proceedings Volume PC12512, PC1251208 (2023) https://doi.org/10.1117/12.2666270

KEYWORDS: Single photon avalanche diodes, Sensors, Readout integrated circuits, Silicon, Spectroscopy, Sensor performance, Photons, Near infrared spectroscopy, Functional imaging, Field programmable gate arrays

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Proceedings Article | 30 May 2022 Presentation

A novel 32x32 InP/ InGaAs SPAD array for multi-channel time-gated diffuse correlation spectroscopy

Marco Renna, Jonathan Richardson, George Jordy, Tom Cheng, Eric Ringdahl, Mitchell Robinson, Nisan Ozana, Niyom Lue, Brian Aull, Stefan Carp, Erik Duerr, Maria Angela Franceschini, Megan Blackwell

Proceedings Volume PC12089, PC120890E (2022) https://doi.org/10.1117/12.2619112

KEYWORDS: Indium gallium arsenide, Spectroscopes, Sensors, Photons, Tissue optics, Spectroscopy, Imaging systems, Head, Brain, Single photon detectors

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Proceedings Article | 2 March 2022 Presentation

Design and characterization of a multi-channel time-gated diffuse correlation spectroscopy system at 1064nm

Marco Renna, Jonathan Richardson, George Jordy, Tom Cheng, Mitchell Robinson, Nisan Ozana, Dibbyan Mazumder, Niyom Lue, Brian Aull, Bernhard Zimmerman, Stefan Carp, Erik Duerr, David Boas, Maria Angela Franceschini, Megan Blackwell

Proceedings Volume PC11959, PC1195908 (2022) https://doi.org/10.1117/12.2610207

KEYWORDS: Spectroscopes, Spectroscopy, Sensors, Photons, Imaging systems, Head, Single photon detectors, Single photon, Sensor performance, Semiconductor lasers

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