A spread spectrum approach to time-domain near-infrared diffuse optical imaging using inexpensive optical transceiver...

Area of Science:

• Biomedical Optics
• Spectroscopy
• Instrumentation

Background:

• Time-domain near-infrared spectroscopy (TD-NIRS) is valuable for non-invasive tissue analysis.
• Conventional pulsed TD-NIRS systems can be bulky and expensive.

Purpose of the Study:

• To introduce a compact and cost-effective time-domain system for near-infrared spectroscopy.
• To demonstrate the feasibility of using spread spectrum techniques for NIRS.

Main Methods:

• A single-channel instrument was developed using a commercial optical transceiver and a Kintex 7 field programmable gate array (FPGA).
• The FPGA modulated the transceiver with maximum-length sequences at up to 10Gb/s.
• The system's instrument response function (IRF) was characterized with a full width at half maximum (FWHM) under 600 ps.

Main Results:

• The compact system achieved an IRF FWHM under 600 ps.
• Phantom measurements validated the instrument's performance.
• Proof-of-concept *in vivo* measurements demonstrated comparable performance to conventional pulsed TD-NIRS systems.

Conclusions:

• The developed spread spectrum time-domain NIRS system is compact and utilizes low-cost components.
• This approach offers a viable alternative to conventional pulsed TD-NIRS systems.
• The system shows promise for accessible biomedical optical measurements.