Overcoming acquisition time and resolution limits of photoacoustic imaging using dual comb scanning

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This PhD project research investigates a transformative method that employs dual optical frequency combs to overcome the limit due to the wavelength sweeping time. A frequency comb is a light source simultaneously emitting 10s-100s of wavelength tones with equal frequency spacing. By developing a new dual frequency comb and associated real-time signal processing technologies for photoacoustic sensing, we aim to reduce the sensing signal acquisition time by more than two orders of magnitude, enabling fast photoacoustic imaging for wide impact in medicine and disease studies. Our method combines the concept of dual-frequency comb spectroscopy with Fabry-Perot based ultrasound detection for biomedical photoacoustic imaging. Photoacoustic dual-comb multi-heterodyne detection in conjunction with real-time FPGA hardware processing enables the rapid read-out of the sensor with high resolution and precision (traceable to the SI-time standard). Therefore, it allows for a significantly improved signal acquisition time and improved signal to noise ratio.The student will work with the supervisor on the following subjects:a) Based on our preliminary studies, further improve the modelling of dual frequency comb approach for photoacoustic imaging, understanding the fundamental acquisition time and signal to noise ratio limits;b) Carry out experimental studies using the dual-comb system at EEE [5] and the Fabry-Perot ultrasound sensors developed by the photoacoustic group. Further improve the dual comb set up to enable flexibility for different sensors (e.g., sensors with different finesse and thermal stability);c) Innovate signal processing strategies (e.g., equalizers, calibration algorithms) for fast signal acquisition and improved resolution.This project will involve both analytical and experimental work, bringing together expertise in optical signal processing and photoacoustic sensing to overcome the time acquisition limit in conventional photoacoustic systems. The new method studied here also allows for an improved SNR for enhanced imaging resolution.