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

本博士课题研究了一种利用双光频梳克服波长扫描时间限制的变革性方法。频率梳是一种光源，它以相同的频率间隔同时发射10s-100s波长的音调。通过开发一种新的双频梳和相关的光声传感实时信号处理技术，我们的目标是将传感信号采集时间缩短两个数量级以上，使快速光声成像在医学和疾病研究中具有广泛的影响。我们的方法结合了双频梳状光谱的概念和基于法布里-珀罗的生物医学光声成像超声检测。光声双梳多外差检测与实时FPGA硬件处理相结合，使传感器的快速读出具有高分辨率和精度（可追溯到si时间标准）。因此，它允许显著改善信号采集时间和改善信噪比。在前期研究的基础上，进一步完善双频梳法的光声成像建模，了解基本的采集时间和信噪比限制；b)利用EEE[5]双梳系统和光声组研制的Fabry-Perot超声传感器进行实验研究。进一步改进双梳设置，以实现不同传感器的灵活性（例如，具有不同精细度和热稳定性的传感器）；c)创新信号处理策略（例如，均衡器、校准算法），以实现快速信号采集和提高分辨率。该项目将包括分析和实验工作，汇集光信号处理和光声传感方面的专业知识，以克服传统光声系统的时间采集限制。本文研究的新方法还允许提高信噪比以增强成像分辨率。

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.