Simultaneous dual-wavelength photoacoustic radar imaging using waveform engineering with mismatched frequency modulated excitation

Abstract

The spectroscopic imaging capability of photoacoustics (PA) without the depth limitations of optical methods offers a major advantage in preclinical and clinical applications. Consecutive PA measurements with properly chosen wavelengths allow composition related information about blood or tissue. In this work, we propose and experimentally introduce modulation waveform engineering through the use of mismatched (uncorrelated or weakly correlated) linear frequency modulated signals for PA characterization and imaging. The feasibility of the method was tested on oxygen saturated hemoglobin and deoxygenated hemoglobin in vitro in a blood circulating rig. The method was also employed for in vivo imaging of a neck carcinoma tumor grown in a mouse thigh. The proposed method can increase the accuracy and speed of functional imaging by simultaneous PA probing with two wavelengths using portable laser-diode based PA imaging systems.

An analytical study of photoacoustic and thermoacoustic generation efficiency towards contrast agent and film design optimization

“…However, in many cases such as microsecond-pulse or continuous-wave (CW) modulated PA/TA effect [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], the EM illumination cannot be simply treated as impulse input due to the unsatisfied thermal and stress confinements. Lastly, treating the contrast agents or film as a damped mechanical oscillator [35], [36], [41], the selectivity and signal strength will be further improved by matching its mechanical resonance frequency with EM modulation frequency.…”

Switchable dual-wavelength Q-switched fiber laser using multilayer black phosphorus as a saturable absorber

“…When operating at the dual-wavelength state, to further improve the two wavelengths, the laser may be applied to effectively generating a signal at 0.1 THz, indicating its potential applications in terahertz generation. In addition, our dual-wavelength Q-switched fiber laser can also be applied to laser radar [38].…”

High-Frame-Rate Synthetic Aperture Ultrasound Imaging Using Mismatched Coded Excitation Waveform Engineering: A Feasibility Study

“…It should be emphasized that the presented methods are not only useful for biomedical US imaging, but also there is a definite need in many similar fields such as sonar [17], radar [18], NDE US, as well as photoacoustics (PA). The mismatched chirps have already been employed in PA for simultaneous in vivo functional imaging with two wavelengths [34]. …”