Imaging Parhyale hawaiensis embryogenesis with frequency domain photoacoustic microscopy: A novel tool in developmental biology

Optoacoustic interferometric characterization system (OPTICS) for the evaluation of fuel quality through speed of sound measurements

Ultrasonic techniques have been applied to assess crucial physical parameters in various types of fuels including the speed of sound (SoS), the bulk modulus and the acoustic attenuation coefficient. Such investigations may have important practical significance as the knowledge of fuel properties is directly related to the analysis of combustion characteristics, engine's overall performance and exhaust emission in the environment. Nevertheless, typical pulse-echo acoustic methods, require the exact determination of both acoustic source - reflector distance and the time of flight of a finite temporal width ultrasonic pulse, setting thus an upper limit as regards the accuracy of the measurements. To encounter these challenges, we present a novel technology implemented through a low-cost and potentially portable optoacoustic interferometric characterization system (OPTICS) for the investigation of SoS variations in common fuels including automotive diesel, hydrous ethanol and gasoline. At 25 °C, diesel/kerosene blends demonstrated a SoS variation ranging from 1322.91 m/s (0.6 diesel volume fraction) to 1349.79 m/s (diesel fuel only), whereas hydrous ethanol samples varied between 1199.92 m/s (0.95 ethanol volume fraction) to 1149.39 m/s (pure ethanol only). Finally, assessments for 95 and 100 research octane number (RON) gasoline blends showed a SoS range from 1134.42 m/s (RON 95) to 1159.86 m/s (RON 100). The high precision and repeatability (relative uncertainty: ∼10-4) of the performed SoS measurements in controlled samples, has demonstrated the promising potential of OPTICS for the evaluation of fuel physical properties as well as the potential detection of contamination with adulterants.

Bimodal optical and optoacoustic multiview microscope in the frequency-domain

Hybrid fluorescence and optoacoustic microscopy systems have recently emerged as powerful imaging modalities concurrently capturing both radiative and non-radiative molecular relaxations in biological tissues. Nevertheless, such approaches provide limited information as specimens are imaged exclusively from one side, not permitting the acquisition of their full anatomical, structural, or functional features in multiple views of interest. Herein we present a bimodal optical and optoacoustic multiview (BOOM) cost-efficient microscope operating in the frequency-domain for the comprehensive label-free imaging of established and emerging model organisms. Thus, the capabilities of BOOM microscopy have been proven suitable for highly demanding observations in developmental biology and embryology.

Deep learning-assisted frequency-domain photoacoustic microscopy

Frequency-domain photoacoustic microscopy (FD-PAM) constitutes a powerful cost-efficient imaging method integrating intensity-modulated laser beams for the excitation of single-frequency photoacoustic waves. Nevertheless, FD-PAM provides an extremely small signal-to-noise ratio (SNR), which can be up to two orders of magnitude lower than the conventional time-domain (TD) systems. To overcome this inherent SNR limitation of FD-PAM, we utilize a U-Net neural network aiming at image augmentation without the need for excessive averaging or the application of high optical power. In this context, we improve the accessibility of PAM as the system's cost is dramatically reduced, and we expand its applicability to demanding observations while retaining sufficiently high image quality standards.