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Non-contact laser ultrasonic technique has been increasingly implemented for non-destructive inspections in harsh environments, high-temperature fields, and components having complex geometries. However, the poor signal-to-noise ratio and low amplitude of laser generated ultrasonic signals under a thermoelastic regime severely restrict its applications. Here, a sensitivity-enhanced all-optical probe was proposed for laser ultrasonic non-destructive testing. It consists of an optical sensor and an ellipsoidal acoustic cavity, where an optical sensor is placed at one focus of the cavity, and the detection point is set at another focus. The ultrasound signals are focused through the cavity and detected by the optical sensor. Side-by-side comparison experiments were carried out, and the results show that the probe can improve the signal amplitude by about 7.8 times compared to using a traditional optical sensor alone. The probe can make laser ultrasound detect defects with lower laser energy, which is of great significance to improve the efficiency of non-contact defect detection. [ABSTRACT FROM AUTHOR]

In vivo wide-field brain microscopy has remained a non-trivial challenge in life science research, which would provide indispensable preclinical insight into the whole-brain metabolism and hemodynamic. Here, we developed an ultra-compact micro-photoacoustic tomography (μPAT) system for fast brain imaging equipped with a 10 MHz 256-element full-ring ultrasound transducer array and 100 MS/s/ch multi-channel parallel data acquisition. The system design and calibration are presented in detail, along with the 62 μm in-plane resolution comparable to the level of acoustic-resolution photoacoustic microscopy. The μPAT system provided the ability to noninvasively use high-resolution mapping of the microvascular network of the full-view brain at different depths, cerebral ischemia, and intracerebral foreign-body. Ultra-compact μPAT holds great potential to take the technology out of the lab for preclinical imaging and clinical translation. [ABSTRACT FROM AUTHOR]