Integration of microlenses on surface-micromachined optical ultrasound transducer array to improve detection sensitivity for parallel data readout

This Letter reports the integration of microlenses (MLs) on a surface-micromachined optical ultrasound transducer (SMOUT) array to enable parallel ultrasound data readout from a multiplicity of elements. The MLs are fabricated by photoresist patterning and reflow, and their focal lengths are optimized with parametric studies. Experiments are conducted to characterize the acoustic responsivity and its uniformity of the SMOUT-ML elements under different conditions. The temporal stability of SMOUT-ML elements immersed in water is assessed by monitoring their acoustic response continuously for 1 week. Parallel ultrasound sig-nal readout is simulated with a small group of SMOUT-ML elements. Experimental results show that high acoustic sen-sitivity and excellent long-term stability can be achieved by the ML-integrated SMOUT array, which could provide a promising approach for enabling parallel ultrasound data acquisition for improving the imaging speed of 3D acoustic tomography. (c) 2023 Optica Publishing Group

Automated summary

This Letter demonstrates the integration of microlenses (MLs) on a surface-micromachined optical ultrasound transducer (SMOUT) array for parallel ultrasound data readout. The MLs are fabricated through photoresist patterning and reflow, with optimized focal lengths. The experimental results show that the ML-integrated SMOUT array achieves high acoustic sensitivity and excellent long-term stability, providing a promising approach for parallel ultrasound data acquisition and improving the imaging speed of 3D acoustic tomography.