High-intensity focused ultrasound sound pressure realization up to 100 MPa based on a differential high bandwidth homodyne laser interferometer

High-intensity focused ultrasound (HIFU) has emerged as a promising noninvasive technology for medical applications, including tumor ablation and targeted drug delivery, where precise control of acoustic pressure is critical. However, the traceable sound pressure amplitude, in the range of several megapascals, is much lower than the actual application of 100 megapascals, which compromises the metrological traceability and impedes clinical translation. In this study, we present a differential high-bandwidth homodyne laser interferometer designed for the accurate realization of HIFU acoustic pressure under treatment conditions. The system employs a four-channel detection scheme and a focused measurement beam to enhance its robustness against pellicle deflection and environmental disturbances. By integrating high-speed photodetection and a nonlinear error suppression algorithm based on arctangent demodulation, the system achieved a bandwidth of 500 MHz while maintaining high sensitivity. The experimental results demonstrated the successful measurement of HIFU pressures up to 124 MPa peak-to-peak, with a resolution better than 0.25 MPa. Comparative studies using a commercial heterodyne vibrometer (UHF-120) confirmed the accuracy and cost-effectiveness of the proposed homodyne system. This study provides a reliable and traceable method for high-pressure ultrasonic metrology, supporting the development and safety assurance of HIFU-based therapies.