Lithium niobate-based optically transparent transducer for broadband ultrasound transceiving

High-quality multimodal imaging technology is widely used in the biomedical field. Because the traditional transparent ultrasound transducer is opaque, the optical axis has to be another bypass, leading to the problems such as large volume, low integration and insufficient signal to noise ratio of the imaging equipment. Therefore, a novel optically transparent transducer is proposed herein for ultrasound transceiving. In this design, the acoustic-electric conversion element is made of a 100-μm-thickness lithium niobate crystal. Transparent indium tin oxide conductive layers are deposited onto the top and bottom surfaces of the circular or square crystal. A customized round metal housing is used for protection and encapsulation, and the optical resin acts as the acoustic matching layer and backing. Experimental results show that the new ultrasound transducer has a wider frequency band up to 40 MHz and a shorter response, compared to the commonly used piezoelectric ceramic ultrasound transducers on the market. The ultrasound transducer has the obvious advantages of compact and portable structure, wideband transparency, high sensitivity and high-frequency response. The proposed approach demonstrates the potential for seamless integration of ultrasound, photoacoustic, fluorescence, and other multimodal imaging techniques, thereby effectively advancing the development of photoacoustic imaging technology in biomedical applications.