High intensity focused ultrasound (HIFU) is a noninvasive treatment technique to induce thermal or mechanical bioeffects. Characterising the wave field is essential for reliable and reproducible transducer operation in clinical use. This paper presents a schlieren technique to visualise and quantify transducer wave fields. https://www.jmannino.com/great-save-Camiseta-Groves-de-corte-ajustado-con-ribete-de-algod-n-org-nico-Saxe-super-grab/