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-deal-British-Enfield-No-5-Jungle-Carbine-Bayonet-w-Scabbard-Standard-Grade-deal-zone/