Immersion optical clearing of biological tissues in the THz range Daria S. Ustiantseva¹, Daria R. Il'enkova¹, Valery V. Tuchin², Nikita V. Chernomyrdin¹, Kirill I. Zaytsev¹; ¹Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia; ²Saratov State University, Saratov, Russia.