Rainbow schlieren measurements in underexpanded jets from square supersonic micro nozzles Hiroaki Maeda, Hikaru Fukuda, Shinichiro Nakao, Yoshiaki Miyazato and Yojiro Ishino EPJ Web Conf., 180 (2018) 02058 Published online: 04 June 2018 DOI: 10.1051/epjconf/201818002058