OPTICAL PROBING OF PHOTOACOUSTIC PROPAGATION FOR NONCONTACT MEASUREMENT OF FLOWS, TEMPERATURES AND CHEMICAL COMPOSITIONS A.C. Tam, W. Zapka, H. Coufal et B. Sullivan J. Phys. Colloques, 44 C6 (1983) C6-203-C6-207 DOI: 10.1051/jphyscol:1983631