A review is given of the papers presented at the Third All-Union Symposium on Optical Echo and Coherent Spectroscopy. The physics of optical transient and superradiant phenomena and the results of applications of these phenomena in spectroscopy were discussed at the Symposium. A new branch of optical spectroscopy is now in existence and it is called coherent spectroscopy. Methods used in this spectroscopy and possible technical applications of these phenomena were discussed in detail at the Symposium.
Spectroscopy (PECS) is a regular quadrennial scientific meeting. Symposium originates in Kazan at the Physical-Technical Institute of the Kazan Branch of the USSR Academy of Sciences (now the E. K. Zavoisky Physical-Technical Institute), where in 1963 the phenomenon of the photon echo was theoretically predicted. The first PECS was held in 1973 as All-Union Conference shortly after the first in the USSR experiments on the photon echo in a ruby crystal. The second symposium was also held in Kazan in 1981.