This paper proposes a measurement complex for diagnosing the photometric an
d space-time properties of the leader of a lightning discharge. It is assum
ed that it can be used to develop a technology for the optimum reception an
d formation of signals for controlling a laser beam that forms a long spark
. The transmission of the atmosphere in the region to 200 nm and the backgr
ound radiation under thunderstorm conditions have been experimentally studi
ed. (C) 1999 The Optical Society of America.