Simultaneous recording of near-field and far-field patterns of lasers

A technique for simultaneous recording of near-field and far-field diffraction patterns at several exposures for a single laser pulse has been developed. A ruby laser and a neodymium doped glass laser have been investigated. The Nd(+3) laser shows striking high order cylindrical mode operation as a result of thermal stress. The time resolved output of this laser shows the usual spikes about 500 nsec wide. When the cylindrical mode operation takes place some of the spikes consist of a large number of ultrashort pulses.