Abstract

A feature common to many ultrafast experiments is the use of an optical delay line to provide a precise delay of one light pulse relative to another. Often a delay of three nanoseconds or larger is required to obtain sufficient overlap with data measured using fast photodiodes or photomultiplier tubes. As the length of the delay line increases, the problem of alignment to maintain beam overlap becomes severe, particularly if the overlapping beams are tightly focused. In this talk, we demonstrate that delay alignment can be dramatically improved and the required mechanical stability of the delay line significantly relaxed by the use of an active feedback system. The need for time consuming alignment procedures is eliminated.

© 1986 Optical Society of America