Fast Light-Pulse Measurement Schemes

An ultrafast circuit for photodiodes makes it possible to realize the highest fidelity and fastest time domain response capabilities (on the order of 100 ps rise-time response) for measuring fast light pulses. The circuit utilizes triaxial cable as a simple improved means of overcoming the inherent response limitations posed by customary photodiode circuits and components. The triaxial cable circuit can be utilized for both solid-state and vacuum photodiodes, and can be readily adapted to various light-pulse measurement schemes. This paper includes a description of the basic triaxial cable circuit, a calculation of its response capability with a typical photodiode, and an adaptation to a scheme for measuring interpulse intervals of several sequential light-pulse sources.