Electron-optical wide band signal measurement system

Abstract

Electrical signals are measured (analyzed and displayed) with picosecond resolution and sensitivity in the microvolt (less than 100 microvolts) range by electron-optically sampling the signal. Sampling electron bursts are produced in response to a train of subpicosecond optical pulses. A beam of these electron bursts samples successive portions of the signal as it is transmitted as a travelling wave along deflection plates which act as a transmission line. The bursts are deflected in accordance with the amplitude of the successive portions of the signal and translated into spots of light, as on a phosphor screen. The deflection is significantly less than the diameter of the spot. The deviation of the spot with respect to the position thereof in the absence of the signal on the deflection plates is translated into a difference output. The signal to be analyzed is generated, synchronously with the optical pulses, to propagate along the deflection plates in variably delayed relationship therewith. The signal is optically-induced using a separate beam of the optical pulses which is desirably chopped into optical pulses. The difference output is processed, preferably by a lock-in amplifier and signal averager; the lock-in amplifier being synchronized with the chopping of the beam into the optical pulses, and displayed on a time base synchronous with the variable delay of the optical pulses. Accordingly, the signal is displayed on an expanded time scale for measurement and other analysis.