Freely propagating terahertz pulses are usually measured by sampling techniques such as photoconductive antenna or electro-optical sampling. Although these sampling techniques provide good signal-to-noise ratios and adequate temporal resolution, they cannot be used for measurement on a single-shot basis. The present invention provides a system for measuring a terahertz frequency pulse propagating in a free-space optical path using an optical streak camera and an electro-optical modulator.

Electro-optic crystals and photoconductive dipole antennas have been widely used in terahertz (THz) time-domain spectroscopy and related imaging applications. In the standard apparatus used for THz time-domain spectroscopy a separate transmitter and receiver are used for the emission and detection of the THz signal. Because detection is the reverse process of emission, the transmitter and the receiver can be identical devices.