Photoconductive circuit element reflectometer

A method of electronically characterizing semiconductor devices or circuits at millimeter wavelength frequencies through analysis of slowed-motion images of the signals reflected from such devices, comprising:

• focusing a first series of laser light pulses on a first photoconductive circuit element biased by a direct current voltage from a voltage source, thereby producing a series of electrical pulses with pulse widths of approximately 2 ps;
• conditioning said electrical pulses to improve the frequency related amplitude characteristics of said electrical pulses;
• propagating said conditioned electrical pulses along a transmission line to a semiconductor device under test;
• admitting samples of the signals propagating along said transmission line means through a plurality of second photoconductive circuit elements coupled to said transmission line and modulated into very short periods of conductance by a second series of extremely short laser light pulses spaced apart in time a determinable period from said first laser light pulses and focused on said plurality of photoconductive circuit elements;
• electronically filtering out high-frequency components from said samples admitted by said plurality of second photoconductive circuit elements;
• and
• outputting said samples in the form of slowed-motion images of said signals propagating along said transmission line.