Patent ID: 7119339

Claim:
An apparatus for performing coherent terahertz (THz) wave computed tomography, the apparatus comprising: i. a sensor for modulating an amplitude of incident optical radiation as a result of illuminating the sensor with THz-frequency electromagnetic radiation; ii. means for generating a probe beam, said probe beam including pulsed optical radiation directed onto the sensor along a first path and exiting the sensor along a second path and; iii. means for generating a pulsed THz radiation beam directed onto the sensor through a third path wherein said third path includes: a. a sample area, b. a THz radiation beam focusing system having at least one focusing element with a diameter, c. a support for holding a sample in the sample area at a first orientation relative to a propagation direction of the pulsed THz radiation beam, and d. means for altering the first orientation; and iv. a detector in the second path for detecting the amplitude of the pulsed optical radiation beam; wherein: a. the sample area is smaller than the Rayleigh range of the THz beam; and b. the focusing system is designed to focus an imaging plane adjacent the sample area onto the sensor.