Interferometry in terahertz imaging

Abstract

Terahertz Time-Domain Spectroscopy (THz-TDS) techniques have been shown over the last decade to be useful in many diverse applications. This thesis describes the implementation of interferometry in imaging with few-cycle terahertz pulses for the purpose of enhancing depth resolution. By configuring terahertz imaging optics in a Michelson interferometric arrangement, a phase shift of approximately Pi radians can be introduced between the interferometer's two arms via the Gouy effect. The resulting destructive interference provides a nearly background-free measurement and a dramatic enhancement in imaging sub-coherence length features. It is possible to image features thinner than 4% of the coherence length of the radiation. This technique could have applications in THz imaging and other THz-TDS systems, as well as in other low-coherence optical tomographic measurements.