This invention is directed to a unique imaging microscope operating within the electromagnetic terahertz frequency regime for medical applications. Unlike optical spectroscopes that only measure the intensity of light at specific frequencies, the terahertz domain allows for the precise measurements of the refractive index and absorption coefficient of samples that interact with the terahertz waves. Various liquids and gases molecules interact within the terahertz frequency band and their unique resonance lines allow their molecular structure to be identified. The electro-optic terahertz imaging system provides a novel non-invasive, non-ionizing, and highly sensitive tool producing sharp spatial and temporal contrast results. The THz microscope may dramatically enhance pathological inspection and analysis of tissues. In addition to helping in diagnosis, it may also be useful in helping to discover causes of the pathology, by giving new molecular-level information that is linked with morphological changes in the tissuecells. The microscope may also be used to investigate rapid biochemical responses to selected stimuli, giving new insight into biological processes.