Light from a tissue sample undergoes self-interference on a detector. A low coherence light source may illuminate the sample, and an interferometer receives light from the sample, divides and directs the received light along two paths, phase-delaying one and recombining the beams on a detector to form a signal. A processor coordinated with the phase delay and optionally with spatial scanning or detector array addresses, converts the signal to a tomographic image. Using self-interfering radiation from the sample, rather than interference of a reference source and a return signal, permits imaging with light naturally emitted by the sample, or with wavelength-shifted, delayed or induced light signals, allowing new diagnostic imaging modalities. The processor may create images in registry from different (for example, close but separable) wavelengths. Systems may also operate without an illumination source or may apply other stimuli to evoke emission from the sample.