A system and method of optical reflectometry and optical coherence tomography (OCT) is provided by using a wavefront-division interferometer where a beam is split into side-by-side beam portions. The interference is tuned by changing the phase difference between the beam portions. The interference contrast is adjusted by changing the ratio of the beam portions. The structure of the optical reflectometry and OCT is compact and insensitive to environmental changes. Methods are also provided for multi-level and multi-layer optical data storage systems.