This paper describes in-phase and anti-phase interferences effects that can exhibit deep amplitude nulls and sharp phase transitions. In order to broaden the range of the amplitude null and phase transition, a series of light sources are arrayed in one, two, or three dimensions with an appropriate detection system located in the null plane of each array. The system is expected to be ideal for locating a small absorption/scattering discontinuities in a relatively homogenous scatterer such as human breast. The techniques of scanning are mechanical and electrical, or by as yet untested optical elements.
"Multielement phased arrays for phase modulation imaging", Proc. SPIE 1888, Photon Migration and Imaging in Random Media and Tissues, (14 September 1993); doi: 10.1117/12.154653; https://doi.org/10.1117/12.154653