A phased-array MASER detector for synthetic aperture interferometric three-dimensional imaging. The detector elements, for example 102-106 zero bias Schottky detector diodes with sufficient sensitivity to reliably detect various values of MASER radiation, are arranged in layers offset in three dimensions. The phased-array MASER detector is particularly useful for detecting characteristics in a biological object using low energy (2-10 Watts), coherent MASER radiation. MASER intensity data of an interferometric pattern is collected by the detector array, is deconvolved, and is used to generate three-dimensional energy activity maps for a given time slice or on a time-shifting basis.