An imager for in vivo viewing of diseased tissue by way of fluorescently conjugated molecules. A generally planar imaging surface with a microlens array. The imager may be modular, such that a plurality of generally planar imaging surfaces can be used to image various aspects of disease tissue simultaneously. Certain implementations include an angle-selective imager, wherein light from substantially perpendicular to the plane of the imager is received, while incident light is selectively eliminated.