In some aspects, the present invention embodies both the method and apparatus for converting a pattern of irradiation to a visible image. An embodiment of the present invention provides an array of micro-electro-mechanical sensors with each sensor includes a deflectable micro-cantilever, responsive to absorbed incident radiation and to an applied repulsive electrostatic field. In an aspect, the sensor device also includes a null-sensing circuit coupled to a switch contact on or near the substrate, which senses when the micro-cantilever reaches its null location, by electrical connection with an upper switch contact on the micro-cantilever. Other embodiments are also described.