A fiber-optic network for communicating non-invasive, real-time, in-situ semiconductor wafer radiance and emissivity measurements. The fiber-optic network includes a plurality of optical fibers, a plurality of fiber-optic bundles, and a chopper multiplexer. The fiber-optic bundle provides for the simultaneous transmission and receipt of coherent infrared light energy and radiant heat energy from a semiconductor wafer within a fabrication reactor. The fiber-optic bundles are designed to be sufficiently small to fit within hollow light pipe in a lamp module that directs optical heating energy to the wafer. This substantially eliminates measurement error that the lamp module generates in known measurement devices. Use of optical fibers for transmitting and receiving laser energy and wafer radiance permits precision placement of the fiber-optic bundles to measure multiple temperatures on the semiconductor wafer surface.