Abstract: An improved laser mirror and heat exchanger and method of fabrication is described which comprises, in a preferred embodiment thereof, a carbon/carbon fiber matrix substrate having deposited thereon a transitional composition layer of carbon and tungsten carbide, and one or more layers of tungsten or tungsten carbide. These layers define a desired network of coolant passageways formed by depositing a low melting point material, such as antimony, in a raised pattern and thereover depositing the tungsten-containing layer, and subsequently melting out the low melting point material. The tungsten-containing layer may then be polished on the exposed surface to a laser mirror finish.