The laser-induced luminescence of direct gap semiconductors can be measured with high spatial (1 μm) and temporal (<1 ns) resolution. A profiling technique is described for in-situ measurements during laser processing. It allows the evaluation of temperature, carrier density and band gap energy within the focal zone. The technique has been applied to (Al,Ga)As heterostructure material subjected to highly focused CW-Kr-ion laser radiation. The measurements reveal low temperature rises (<200 deg.C) at high excitation densities (>1 MW/cm2) and an inhomogeneous distribution of optically excited carriers for concentrations above 2×1017 cm-3