A new diagnostic technique can be used to measure simultaneously the excess free‐carrier lifetime &tgr; and the diffusion lengthLwith spatial resolution in semiconductor samples. The technique uses pulses of above‐band‐edge light to generate carriers near the sample surface. The carrier density evolution into the bulk is measured by means of the free‐carrier absorption of an ir laser beam. Computer fitting the time variation of the absorption at any beam position to the carrier transport equation yields &tgr; andL, enabling the diffusion coefficientD=L2/&tgr; to be evaluated. Using 104‐W/cm2injection light and a 3.39‐&mgr;m laser probe on a 1500‐&OHgr; cm silicon sample yielded bulk values in good agreement with calculated and independently measured values.