A laser scanning system has been developed by the National Renewable Energy Laboratory for the rapid characterization of crystal defects in single- and poly-crystalline semiconductors. The scanning defect mapping system has been commercialized by Labsphere, Inc. as the PVScan 5000. In the unprocessed material, the system produces digital color maps of the spatial distributions of dislocations and grain boundaries simultaneously. After device fabrication, the PVScan 5000 is used to produce photoresponsivity maps of the light beam induced current (LBIC) on a photovoltaic device such as a solar cell or a photodetector. An additional feature is that it also measures the spatial distributions of optical reflectance, both specular and diffuse, which can be applied to the LBIC maps to determine the internal responsivity of the device. The internal responsivity is proportional to the minority carrier diffusion length of silicon devices. It may be possible, therefore, to determine the diffusion length for certain devices.