We present a near-field optical beam induced current study of aged high power laser diode arrays (LDA). A near-field scanning optical microscope was used as a light source for creating a photocurrent or a photovoltage in the LDA. Mechanisms generating the signal as well as methodical aspects such as resolution limits and application fields of the technique are discussed. The method is demonstrated to provide insight into the microscopic aging properties of LDAs. Both monitoring of the aging status as well as the localization of defects becomes possible.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.