The heterodyne laser interferometer installed on the new Cameca SC‐Ultra SIMS apparatus permits an in situ depth evaluation during depth profiling. The aim of this work is an investigation of the laser interferometer advantages and limitations for profiling of dopants in silicon. The laser depth calibration has been compared with the one determined by measuring the crater final depth with a stylus mechanical profilometer. Some experimental conditions where this approach can provide accurate results have been identified and confirm the usefulness of this device. © 2003 American Institute of Physics