a system and method for in - line inspection of specimens such as semiconductor wafers is provided . the system provides scanning of sections of specimens having predetermined standardized characteristics using a diffraction grating that widens and passes nth order wave fronts to the specimen surface and a reflective surface for the transmitted light beam . light energy is transmitted in a narrow swath across the portion of the surface having the standardized features . the wavefronts are combined using a second diffraction grating and passed to a camera system having a desired aspect ratio .