A system and method are presented for optical inspection of reticles by simulating the operation of a selected stepper. The system utilizes a flying spot inspection technique and includes a scanning apparatus and a detection unit. The scanning apparatus uses a laser source similar to that of the stepper of interest. First and second light directing assemblies are accommodated in the optical paths of, respectively, incident and transmitted light, and are designed so as to provide coherence of the light substantially equal to that of the stepper.