An optically-based system and method are disclosed for detecting surface pits and their average depth in a metal film by an examination of pulse shape in a reflected probe beam pulse. Also disclosed is an optically-based system and method for detecting an occurrence of a failure in a CMP process by detecting surface pits in a metal film by an examination of pulse shape in a reflected probe beam pulse. Also disclosed is an optically-based system and method for providing quality indications to a CMP process for enabling control of the CMP process by detecting surface pits in a metal film by an examination of pulse shape in a reflected probe beam pulse, where the pulse shape has a twin peak shape that is indicative of a presence of a surface pit.