In some embodiments, the present disclosure relates to a wafer edge trimming apparatus that includes a processing chamber defined by chamber housing. Within the processing chamber is a wafer chuck configured to hold onto a wafer structure. Further, a blade is arranged near an edge of the wafer chuck and configured to remove an edge potion of the wafer structure and to define a new sidewall of the wafer structure. A laser sensor apparatus is configured to direct a laser beam directed toward a top surface of the wafer chuck. The laser sensor apparatus is configured to measure a parameter of an analysis area of the wafer structure. Control circuitry is to the laser sensor apparatus and the blade. The control circuitry is configured to start a damage prevention process when the parameter deviates from a predetermined threshold value by at least a predetermined shift value.