A system configured to inspect a wafer, comprising: an illumination subsystem configured to direct a first of multiple pulsed light beams to an area on a wafer earlier in time than a second of the multiple pulsed light beams is directed to the area by the illumination subsystem, wherein the first and second of the multiple pulsed light beams have different shapes and sizes on the wafer from each other, and wherein the first and second of the multiple pulsed light beams have different wavelengths from each other, different polarizations from each other, or different wavelengths and polarizations from each other; a scanning subsystem configured to scan the multiple pulsed light beams across the wafer; a collection subsystem configured to image light scattered from the area on the wafer to one or more sensors (130, 132), wherein the one or more sensors (130, 132) generate output responsive to the scattered light; and a computer subsystem configured to detect defects on the wafer using the output of the one or more sensors (130, 132) and to use the output responsive to the scattered light from the area due to illumination by the first of the multiple pulsed light beams to determine a power of the second of the multiple pulsed light beams that should be directed to the area; wherein the illumination subsystem comprises a Q-switched laser, and wherein the computer subsystem is configured to prevent the generation of the second of the multiple pulsed light beams that would illuminate the area from the Q-switched laser when the power of the second multiple pulsed light beams that should be directed to the area is determined to be zero. an illumination subsystem configured to direct a first of multiple pulsed light beams to an area on a wafer earlier in time than a second of the multiple pulsed light beams is directed to the area by the illumination subsystem, wherein the first and second of the multiple pulsed light beams have different shapes and sizes on the wafer from each other, and wherein the first and second of the multiple pulsed light beams have different wavelengths from each other, different polarizations from each other, or different wavelengths and polarizations from each other; a scanning subsystem configured to scan the multiple pulsed light beams across the wafer; a collection subsystem configured to image light scattered from the area on the wafer to one or more sensors (130, 132), wherein the one or more sensors (130, 132) generate output responsive to the scattered light; and a computer subsystem configured to detect defects on the wafer using the output of the one or more sensors (130, 132) and to use the output responsive to the scattered light from the area due to illumination by the first of the multiple pulsed light beams to determine a power of the second of the multiple pulsed light beams that should be directed to the area; wherein the illumination subsystem comprises a Q-switched laser, and wherein the computer subsystem is configured to prevent the generation of the second of the multiple pulsed light beams that would illuminate the area from the Q-switched laser when the power of the second multiple pulsed light beams that should be directed to the area is determined to be zero.