High brightness low energy spread pulsed electron source

Systems and methods for enhancing inspection throughput with a high brightness low energy spread pulsed electron source are described. A plurality of pulsed constituent electron beams are generated. The plurality of pulsed constituent electron beams are combined into a combined electron inspection beam. The combined electron inspection beam has a greater brightness than each of the individual constituent pulsed electron beams. An energy spread of an incoming electron pulse is increased by accelerating a front of the pulse and decelerating a back of the pulse; temporally stretching the pulse using a drift space; and monochromating the pulse by decelerating the front of the pulse and accelerating the back of the pulse. A spherical aberration associated with the electron inspection beam may be corrected. A substrate may be inspected with the combined electron inspection beam. The greater brightness of the combined electron inspection beam enhances the inspection throughput.