A method for increasing the throughput, or the precision, or both the precision and the throughput, of a flow cytometer, or of a hematology analyzer employing a flow cytometer, by utilizing the technique of laser rastering. Laser rastering involves sweeping a laser beam across a flowing sample stream in a hematology analyzer. An apparatus suitable for carrying out the method of this invention comprises an optical module comprising a source of light, a scanning device, a lens or system of lenses, a flow cell, detectors, and filters; and an electronic module comprising preamplifiers, analog signal conditioning elements, analog-to-digital converters, field-programmable gate arrays, digital signal processing elements, and data storage elements.