Abstract: A white blood cell classification system is provided for detecting and classifying white blood cells in a peripheral blood smear. The system includes optical scanning means for scanning the blood smear, a microscope for directing the optical scanning means on the blood smear and means responsive to the scanning means for generating a signal corresponding to the color of the blood smear at the positions scanned. Color processing means are provided which are responsive to the signal for providing a signal representative of the relative darkness of the areas scanned. Detection means are provided which are responsive to the signal. The detection means includes a mask which is normally enabled by the nucleus of of all the white cells but which is not enabled by either platelets, foreign material or red cells in the blood smear. Finally, focusing means responsive to the detection means are provided for moving the position of the focus of the microscope to the optimum position after each white cell is detected.

Abstract: An automatic focusing system is provided for a microscopic instrument having a lens assembly and a platform for supporting an object. The system includes a flying spot scanner, the light from which is directed through the lens assembly at the object. The system includes means responsive to the light directed at the object for generating a signal representative of the color density of the object. The system includes electronic circuitry responsive to the signals and connected to the microscopic instrument for changing the focus of the instrument. The electronic means which are responsive to the signal change the focus of the instrument a plurality of times and includes decision means responsive to the signal for determining the optimum focus and moving the instrument to the optimum focus. The circuitry includes quantization means responsive to the signal which effectively determines the focus position which provides the sharpest resolution of the object examined by the microscopic instrument.