Comparison of methods for uniform laser scanning of centrifuged blood tubes for data acquisition in a hematology analyzer

This paper compares various methods for developing a low cost, uniform velocity laser scanning beam to be used for scanning a centrifuged blood tube in a Hematology Analyzer. For this product, blood is collected from the vein and placed in a hollow tube about three inches in length and 1/8 inch in diameter. The tube is then centrifuged at high speed and settles in layers according to the density of the different components in the blood. These components consist of red blood cells, white blood cells, platelets, and plasma. The glass tube is coated with special chemicals to accent the color of the different components of the blood. This tube is then placed in an instrument that scans each tube eight times with a laser beam to measure the band lengths and then calculates the value of each of these components in the blood. Various scanning methods are compared to determine the best low cost uniform beam scanning technique for this data acquisition application.