LARC Automated Leukocyte Classifier (~ 1974)
The LARC instrument was sold worldwide by Corning in the 1970's to perform an automated leukocyte differential test. The leukocyte differential test determines the % of different blood leukocytes present on a microscope blood smear from a patient blood specimen. These are determined by scanning the glass slide in a regular pattern under a microscope at high magnification to locate the leukocytes, which are surrounded by red blood cells, and then by classifying each leukocyte into one of approximately 6 cell types.
The specifications for the LARC were to locate and classify 100 cells in one minute. This was a very demanding requirement for a microscope imaging system in the 1970’s. Putting this into perspective for the time, the system was based on a Digital Equipment PDP8 computer, and because of the limited memory the images were only 50 x 50 pixels. Also, the system was designed to optically capture each cell through a high resolution 100x oil immersion microscope objective. The detailed design and performance of the LARC system is from reference 9 under Publications.