Dust Quantitation by Microprojection and Comparison Counting

THE work of Brown and others at Pittsburgh ( Brown, Baum, Yant, and Schrenk, 1938)(1) and the success of their light field microprojector (Figure 1) , have shown that the microscopy of dust quantitation can be greatly improved. It has been shown that dark-field microprojection of dust spots on konimeter slides is possible ( Pullen, 1940), and this paper is a discussion of the new microprojector and a new counting method which is made practical by this instrument.
Keywords: apochromatic, arc lamp, microscope, numerical aperture, University of Toronto, Condensers, Costs, Dust, Konimeters, Lamp, Lamps, particles, Screens, Sizing, Standards
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