The theory and construction of an apparatus which permits the rapid measurement of pupillary diameters is presented. This instrument, the koremetron, is portable, and uses the same principle as that involved in observing entoptical phenomena.
R. CLARK JONES, "The Koremetron: An Instrument for Measuring Pupillary Diameters," J. Opt. Soc. Am. 29, 531-534 (1939)