A remote position measuring device with electrical coupling to a computer has been developed for use in the elementary-physics laboratory. Light from a moving object and a fixed-reference lamp is focused by a lens on a hollow, rotating drum with equally-spaced slits. The light passing through a slit is detected with a phototube. The time difference of amplified phototube signals from the object and reference-light sources is a measure of the position coordinate of the object at the time of the object signal. The model constructed has a precision of about 0.03 cm, better than a 3% differential linearity for a 40-cm field of view in the object plane and a sampling rate of 30 sec−1. The device can track more than one object simultaneously and has been successful in providing position samples for two colliding gliders on an air-track.
A Remote-Position Analyzer with Electronic OutputAmerican Journal of Physics
Citation InformationWood, G. Theodore. "A Remote-Position Analyzer with Electronic Output." American Journal of Physics 42 (1974): 952-957.