The Geodimeter (acronym of geodetic distance meter) was the first optical electronic distance meter surveying instrument.[1][2] It was originally developed for measuring the speed of light.[3][4] It was invented in 1947 by Erik Osten Bergstrand and commercialized in 1953 by the AGA (Aktiebolaget Gasaccumulator) company of Sweden.[5][6] It was used in the Transcontinental Traverse.
The Geodimeter business was acquired by SpectraPrecision which was acquired by Trimble Inc.[citation needed]
The mechanism uses a Kerr cell in an optical train that chops a collimated beam of light under the control of a precision electronic oscillator in the megahertz range.[7] It is similar in principle to the mechanical chopper in Fizeau's measurement of the speed of light in air that used a toothed wheel.[8]
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