Geodimeter

[1][2] It was originally developed for measuring the speed of light.

[3][4] It was invented in 1947 by Erik Osten Bergstrand [sv] and commercialized in 1953 by the AGA (Aktiebolaget Gasaccumulator) company of Sweden.

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.

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