# Geodimeter
> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Geodimeter
> Markdown URL: https://mediated.wiki/source/Geodimeter.md
> Source: https://en.wikipedia.org/wiki/Geodimeter
> Source revision: 1337919253
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)
__NOTOC__
thumb|upright=1.35|Operator controls and sight of a Geodimeter
The '''Geodimeter''' (acronym of '''geodetic distance meter''') was the first optical [electronic distance meter](/source/electronic_distance_meter) [surveying instrument](/source/surveying_instrument).{{sfn|Rüeger|2012|p=15}}{{sfn|Bergstrand|1952}}
It was originally developed for [measuring the speed of light](/source/Speed_of_light).{{sfn|Froome|Essen|1969}}{{sfn|Bergstrand|1950}}
It was invented in 1947 by {{ill|Erik Osten Bergstrand|sv|Erik Bergstrand (fysiker)}} and commercialized in 1953 by the [AGA](/source/AGA_AB) (''Aktiebolaget Gasaccumulator'') company of Sweden.{{sfn|Laurila|1960|p=194}}[{{cite web | title=AGA Geodimeter | website=AGA Museum | date=2014-10-03 | url=http://www.aga-museum.nl/page/aga-geodimeter-nasm-2a | access-date=2020-09-24}}]
It was used in the [Transcontinental Traverse](/source/Transcontinental_Traverse).
The Geodimeter business was acquired by SpectraPrecision which was acquired by [Trimble Inc](/source/Trimble_Inc).{{cn|date=September 2022}}
==Electronic mechanism==
The mechanism uses a [Kerr cell shutter](/source/Kerr_cell_shutter) in an [optical train](/source/optical_train) that chops a [collimated beam](/source/collimated_beam) of light under the control of a precision [electronic oscillator](/source/electronic_oscillator) in the [megahertz](/source/megahertz) range.{{sfn|Poling|1959}} It is similar in principle to the mechanical chopper in [Fizeau's measurement of the speed of light in air](/source/Fizeau's_measurement_of_the_speed_of_light_in_air) that used a toothed wheel.[{{citation|publisher=Smithsonian Institution|title=EDM (Geodimeter Model 2A)|work=Database: Physical Sciences Collection - Surveying and Geodesy|date=4 August 2015 |id=catalog number 1998.3094.01|url=https://amhistory.si.edu/surveying/object.cfm?recordnumber=748815|access-date=2018-05-02}}]
==See also==
*[Laser rangefinder](/source/Laser_rangefinder)
*[Lidar](/source/Lidar)
*[Tellurometer](/source/Tellurometer)
==References==
{{reflist}}
===Sources===
*{{cite journal | last=Bergstrand | first=Erik | title=Velocity of Light | journal=Nature | publisher=Springer Science and Business Media LLC | volume=165 | issue=4193 | year=1950 | issn=0028-0836 | doi=10.1038/165405a0 | page=405| bibcode=1950Natur.165..405B | s2cid=4281189 | doi-access=free }}
*{{cite journal|last1=Bergstrand|first1=Erik|title=Distance measuring by means of modulated light|journal=Bulletin Géodésique|volume=24|issue=1|year=1952|pages=243–249|issn=0007-4632|doi=10.1007/BF02526937|bibcode=1952BGeod..26..243B|s2cid=121587208}}
*{{cite book|title=Geodimeter Manual|first=Austin C.|last=Poling|publisher=U.S. Coast and Geodetic Survey|id=Publication 62-2|year=1959|url= https://books.google.com/books?id=GdMGb4zyvTsC}}
*{{citation|chapter=Geodimeter|pages=194–203|title=Electronic Surveying and Mapping: Part 1, Fundamentals of Electronic Surveying|first=Simo|last=Laurila|year=1960|publisher=Institute of Geodesy, Photogrammetry and Cartography, The Ohio State University|hdl=2027/uiug.30112007333120|oclc=58011617|chapter-url=https://hdl.handle.net/2027/uiug.30112007333120|via=[HathiTrust](/source/HathiTrust) |accessdate=May 6, 2021}}
*{{cite book | last1=Froome | first1=K.D. | last2=Essen | first2=L. | title=The Velocity of Light and Radio Waves | publisher=Academic Press | year=1969 | isbn=9780122428500 | url=https://books.google.com/books?id=a7fvAAAAMAAJ | access-date=2020-09-24 }}
*{{cite book | last=Rüeger | first=J.M. | title=Electronic Distance Measurement: An Introduction | publisher=Springer Berlin Heidelberg | year=2012 | isbn=978-3-642-80233-1 | url=https://books.google.com/books?id=QNytBAAAQBAJ&pg=PT15 | access-date=2020-09-24 | page=15}}
==Further reading==
*{{citation|title=The Geodimeter and Tellurometer|first=Austin C. |last=Poling|publisher=American Society of Civil Engineers|doi=10.1061/JSUEAX.0000024|journal=Journal of the Surveying and Mapping Division|volume=84|issue=1|date=April 1958}}
*{{citation|last=Rimington|first=George Robert Lindsay |title=Introduction to the Geodimeter|journal=[Cartography](/source/Cartography_(journal))|volume=1|number=3|date=March 1956|pages=120–124|url=http://www.xnatmap.org/adnm/docs/2013/aganasm/geod+intro.html|archive-url=https://webarchive.nla.gov.au/awa/20150629231721/http://pandora.nla.gov.au/pan/166632/20180227-0206/www.xnatmap.org/adnm/docs/2013/aganasm/geod+intro.html|url-status=dead|archive-date=2015-06-29|via=[Pandora Archive](/source/Pandora_Archive)}}{{cbignore|bot=medic}}
* {{citation|first=J.R.|last=Smith |year=1998|title=The History of Geodimeter|publisher=Spectra Precision|location=Sweden |id=07-98 Publ. No. 571 710 000|url=http://www.geotronics.it/public/geodimeter_story.pdf}}
*{{citation|publisher=Government of Australia|via=[Pandora Archive](/source/Pandora_Archive)|title=NATMAP's Introduction of Electronic Distance Measuring to Australia - Sixty Years On|first=Paul |last=Wise|year=2014|url=http://www.xnatmap.org/adnm/docs/2013/aganasm/nasm.html|url-status=deviated|archive-url=https://webarchive.nla.gov.au/awa/20180226150600/http://pandora.nla.gov.au/pan/166632/20180227-0206/www.xnatmap.org/adnm/docs/2013/aganasm/nasm.html|archive-date=2018-02-26}}{{cbignore|bot=medic}}
==External links==
* [https://celebrating200years.noaa.gov/distance_tools/aga_gm6.html AGA Geodimeter Model 6] (''Going the Distance: A Photo Collection Illustrating the History of Distance Measurement Tools at the [National Geodetic Survey](/source/National_Geodetic_Survey)''){{Dead link|date=January 2026}}
Category:20th-century inventions
Category:Surveying instruments
Category:Swedish inventions
{{Measurement-stub}}
{{Geodesy-stub}}
---
Adapted from the Wikipedia article [Geodimeter](https://en.wikipedia.org/wiki/Geodimeter) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Geodimeter?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.