Smithsonian - National Museum of American History, Behring Center

Physical Sciences Collection - Surveying and Geodesy

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EDM (Ranger)

Catalogue number:

"Ranger LSE Laser Systems & Electronics Inc. Tullahoma, Tenn. Ser. No. 07B1008"

19 inches high, 21.5 inches wide, 17 inches deep

The Ranger was the first of a series of laser-based EDMs developed by Laser Systems & Electronics (LSE). It was introduced in 1970, cost $8,000, and had a "self-contained digital computer" that made it "completely automatic and extremely fast." It had a range of from 1 meter to 6 km with an accuracy of ±5 mm +2 ppm. It weighed 32 lbs, and used a 12-volt power supply. This example belonged to a surveyor who was "always crazy about new gadgets." He bought it after seeing one at the American Congress of Surveying and Mapping meeting in 1970, and used it until 1973.

The impetus for making an EDM with automatic read-out came from Robin Hines, who had observed that the EDMs used by Tennessee Valley Authority surveyors were cumbersome, and that the data had to be sent to headquarters for analysis. William Hollinshead, who designed its computer, worked with the chip designers at Texas Instruments to learn the strengths and weaknesses of the computer chips available at that time. Another critical problem--generating the frequencies needed for the beam--was solved by using a temperature controlled crystal oscillator. There were two patents associated with the Ranger. One (#3,740,141), for "Timing and Measuring Methods and Means for Laser Distance Measurement," was granted in June 1973 to John H. DeWitt Jr. of Nashville, and assigned to LSE. John Shipp and Robin Hines had done the design work, but when they left the firm, their names were removed from the patent application; DeWitt was a member of the LSE board. The other (#3,778,159), for "Distance Measuring Apparatus and Method Utilizing Phase Comparison of Modulated Light Beams," was granted in December 1973 to Hines, Hollinshead, and Thomas O. Bolden, and assigned to LSE.

Ref: LSE, Price List. Ranger and Accessories (Oct. 1, 1970).

LSE, Laser Ranger Specifications.

LSE, Operating Instructions for Laser Ranger.

Further Information:

Laser Systems & Electronics