LOOKING BACK – MAY 2016

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OLDIE BUT A GOODIE (AND STILL IN USE!)
One of the oldest optical instruments still in regular use today, the Geneva lens measure device was first patented in the U.S. on February 24, 1891. This device is used to measure the surface curvature of a lens, and its design has changed very little over the years. Today, most eyecare professionals read the device on a scale of D1.53, but early gauges were provided in different calibration indices, as shown in this 1916 American Optical Advertisement above in green. The lens measure is most useful when the curve being measured is spherical- the surface being measured does not change in surface curvature within the three points of contact used in this gauge. The schematic above in red was from an American Optical 1945 Lab manual and it shows the parts of this tool. Courtesy of the Optical Heritage Museum, opticalheritagemuseum.com

 

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