Spherometers are used to measure the radius of curvature of the surface of a lens or mirror. This is a Basic three legged Spherometer with a 4.25 inch diameter. The Analog Indicator has 1 inch of total range of travel, with 0.001 graduations. The three legged base should be less than half the diameter of the mirror. This allows the testing of zones across the mirror in addition to measuring the radius of curvature. Includes chart for focal length.
Special thanks to Ken Hunter who wrote the spreadsheet and made it available to the ATM community.