A lens clock is a mechanical dial indicator that is used to measure dioptric power of a lens. It is a specialized version of a spherometer. A lens clock measures the curvature of a surface, but gives the result as an optical power in diopters, assuming the lens is made of a material with a particular refractive index.
Other articles related to "lens clock, lens":
... A lens clock can also be used to estimate the thickness of thin objects, such as a hard or gas-permeable contact lens ... Ideally, a contact lens dial thickness gauge would be used for this, but a lens clock can be used if a dial thickness gauge is not available ... To do this, the contact lens is placed concave side up on a table or other hard surface ...
Famous quotes containing the word clock:
“He makes his voyage too late, perhaps, by a true water clock who delays too long.”
—Henry David Thoreau (18171862)