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.
Read more about Lens Clock: How It Works, Radius of Curvature, Estimating Thickness
Famous quotes containing the word clock:
“The stars move still, time runs, the clock will strike,
The devil will come, and Faustus must be damned.
O I’ll leap up to my God: who pulls me down?
See, see, where Christ’s blood streams in the firmament.
One drop would save my soul, half a drop, ah my Christ.”
—Christopher Marlowe (1564–1593)