Center of curvature is generally used in Physics regarding to study of the lenses. It can also be defined as the spherical distance between the point at which all the rays, falling on the lens either seems to converge to it (in case of Convex Lens) or diverge from it (in case of Concave Lens) and the lens itself. Center of curvature In geometry, the center of curvature of a curve is found at a point that is at a distance from the curve equal to the radius of curvature lying on the normal vector. It is the point at infinity if the
Lens clock 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. The lens clock is then brought down on it such that the center prong contacts the lens as close to its center as possible, and the outer prongs rest on the table. The thickness of the lens is then the sagitta formula_4 in the formula above, and can be calculated from the optical power reading, if the distance between the outer prongs is known. Lens clock A lens clock is