Lens Maker’s Formula
LENS MAKER’S FORMULA
All lenses are made up of transparent materials. Any optically transparent material will have a refractive index. The lens formula relates the focal length of a lens with the distance of object and image. For a maker of any lens, knowledge of radii of curvature of the lens is required. This clearly indicates the need for an equation relating the radii of curvature of the lens, the refractive index of the given material of the lens and the required focal length of the lens. The lens maker’s formula is one such equation. It is given as
where µ is the refractive index of the material of the lens; R1 and R 2 are the radii of curvature of the two faces of the lens; f is the focal length of the lens.