Abstract: The apparatus measure the radius of curvature of a reflective or partially reflective surface 18, and comprises first and second lasers 2, 4 which generate two parallel beams a known distance apart. A lens 12 focuses the beams, which are passed via a beam splitter 14 and transform lens 16 to the surface 18. The beams are reflected back via the transform lens 16 and the beam splitter 14 onto a detector 20. A processor 22 calculates the radius of curvature of the surface in dependence of the known distance X separating the beams and the positions of the beams on the detector 20.

Abstract: An apparatus for the measurement of the curvature of a surface includes at least one source of electromagnetic radiation, an electromagnetic radiation detector, and a lens positioned and arranged to focus source radiation reflected from the surface onto the detector. The detector is arranged to provide an output signal characteristic of a position thereon at which the radiation is incident. A signal processor, responsive to the output signal, provides an indication appertaining to curvature of the surface.