Curvature distribution crystal lens

Patent Granted In a prepolishing step, one side of a semiconductor single crystal plate is polished so that, when a semiconductor single crystal plate of Si, Ge, GaAs or the like is inserted in an embossing member followed by plastic deformation under high temperature and high pressure conditions, the inclination of the crystal lattice face to the crystal surface satisfies Johansson diffraction conditions. The semiconductor single crystal plate is held between a protruded pressing member having such a protruded quadratic curve that a light focusing circle has been rotated, and a recessed pressing member having a recessed quadratic curve having a curvature to be satisfied by the crystal lattice of the semiconductor single crystal plate for satisfying Johansson diffraction conditions.