Patent ID: 6229782
Filing Date: 2001-05-08
Classification: B82Y,G02B,G11B

Abstract:
An optical focusing device in an optical recording device for focusing an incident optical beam to a focal spot on an optical recording medium, comprising:an incident surface comprised of a peripheral reflector and a central facet upon which the optical beam impinges;a body through which the incident optical beam passes;a bottom reflective surface for reflecting the optical beam through said body toward said peripheral reflector;a pedestal extending from said bottom reflective surface for defining a focal plane on which the focal spot is formed; andsaid peripheral reflector focusing the optical beam from the bottom reflective surface to the focal spot, and having a generally aspherical shape approximated by even polynomial parameters,wherein said central facet is generally flat and is diffractive and optically transmissive, and said peripheral reflector includes a diffractive phase profile.