Patent ID: 8310745

Claim:
A method for forming a multilayer reflection hologram in an optical recording medium, the optical recording medium including a hologram material layer, the method comprising applying two laser beams to the hologram material layer to form a reflection hologram layer according to an interference pattern of the two laser beams, the method further comprising: generating a first pair of polarized coherent laser beams and a second pair of polarized coherent laser beams that are incoherent with the first pair of polarized coherent laser beams; directing the first pair of polarized coherent laser beams to the hologram material layer from opposite sides thereof, respectively, such that incident angles of the first pair of polarized coherent laser beams are symmetric with respect to the hologram material layer; directing the second pair of polarized coherent laser beams to the hologram material layer from opposite sides thereof, respectively, such that incident angles of the second pair of polarized coherent laser beams are symmetric with respect to the hologram material layer, the incident angles of the first pair of polarized coherent laser beams being different from the incident angles of the second pair of polarized coherent laser beams; and forming the multilayer reflection hologram modulated in a depth direction of the hologram material layer according to an interference pattern of the first pair of polarized coherent laser beams and the second pair of polarized coherent laser beams.