Patent ID: 8004950

Claim:
An optical pickup to be used in combination with an optical information recording medium, comprising: a light source; means for separating an optical beam emitted from said light source into a first optical beam and a second optical beam; a spatial light modulator for receiving said first optical beam; a first lens for converging said first optical beam modulated by said spatial light modulator; and a second lens for converging said second optical beam upon a back focus plane of said first lens, wherein: said first optical beam transmitted through said first lens is applied as a signal beam to said optical information recording medium in a converged optical beam state; said second optical beam transmitted through said first lens is applied as a reference beam to said optical information recording medium in a parallel beam state; said signal beam and said reference beam are optically interfered with each other on said optical information recording medium, and an interference fringe formed by said interference is recorded as a hologram in said optical information recording medium; and said second lens and said means for separating into said first and second beams is one diffraction lens.