Patent ID: 6956811

Claim:
An optical recording/reproducing apparatus, comprising: a moving unit moving above a recording medium by operation of a driving unit; a slider fixedly installed at a free end of the moving unit; a head lens unit comprising an objective lens installed at a top surface of the slider and a converging lens installed below the objective lens to converge light passing through the objective lens above the recording medium; a beam path conversion unit having a selection surface being arranged at an upper portion of the objective lens vertical to an optical axis of the objective lens and transmitting a light beam proceeding toward an optical axis direction of the objective lens; and an optical unit comprising a radiating unit installed at the moving unit for generating and transmitting light to be irradiated onto the recording medium through the beam path conversion unit, the head lens unit and a light receiving unit for sensing light reflected upon the recording medium, wherein the beam path conversion unit comprises a first surface as the selection surface, a second surface for passing incident light and a third surface for reflecting all incident lights, and wherein Equation D 1 D 2 = n 2 - cos 2 ⁢ θ n ⁢ ⁢ sin ⁢ ⁢ θ is satisfied, when an angle of the first surface with the second surface is θ, a diameter of light incident on the second surface is D 2 , a diameter of light transmitting the first surface is D 1 , and a refractive index of the beam path conversion unit is n.