Patent ID: 7965607

Claim:
A hologram recording/reproducing device, comprising: a recording/reproducing optical unit that records information onto a hologram recording/reproducing medium and that reproduces the information from the hologram recording/reproducing medium, the recording/reproducing optical unit including: a laser light source that emits laser light; a spatial-light modulator that generates signal light and reference light from the laser light, the signal light and the reference light having a common light path; a phase mask disposed in the common light path, either near the spatial-light modulator or in a conjugate plane of the spatial-light modulator, wherein the phase mask has a structure which transmits the reference light and the signal light and which is such that a transmission portion of the reference light and a transmission portion of the signal light are uniformly provided; and an objective lens including a first lens portion and a second lens portion, the first lens portion being disposed at an inner peripheral portion of the objective lens and serving as a Fourier transformation lens that focuses the signal light to a predetermined point, and the second lens portion being disposed at an outer peripheral portion of the objective lens and serving as a lens that focuses the reference light and having focuses that are continuously or discretely disposed in an optical-axis direction of the objective lens and at portions in the hologram recording/reproducing medium along a length in the optical-axis direction of the objective lens extending through the predetermined point where the signal light is focused, wherein the second lens portion is formed as the outer peripheral portion of a conical or an Axicon lens.