Optical information recording/reproducing apparatus
An optical information recording/reproducing apparatus, to apply holograms of an angle multiplex recording method therein includes: a light source to emit a light beam; a divider unit to divide the light beam into a signal beam and a reference light; an angle variable unit to change an angle of the reference light incident upon an optical information recording medium; a spatial light modulator unit to add information to the signal beam; an objective lens to irradiate the signal beam on the medium; an image pickup unit to detect a diffracted light generating from a recording region, when the reference light is irradiated on the medium; and an optical element to shape a form of light flux of the reference light, so that a light flux diameter of the reference light in a multiplex direction becomes larger than the light flux diameter of the reference light in a pitch direction.
1. An optical information recording/reproducing apparatus, applying hologram of a angle multiplex recording method therein, comprising:
a light source, which is configured to emit a light beam thereform;
a divider unit, which is configured to divide the light beam emitting from the light source into a signal beam and a reference light;
an angle variable unit, which is configured to change an angle of the reference light incident upon an optical information recording medium;
a spatial light modulator unit, which is configured to add information to the signal beam;
an objective lens, which is configured to irradiate the signal beam upon the optical information recording medium;
an image pickup unit, which is configured to detect a diffracted light generating from a recording region within the optical information recording medium, when the reference light is irradiated upon the optical information recording medium; and
an optical element, which is configured to shape a form of light flux of the reference light, wherein
said optical element shapes up the form of light flux of the reference light, so that a light flux diameter of the reference light in a multiplex direction comes to be larger than the light flux diameter of the reference light in a pitch direction.
2. The optical information recording/reproducing apparatus, as described in the claim 1 , wherein
said optical element changes the form of light flux of the reference light, depending on an incident angle of the reference light.
3. The optical information recording/reproducing apparatus, as described in the claim 2 , wherein
said optical element shapes up the form of light flux of the reference light, so that an energy density contributing to recording on the optical information recording medium comes to be nearly constant, within a range, where the reference light is incident upon.
4. The optical information recording/reproducing apparatus, as described in the claim 2 , wherein
said optical element changes the form of light flux of the reference light in a first order.
5. The optical information recording/reproducing apparatus, as described in the claim 4 , wherein
a direction of shaping made by said optical element is a multiplex direction.
6. The optical information recording/reproducing apparatus, as described in the claim 2 , wherein
said optical element changes the form of light flux of the reference light into the multiplex direction depending on the incident angle of the reference light, and also fixes the form of light flux of the reference light in the pitch direction.
7. The optical information recording/reproducing apparatus, as described in the claim 1 , wherein
said optical element changes the form of light flux of the reference light, so that a total light amount of the reference light incident upon the optical information recording medium and a total light amount of the reference light emitting from the light source come to be equal to, approximately.
8. The optical information recording/reproducing apparatus, as described in the claim 1 , wherein
said optical element has at least either one of a beam shaper and a rectangular iris.
9. The optical information recording/reproducing apparatus, as described in the claim 8 , wherein
said iris constructing said optical element is a fixed iris.
10. The optical information recording/reproducing apparatus, as described in the claim 9 , wherein
said optical element has a relay lens having a barrel type distortion, or a beam expander, in addition to, or in the place thereof.
11. The optical information recording/reproducing apparatus, as described in the claim 10 , wherein
said iris building up said optical element is a variable iris.
12. The optical information recording/reproducing apparatus, as described in the claim 1 , wherein
said optical element is a wedge prism.
13. The optical information recording/reproducing apparatus, as described in the claim 12 , wherein
a rotation shaft is provided at such a position that fluctuation of a center of light flux of the reference light exiting from said wedge prism come to nearly minimum, in said angle variable unit.
14. The optical information recording/reproducing apparatus, as described in the claim 1 , wherein
said optical element shapes up the form of light flux of an irradiation light into the following:
size in multiplex direction=P×φ air-multi /E×φ media-multi ×φ media-pitch
where averaged values of light flux diameters contributing to recording within an air and the optical information recording medium are “φ air-multi ” and “φ air-multi ”, energy irradiating on the optical information recording medium is “P”, an energy density within the optical information medium is “E”, and a light flux diameter contributing to recording in the pitch direction within the optical information recording medium is “φ media-pitch ”, respectively.