Angular multiplexing apparatus for holographic storage medium
View Patent ↗An angular multiplexing apparatus for a holographic storage medium. The angular multiplexing apparatus includes a reconstructing reference beam generator, translated in parallel to a number of positions, for generating a number of reconstructing reference beams which propagate in parallel to one another at the positions, respectively, and a mirror array having a plurality of planes of reflection for generating a plurality of reflected beams which are converged into a reconstructing position of the holographic storage medium.
1. An angular multiplexing apparatus for a holographic storage medium, comprising:
a reconstructing reference beam generator, translated by a translating unit to a number of positions, for generating a number of reconstructing reference beams which propagate in parallel through said number of positions, respectively; and
a mirror array having a plurality of planes of reflection for generating a plurality of reflected beams which are converged into a reconstructing position of the holographic storage medium at a plurality of incidence angles, respectively, wherein each reconstructing reference beam is reflected by a plane of reflection to be a reflected beam.
2. The angular multiplexing apparatus of claim 1 , wherein the reconstructing reference beam generator includes a unit for converting a plane reference beam into a spherical reference beam, which is used to generate said number of reconstructing reference beams, so that each reconstructing reference beam corresponds to the spherical reference beam.
3. The angular multiplexing apparatus of claim 2 , wherein the converting unit is a lens.
4. The angular multiplexing apparatus of claim 3 , wherein a total path of the spherical reference beam and the reflected beam from the lens to the reconstructing position is substantially equivalent to a focal length of the lens.
5. The angular multiplexing apparatus of claim 4 , wherein a perpendicular distance x from the reconstructing position to the spherical reference beam, a distance y from an intersecting point between a line passing though the reconstructing position and the spherical reference beam to a reflecting point of the plane of reflection in the mirror array from which the reflected beam corresponding to the spherical reference beam is generated, and an inclination angle φ of the plane of reflection to the line are calculated as:
y
+
r
=
c
,
y
>
0
,
r
>
0
,
c
>
0
,
x
=
r
cos
θ
=
c
cos
θ
1
+
sin
θ
,
y
=
r
sin
θ
=
c
sin
θ
1
+
sin
θ
,
φ
=
π
2
-
θ
2
wherein θ is an incidence angle of the reflected beam onto the reconstructing position and a constant c is a sum of a distance from the intersecting point to the reflecting point and a distance from the reflecting point and the reconstructing position.
6. The angular multiplexing apparatus of claim 5 , wherein the constant c is the focal length of the lens when the lens is located at the intersecting point.
7. The angular multiplexing apparatus of claim 1 , wherein paths of said number of reconstructing reference beams are substantially perpendicular to a translation direction along which the reconstructing reference beam generator is translated.
8. An angular multiplexing apparatus for a holographic storage medium, comprising:
a reconstructing reference beam generator, translated by a translating unit to a number of positions, for generating a reconstructing reference beam which propagates through one of the number of positions; and
a mirror array having a plurality of planes of reflection for reflecting the reconstructing reference beam by one of the plurality of planes of reflections to generate a reflected beam to be converged into a reconstructing position of the holographic storage medium at an incidence angle,
wherein a path of the reconstructing reference beam is substantially perpendicular to a translation direction of the reconstructing reference beam generator and the reconstructing reference beam generator is translated by the translating unit to another position to generate another reconstructing reference beam, which is reflected by another plane of reflection to generate another reflected beam to be converged into the reconstructing position of the holographic storage medium at another incidence angle.
9. The angular multiplexing apparatus of claim 8 , wherein the reconstructing reference beam generator includes a unit for converting a plane reference beam into a spherical reference beam so that the reconstructing reference beam corresponds to the spherical reference beam.
10. The angular multiplexing apparatus of claim 9 , wherein the converting unit is a lens.
11. The angular multiplexing apparatus of claim 10 , wherein a total path of the spherical reference beam and the reflected beam from the lens to the reconstructing position is substantially equivalent to a focal length of the lens.
12. The angular multiplexing apparatus of claim 11 , wherein a perpendicular distance x from the reconstructing position to the spherical reference beam, a distance y from an intersecting point between a line passing though the reconstructing position and the spherical reference beam to a reflecting point of the plane of reflection in the mirror array from which the reflected beam corresponding to the spherical reference beam is generated, and an inclination angle φ of the plane of reflection to the line are calculated as:
y
+
r
=
c
,
y
>
0
,
r
>
0
,
c
>
0
,
x
=
r
cos
θ
=
c
cos
θ
1
+
sin
θ
,
y
=
r
sin
θ
=
c
sin
θ
1
+
sin
θ
,
φ
=
π
2
-
θ
2
wherein θ is the incidence angle of the reflected beam onto the reconstructing position and a constant c is a sum of a distance from the intersecting point to the reflecting point and a distance from the reflecting point and the reconstructing position.
13. The angular multiplexing apparatus of claim 12 , wherein the constant c is the focal length of the lens when the lens is located at the intersecting point.