Hologram recorder

Abstract

A multiple hologram recorder includes an optical system and an incident angle controller. The optical system applies a recording beam and a reference beam to a unit recording region of a hologram recording medium. The recording beam is modulated in accordance with information to be recorded. The reference and the recording beams have the same wavelength. The angle controller adjusts the incident angle of the recording or reference beam to preset angles. Every time the incident angle is adjusted to one set angle, one-page holographic recording is performed. The set angles include a reference angle associated with an angular interval. The incident angle controller causes the incident angle to continuously vary within the angular interval when the incident angle is adjusted to the reference angle. This continuous variation is performed with the recording and the reference beams irradiating the unit recording region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the overall configuration of a hologram recorder according to a first embodiment of the present invention.

FIG. 2 is a schematic view illustrating the hologram recording operation of the recorder of FIG. 1.

FIG. 3 is a plan view illustrating the spatial modulation pattern shown in FIG. 2.

FIG. 4 is a schematic view illustrating the hologram reproducing operation of the recorder of FIG. 1.

FIGS. 5A and 5B are graphs illustrating the optical properties of holograms.

FIG. 6 is a flow chart showing the recording procedure by the hologram recorder of FIG. 1.

FIG. 7 is a flow chart showing the reproducing procedure by the hologram recorder of FIG. 1.

FIG. 8 is a flow chart showing the procedure following that of FIG. 7.

FIG. 9 shows the overall configuration of a hologram recorder according to a second embodiment of the present invention.

FIG. 10 shows the overall configuration of a hologram recorder according to a third embodiment of the present invention.

Claims

1. A hologram recorder for multiple holographic recording, the recorder comprising: an optical system for applying a recording beam and a reference beam to a unit recording region of a hologram recording medium, the recording beam being modulated in accordance with information to be recorded, the reference beam having a same wavelength as the recording beam; andan incident angle controller for adjusting an incident angle of one of the recording beam and the reference beam to predetermined set angles, the adjustment of the incident angle to a selected one of the set angles enabling holographic recording for a page;wherein the set angles include at least one reference angle associated with an angular interval containing the reference angle,wherein the incident angle controller causes the incident angle to continuously vary within the angular interval when the incident angle is to be adjusted to the reference angle, the continuous variation of the incident angle being performed with the recording beam and the reference beam kept irradiating the unit recording region.

2. The hologram recorder according to claim 1, wherein the angular interval is shorter than an interval between the set angles.

3. The hologram recorder according to claim 1, wherein address information necessary for access is recorded in the page by holographic recording.

4. A hologram recorder for multiple holographic recording, the recorder comprising: an optical system for applying a recording beam and a reference beam to a unit recording region of a hologram recording medium, the recording beam being modulated in accordance with information to be recorded, the reference beam having a beam wavelength same as a beam wavelength of the recording beam; anda wavelength controller for adjusting the beam wavelength to predetermined set wavelengths, the adjustment of the beam wavelength to a selected one of the set wavelengths enabling holographic recording for a page;wherein the set wavelengths include at least one reference wavelength associated with a wavelength range containing the reference wavelength,wherein the wavelength controller causes the beam wavelength to continuously vary within the wavelength range when the beam wavelength is to be adjusted to the reference wavelength, the continuous variation of the beam wavelength being performed with the recording beam and the reference beam kept irradiating the unit recording region.

5. A hologram recorder for multiple holographic recording, the recorder comprising: an optical system for applying a recording beam and a reference beam to a unit recording region of a hologram recording medium, the recording beam being modulated in accordance with information to be recorded, the reference beam having a wavelength same as a wavelength of the recording beam and being speckle-modulated; anda speckle size controller for adjusting a speckle size of the reference beam to predetermined set sizes, the adjustment of the speckle size to a selected one of the set sizes enabling holographic recording for a page;wherein the set sizes include at least one reference size associated with a size range containing the reference size,wherein the speckle size controller causes the speckle size to continuously vary within the size range when the speckle size is to be adjusted to the reference size, the continuous variation of the speckle size being performed with the recording beam and the reference beam kept irradiating the unit recording region.

6. A hologram recording method for multiple holographic recording, the method comprising the steps of: applying a recording beam and a reference beam to a unit recording region of a hologram recording medium, the recording beam being modulated in accordance with information to be recorded, the reference beam having a same wavelength as the recording beam;adjusting an incident angle of one of the recording beam and the reference beam to predetermined set angles; andrecording a hologram for a page every time the incident angle is adjusted to one of the set angles;wherein the set angles include at least one reference angle associated with an angular interval containing the reference angle,wherein the incident angle is caused to continuously vary within the angular interval when the incident angle is to be adjusted to the reference angle, the continuous variation of the incident angle being performed with the recording beam and the reference beam kept irradiating the unit recording region.

7. A hologram recording method for multiple holographic recording, the method comprising the steps of: applying a recording beam and a reference beam to a unit recording region of a hologram recording medium, the recording beam being modulated in accordance with information to be recorded, the reference beam having a beam wavelength same as a beam wavelength of the recording beam;adjusting the beam wavelength of the recording beam and the reference beam to predetermined set wavelengths; andrecording a hologram for a page every time the beam wavelength is adjusted to one of the set wavelengths;wherein the set wavelengths include at least one reference wavelength associated with a wavelength range containing the reference wavelength,wherein the beam wavelength is caused to continuously vary within the wavelength range when the beam wavelength is to be adjusted to the reference wavelength, the continuous variation of the beam wavelength being performed with the recording beam and the reference beam kept irradiating the unit recording region.

8. A hologram recording method for multiple holographic recording, the method comprising the steps of: applying a recording beam and a reference beam to a unit recording region of a hologram recording medium, the recording beam being modulated in accordance with information to be recorded, the reference beam having a wavelength same as a wavelength of the recording beam and being speckle-modulated;adjusting a speckle size of the reference beam to predetermined set sizes; andrecoding a hologram for a page every time the speckle size is adjusted to one of the set sizes;wherein the set sizes include at least one reference size associated with a size range containing the reference size,wherein the speckle size is caused to continuously vary within the size range when the speckle size is to be adjusted to the reference size, the continuous variation of the speckle size being performed with the recording beam and the reference beam kept irradiating the unit recording region.