OPTICAL RECORDING DEVICE AND OPTICAL RECORDING AND REPRODUCTION DEVICE

• US 20090213718A1
• Filed: 11/06/2008
• Published: 08/27/2009
• Est. Priority Date: 02/26/2008
• Status: Active Grant

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: MINABE, Jiro, OGASAWARA, Yasuhiro
• Granted Patent: US 8,050,164 B2
• Time in Patent Office: Days
• US Class Current: 369/112.240
• CPC Class Codes: G03H 1/04 Processes or apparatus for producing holograms G03H1/26 takes precedence
• CPC Class Codes: G03H 1/0465 Particular recording light; Beam shape or geometry G03H1/06 takes precedence
• CPC Class Codes: G03H 2222/35 Transverse intensity distribution of the light beam
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/1378 Separate aberration correction lenses; Cylindrical lenses to generate astigmatism; Beam expanders
• CPC Class Codes: G11B 7/1381 Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops G11B7/1353 - G11B7/1369 take precedence

Abstract

An optical recording device includes a light source, a spatial light modulator, a correcting optical system and a light guiding section. The spatial light modulator includes plural pixels, a signal light region that displays a signal light pattern, and a reference light region that displays a reference light pattern. The spatial light modulator modulates and outputs incident light for each pixel in accordance with a display pattern. The correcting optical system includes a pair of axicon lenses that correct the emitted light from the light source so as to flatten the light intensity distribution thereof on an irradiated surface of the spatial light modulator. The light guiding section guides the corrected light to the spatial light modulator. The signal light and the reference light are irradiated onto an optical recording medium simultaneously and a hologram is recorded into the optical recording medium.

Claims

1. An optical recording device comprising:

a light source that emits coherent light;

a spatial light modulator that is formed from a plurality of pixels that are two-dimensionally arrayed, that comprises a signal light region that displays a signal light pattern when generating signal light, and a reference light region that is disposed so as to surround the signal light region and displays a reference light pattern when generating reference light that is coaxial with the signal light, and that modulates and outputs incident light for each pixel in accordance with a display pattern;

a correcting optical system that is disposed between the light source and the spatial light modulator and comprises a pair of axicon lenses that correct the light that has been emitted from the light source so as to flatten the light intensity distribution thereof on an irradiated surface of the spatial light modulator; and

a light guiding section that guides the light that has been corrected by the correcting optical system to the spatial light modulator,

wherein the signal light and the reference light generated by the spatial light modulator are irradiated onto an optical recording medium simultaneously and a hologram is recorded into the optical recording medium.

2. The optical recording device according to claim 1, further comprising a mask that is disposed between the light source and the correcting optical system and comprises a blocking portion that blocks the light in the vicinity of the optical axis.

3. The optical recording device according to claim 1, wherein the pair of axicon lenses that form the correcting optical system are disposed such that conical surfaces thereof face each other and are disposed apart from each other by a distance L that is defined in the following expression:

$L=\frac{D}{2<br><br><br><br>\tan <br><br>\left[{\sin }^{-1}<br><br>\left\{n<br><br><br><br>\sin <br><br>\left(\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right)\right\}-\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right]}$

wherein, the distance L is an optical axis component distance of an optical path length between the axicon lenses, φ

represents the angle of the apex angle of the axicon lenses, D represents the beam diameter of the incident light, θ

represents the angle of refraction resulting from the axicon lenses, and n represents the index of refraction of the axicon lenses, with the index of refraction in air being 1.

4. The optical recording device according to claim 2, wherein the pair of axicon lenses that form the correcting optical system are disposed such that conical surfaces thereof face each other and are disposed apart from each other by a distance L that is defined in the following expression:

$L=\frac{D}{2<br><br><br><br>\tan <br><br>\left[{\sin }^{-1}<br><br>\left\{n<br><br><br><br>\sin <br><br>\left(\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right)\right\}-\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right]}$

wherein, the distance L is an optical axis component distance of an optical path length between the axicon lenses, φ

represents the angle of the apex angle of the axicon lenses, D represents the beam diameter of the incident light, θ

represents the angle of refraction resulting from the axicon lenses, and n represents the index of refraction of the axicon lenses, with the index of refraction in air being 1.

5. An optical recording and reproduction device comprising:

a light source that emits coherent light;

a spatial light modulator that is formed from a plurality of pixels that are two-dimensionally arrayed, that comprises a signal light region that displays a signal light pattern when generating signal light, and a reference light region that is disposed so as to surround the signal light region and displays a reference light pattern when generating reference light that is coaxial with the signal light, and that modulates and outputs incident light for each pixel in accordance with a display pattern;

a diaphragm mechanism that is disposed between the light source and the spatial light modulator and comprises an opening portion whose diameter contracts during reproduction to restrict the beam diameter of the light that passes therethrough;

a correcting optical system that is disposed between the diaphragm mechanism and the spatial light modulator, that comprises a pair of axicon lenses that are disposed such that conical surfaces thereof face each other, and which, during recording, corrects the light that has passed through the opening portion in the diaphragm mechanism so as to flatten the light intensity distribution thereof on an irradiated surface of the spatial light modulator and, during reproduction, corrects the light that has passed through the opening portion in the diaphragm mechanism such that a region other than the signal light region of the spatial light modulator is irradiated therewith; and

a light guiding section that guides the light that has been corrected by the correcting optical system to the spatial light modulator,

wherein, during recording, the signal light and the reference light generated by the spatial light modulator are irradiated onto an optical recording medium and a hologram is recorded into the optical recording medium, and

during reproduction, the reference light generated by the spatial light modulator is irradiated onto the optical recording medium on which the hologram has been recorded, and the signal light is reproduced.

6. The optical recording and reproduction device according to claim 5, further comprising a mask that is disposed between the light source and the correcting optical system and comprises a blocking portion that blocks the light in the vicinity of the optical axis.

7. The optical recording and reproduction device according to claim 5, wherein the pair of axicon lenses that form the correcting optical system are disposed such that conical surfaces thereof face each other and are disposed apart from each other by a distance L that is defined in the following expression:

$L=\frac{D}{2<br><br><br><br>\tan <br><br>\left[{\sin }^{-1}<br><br>\left\{n<br><br><br><br>\sin <br><br>\left(\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right)\right\}-\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right]}$

wherein, the distance L is an optical axis component distance of an optical path length between the axicon lenses, φ

represents the angle of the apex angle of the axicon lenses, θ

represents the beam diameter of the incident light, θ

represents the angle of refraction resulting from the axicon lenses, and n represents the index of refraction of the axicon lenses, with the index of refraction in air being 1.

8. The optical recording and reproduction device according to claim 6, wherein the pair of axicon lenses that form the correcting optical system are disposed such that conical surfaces thereof face each other and are disposed apart from each other by a distance L that is defined in the following expression:

$L=\frac{D}{2<br><br><br><br>\tan <br><br>\left[{\sin }^{-1}<br><br>\left\{n<br><br><br><br>\sin <br><br>\left(\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right)\right\}-\frac{\mathrm{\pi <br><br>}-\mathrm{\varphi <br><br>}}{2}\right]}$

wherein, the distance L is an optical axis component distance of an optical path length between the axicon lenses, φ

represents the angle of the apex angle of the axicon lenses, θ

represents the beam diameter of the incident light, θ

represents the angle of refraction resulting from the axicon lenses, and n represents the index of refraction of the axicon lenses, with the index of refraction in air being 1.

9. The optical recording and reproduction device according to claim 5, wherein

the correcting optical system, during reproduction, corrects the light that has passed through the opening portion in the diaphragm mechanism into ring-shaped light that corresponds to the shape of the reference light region of the spatial light modulator, and

the light guiding section guides the ring-shaped light generated by the correcting optical system to the reference light region of the spatial light modulator while adjusting the optical path of that light.

10. The optical recording and reproduction device according to claim 6, wherein

the correcting optical system, during reproduction, corrects the light that has passed through the opening portion in the diaphragm mechanism into ring-shaped light that corresponds to the shape of the reference light region of the spatial light modulator, and

the light guiding section guides the ring-shaped light generated by the correcting optical system to the reference light region of the spatial light modulator while adjusting the optical path of that light.

11. The optical recording and reproduction device according to claim 7, wherein

the correcting optical system, during reproduction, corrects the light that has passed through the opening portion in the diaphragm mechanism into ring-shaped light that corresponds to the shape of the reference light region of the spatial light modulator, and

the light guiding section guides the ring-shaped light generated by the correcting optical system to the reference light region of the spatial light modulator while adjusting the optical path of that light.

12. The optical recording and reproduction device according to claim 8, wherein

the correcting optical system, during reproduction, corrects the light that has passed through the opening portion in the diaphragm mechanism into ring-shaped light that corresponds to the shape of the reference light region of the spatial light modulator, and

the light guiding section guides the ring-shaped light generated by the correcting optical system to the reference light region of the spatial light modulator while adjusting the optical path of that light.