JP4730490B2 - Manufacturing method of optical fiber with display function - Google Patents

Description

[0001]
The present invention relates to a method for manufacturing an optical fiber having a display function.
[0002]
[Prior art]
A technique for recording a diffraction grating in an optical fiber and making an optical demultiplexer, an optical multiplexer, a Fabry-Perot interferometer, etc. by utilizing the wavelength selectivity has been put into practical use (for example, JP-A-11-84623). ).
[0003]
In general, as shown in FIG. 5, a computer generated hologram or phase shift mask 4 is disposed in the vicinity of an optical fiber 1 composed of a core 2 and a cladding 3 around the core 2, and excimer laser light or argon laser absorbed by the optical fiber 1. Light 5 is irradiated onto a computer-generated hologram (phase shift mask) 4, and diffracted lights 6 and 7 of different orders resulting therefrom are caused to interfere with each other in the optical fiber 1 to cause a refractive index change in the optical fiber 1 to record interference fringes 8. Method is used. The refractive index change is generated by the diffusion of germanium oxide in the glass.
[0004]
Conventionally, there have been self-luminous display devices such as electric signboards and projectors, but all have problems that the devices are large and heavy.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the current state of the prior art, and an object of the present invention is to produce an optical fiber having a display function capable of diffracting light guided in the optical fiber to the outside and performing a desired display. Is to provide a method.
[0006]
[Means for Solving the Problems]
The optical fiber having a display function of the present invention that achieves the above object has a volume hologram or diffraction grating recorded therein, and the light guided through the inside is diffracted and a specific pattern is emitted from the side surface. It is a feature.
[0007]
In this case, a plurality of element diffraction gratings are recorded side by side in the direction along the axis of the optical fiber, and each element diffraction grating diffracts the light guided inside in a specific direction. A specific pattern may be generated by the integration of light.
[0008]
The specific pattern may be a two-dimensional image, and a plurality of two-dimensional images may be reproduced from a plurality of different holograms arranged in a direction along the axis of the optical fiber.
[0009]
Also, a plurality of volume holograms or diffraction gratings may be recorded in the optical fiber, and each volume hologram or diffraction grating may selectively diffract light having a different wavelength.
[0010]
The method for producing an optical fiber having a display function according to the present invention is a method characterized in that a volume hologram or a diffraction grating is recorded inside by interference between light guided in the optical fiber and light incident from a side surface. .
[0011]
In this case, an interference fringe having a configuration in which light guided in the optical fiber is diffracted and emitted from the side surface can be produced by interference by two light beams from the side surface of the optical fiber.
[0012]
In this case, it is desirable that at least one of the light incident from the side surface is incident through an optical transparent body that is in close contact with the optical fiber via the refractive index matching liquid.
[0013]
In addition, light incident from the side surface can be generated by a computer generated hologram.
[0014]
In the present invention, a volume hologram or diffraction grating is recorded inside, and the light guided inside is diffracted and a specific pattern is emitted from the side surface. Depending on the manufacturing method, an optical fiber capable of various displays can be obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The principle of the optical fiber having a display function of the present invention is that a volume hologram or diffraction grating is recorded inside the optical fiber, and in addition to the optical waveguide function, the guided light is diffracted from the side to the outside and specified. The function of displaying the pattern is added, thereby realizing a very small display device. Hereinafter, the manufacturing method will be described based on examples.
[0016]
FIG. 1 shows a manufacturing method (a) of an optical fiber having a display function of Example 1 of the present invention and its display function (b). As shown in FIG. 1A, when a display object 10 is arranged along the side surface of the optical fiber 1 and illuminated with illumination light 11, object light 12 is generated from the display object 10. On the other hand, if the illumination light 11 and the coherent reference light 13 are guided in the optical fiber 1, the object light 12 incident on the inside from the side surface of the optical fiber 1 and the reference light 13 guided in the optical fiber 1 are generated. Interference fringes of the volume hologram 14 are recorded as a change in refractive index (phase type) due to interference inside the optical fiber 1.
[0017]
As shown in FIG. 1B, when guided light 15 having the same wavelength traveling in the opposite direction to the reference light 13 is incident on such a volume hologram 14, display light (reproduction) proceeding in the direction opposite to the object light 12 at the time of recording. Light) 16 exits from the side surface of the optical fiber 1 and forms an image 17 at the position of the original display object 10. Therefore, when the guided light 15 is passed through the optical fiber 1 in which the volume hologram 14 is recorded, the display image 17 is displayed and can be observed or projected.
[0018]
When the guided light 15 is incident from the same direction as the reference light 13, the display light (reproduction light) 16 displays the virtual image at the position of the display object 10.
[0019]
FIG. 2 shows a method of manufacturing an optical fiber having a display function according to the second embodiment of the present invention. In this embodiment, instead of preparing a display object having the display pattern 10 ′, a plurality of beam-like object lights 12 ₁ , 12 ₂ , 12 ₃ separately emitted from the respective pixels of the display pattern 10 ′ in the direction of the optical fiber 1. , 12 ₄ , 12 ₅ ,... And a plurality of beam-like object lights 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ,. , And the object light 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ,... And the reference light 13 guided in the optical fiber 1 at different positions or the same position in the optical fiber 1. The number of volume type diffraction gratings (holograms) 14 ₁ , 14 ₂ , 14 ₃ , 14 ₄ corresponding to the number of object beams 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ,. , 14 _5, the refractive index change ... (position It is to record as a type). When a plurality of volume diffraction gratings (holograms) are recorded at the same position, multiple recording is performed.
[0020]
In this case as well, similarly to the case of FIG. 1B, volume-type diffraction gratings (holograms) 14 ₁ , 14 ₂ , 14 ₃ , 14 ₄ are guided through the optical fiber 1 with the same wavelength traveling in the opposite direction to the reference light 13. , 14 ₅ ,..., Display light (reproducing light) traveling in the opposite direction to the object lights 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ,. The image of the original display pattern 10 'is displayed by going out from one side surface and accumulating these diffracted lights. In this case as well, the virtual image of the display pattern 10 ′ can be displayed by making the guided light incident from the same direction as the reference light 13.
[0021]
FIG. 3 shows a manufacturing method (a) of an optical fiber having a display function according to the third embodiment of the present invention and a display function (b) thereof. Hologram recording is preferably performed at the same wavelength as reproduction. However, in the case of an optical fiber, recording is possible only with ultraviolet light (KrF excimer laser wavelength 248 nm, ArF excimer laser wavelength 193 nm, etc.) absorbed by the glass material. Currently. When reproducing with ultraviolet light, there is no problem, but when used for display, it is naturally necessary to reproduce with visible light. Therefore, this embodiment is a specific example of recording with ultraviolet light and reproducing with visible light.
[0022]
At the time of recording, as shown in FIG. 3A, a prism 18 for making the object light 12 and the reference light 13 ′ easy to enter from the side surface of the optical fiber 1 is provided with a refractive index matching liquid (index matching liquid) 19. Through the optical fiber 1, the object beam 12 and the reference beam 13 ′ coherent with the object beam 12 are incident from different surfaces of the prism 18, and interfere with each other inside the optical fiber 1 to form the volume hologram 14. Record. Let the interference fringe be 20 and the direction of the interference fringe 20 be a (the interference fringe 20 is a curved surface, but the direction of the tangent plane of the interference fringe 20 at the center).
[0023]
Here, as a specific example, the recording wavelength of the object beam 12 and the reference beam 13 ′ is a KrF excimer laser beam of 248 nm, and the reproduction wavelength of the volume hologram 14 is a semiconductor laser beam of 630 nm.
[0024]
And the inclination with respect to the axis | shaft of the optical fiber 1 of the direction a of the interference fringe 20 of the volume hologram 14 is set to 45 degrees, and a symbol is attached as follows.
The angle θ _i = 45 ° between the illumination light during reproduction and the reproduction light with respect to the direction a of the interference fringe 20 (FIG. 3B)
Interference fringe 20 pitch: d
The angle of the object beam 12 and the reference beam 13 ′ during recording with respect to the direction a of the interference fringe 20: φ _r (FIG. 3A)
Recording wavelength λ _r = 248 nm
・ Reproduction wavelength λ _i = 630 nm
In this case, the following equation holds.
[0025]
2 sin θ _i = λ _i / d
2sinφ _r = λ _r / d
From this calculation,
d = 0.446 μm
φ _r = 16.2 °
By exposing the object beam 12 and the reference beam 13 ′ from the side surface of the optical fiber 1 at an angle φ _r = 16.2 ° satisfying the above values, the inclination of the interference fringe 20 is inclined with respect to the axis of the optical fiber 1. A volume hologram 14 of 45 ° is recorded on the optical fiber 1. At this time, there is a difference in refractive index between the core 2 and the clad 3 of the optical fiber 1. However, since any of the light beams 12 and 13 ′ is at some angle with respect to the axis of the optical fiber 1, the core 2 and the clad 3 Even though the direction of travel may change to some extent due to refraction at the interface, there will be no total reflection. Further, if the optical fiber 1 is directly irradiated with the object light 12 and the reference light 13 ′, the cylindrical surface of the optical fiber 1 acts as a lens, so that the incident surface is flat via the refractive index matching liquid 19 as described above. It is desirable that the prism 18 is in close contact.
[0026]
When the guided light 15 ′ of visible light (wavelength: 630 nm) is incident on the volume hologram 14 thus recorded with ultraviolet light, as shown in FIG. 3B, display light (reproduction light) 16 ′. Exits from the side of the optical fiber 1 to form a display image 17 '. Therefore, when the guided light 15 ′ is passed through the optical fiber 1 in which the volume hologram 14 is recorded, the display image 17 ′ is displayed and can be observed or projected. Also in this case, the virtual image of the display image 17 ′ can be displayed by making the guided light 15 ′ incident from the opposite direction.
[0027]
In this case, the object light 12 enters through the prism 18 at the time of recording, but the reproduction light does not pass through the prism 18 and is refracted on the side surface of the optical fiber 1 to cause distortion. It is desirable to use object light 12 that corrects this.
[0028]
As described above, when the recording wavelength and the reproduction wavelength are different from each other, an aberration occurs in the reproduced image. Therefore, it is desirable to prepare object light 12 that corrects this aberration in advance. For this purpose, for example, a distorted subject is used.
[0029]
FIG. 4 shows the configuration of an optical fiber having a display function according to the fourth embodiment of the present invention. In the above embodiment, the wavelength diffracted from the volume hologram or volume diffraction grating recorded on the optical fiber 1 is one, but in the case of FIG. 4, different R (red) and G (green) are used. , B (blue) Three volume holograms 14 _R , 14 _G , 14 _B diffracted at each of the three wavelengths are multiplexed or recorded in different positions in the optical fiber 1 and reproduced by the method of any of the above embodiments. Then, light including the same three wavelengths as the guided light 15 ″ in the case of display is made incident on these volume holograms 14 _R , 14 _G , 14 _B , and display light (reproduction light) 16 _R , 16 _G , 16 _B is simultaneously diffracted and superimposed on the display surface to display a full-color display image 17 ″.
[0030]
Note that the object light 12 or the like to be recorded need not be generated from the actual display object 10, and may be generated by a computer-generated hologram, for example.
[0031]
As described above, the optical fiber having the display function of the present invention and the manufacturing method thereof have been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications are possible. For example, a plurality of volume holograms can be recorded in a direction along the axis of the optical fiber, and a plurality of two-dimensional images can be reproduced separately from each volume hologram.
[0032]
【The invention's effect】
As is clear from the above description, according to the optical fiber having the display function of the present invention and the manufacturing method thereof, the volume hologram or diffraction grating is recorded inside, and the light guided inside is diffracted from the side surface. Since a specific pattern is emitted, an optical fiber capable of various displays can be obtained by a simple manufacturing method using an extremely light and thin optical fiber.
[Brief description of the drawings]
FIG. 1 is a diagram showing a method for producing an optical fiber having a display function according to a first embodiment of the present invention and a display function thereof.
FIG. 2 is a diagram showing a method for producing an optical fiber having a display function according to a second embodiment of the present invention.
FIG. 3 is a diagram showing a method of manufacturing an optical fiber having a display function according to a third embodiment of the present invention and the display function.
FIG. 4 is a diagram illustrating a configuration of an optical fiber having a display function according to a fourth embodiment of the present invention.
FIG. 5 is a diagram for explaining a method of recording a diffraction grating in a conventional optical fiber.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber 2 ... Core 3 ... Cladding 4 ... Computer-generated hologram (phase shift mask)
5 ... ultraviolet laser beam 6,7 ... diffracted light 8 ... fringe 10 ... display object 10 '... display pattern 11 ... illumination light 12, 12 _1, 12 _2, 12 _3, 12 _4, 12 ₅ ... object beam 13, 13 '... Reference beams 14, 14 _R , 14 _G , 14 _B ... Volume holograms 14 ₁ , 14 ₂ , 14 ₃ , 14 ₄ , 14 ₅ ... Volume diffraction grating (hologram)
15, 15 '... guided light _{16,16', 16 R, 16 G} , 16 B ... display light (reproducing light)
17, 17 ′... Display object image (display image)
18 ... Prism 19 ... Refractive index matching liquid (index matching liquid)
20 ... interference fringes

Claims (3)

A method for producing an optical fiber in which visible light of three wavelengths guided through an optical fiber is diffracted and a specific full-color pattern is emitted from a side surface. The red, green, and blue are guided through the optical fiber. An optical fiber having a display function, characterized in that each of three multiple-recorded interference fringes configured to be diffracted at each of the three wavelengths and emitted from the side surface is produced by interference by two light beams of ultraviolet light from the side surface of the optical fiber. Manufacturing method.   2. An optical fiber having a display function according to claim 1, wherein at least one of the ultraviolet light incident from the side is incident through an optical transparent body in close contact with the optical fiber via a refractive index matching liquid. Method.   2. The method for producing an optical fiber having a display function according to claim 1, wherein the ultraviolet light incident from the side surface is generated by a computer-generated hologram.

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