JP2003270680A - Optical path switching element, spatial light modulator, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical path switching element and a spatial light modulator which have simple structure and have high durability and light use efficiency, and to provide an image display device using the same. <P>SOLUTION: The optical path switching element is provided with a light incidence part 3 on which light is made incident through a light guiding member 1, a reflection part 6 which reflects incident light made incident from the light incidence part 3, and a light emission part 4 which emits light reflected by the reflection part 6 to the outside as exit light through the light guiding member 1. A refractive index varying material 5 is enclosed in an optical path including the reflection part 6, and a signal is given to the refractive index varying material 5 in accordance with information to change the refractive index, thus switching the optical path. The reflection part 6 has a plurality of reflection faces 18, and intervals of adjacent reflection faces 18 arranged in the direction of light incidence are not made uniform in the arrangement direction. Thus, spread of light reflection caused by diffraction is suppressed to improve the light use efficiency. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path switching element, a spatial light modulator and an image display device, and more specifically,
The present invention relates to an optical path switching element that switches an optical path by changing a reflection direction of incident light to switch light, and a spatial light modulator and an image display device using the same.

[0002]

2. Description of the Related Art A device for switching light by changing an optical path by changing a reflection direction of incident light and a spatial light modulator using the same are disclosed in, for example, Japanese Patent Laid-Open No. 5-1.
It is known that a large number of minute rotating mirrors as shown in Japanese Patent No. 96880 are arranged two-dimensionally. FIG. 19 is a plan view of a conventional spatial light modulator, in which only the rectangular torsion beam reflecting surface 60 and the beam support post 61 are observed. 20 is a cross-sectional view of one rotating mirror of the spatial light modulator shown in FIG. 19, FIG. 20 (A) is a cross-sectional view taken along a hinge, and FIG. 20 (B) is a cross-sectional view taken in a direction perpendicular to it. The beam support post 61 is a hinge 7 connected to the post 73.
A twist of 1 allows the beam 60 to rotate towards the ground electrode 72. The driving force is given by the voltage applied to the address electrode 75 supported by the post 74. The voltage is applied to the address electrode 75 by applying a signal from a CMOS circuit (not shown) provided on the substrate layer 82 to the metal layer 81.
It is done by transmitting through. By changing the rotation state of the beam 60 for each rotating mirror, the incident light can be spatially two-dimensionally modulated. In this method, the structure of the rotary mirror is complicated in order to obtain a large rotation angle, and there is a problem that the manufacturing cost becomes high.

Another technique is disclosed in Japanese Patent Laid-Open No. 11-20.
There is an optical switching element disclosed in Japanese Patent No. 2222. FIG. 21 is an operation explanatory diagram of the optical switching element proposed in Japanese Patent Laid-Open No. 11-202222. Light guide section 9 provided with a total reflection surface 94 capable of totally reflecting and transmitting light
0, a prism 102 capable of capturing the evanescent light by bringing the extraction surface 101 close to the total reflection surface, reflecting the light and emitting the evanescent light, and a drive unit 110 driving the optical switching unit. On the other hand, it is configured to be laminated in this order. The cell on the right side of FIG. 21 shows a state in which the prism 102 is located at a position separated by the extraction distance or more at which the evanescent light leaks by operating the driving unit 110. At this time, the light ray 91 propagating in the light guide section 90 is totally reflected by the total reflection surface 94 as shown in FIG.
Is totally reflected by and is emitted as a light ray 93 in the right direction in the figure. When the drive unit 110 is not operated, the prism 102 is closer than the extraction distance where the evanescent light leaks like the cell on the left side of FIG. As shown in FIG. 5, the light enters the prism 102 without being reflected by the total reflection surface 94. The light rays that have entered the prism 102 are reflected by the reflecting surface 102a of the prism and are transmitted through the light guide portion 90 and emitted as the light rays 92 shown in FIG.

In this system, to switch between two states of extraction and non-extraction of evanescent light,
A relatively simple driving mechanism can be adopted because it requires only a minute displacement of about the wavelength of light or less, but since the structure of the prism 102 as shown in FIG. It is difficult to form the film uniformly on the substrate, so that there is a problem that the manufacturing yield is reduced and the cost is increased. Further, when the prism 102 is brought close to the total reflection surface 94, there is a problem that van der Waals force or liquid bridging force acts and peeling becomes difficult.

Still another technique is Japanese Patent Laid-Open No. 2000-1.
There is an optical switching element disclosed in Japanese Patent No. 71813. FIG. 22 is a diagram showing a schematic configuration of an optical switching element proposed in Japanese Patent Laid-Open No. 2000-171813. By applying a voltage to the liquid crystal 126 brought into contact with the light guide body 121 that transmits light by total reflection, the orientation of the liquid crystal molecules is controlled, and thereby the effective refractive index is adjusted to a value for extraordinary light and a value for extraordinary light. Vary between. As a result, the incident light (linearly polarized light) 122 is totally reflected light 1
It is possible to switch between a state of being emitted as 24 and a state of being transmitted light and then being turned by the reflective film 125 to be emitted as the reflected light 123. This system does not have the above-mentioned problems because it does not have a mechanical driving part, but when the reflecting surfaces arranged in the incident direction of light are arranged at a constant cycle, the emitted light is diffracted. However, there is a problem that the light utilization efficiency decreases.

[0006]

The present invention solves the above problems and has a simple structure, high durability, and high light utilization efficiency, an optical path switching element, a spatial light modulator, and an image display using the same. The purpose is to provide a device. More specifically, (1) to provide an optical path switching element having a simple structure, high durability, and high light utilization efficiency (claim 1),
(2) to provide an optical path switching element capable of increasing the S / N ratio (claim 2); and (3) to provide an optical path switching element with low cost and high reliability (claim 3), (4) ) In addition to the above, an optical path switching element capable of further increasing the S / N ratio is provided (claim 4) (5) An optical path switching element capable of further increasing the S / N ratio is provided (claim 5) (6). ) In addition to the above, to provide an optical path switching element that is easy to manufacture (claim 6), (7) To provide an optical path switching element that is easy to manufacture and can improve light utilization efficiency (claim 7), (8) In addition to the above, providing an optical path switching element having a fast response speed (claim 8), (9) In addition to the above, providing an optical path switching element having a small optical loss (claim 9),
(10) In addition to the above, an optical path switching element capable of further increasing the light utilization efficiency is provided (claim 10), (11) An optical path switching element having a faster response speed is provided (claim 11), (12). ) To provide a spatial light modulator having a simple structure, high durability, and high light utilization efficiency (claim 1)
2) and (13) It is an object of the invention to provide an image display device having high durability and high light utilization efficiency (claim 13).

[0007]

According to a first aspect of the present invention, there is provided a light incident portion via a light guide member, a reflecting portion for reflecting incident light entering from the light incident portion, and light reflected by the reflecting portion. Is a light emitting portion that emits to the outside as emitted light through the light guide member, a refractive index variable substance is enclosed in an optical path including the reflecting portion, and a signal is transmitted to the refractive index variable substance according to information. In an optical path switching element having a signal input means for causing a change in refractive index, the reflecting portion has a configuration in which a plurality of reflecting surfaces are arranged in a light incident direction, and an interval between adjacent arranged reflecting surfaces. Is not constant in the array direction.

According to a second aspect of the present invention, in the first aspect of the present invention, the incident light is transmitted through the interface between the light guide member and the refractive index variable substance by the change in the refractive index of the refractive index variable substance due to the signal. It is characterized in that it is performed in a range where total reflection occurs.

According to a third aspect of the present invention, in the first aspect of the present invention, the change in the refractive index of the variable refractive index substance due to the signal is completely absorbed by the incident light at the interface between the light guide member and the variable refractive index substance. It is characterized in that it is performed in a range that does not reflect light.

According to a fourth aspect of the present invention, in the third aspect of the invention, the change in the refractive index of the variable refractive index material due to the signal is reflected by the reflecting section at the light emitting section and the light guide member and It is characterized in that it is performed within a range in which a first state in which total reflection occurs at an interface with an external substance that comes into contact and a second state in which total reflection does not occur can be obtained.

According to a fifth aspect of the present invention, in the invention according to any one of the third and fourth aspects, there is provided a second light emitting portion capable of outputting the emitted light to the outside through the second light guide member. It is characterized by being provided.

According to a sixth aspect of the present invention, there is provided a flat plate light guide according to any one of the first to fifth aspects, which is optically joined to the light incident portion and has a refractive index substantially equal to that of the light guide member. It is characterized by being provided.

According to a seventh aspect of the invention, in the invention according to any one of the first to sixth aspects, the refractive index variable substance is liquid crystal.

According to an eighth aspect of the invention, in the invention according to any one of the first to sixth aspects, the refractive index variable substance is a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix. It is characterized by.

The invention of claim 9 is characterized in that, in the invention of claim 8, the liquid crystal is a droplet having a particle diameter of ⅕ or less of a wavelength of incident light.

According to a tenth aspect of the invention, in the invention according to any one of the seventh to ninth aspects, all the liquid crystal molecules are aligned in substantially one direction when no voltage is applied.

An eleventh aspect of the present invention is characterized in that, in the invention according to any one of the seventh to tenth aspects, the liquid crystal is a dual frequency drive liquid crystal.

A twelfth aspect of the present invention is a spatial light modulator in which the reflecting surfaces of the optical path switching element according to any one of the first to eleventh aspects are arranged in a two-dimensional array, and each reflecting surface has a reflecting surface. It is characterized in that two-dimensional optical modulation is performed by independently controlling the signal application to the refractive index variable substance in contact with each of the reflecting surfaces.

According to a thirteenth aspect of the present invention, the spatial light modulator according to the twelfth aspect, means for causing a light beam to enter the spatial light modulator, and an image formed by the spatial light modulator are projected and displayed on a screen. And means.

Here, in the present embodiment, the plurality of reflecting portions arranged in the light incident direction allow incident light to be incident obliquely above the reflecting portion, and in the present element, the reflecting member on which the reflecting portion is formed is laminated on the substrate surface. It is assumed that the reflecting portions are arranged in the projection axis direction obtained by projecting the incident optical axis of light from the vertical direction.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The feature of the present invention is that a light incident portion via a light guide member, a reflecting portion for reflecting incident light entering from the light incident portion, and light reflected by the reflecting portion are The refractive index variable substance is enclosed in the optical path including the reflection part, and is provided with a light emitting part that emits to the outside through the light guide member, and a refractive index is given to the refractive index variable substance according to information. In an optical path switching element having a signal input means for causing a change, the reflecting portion has a plurality of reflecting surfaces, and an interval between adjacent reflecting surfaces arranged in the light incident direction is not constant with respect to the arrangement direction. The optical path switching element is characterized by

Here, let the refractive index of the light guide member be n.₁, Refractive index
The refractive index of the variable substance is n_TwoAnd the light transmitted through the light guide member
Is an angle (incident angle) with the normal of the surface that constitutes the light incident part
Θ ₁, When the incident light enters the refractive index variable substance,
The angle (refraction angle) formed by the normal line of the surface forming the light incident part
θ_TwoThen, the following equation holds according to Snell's law.
One. sin θ_Two/ Sin θ₁= N₁/ N_Two… (1)

When n ₂ is changed by an external signal,
When θ ₂ changes according to the equation (1), and as a result, the reflection angle at the reflecting portion changes, or n ₂ becomes smaller than n ₁ and the following equation (2) is satisfied, the incident light is not guided. Total reflection occurs at the interface between the optical member and the refractive index variable substance. n ₁ sin θ ₁ > n ₂ (2) Thus, if the light output is detected at a predetermined position, the light output changes with a change in n ₂ , and optical switching by signal application becomes possible.

According to the present invention, in the optical path switching element that operates as described above, the reflecting portion has a plurality of reflecting surfaces, and the intervals between adjacent reflecting surfaces arranged in the light incident direction are not constant with respect to the arrangement direction. Therefore, the spread of the emitted light due to diffraction can be reduced, and as a result, the light utilization efficiency can be improved (claim 1).

Further, since the refractive index of the variable refractive index substance is changed by a signal within a range in which the incident light is transmitted and totally reflected at the interface between the light guide member and the variable refractive index substance, a high S / N ratio is obtained. Can be obtained (Claim 2).

Further, the refractive index of the light guide member is changed by a signal within a range in which the incident light is not totally reflected at the interface between the light guide member and the light guide member. Since there are few restrictions of (3), devices and systems can be realized using inexpensive materials (claim 3).

In the above description, the change in the refractive index of the variable-refractive-index material due to a signal is referred to as a first state in which the light reflected by the reflecting portion is totally reflected at the interface between the light guide member and the external material in contact with it in the light emitting portion. However, it is preferable to perform it within a range in which the second state in which the total reflection does not occur can be taken. In this case, θ ₂
The amount of change in the output angle is much larger than the amount of change in
A higher S / N ratio is obtained (claim 4).

Further, it is preferable to provide a second light emitting portion capable of outputting emitted light to the outside through the second light guide member. The light emitted from the light emitting portion again enters the second light guide member and is emitted from the second light emitting portion. The amount of change in the emission angle at this time can be made larger than that without the second light guide member, and a higher S / N ratio can be obtained (claim 5).

Further, it is preferable to provide a flat plate light guide member which is optically joined to the light incident part and has a refractive index substantially equal to that of the light guide member, from the viewpoint of easy manufacture. In this case, since the light guide member may be optically joined after the device including the flat plate light guide, the reflection part, and the variable refractive index material enclosed between the devices is manufactured, the light guide having a complicated shape may be used. Manufacturing is significantly easier than manufacturing a device using a member (claim 6).

As the refractive index variable substance, any substance whose refractive index is changed by applying energy from the outside can be used, but a so-called electro-optical material whose refractive index is changed by an electric field for ease of control. Can be preferably used. As the electro-optical material, solid crystals such as LiNbO ₃ exhibiting the Pockels effect, BaTiO ₃ exhibiting the Kerr effect, PLZT, and liquid crystals are known. Among them, a large amount of change in refractive index per electric field strength and fluidity are known. Liquid crystal is preferable because of its presence. Since the amount of change in the refractive index is large, the incident angle θ ₁ can be reduced or the angle margin can be increased. As a result, light loss can be reduced, that is, light utilization efficiency can be increased. Further, since it has fluidity, it is possible to easily realize optical contact with the light guide member (or the flat plate light guide) and the reflecting portion (claim 7).

From the viewpoint of response speed, it is preferable to use a liquid crystal / polymer composite as the refractive index variable substance. As such a liquid crystal / polymer composite, a so-called polymer dispersed liquid crystal in which liquid crystal droplets are dispersed in a polymer matrix can be preferably used. It has been experimentally found that the response speed of polymer-dispersed liquid crystals becomes faster as the particle size of liquid crystal droplets is made smaller, and in particular, it is ⅕ of the wavelength of incident light.
The particle size below is preferable because scattering is reduced and light transmittance is increased, that is, light loss is significantly reduced. The particle size referred to here is a particle size representative of the structure, and normally, the average particle size measured by an electron micrograph or the like is preferably used (claims 8 and 9).

In the above liquid crystal, it is preferable that all liquid crystal molecules are aligned substantially in one direction when no voltage is applied. By making this direction substantially orthogonal to the direction in which liquid crystal molecules are aligned (electric field direction) when a voltage is applied, a large difference in refractive index can be obtained, so that the incident angle θ ₁ can be reduced or the angle margin can be increased. . As a result, light loss can be reduced, that is, light utilization efficiency can be increased (claim 10).

The liquid crystal is preferably a dual frequency drive liquid crystal. The dual frequency drive liquid crystal is a liquid crystal in which the sign of the dielectric anisotropy of the liquid crystal differs depending on the frequency of the voltage applied to the liquid crystal,
It is characterized by a high-speed alignment operation. Dielectric anisotropy is a property in which the dielectric constant differs between the major axis direction and the minor axis direction of liquid crystal molecules, and when an electric field is applied, the direction with the larger dielectric constant faces the electric field direction.
Since the dielectric anisotropy is positive when the dielectric constant in the major axis direction of the liquid crystal molecule is larger than the dielectric constant in the minor axis direction, when the dielectric anisotropy is positive, the major axis of the liquid crystal molecule is in the electric field direction. When the liquid crystal molecules are oriented and the dielectric anisotropy is negative, the short axis of the liquid crystal molecules is oriented in the electric field direction. In the dual-frequency driving liquid crystal, when the long axis is oriented in the electric field direction or when the short axis is oriented in the electric field direction, the Lorentz force acts on the liquid crystal molecules, so that the alignment movement is larger than that of a normal liquid crystal material such as nematic liquid crystal. Since it is performed at high speed, the response speed can be increased (claim 11).

In the above-mentioned optical path switching element of the present invention, the reflecting surfaces are arranged in a two-dimensional array, and the signal application to the refractive index variable substance in contact with each reflecting surface is independently controlled for each reflecting surface, thereby forming a two-dimensional space. An optical modulator can be constructed. Since such a spatial light modulator has a simple structure,
High durability, low cost, and high light utilization efficiency. (Claim 12).

By providing the above spatial light modulator, the light beam incident means, and the means for enlarging and projecting the image formed by the spatial light modulator on the screen, the image display device is durable and inexpensive and has high light utilization efficiency. Can be configured (claim 13).

(Embodiment 1) FIGS. 1 and 2 are views for explaining a first embodiment of the present invention. Glass,
The light rays from the light source are incident on the refractive index variable substance 5 through the optically transparent light guide member 1 made of plastic or the like, and the light rays reflected by the reflection section 6 are transmitted to the outside of the light guide member 1. It has a light emitting portion 4 for emitting light. The reflecting portion 6 is composed of a reflecting surface 18 that substantially converts incident light into outgoing light, and an inverted inclined surface 19 that shares one side with the reflecting surface 18. The reflecting member 15 including the reflecting portion 6 is formed by forming an inclined surface on a substrate 9 made of Si, glass or the like with an insulator 8 made of glass, plastic or ceramics such as silicon oxide, silicon nitride, aluminum oxide, etc. Al, Ag
It is possible to obtain the high reflectance metal film 7 made of, for example, by a known method such as vacuum deposition or sputtering. Moreover, you may pattern by photolithographic etching as needed. This metal film 7 also acts as an electrode. It is preferable that a drive element for applying a signal voltage corresponding to information is formed on the metal film 7 on the substrate 9 and is connected to an interface section for converting information data into a voltage signal.

As the reflecting portion, a structure in which the insulator 8 also serves as the substrate 9 or a structure in which the metal plate or the semiconductor wafer is used as the substrate to directly form the inclined surface may be used. As an example of a suitable inclined surface forming method, there is an anisotropic etching method of performing dry etching by patterning using a photomask on which a pattern of area gradation or density gradation is formed. Liquid crystal can be preferably used as the refractive index variable substance 5. As the liquid crystal material, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal or the like can be used, and a single or a mixture of two or more kinds of liquid crystal compounds or a mixture containing a substance other than the liquid crystal compounds may be used. The light incident part 3 is provided with a transparent electrode 10 made of ITO or the like for applying a voltage to the refractive index variable substance 5. An alignment film (not shown) made of SiO, polyimide or the like is preferably formed on at least the surfaces of the transparent electrode 10 and the metal film 7 in order to align the liquid crystal molecules in advance. When the variable refractive index material 5 is made of a fluid material such as liquid crystal, it is preferable to form and hold a sealing agent 11 made of an epoxy resin or the like mixed with a spacer material, if necessary. If an example of the manufacturing process is shown, a thermosetting epoxy resin is partially provided in the peripheral portion of the light guide member 1 (or the reflection member 15) as an opening portion (injection hole).
After printing, the reflective member 15 (or the light guide member 1) is attached and heat-cured. After injecting the liquid crystal through the injection hole, the hole is closed with an adhesive to complete the process.

FIG. 1 shows a case where the refractive index n ₂ of the refractive index variable substance 5 is smaller than the refractive index n _{1 of the} light guide member and a signal satisfying the above formula (2) is applied. Since the light is totally reflected at 3 and emitted in a direction different from that of the light emitting portion 4, it is not detected by the photodetector 13 provided facing the light emitting portion 4 (OFF state). FIG. 2 shows a case where a signal is applied so that n ₂ becomes approximately the same as n _1, and the incident light enters the refractive index variable substance 5 and reaches the reflection part 6. The angle between the normal line of the surface constituting the normal to the light incident portion of the reflecting surface 18, i.e. the inclination angle alpha of the reflecting surface _{18 α = θ 2/2 (} ≒ θ 1 /
If it is set to 2), the reflected light is vertically incident on and emitted from the light emitting unit 4, and is detected by the photodetector 13 (ON state).

When the incident area is large, the distance from the light incident portion 3 to the reflecting portion 6, that is, the layer thickness of the refractive index variable substance 5 can be reduced by forming a plurality of reflecting surfaces, and as a result, It is possible to reduce a voltage signal or the like (driving energy) applied to cause a change in the refractive index. Further, in the case of performing two-dimensional spatial light modulation, it is necessary to have a plurality of reflecting surfaces to which signals can be independently applied according to image data and the like. In such a case, if the spacing between adjacent reflecting surfaces arranged in the light incident direction is constant with respect to the arrangement direction, the light emitted from each reflecting surface is diffracted and emitted in a direction different from the regular reflection direction. Occurs, and part of the light is not taken into the photodetector, resulting in a decrease in light utilization efficiency. In this embodiment, the intervals between the adjacent reflecting surfaces 18 arranged in the light incident direction are not constant in the arrangement direction. That is, as shown in FIG. 2, the influence of diffraction is reduced by making the interval between the adjacent reflecting surfaces 18 different from P1, P2, and P3 in order.

Specific calculation results will be shown. Let ψ be the angle between the incident light and the normal to the reflecting surface 18 (the angle of incidence on the reflecting surface).
i, the angle between the diffracted light and the normal of the reflecting surface 18 (ψi direction is positive with the normal direction being 0 °), the diffraction order is n, the wavelength is λ, and the array period of the reflecting surface 18 (pitch ) Is P, the following formula is established. nλ = P (sin ψi + sin ψd) (3) If θ ₂ ≈θ ₁ = 70 ° and α = 35 °, then ψi = 35
It becomes °. Table 1 shows the result of calculating ψd (°) from the equation (3) when λ = 0.63 μm.

[0041]

[Table 1]

Ψd = -35 when n = 0 regardless of pitch
° (regular reflection). Considering up to the second-order diffraction, the spread from the specular direction is about ± 9 ° at P = 10 μm, P = 3
It can be seen that it is about ± 3 ° at 0 μm and about ± 1.8 ° at P = 50 μm. From the viewpoint of driving energy or spatial resolution (resolution) when performing two-dimensional spatial light modulation, a smaller pitch is desirable. In FIG. 2, if P1 =
When P2 = P3 = 10 μm, the emitted light has a spread of about ± 9 °, but P1 = 10 μm and P2 = 12.
If Pm = 5 μm and P3 = 7.5 μm, the period does not become constant, so no diffraction occurs.

When the irradiation area is further widened, that is, the number of reflecting surfaces 18 is increased, the average pitch is 10 μm.
It is extremely difficult in manufacturing to keep all the intervals of the adjacent reflecting surfaces 18 different while keeping the above (required for making the in-plane distribution of the total emitted light amount uniform). In that case, for example, each surface spacing is set to the above value, and P1, P2, P3, P1, P2, P3,
By repeating P1, P2, P3, ..., the cycle P is P1 + P2
+ P3 = 30μm, and the spread of outgoing light is about ± 3 °
Decrease to. Furthermore, P1 = 10 μm, P2 = 13 μm,
P3 = 7 μm, P4 = 11 μm, P5 = 9 μm,
Set each surface spacing to P1, P2, P3, P4, P5, P1, P
2, P3, P4, P5, P1, P2, P3, P4, P
5 and so on, the cycle P becomes P1 + P2 + P3 + P4 +
P5 = 50μm, and the spread of outgoing light is about ± 1.8
Decrease to °. In addition, since the higher order diffraction efficiency decreases as the pitch increases, the amount of light in the expanded portion decreases.
Therefore, if it is spread to this extent, there is practically no problem.

As a concrete example, the light guide member 1 is flinted.
Made with glass SF18 (nd = 1.722), refractive index
The variable substance 5 is a nematic liquid crystal E7 (ordinary light refractive index no =
1.522, extraordinary light refractive index ne = 1.746, Merck)
And the liquid crystal molecules 12 are preliminarily illustrated by using an alignment film (not shown).
1 is parallel to the surface (incident surface) that constitutes the light incident part 3
Orient it in the direction perpendicular to the paper surface. Si as the alignment film
Known materials such as O and polyimide can be used, and at least
It is preferably formed on the surfaces of the transparent electrode 10 and the metal film 7.
Good In the state of FIG. 1 (no voltage applied), laser light (wavelength 6
33 nm) as P-polarized light and θ₁Incident at = 69 °
And the refractive index of the liquid crystal is n for this light. _Two= Ne ・ no
/ (No^Twocos^Twoθ₁+ Ne^Twosin^Twoθ₁)^1/2
Since ≈1.546, the formula (2) is satisfied and total reflection is performed.
It Liquid crystal molecules are aligned substantially perpendicular to the light incident portion 3.
When a voltage is applied between the transparent electrode 10 and the metal film 7 (Fig.
2 state), the refractive index of the liquid crystal is n for the same light._Two’
= Ne ・ no / (ne^Twocos^Twoθ₁+ No^Twosin^Two
θ₁)^1/2Since ≈1.712, the formula (2) is satisfied.
Instead, the incident light passes through the refractive index variable substance (liquid crystal) and is reflected.
Reach the shooting surface 18. Refraction angle θ_Two≒ 70 °, so
When α = 35 °, the incident light is reflected by the reflecting surface 18,
The light is emitted from the light emitting portion 4 almost vertically.

(Embodiment 2) FIGS. 3 and 4 are diagrams for explaining a second embodiment of the present invention. The basic configuration of this embodiment is the same as that of the first embodiment, but the light guide member 1 and the refractive index variable substance 5 are prevented from being totally reflected at the interface between the light guide member 1 and the refractive index variable substance 5. The materials and shapes are changing. In FIG. 3, the refractive index n ₂ of the refractive index variable material 5 is larger than the refractive index n ₁ of the light guide member 1, and the refraction angle θ ₂ becomes smaller than the incident angle θ ₁ according to the equation (1). Reflective surface 18
When the inclination angle alpha is set to _{α ≒ θ 1/2 (>} θ 2/2), the surface constituting the surface and the light emitting portion 4 constituting the light incident portion 3 to be parallel, reflective surface since light reflected by the 18 incident at an angle of φ ₁ ≒ θ ₁ -θ ₂ with respect to the light emitting section 4, an external material in contact with the light guide member 1 is air (n _a =
In the case of 1), the output angle φ ₂ = sin ⁻¹ (n ₁ sin φ)
Emit at ₁ ). In FIG. 4, when n ₂ is approximately the same as n ₁ , θ ₂ is substantially equal to θ ₁ , so that the incident light is reflected by the reflecting surface 18 and is emitted from the light emitting portion 4 substantially vertically. If the photodetector 13 is installed facing the light emitting unit 4 with a sufficient distance, it is hardly detected in the case of FIG. 3 (OFF state), but is detected in the case of FIG. 4 (ON state).

Also in this case, the spread of the outgoing light due to diffraction can be reduced by making the interval between the adjacent reflecting surfaces different as in the first embodiment, but unlike the first embodiment, it is in the ON state (at the time of FIG. 4). ), As well as the off state (at the time of FIG. 3)
Is also affected by diffraction, so that the spread of the emitted light is also reduced. As a result, the amount of leaked light (the amount of light detected when turned off) is reduced, which also contributes to the improvement of the S / N ratio.

As a concrete example, the light guide member 1 is made of crown glass BK7 (nd = 1.517), and the refractive index variable substance 5 is made of the nematic liquid crystal E7 (ordinary light refractive index no =
1.522, the extraordinary light refractive index ne = 1.746), and the liquid crystal molecules 12 are parallel to the surface (incident surface) constituting the light incident part 3 as shown in FIG. Orient in the vertical direction. Known materials such as SiO and polyimide can be used for the alignment film, and at least the transparent electrode 1
0 and the surface of the metal film 7 are preferably formed. Figure 3
Light (wavelength 633 nm) in the state of (no voltage applied)
Is incident as S-polarized light at θ ₁ = 60 °, the refractive index of the liquid crystal is n ₂ ≈1.746 for this light.
According to the equation (1), θ ₂ ≈49 °. The light reflected by the reflecting surface 18 is refracted even when it crosses the light incident portion 3 again, so that φ ₁ ≈13 ° and φ ₂ ≈20 ° from the light emitting portion 4.
Emit at. When a voltage is applied between the transparent electrode 10 and the metal film 7 so that the liquid crystal molecules are aligned substantially perpendicular to the light incident portion 3 (state of FIG. 4), the refractive index of the liquid crystal is n for the same light. since the ₂ '≒ 1.522, the θ ₂ ≒ 60 °. When α is set to 30 °, the incident light is reflected by the reflecting surface 18 and is emitted from the light emitting portion 4 almost vertically.

(Third Embodiment) FIGS. 5 and 6 are views for explaining a third embodiment of the present invention. The basic configuration of this embodiment is the same as that of the second embodiment, except that in the light emitting portion 4, total reflection is performed at the interface between the light guide member 1 and an external substance in contact with the light guide member 1 (FIG. 5). The shape of the light guide member 1 is changed so that the light guide member 1 can be in a non-reflecting state (FIG. 6). Further, a second light guide member 20 for allowing the light emitted from the light emitting portion 4 at the time of FIG. 6 to enter again and emitting the light from the second light emitting portion 21 is provided. The refractive index of the second light guide member 20 is selected to be substantially the same as that of the light guide member 1. In this example, the light emitting portion 4 and the second light guide member 20 (both finished with a smoothness about the wavelength of the incident light) are brought into close contact with each other to form a gap (air layer 2) of about the wavelength of the incident light. Have.

FIG. 5 shows the case where the refractive index n ₂ of the refractive index variable material 5 is larger than the refractive index n ₁ of the light guide member 1, and the refraction angle θ ₂ becomes smaller than the incident angle θ ₁ according to the equation (1). Reflective surface 18
When the inclination angle alpha is set to _{α ≒ θ 1/2 (>} θ 2/2), the angle formed between the surface constituting the surface and the light emitting portion 4 constituting the light incident portion 3 and beta, reflective surface since light reflected by the 18 incident at an angle of _{φ 1 ≒ β + θ 1 -θ} 2 with respect to the light emitting section 4, an external material in contact with the light guide member 1 is air (n _a =
In the case of 1), n ₁ sin φ ₁ > 1, that is, θ ₂ <β
If + θ ₁ −sin ⁻¹ (1 / n ₁ ) is satisfied, the light is totally reflected and absorbed by the light absorption film 14. In FIG. 6, when n ₂ is approximately the same as n ₁ , θ ₂ is approximately equal to θ ₁ , so the reflected light enters the light emitting portion at an angle of approximately φ ₁ ′ = β, and the emission angle φ ₂ = Sin ⁻¹ (n ₁ sin β), but immediately enters the second light guide member 20. Second light emitting portion 21
If the surface forming the light incident portion 3 and the surface forming the light incident portion 3 are parallel to each other, the light is emitted from the second light emitting portion 21 substantially vertically. When the photodetector 13 is installed so that the emitted light in FIG. 6 is incident vertically on the detection surface, it is detected in the case of FIG. 6 (on state), but is hardly detected in the case of FIG. 5 (off state). ).

As a concrete example, the light guide member 1 and the second light guide member 20 are made of crown glass BK7 (nd = 1.5).
17), and the refractive index variable material 5 is a nematic liquid crystal E7 (ordinary light refractive index no = 1.522, extraordinary light refractive index ne.
= 1.746), the liquid crystal molecules 12 are aligned in advance in a direction parallel to the surface (incident surface) forming the light incident portion 3 and perpendicular to the paper surface by using an alignment film (not shown). A known material such as SiO or polyimide can be used as the alignment film, and it is preferably formed on at least the surfaces of the transparent electrode 10 and the metal film 7. θ ₁ = 60 °, α = 30 °, β =
When the laser beam (wavelength 633 nm) is incident as S-polarized light in the state of FIG. 5 (no voltage applied) with the angle set to 35 °, the refractive index of the liquid crystal becomes n ₂ ≈1.746 for this light. , Θ ₂ ≈49 ° according to the equation (1). Reflective surface 1
The light reflected at 8 is refracted even when it crosses the light incident portion again, so that φ ₁ ≈β + 13 ° = 48 °, and n ₁ sin φ
_{Since 1} > 1 is satisfied, it is totally reflected by the light emitting portion 4 and absorbed by the light absorbing film 14. When a voltage is applied between the transparent electrode 10 and the metal film 7 to align the liquid crystal molecules substantially perpendicularly to the light incident part 3 (state of FIG. 6), the refractive index of the liquid crystal is n for the same light. since the _{2 '≒ 1.522, θ 2 ≒} 60 °
Becomes The reflected light travels straight and is emitted from the second light emitting portion 21 substantially vertically.

(Fourth Embodiment) FIGS. 7 and 8 are views for explaining a fourth embodiment of the present invention. As in the first embodiment, the OFF state is shown in FIG. 7 and the ON state is shown. This is shown in FIG. In the figure, reference numeral 17 denotes a flat plate light guide whose refractive index is substantially the same as that of the light guide member 1, and is optically joined to the light incident portion 3. Other configurations are the same as those in the first embodiment, and the operation principle is also the same. Optical joining is a state in which the two members are in close contact with each other so that the gap between them is sufficiently smaller than the wavelength of light used, and specifically, a fluid object is interposed between them. Can be obtained by A fluid object may be solidified after ensuring close contact with both members. More specifically, as the fluid object, it is preferable to use a low-volatile liquid or a photocurable adhesive whose refractive index is substantially the same as that of the light guide member 1 and the flat plate light guide 17. In this embodiment, the refractive index variable substance 5
Since the flat plate light guide 17 is in contact with the transparent electrode 10
Is formed on the flat plate light guide 17. In this case, the light guide member 1
Since it is only necessary to perform the joining at the end, the main part of the device can be manufactured without using a light guide member having a complicated shape, so that the yield can be improved and the cost can be reduced.

(Fifth Embodiment) FIGS. 9 and 10 are views for explaining a fifth embodiment of the present invention. As in the fourth embodiment, the OFF state is shown in FIG. 9 and the ON state is shown. Is shown in FIG. The present embodiment has the same configuration as that of the fourth embodiment except that a polymer dispersed liquid crystal is used as the refractive index variable substance 5. Polymer dispersed liquid crystal is polymer matrix 2
3 has liquid crystal droplets 22 dispersed therein. Liquid crystal materials include nematic liquid crystal, smectic liquid crystal,
A cholesteric liquid crystal or the like can be used, and a single or a mixture of two or more kinds of liquid crystal compounds or a mixture containing a substance other than the liquid crystal compounds may be used. The polymer matrix material is preferably a transparent polymer, and may be a thermoplastic resin, a thermosetting resin, or a photocurable resin. Polymer-dispersed liquid crystals may be produced by (1) a polymerization phase separation method in which a liquid crystal and a thermo- or photo-curable (polymerizable) monomer, oligomer, or prepolymer are used to form a solution, and phase separation is performed by polymerization. A solvent evaporation phase separation method in which a solution is made of a solvent and a solvent, and the solvent is evaporated to cause phase separation, (3) After heating and dissolving the liquid crystal and the thermoplastic polymer,
A thermal phase separation method in which phase separation is performed by cooling can be used.

As the polymer, it is preferable to use an ultraviolet curable resin from the viewpoints of ease of manufacturing process, separability from the liquid crystal phase and the like. As a specific example, an ultraviolet curable acrylic resin is exemplified, and a resin containing an acrylic monomer or an acrylic oligomer which is polymerized and cured by ultraviolet irradiation is particularly preferable. Examples of such monomers or oligomers include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, melamine acrylate, and (poly) phosphazene methacrylate. As another example, a thiol-ene system can be preferably used because it has a high photocuring speed. In addition, a photopolymerization initiator may be used for rapid polymerization, and examples thereof include acetophenones such as dichloroacetophenone and trichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, benzophenone, Michler's ketone, benzoyl, benzoin alkyl ether, and benzyldimethyl. Ketal, monosulfide, thioxanthones,
Examples thereof include azo compounds, diallyl iodonium salts, triallyl sulfonium salts, and bis (trichloromethyl) triazine compounds.

After the liquid material in which the liquid crystal material is uniformly dissolved in this ultraviolet curable compound is injected between the reflecting member 15 and the light guide member 1, the ultraviolet curable compound is cured by irradiating with ultraviolet light. Phase separation of liquid crystal material,
A polymer dispersed liquid crystal layer is formed. The results of detailed investigation of the relationship between liquid crystal droplet size and response speed are shown below. The size of the liquid crystal droplets in the polymer-dispersed liquid crystal can be changed by changing the composition of the prepolymer, the mixed concentration of the liquid crystal, the ultraviolet intensity during curing, and the like. FIG. 11 shows the relationship between the liquid crystal droplet size and the response speed. Liquid crystal materials are E7 and B
L24 (no = 1.513, ne = 1.717, Merck & Co., Inc.), and NOA60, 65 and 81 (Norland Co., Ltd.) were appropriately used as prepolymers. To measure the response speed, a pulse voltage (200 V) was applied to the sample 37 using the device shown in FIG.
The total of the rise time (Ton) and the fall time (Toff) of the optical output when the voltage was applied was measured. In Sample 37, the polymer dispersed liquid crystal layer 40 had a thickness of 20 μm and an optical path length of 1 mm.

FIG. 13 schematically shows the states when an electric field is not applied to the polymer dispersed liquid crystal and when it is applied.
Since the liquid crystal droplets are randomly oriented when no electric field is applied, the refractive indices in the x-axis, y-axis, and z-axis directions are all equal, and the entire layer is an optically isotropic medium. When an electric field is applied in the z direction, the molecular axes of the liquid crystal molecules are aligned with this direction, so that the refractive index in the z axis direction increases and the refractive indices in the x axis direction and the y axis direction remain equal to each other, but the magnitude decreases. Become. As shown in FIG. 12, when light is incident from the x direction perpendicular to the electric field direction, birefringence occurs on the yz plane, so that the polarization state can be changed and the light output through the analyzer changes. In the present invention, such a birefringence phenomenon is not used, but the behavior of liquid crystal molecules when an electric field is applied and the accompanying change in the refractive index are used.
The response speed of 1 can be similarly applied to the present invention. It can be seen from FIG. 11 that the response speed increases as the liquid crystal droplet size decreases.

Furthermore, enter the particle size of the liquid crystal droplets.
1/5 or less of the wavelength of emitted light, more preferably 1/10 or less
Is preferable from the viewpoint of light transmittance. Ray below
The result of calculating the light transmittance from the Lie scattering theory is shown. volume
If the spherical scatterer of V exists at a number density N, the medium of thickness L
The light transmittance T of the body is expressed by the following equation (4).   T = exp (-NRL), R = 24π^Three((M^Two-1) / (m^Two+2))^TwoV ^Two / Λ^Four  … (4)

Here, R is the scattering cross section, m is the ratio of the refractive index of the scatterer to the medium, and λ is the wavelength of the light used. Transmittance T when m = 1.07 and L = 100 μm
Was calculated using the particle size d of the scatterer, that is, the liquid crystal droplets, the volume fraction (= NV), and the wavelength λ as parameters. As can be seen from the equation, T decreases as d increases (that is, V increases) and λ decreases. Further, the transmittance is preferably 90% (T = 0.9) or more from the viewpoint of light utilization efficiency. Figure 14 is T
= 0.9, the volume fraction is 10% (d (0.
1)), 30% (d (0.3)) and 50% (d (0.3)).
5)) is plotted with respect to wavelength. When the volume fraction is small, the amount of change in refractive index is small and S /
Since the N ratio cannot be obtained, the volume fraction is preferably 10% or more, more preferably about 50%. If the volume fraction is higher than this, production becomes extremely difficult. From this point of view, from FIG. 14, it is preferable that d is λ / 5 or less for wavelengths in the visible to infrared region applied as an optical path switching element, and
It is more preferably / 10 or less. Although m and L were fixed in this calculation, it is considered that the values are less than this in an actual device, so there is no problem within the above grain size range.

As a concrete example of the polymer-dispersed liquid crystal, a nematic liquid crystal BL24 (no = 1.513, ne = 1.7) is used.
17, Merck) UV curable prepolymer NOA8
Dissolve in 1 (Norland) (liquid crystal weight concentration 45%),
The light guide member 1 and the flint glass SF2 (nd = 1.64) were irradiated with ultraviolet rays (400 mW / cm2) (the average particle size of the liquid crystal droplets was about 60 nm).
8), laser light (wavelength 633 nm) is incident as P-polarized light at an incident angle θ ₁ = 75 °. In FIG. 9 (when no electric field is applied), the orientation of the droplets 22 in which the liquid crystal molecules are oriented is random, so that the entire layer is an optically isotropic medium and its refractive index is almost equal to that of the liquid crystal. Volume average (≈1.57) of average refractive index (≈ (2no + ne) /3≈1.58) and refractive index of polymer matrix (≈1.56)
(The liquid crystal volume fraction was estimated to be about 35%). In this case, the alignment treatment is not performed in advance. At this time, since the expression (2) is satisfied, total reflection occurs. In FIG. 10, liquid crystal molecules are aligned in the direction of the electric field, and the refractive index of the polymer dispersed liquid crystal layer with respect to the polarized light is the refractive index of the liquid crystal (ne · no).
/ (Ne ² cos ² θ ₁ + no ² sin ² θ ₁ ) ^1/2 =
1.70) and the refractive index of the polymer matrix (≈1.56) can be regarded as the volume average (≈1.61). At this time, according to the formula (1), the refraction angle becomes θ ₂ ≈78 °, and α =
If it is set to 39 °, the reflected light is emitted from the emitting portion 4 almost vertically, and is detected by the photodetector 13. The switching time between the state of FIG. 9 and the state of FIG. 10 is on the order of several tens of μs, and this value is faster than the bulk liquid crystal by two digits or more.

(Sixth Embodiment) FIGS. 15 and 16 are views for explaining a sixth embodiment of the present invention. This embodiment has the same configuration as that of the fifth embodiment except that all liquid crystal molecules in the droplets are aligned in substantially one direction when no voltage is applied (at the time of FIG. 15). It is preferable that this arrangement direction is substantially orthogonal to the direction (electric field direction) in which liquid crystal molecules are aligned when a voltage is applied (in FIG. 16), and is horizontal to the light incident portion 3 and perpendicular to the paper surface. Specifically, when the polymer dispersed liquid crystal of the same material and formulation as in the fifth embodiment is used, the polymer dispersed liquid crystal at the time of FIG. 15 is applied to the same incident light (P polarized light, θ ₁ = 75 °). The refractive index of the layer is the refractive index of the liquid crystal (ne · no / (no ² cos ² θ ₁ + ne ² sin ²
It can be regarded as a volume average (≈1.55) of θ ₁ ) ^1/2 = 1.52) and the refractive index of the polymer matrix (≈1.56). At this time, total reflection is performed to satisfy the formula (2),
In the case of the fifth embodiment where the critical angle is about 70 ° (about 72 °)
Will be smaller than. In other words, because the margin of the incident angle is wide, light with a wider angle distribution can be used,
It leads to improvement of light utilization efficiency. In FIG. 16, liquid crystal molecules are aligned in the direction of the electric field, and the refractive index of the polymer dispersed liquid crystal layer for the same light is (ne.no/(ne ² cos ²
θ ₁ + no ² sin ² θ ₁ ) ^1/2 = 1.70) and the refractive index of the polymer matrix (≒ 1.56), the volume average (≒ 1.56)
1.61). At this time, the refraction angle becomes θ ₂ ≈78 ° according to the equation (1), and if α = 39 ° is set, the reflected light is emitted from the emitting portion 4 almost vertically and detected by the photodetector 13.

As a method of preliminarily aligning liquid crystal molecules in one direction, it is possible to use the following method other than the method using the alignment film as described above. The liquid crystal can be oriented in one direction by applying an electric field when polymerizing the polymer matrix material. At this time, the prepolymer in contact with the liquid crystal is dragged by the alignment of the liquid crystal and is aligned in the same direction. When the prepolymer is polymerized in this state, the interface with the liquid crystal is fixed in a form following the alignment of the liquid crystal. Since this interface structure functions as an alignment film for the liquid crystal, even if the electric field is released after the polymer matrix material is cured, the liquid crystal is aligned in the electric field direction applied during the polymerization.
Also, a method of using a magnetic field instead of an electric field can be preferably used.

(Embodiment 7) A seventh embodiment of the present invention will be described with reference to FIGS. 1, 2 and 17. In this embodiment, the basic element structure is the same as that of the first embodiment, but a dual frequency driving liquid crystal is used as the refractive index variable substance 5. FIG. 17 shows the frequency characteristic of the dielectric anisotropy of the dual frequency drive liquid crystal. When the frequency of the applied voltage increases and exceeds the crossover frequency fc, the dielectric anisotropy becomes negative. When a voltage having a frequency f ₁ equal to or lower than the crossover frequency is applied, the liquid crystal molecules are aligned in the electric field direction (FIG. 2). When a voltage with a frequency f ₂ higher than the crossover frequency is applied, the long axis of the liquid crystal is aligned in a direction substantially perpendicular to the electric field, that is, in a direction substantially parallel to the light incident portion 3. Can be aligned in the direction perpendicular to the paper surface (Fig. 1).

In the dual-frequency driving liquid crystal, the Lorentz force acts on the liquid crystal molecules regardless of whether the long axis is oriented in the electric field direction or the short axis is oriented in the electric field direction. Therefore, compared with a normal liquid crystal material such as a nematic liquid crystal. The orientation movement is performed at high speed. For example, when switching from the state of FIG. 2 to the state of FIG. 1, in a normal nematic liquid crystal, the return due to the alignment regulating force when the voltage is set to 0 V is used, so that it takes several ms to several tens of ms for the response. 1 when using a frequency drive liquid crystal to force an orientation change in a high frequency electric field
Responses in ms or less are possible.

The two-frequency driving liquid crystal is, for example, 2, 3
-Dicyano-4-pentyloxyphenyl-4- (trans-4-ethylcyclohexyl) benzoate, 2,
3-dicyano-4pentyloxyphenyl-trans-
4-propyl-1-cyclohexanecarboxylate,
2,3-dicyano-4-ethoxyphenyl-4- (trans-4-pentylcyclohexyl) benzoate,
2,3-dicyano-4-ethoxyphenyl-4- (trans-4-butylcyclohexyl) benzoate, 2,
3-dicyano-4-butoxyphenyl-4- (trans-4-butylcyclohexyl) benzoate and the like can be used.

As a specific example, the light guide member 1 is made of flint glass SF8 (nd = 1.689), and the refractive index variable substance 5 is used as the dual frequency drive liquid crystal MX001543 (no =
1.4978, ne = 1.7192, crossover frequency fc≈20 kHz, Merck & Co., Inc.) and liquid crystal molecules 12 are preliminarily used as shown in FIG.
It is oriented substantially parallel to and perpendicular to the paper surface.
A known material such as SiO or polyimide can be used as the alignment film, and it is preferably formed on at least the surfaces of the transparent electrode 10 and the metal film 7. Frequency f ₂ = 100 kHz above the crossover frequency between the transparent electrode 10 and the metal film 7.
When a laser beam (wavelength 633 nm) is made incident as P-polarized light at an incident angle θ ₁ = 70 ° under the condition that a voltage of z is applied (FIG. 1), the refractive index of the liquid crystal is n ₂ = ne for this light.
・ No / (no ² cos ² θ ₁ + ne ² sin ² θ ₁ )
^{Since 1/2} ≈ 1.519, the formula (2) is satisfied and total reflection is performed. Frequency f ₁ = 1k below crossover frequency
When a voltage of Hz is applied (FIG. 2), the refractive index of the liquid crystal is n ₂ ′ = ne · no / (ne ² cos) for the same light.
^{Since 2} θ ₁ + no ² sin ² θ ₁ ) ^1/2 ≈1.688, the refraction angle becomes θ ₂ ≈70 ° according to the equation (1), and if α = 35 ° is set, the reflected light is light. The light is emitted from the emission unit 4 substantially vertically and detected by the photodetector 13.

Eighth Embodiment FIG. 18 is a diagram for explaining the eighth embodiment of the present invention and is a perspective view of a two-dimensional spatial light modulator 50. The basic configuration of this embodiment is the same as that of the first, fourth to seventh embodiments, but the metal film 7 also serving as an individual electrode is arranged in a two-dimensional array. Although not clear in FIG. 18,
The distance between adjacent reflection surfaces arranged in the left-right direction on the paper surface is not constant in the arrangement direction. The substrate 9 is provided with drive elements (not shown) connected to the individual electrodes and selectively supplying signals to them. By selectively applying a voltage signal to each individual electrode arranged in an array, only the reflected light from the selected individual electrode (metal film 7) is emitted from the light emitting portion 4, and the planar light is turned on. / OFF (spatial light modulation) is possible. Light from a light source such as an LED array or a lamp is made to be P-polarized light through a collimating lens (or an optical integrator) and a polarization conversion optical system, and is made incident on the refractive index variable substance 5 from the light guide member 1 and outside the light emitting portion 4. An image display device can be formed by installing a projection lens and projecting on a screen.

In the image display device using the two-dimensional array type spatial light modulator, incident light of a plurality of wavelengths such as red, green and blue is used to display images of respective colors in a time division manner (field sequential system). ), A full-color image can be displayed by providing a plurality of spatial light modulators and projecting images of respective colors at the same time.

[0067]

As is apparent from the above description, according to the optical path switching element of the present invention, the light incident portion via the light guide member, the reflecting portion for reflecting the incident light entering from the light incident portion, It consists of a light emitting part that emits the light reflected by the reflecting part to the outside as outgoing light through the light guide member, and the refractive index variable substance is enclosed in the optical path including the reflecting part. In the optical path switching element provided with a signal input means for giving a signal to cause a change in the refractive index, the reflecting portion has a plurality of reflecting surfaces, and the distance between adjacent reflecting surfaces arranged in the projection axis direction of the incident optical axis is small. By making it non-uniform in the arrangement direction, it is possible to provide an optical path switching element having a simple structure, high durability, and high light utilization efficiency. In addition to the above, by changing the refractive index of the variable refractive index material within the range in which incident light is transmitted and totally reflected at the interface between the light guide member and the variable refractive index material, the S / N ratio It is possible to provide a high optical path switching element.

Further, by changing the refractive index of the variable refractive index material within the range in which the incident light is not totally reflected at the interface between the light guide member and the variable refractive index material, a low-cost and highly reliable optical path can be obtained. A switching device can be provided. Further, the first state in which the light reflected by the reflecting portion is totally reflected at the interface between the light guide member and the external substance in contact with the light emitting portion,
By adopting the second state in which total reflection is not performed, an optical path switching element having a higher S / N ratio can be provided in addition to the above. Further, since the second light emitting portion capable of emitting the emitted light to the outside via the second light guide member is provided, it is possible to provide an optical path switching element having a higher S / N ratio.

Further, by optically joining the light guide member and providing a flat plate light guide having a refractive index substantially equal to that of the light guide member,
In addition to the above, it is possible to provide an optical path switching element that is easy to manufacture. Also, since the refractive index variable substance is made of liquid crystal,
Further, it is possible to provide an optical path switching element that is easy to manufacture and can improve the light utilization efficiency. In addition, the refractive index variable substance is a liquid crystal in which a liquid crystal material is dispersed and held in a polymer matrix.
By using a polymer composite (polymer dispersed liquid crystal), it is possible to provide an optical path switching element having a high response speed in addition to the above. In addition to the above, an optical path switching element with a small optical loss is provided by using a polymer-dispersed liquid crystal as the refractive index variable substance and using the liquid crystal as a droplet having a particle diameter of ⅕ or less of the wavelength of incident light. can do.

In addition to the above, it is possible to provide an optical path switching element in which the light utilization efficiency can be further increased by making all the liquid crystal molecules aligned in substantially one direction when no voltage is applied. Further, by using a dual frequency driving liquid crystal as the liquid crystal, it is possible to provide an optical path switching element having a faster response speed.

Further, according to the spatial light modulator of the present invention, by arranging the optical path switching elements as described above in a two-dimensional array, the space having a simple structure and high durability and high light utilization efficiency is obtained. An optical modulator can be provided. Further, according to the image display device of the present invention, it is possible to provide an image display device having high durability and high light utilization efficiency by projecting an image formed by the above spatial light modulator on a screen. it can.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is another diagram for explaining the first embodiment of the present invention.

FIG. 3 is a diagram for explaining a second embodiment of the present invention.

FIG. 4 is another diagram for explaining the second embodiment of the present invention.

FIG. 5 is a diagram for explaining a third embodiment of the present invention.

FIG. 6 is another diagram for explaining the third embodiment of the present invention.

FIG. 7 is a diagram for explaining a fourth embodiment of the present invention.

FIG. 8 is another diagram for explaining the fourth embodiment of the present invention.

FIG. 9 is a diagram for explaining a fifth embodiment of the present invention.

FIG. 10 is another diagram for explaining the fifth embodiment of the present invention.

FIG. 11 is a diagram showing a relationship between liquid crystal droplet size and response speed.

FIG. 12 is a schematic view showing an apparatus for measuring the response speed of liquid crystal droplets.

FIG. 13 is a diagram schematically showing a state where an electric field is not applied to the polymer dispersed liquid crystal and a state where an electric field is applied.

FIG. 14: Particle size of T = 0.9 and volume fraction of 10
It is the figure plotted with respect to wavelength in the case of%, 30%, and 50%.

FIG. 15 is a diagram for explaining the sixth embodiment of the present invention.

FIG. 16 is another diagram for explaining the sixth embodiment of the present invention.

FIG. 17 is a diagram for explaining the seventh embodiment of the present invention.

FIG. 18 is another view for explaining the eighth embodiment of the present invention.

FIG. 19 is a plan view of an example of a conventional spatial light modulator.

20 is a view showing a cross-sectional view of one rotating mirror in FIG.

FIG. 21 is an operation explanatory diagram of the optical switching element disclosed in Japanese Patent Laid-Open No. 11-202222.

FIG. 22 is a diagram showing a schematic configuration of an optical switching element proposed in Japanese Patent Laid-Open No. 2000-171813.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light guide member, 3 ... Light incident part, 4 ... Light emitting part, 5 ... Refractive index variable substance, 6 ... Reflecting part, 7 ... Metal film, 8 ... Insulator, 9
... substrate, 10 ... transparent electrode, 11 ... sealing agent, 12 ... liquid crystal molecule, 13 ... photodetector, 14 ... light absorbing film, 15 ... reflecting member, 17 ... flat plate light guide, 18 ... reflecting surface, 19 ... reverse Inclined surface, 20 ... second light guide member, 21 ... second light emitting portion, 2
2 ... Liquid crystal droplets, 23 ... Polymer matrix, 3
7 ... Sample, 40 ... Polymer dispersed liquid crystal layer, 50 ... Two-dimensional spatial light modulator, 60 ... Square torsion beam reflecting surface, 61
... Beam support post, 71 ... Hinge, 72 ... Ground electrode,
73 ... Post, 74 ... Post, 75 ... Address electrode, 8
DESCRIPTION OF SYMBOLS 1 ... Metal layer, 82 ... Substrate layer, 90 ... Light guide part, 91, 92
... Rays, 94 ... Total reflection surface, 101 ... Extraction surface, 102 ... Prism, 110 ... Driving part, 121 ... Light guide, 122 ... Incident light (linearly polarized light), 123 ... Reflected light, 124 ... Total reflection light, 125 … Reflective film, 126… liquid crystal.

Continued front page    F-term (reference) 2H088 EA37 EA45 GA02 GA03 GA04                       GA10 HA21 HA24 HA28 JA04                       KA01 KA06 KA25 MA20                 2K002 AA07 AB05 BA06 CA14 DA14                       EB08 EB09 HA03                 2K103 AA05 AA14 BB03

Claims (13)

[Claims] 1. A light incident part through a light guide member, a reflection part for reflecting incident light entering from the light entrance part, and light reflected by the reflection part for emission light through the light guide member. And a signal output means for generating a refractive index change by giving a signal to the refractive index variable substance in accordance with information and enclosing a refractive index variable substance in an optical path including the reflection part. In the optical path switching element provided, the reflecting portion has a configuration in which a plurality of reflecting surfaces are arranged in a light incident direction,
An optical path switching element characterized in that the intervals between the adjacent reflection surfaces arranged are not constant in the arrangement direction. 2. The refractive index change of the variable refractive index material according to the signal is performed within a range in which the incident light is transmitted and totally reflected at an interface between the light guide member and the variable refractive index material. The optical path switching element according to claim 1. 3. The refractive index change of the refractive index variable substance according to the signal is performed within a range in which the incident light is not totally reflected at the interface between the light guide member and the refractive index variable substance. 1. The optical path switching element described in 1. 4. The change in the refractive index of the variable refractive index material caused by the signal is totally reflected at the interface between the light guide member and the external material in contact with the light guide member at the light emitting portion. The optical path switching element according to claim 3, wherein the optical path switching element is performed within a range in which one state and a second state in which total reflection is not performed can be obtained. 5. The second light emitting portion capable of outputting the emitted light to the outside via the second light guide member is provided. Optical switching element. 6. The flat light guide body, which is optically joined to the light incident portion and has a refractive index substantially equal to that of the light guide member, is provided. Optical switching element. 7. The optical path switching element according to claim 1, wherein the variable refractive index material is liquid crystal. 8. The optical path switching device according to claim 1, wherein the variable refractive index material comprises a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix. element. 9. The optical path switching element according to claim 8, wherein the liquid crystal is a droplet having a particle diameter of ⅕ or less of a wavelength of incident light. 10. The liquid crystal molecules are aligned in substantially one direction when no voltage is applied.
The optical path switching element according to any one of 1. 11. The optical path switching element according to claim 7, wherein the liquid crystal is a dual frequency driving liquid crystal. 12. A spatial light modulator in which the reflecting surfaces of the optical path switching element according to any one of claims 1 to 11 are arranged in a two-dimensional array, wherein the refractive index variable substance is in contact with each reflecting surface. A spatial light modulator characterized by performing two-dimensional light modulation by independently controlling signal application to each reflection surface. 13. A spatial light modulator according to claim 12, a means for causing a light beam to enter the spatial light modulator, and means for projecting and displaying an image formed by the spatial light modulator on a screen. An image display device characterized by.