JPH06281908A - Liquid crystal optical device and illuminator using it - Google Patents

Abstract

PURPOSE:To provide a high quenching ratio and a high optical modulation function. CONSTITUTION:This device is constituted so that a liquid crystal optical element 30 provided with a light source, an optical fiber 51 and a liquid crystal solidified substance composite material layer 30B, a condensing reflection means 45 and the optical fiber 52 are provided, and a light absorbing body 70 is provided on a part of the surface of the liquid crystal optical element 30, or projecting and recessing parts are formed on a boundary in an optical path, or the boundary having an inclination angle alpha for the optical path is provided, and an unwanted normal reflection beam is reduced, and the optical modulation is performed when the beam passes through the liquid crystal solidified substance composite material layer 30B twice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal optical device using an optical fiber and a transmission / scattering type liquid crystal optical element having a liquid crystal solidified composite, and an illuminating device using the same.

[0002]

2. Description of the Related Art A liquid crystal optical device in which a liquid crystal optical element is arranged between a light source and an optical fiber for optical transmission and the amount of light transmitted from the light source to the optical fiber is controlled by the liquid crystal optical element has been known. There is. Furthermore, an illumination device and a light distribution device using an optical fiber for transmitting optical energy or an optical fiber bundle in which a single optical fiber is bundled, a light source and a liquid crystal optical element have been proposed.

Further, there has been proposed a structure in which an optical fiber is used as a light guiding means from the light source to the liquid crystal optical element, and the liquid crystal optical element is arranged between the optical fibers. Also,
An optical variable attenuator has been proposed which uses a low-loss thin optical fiber for optical communication information transmission on the light incident side and the light emitting side of a liquid crystal optical element. FIG. 6 shows a conventional example 2 of an optical modulator using two optical fibers and a reflective liquid crystal display.

Further, it is possible to reduce light loss by using a liquid crystal optical element having a liquid crystal solidified composite having a transmission / scattering type operation mode and capable of controlling light without a polarizing plate. Therefore, it is proposed that an optical variable attenuator can be constructed even by using a reflective liquid crystal optical element and a lens. FIG. 5 shows Conventional Example 1. Input optical fiber 5
1, the output optical fiber 52, the convex lens 41, and the reflective liquid crystal optical element 30.

[0005]

In the case of the liquid crystal optical device having the structure of the above-mentioned conventional example, since the liquid crystal optical device has the reflective structure, it passes through the electro-optical functional layer of the liquid crystal optical element at least twice. The scattering power of the electro-optical functional layer is 1
This is a dramatic improvement over the transmissive element configuration in which light passes only once.

However, since a part of the interface reflection generated at the interface of the liquid crystal optical element and the interface of the condenser lens always enters the optical fiber on the light emitting side, when the liquid crystal display element is in the off state, The amount of light emitted from the optical fiber does not decrease. That is, it cannot be said that the extinction ratio of emitted light by applying or not applying a voltage to the liquid crystal optical element is sufficiently higher than that of the transmissive element structure.

Therefore, the dynamic range of the change in the amount of light accompanying the voltage application to the liquid crystal optical element has not been improved and remains at a low value as compared with the transmissive element structure.

[0008]

The present invention has been made to solve the above-mentioned problems, and includes a light source, a first light guiding means, a front substrate on which a front electrode is formed, and a back electrode. The liquid crystal and solidified substance composite in which the liquid crystal is dispersed and held in the solidified substance matrix is sandwiched between the liquid crystal and the back substrate, and the liquid crystal is controlled by the electric field generated between the electrodes. Light is scattered when it does not match the refractive index, and light is transmitted when the refractive index of the liquid crystal almost matches the refractive index of the solidified matrix. Reflecting means and second light guiding means are provided, and liquid crystal optics is provided between the first light guiding means and the light collecting reflecting means and between the second light guiding means and the light collecting reflecting means. Light emitted from the light source and introduced into the first light guide means is a liquid crystal optical element. After passing through the liquid crystal optical element, it reaches the condensing reflecting means, is reflected by the condensing reflecting means, passes through the liquid crystal optical element again, and is emitted from the liquid crystal optical element. After passing through the layer twice, the light is incident on the second light guide means, and at this time, the light amount is controlled by the degree of scattering of light of the liquid crystal solidified composite layer, and the output end of the first light guide means and the first light guide means. Provided is a liquid crystal optical device (1), characterized in that the input ends of the two light guiding means are arranged at positions mutually conjugate with respect to the reflecting surface of the condensing reflecting means.

Also provided is a liquid crystal optical device (2) characterized in that an optical fiber is used as the first or second light guiding means in the above liquid crystal optical device (1). Also, in the above liquid crystal optical device (1), there is provided a liquid crystal optical device characterized in that a bundle fiber is used as the first or second light guide means. Further, in any one of the above liquid crystal optical devices (1) to (3), a light absorber or unevenness is formed as a regular reflection light reducing means on a part of the front substrate side surface of the liquid crystal optical element. A characteristic liquid crystal optical device (4) is provided. In any one of the above liquid crystal optical devices (1) to (4),
Provided is a liquid crystal optical device (5), characterized in that at least one electrode surface is provided with irregularities as means for reducing regular reflection light. Further, in any one of the above liquid crystal optical devices (1) to (5), the condensing reflecting means comprises one of a quadric surface mirror such as a spherical mirror, an elliptic mirror, or a parabolic mirror. A liquid crystal optical device (6) is provided.
Furthermore, an illuminating device using any one of the above liquid crystal optical devices (1) to (6) is provided.

In the liquid crystal optical device of the present invention, since the light absorber or the unevenness is formed on a part of the surface of the liquid crystal optical element on the front substrate side as the regular reflection light reducing means, the light is incident on the second light guiding means. The unnecessary regular reflection that occurs is reduced. Alternatively, in the liquid crystal optical device of the present invention, since fine irregularities are formed on the transparent electrode surface of the liquid crystal optical element as unnecessary regular reflection light reducing means, a liquid crystal solidified composite layer and a substrate glass with a transparent electrode are formed. Unnecessary regular reflections that occur at the interfaces of the are reduced.

Further, in order to positively suppress the regular reflection light due to the interface between the condensing reflecting means and the liquid crystal optical element,
(EN) Provided is a liquid crystal optical device which adopts an integral structure and is compact, mechanically strong and optically excellent.

[0012]

According to the present invention, light is emitted through the liquid crystal solidified composite layer.
Since the light passes through the optical path, the effective scattering ability of the transmission-scattering type optical element is improved. Further, in the configuration of this case, the extinction ratio and the dynamics caused by the interface reflection of each optical element which occurs because the transmission-scattering type liquid crystal optical element is installed between the light source and the optical fiber in the reflection type configuration. Range deterioration is improved. As a result, a higher extinction ratio can be obtained as compared with a conventional optical device using a transmission-scattering type liquid crystal optical element having a transmission type element configuration and a reflection type element configuration and an optical fiber.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples. (Examples 1 to 4) A cross-sectional view of Example 1 of the present invention is schematically shown in FIG. In this embodiment, the light emitted from the light source installed outside is collected, guided by the first light guide means 51 composed of an optical fiber, emitted from the output end thereof, and passes through the liquid crystal optical element 30. Then, the light is reflected by the condensing reflection means 45 and is directed toward the input end of the second light guide means 52.

At this time, the emission end of the first light guide means 51 and the incident end of the second light guide means 52 are not conjugate with each other with respect to the condensing reflection means 45 having a reflection surface composed of a quadric surface. The entrance end and the exit end are arranged at the positions. One of the features of the present invention is that the condensing reflection means is provided behind the liquid crystal optical element.

For example, if a spherical mirror is used as the condensing reflecting means 45 as in the first embodiment, it may be arranged near the center of the sphere. Further, the incident end and the emitting end of the optical fiber are interchangeable, and there is no particular difference. In this embodiment, the convex surface of the transparent plano-convex lens is processed as a spherical surface, and aluminum,
A metal mirror is formed on its surface, and a liquid crystal optical element 3
It is provided on the back side of the back substrate 32 of 0 with a flat surface in close contact with an optical adhesive whose refractive index is equal to that of the plano-convex lens.

In this case, it is preferable that the front substrate 31, the back substrate 32, and the condensing reflecting means 45, which is a plano-convex lens, have almost the same or similar refractive indexes. This is because unnecessary reflection occurs when there is a difference in refractive index. In FIG.
When the liquid crystal optical element is in the transparent state, the path of the light beam that the light emitted from the first light guide means 51 efficiently enters into the second light guide means 52 is described.

On the other hand, when the liquid crystal optical element is in the scattering state, the light emitted from the first light guide means 51 and passing through the liquid crystal optical element is scattered, and the light reaching the second light guide means 52 is significantly reduced. . However, part of the light that is normally reflected at the interface of the front substrate of the liquid crystal optical element before passing through the liquid crystal optical element is directly incident on the second light guide means 52 regardless of the transmission / scattering state of the liquid crystal optical element. To do. Usually such an optical path exists. The place where such regular reflected light is generated is determined by the positional relationship among the first light guide means 51, the second light guide means 52, and the front substrate 31 of the liquid crystal optical element 30.

That is, with respect to the apex angle formed by connecting the light beam at the exit end of the first light guide means 51 to the entrance end of the second light guide means 52 via the specific region of the front substrate 31, This is a positional relationship in which the perpendicular line of the specific area of the front substrate 31 is an angle bisector. The shapes and areas of the regions thus limited are the exit end shape of the first light guide means 51, the entrance end shape of the second light guide means 52, the exit end of the light guide means 51 and the second light guide. It is determined by the positional relationship between the incident end of the means 52 and the front substrate 31 of the liquid crystal optical element 3.

Preferably, the shape of the exit end of the first light guide means 51 and the shape of the entrance end of the second light guide means 52 are matched to the shape having the larger inner area. At the interface of the front substrate other than this area, even if regular reflection occurs, it does not enter the incident end of the second light guide means 52, so that when the liquid crystal optical element is in the scattering state, the dark level is increased as a background light component. There is no.

On the front substrate 31 of the liquid crystal optical element 30,
There are two interfaces where the above-mentioned unnecessary regular reflection occurs, that is, the interface with air and the interface between the liquid crystal solidified composite and the transparent electrode. As a means for reducing the regular reflection at such an interface, formation of an antireflection film is generally considered. But,
It is difficult to completely eliminate the reflected light with an antireflection film,
In particular, when the antireflection wavelength band is as wide as the entire visible light, the residual reflectance is about 0.5%.

Further, at the interface between the liquid crystal solidified composite and the transparent electrode, the liquid crystal layer and the solidified layer are mixed at the transparent electrode interface, and therefore the antireflection effect applicable to both is almost impossible in principle.

In such a case, as described above, the black light absorber 70 is provided only in a specific region of the front substrate 31 shown in FIG. It is effective to reduce the regular reflection light that reaches the second light guide means 52. If the black coating or the unevenness is formed on the interface of the front substrate 31 with the air, the interface region between the liquid crystal solidified composite and the transparent electrode is also masked, which is sufficient. The above is the characteristic part of this embodiment.

The constituent features of the present embodiment are that a driving circuit for supplying a signal voltage between the electrodes for driving the liquid crystal solidified composite layer which has the optical modulation function in the reflective liquid crystal optical element is further provided. .

Next, the details of each part such as the constitution of the liquid crystal solidified composite used in the present invention will be outlined.

In the liquid crystal optical element of the present invention, a liquid crystal display element is used in which a liquid crystal solidified substance composite in which a nematic liquid crystal is dispersed and held in a solidified substance matrix is sandwiched. In particular,
A nematic liquid crystal having a positive dielectric anisotropy is dispersed and held in a solidified matrix, and the refractive index of the solidified matrix is made to substantially match the ordinary refractive index (n _o ) of the liquid crystal used. It is preferable to use a resin composite. Then, the liquid crystal solidified composite is sandwiched between a pair of substrates with electrodes.

[0026] n _o and the extraordinary refractive index of the nematic liquid crystal (n
_When the refractive index anisotropy, which is the difference from _e ), is Δn, Δn is preferably 0.18 or more. Also, the specific wavelength λ
In order to obtain a high scattering power of the liquid crystal solidified composite layer with respect to (μm), it is preferable that the average particle diameters R (μm) of the liquid crystal are uniform according to the wavelength. Actually, △ n ・ R
It is preferable to satisfy the relationship of ≈λ.

Therefore, using the bundle fiber for optical energy transmission, the wavelength band of visible light (λ = 0.4 to
In the case of modulating light of 0.7 (μm)), the scattering ability in the liquid crystal solidified composite layer becomes almost uniform in the entire wavelength range.
The average particle diameter R of the liquid crystal is preferably distributed in a range satisfying the relationship of 0.4 <Δn · R <0.7.

On the other hand, a single-line fiber for optical communication is used, and light of a single wavelength in the near-infrared wavelength region (λ = 0.8 to 1.6 (μm)) of a semiconductor laser diode or LED in the invisible light region is used as light. When using light, or H which is a visible light oscillation laser
When using light of a single wavelength from an e-Ne laser or a semiconductor laser for optical measurement, the average particle diameter R of the liquid crystal is Δn · R≈λ
A structure having a small particle size distribution that satisfies the above is preferable.

As the substrate with electrodes, a substrate made of glass, plastic, ceramic or the like, on which electrodes are provided, is used. The substrate may have a fixed shape or may be a flexible substrate such as a plastic film. Further, it may be a substrate having a spectral characteristic of absorbing ultraviolet light or absorbing or reflecting light of an unnecessary wavelength.

In the present invention, a transparent material is used for at least the substrate on the incident surface side. Further, glass is suitable for forming a flat substrate surface with less optical distortion.

A liquid crystal solidified composite is sandwiched between a pair of substrates each having an electrode. In this liquid crystal solidified composite, an electric field is generated by applying a voltage, the orientation of liquid crystal molecules is changed according to the electric field, and the refractive index of the liquid crystal in the liquid crystal solidified composite is changed. Light is transmitted when the refractive index of the solidified matrix is substantially the same as the refractive index of the liquid crystal, and light is scattered when the refractive index is not the same. Since the liquid crystal optical element using this liquid crystal solidification composite does not use a polarizing plate, an optical modulator with little optical loss can be obtained.

Specifically, as a liquid crystal display device, a liquid crystal solidified substance composite comprising a solidified substance matrix in which a large number of fine holes are formed and a nematic liquid crystal filled in the holes is used. The liquid crystal solidified composite is sandwiched between electrode substrates. The refractive index of the liquid crystal changes depending on the state of voltage applied between the electrodes, and the relationship between the refractive index of the solidified matrix and the refractive index of the liquid crystal changes. It is possible to use a liquid crystal optical element that is in a transmissive state when the refractive indexes of these two are substantially the same, and is in a scattering state when the refractive indexes are different.

A liquid crystal solidified substance composite composed of a solidified substance matrix having a large number of fine pores formed therein and a liquid crystal filled in the pores is such that the liquid crystal is contained in a liquid bubble such as a microcapsule. It is a structure.

However, individual microcapsules do not have to be completely independent, and liquid bubbles of individual liquid crystals may communicate with each other through a slit like a porous body. Furthermore, the degree of communication may be high, and the liquid crystal may be connected in a stitch shape.

The liquid crystal solidified composite used in the present invention is manufactured, for example, as follows. The nematic liquid crystal and the curable compound forming the solidified matrix are mixed to form a solution or latex. Then, this may be subjected to photo-curing, heat-curing, curing by removing a solvent, reaction curing, etc. to separate the solidified matrix so that the nematic liquid crystal is dispersed in the solidified matrix.

The curable compound used is preferably a photocurable or thermosetting type because it can be cured in a closed system. In particular, it is preferable to use a photo-curing type curable compound because it can be cured in a short time without being affected by heat. As a specific manufacturing method, a cell is formed using a sealing material as in the conventional normal nematic liquid crystal, an uncured mixture of a nematic liquid crystal and a curable compound is injected from an injection port, and the injection port is sealed. After that, it can be cured by irradiation with light or heating.

In the case of the liquid crystal optical element of the present invention, an uncured mixture of a nematic liquid crystal and a curable compound is supplied, for example, onto a substrate provided with a transparent electrode as an electrode without using a sealing material. After that, the other substrate with the transparent electrode can be overlaid and cured by light irradiation or the like. Of course, thereafter, a sealing material may be applied to the periphery to seal the periphery. According to this production method, the uncured mixture of the nematic liquid crystal and the curable compound may be simply supplied by roll coating, spin coating, printing, coating with a dispenser, or the like, so that the injection step is simple,
Very good productivity.

Further, in the uncured mixture of these nematic liquid crystal and the curable compound, ceramic particles for controlling the substrate gap, plastic particles, spacers such as glass fibers, pigments, dyes, viscosity modifiers and the like of the present invention You may add the additive which does not adversely affect the performance of.

Although the production method by the photopolymerization method has been described above, the microencapsulated liquid crystal can be formed by the emulsion method in addition to the above. It is also possible to form a liquid crystal solidified substance composite having substantially uniform capsule particle diameters by using a microporous glass and squeezing the liquid crystal material into the liquid of the capsule encapsulating material through a substantially uniform glass hole.

Next, other components will be described. The incident-side and exit-side optical fibers used as the light guide means are bundled with fibers having a numerical aperture (NA) of 0.57 and having a core of multi-component glass of 50 μm and a diameter of 5 mm. I used one.

The surface of the liquid crystal optical element on the light incident surface side is coated with an antireflection film, and the center thereof has a diameter of about 5 m.
m of black paint was applied to provide the light absorber 70 to eliminate reflection at that portion.

The bundle type optical fibers on the light incident side and the light emitting side are arranged so as to be regularly reflected at an incident angle of 8 degrees with respect to the liquid crystal solidified composite layer of the liquid crystal optical element, and each bundle is further provided. The centers of the end faces of the fibers are installed in optically conjugate positions near the center of the condensing reflection means 45 (a spherical surface having a radius of curvature of 50 mm in this embodiment).

A visible light source such as a halogen lamp, an Xe lamp or a metal halide lamp was guided to the incident side optical fiber to be incident light. A rectangular wave of 100 Hz was applied as an alternating current between the electrodes of the liquid crystal optical element, and the effective voltage value was modulated by an external circuit to change the transmission / scattering state of the liquid crystal optical element to obtain a dimmer.

The optical characteristics of the liquid crystal optical device of the present invention manufactured with such a configuration were measured. The results are summarized in Table 1. In Table 1, the relative light transmittance is 100 in Example 1.
%. Further, the measured extinction ratio indicates the range of the light quantity value ratio of the emission side optical fiber with respect to the applied voltage values 0 V and 30 V of the liquid crystal optical element.

As a second embodiment, the liquid crystal optical element 30 of the present invention shown in FIG. 1 is formed with an antireflection film on the front surface side but does not have a black light absorber (second embodiment), which is unnecessary. One in which only a light absorber is formed to remove reflection (Example 3), and further, either an antireflection film or a light absorber is provided on the surface side of the liquid crystal optical element 30 of the present invention shown in FIG. 1 as Example 4. The same optical characteristics were evaluated for the structure not formed, and the results are described. Also, as Comparative Example 1, the measurement result in the case of the conventional configuration shown in FIG. 5 (using a plano-convex lens having a focal length of about 150 mm) is also shown.

[0046]

[Table 1]

From these results, it can be seen that the structure of the present invention achieves a dramatic improvement in the extinction ratio with almost no optical loss. Therefore, by using the present liquid crystal optical device as a dimmer, the amount of outgoing light corresponding to the applied voltage value can be adjusted arbitrarily and at high speed without a large loss of light amount.

In the liquid crystal optical device of the present invention, the light emitting end of the bundle fiber 51 is installed toward the object to be illuminated, and an electric signal of a photodetector such as a photomultiplier tube or a Si photo diode is locked by a lock-in amplifier. It can be used as a fiber type optical chopper required for optical measurement with a high / N ratio.
Compared with the conventional rotating window type chopper or vibration type chopper, small size and high speed optical chopping becomes possible.

Further, by performing high-speed shuttering of the liquid crystal optical element in synchronism with the acquisition timing of the image accumulation of an image measuring device such as a CCD camera, image measurement with a high S / N ratio can be performed, and the image after the image measurement can be measured. Binarization,
Alternatively, high precision and high speed processing is possible in applications such as shape recognition.

Since the area where the light absorber 70 is formed is very small, it hardly contributes to the deterioration of the reflectance of the liquid crystal optical element.

The reflecting surface of the condensing reflecting means 45 may be a metal reflecting mirror of aluminum, silver or the like, or an optical interference multilayer film reflecting mirror. In the former case, the device is easy to manufacture and the device can be constructed without complicating the structure. In the latter case, it is also possible to form a cold mirror having a spectral characteristic of transmitting heat rays and reflecting only visible light, depending on the structure of the optical interference multilayer film, and it is also possible to use a specific semiconductor laser wavelength used in optical communication. The reflectance is about 10
There is a degree of freedom to form a 0% mirror.

(Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, the liquid crystal optical element 30 and the condensing reflection means 46 are spatially separated.

In the case of a transmissive liquid crystal optical element, unlike a reflective liquid crystal optical element, flatness of the substrate is not required. Therefore, a thin and inexpensive transparent substrate such as a PET film is used, and a long film is used. There is no problem even if forming technology is used.

In this transmissive liquid crystal optical element 30, the reflected light at the interface of the liquid crystal solidified composite layer is the optical fiber 5 on the output side.
It can be provided so that the angle with respect to the optical path of the liquid crystal solidified composite layer or the like can be changed so as not to cause the deterioration of the extinction ratio upon entering 1.

The reflecting surface may be a metal mirror or a cold mirror using an optical interference multilayer film that reflects visible light and transmits infrared light.

In this embodiment, the reflecting mirror is a cold mirror in order to prevent temperature rise and ensure reproducibility of optical characteristics even in a wide environment temperature. Further, the liquid crystal optical element 30 was surrounded by a constant flow, and the temperature was adjusted by air conditioning. Temperature sensors were provided on the surface and inside of the liquid crystal optical element 30, and the air conditioning was automatically controlled as appropriate to bring the temperature range into a desired range.

An antireflection film was formed on both surfaces of the liquid crystal optical element 30, and a light absorber 70 was formed near the center of the surface of the liquid crystal optical element 30 on the optical fiber side. Also in this example, a high-performance extinction ratio similar to that in Example 1 was obtained. Further, since the cold mirror has a reflectance of about 10% higher than that of the aluminum reflecting mirror, the relative light transmittance was higher than that of Example 1.

In the structure of this embodiment, the liquid crystal optical element is provided with an appropriate inclination without making the angle between the liquid crystal solidified composite layer and the surface such as the transparent electrode surface and the optical path constant. The interface reflection of the device can be further removed.

In particular, N. A. When a fiber with a small diameter is used as the light guide means, or when light with high directivity such as laser light propagates through the light guide means, the solid angle of the light emitted to the liquid crystal optical element is small, so the liquid crystal optical element The light is concentrated in a narrow area near the center of, and the incident angle is less dispersed.

In such a case, if a light absorber for removing regular reflection is formed in the vicinity of the center of the liquid crystal optical element in order to improve the extinction ratio, the area ratio occupied by the light absorber cannot be ignored, and the light utilization efficiency decreases. Cause of. Therefore, N.
A. When using a small optical fiber of
Alternatively, when a light having a high directivity such as a laser beam propagates through the light guiding means, it is not preferable to form a light absorber for removing regular reflection near the center of the liquid crystal optical element, and the entire liquid crystal optical element 30 has an optical path. Liquid crystal optical element 3 tilted with respect to
It is effective to prevent the interface reflection of the front substrate of 0 from reaching the second light guide means 52.

Here, the tilt angle of the liquid crystal optical element 30 is the angular dispersion of the incident light on the liquid crystal optical element 30 and the first light guiding means 5.
There is a minimum value for removing an unnecessary regular reflection component depending on the shapes of the entrance end and the exit end of the first and second light guide means 52. If the tilt angle is too large, haze of the liquid crystal solidified composite layer is likely to occur, and the transmittance is lowered, which is not preferable. Therefore, in such a case, there is an optimum tilt angle corresponding to the configuration. Such an effect is also applicable to the configuration shown in FIG.

In Example 5 shown in FIG. A. =
When a bundle fiber having a diameter of 5 mm is formed by bundling 0.2 silica fibers, the divergence angle of the light emitted from the bundle fiber is about 23 °. 5 which is the first and second light guiding means
When the bundle fibers 1, 52 are closely contacted in parallel and arranged at the center of the spherical mirror 46 having a radius of curvature of 50 mm, the tilt angle of the liquid crystal optical element with respect to the central optical axis is preferably in the range of 26 ° to 30 °.

(Embodiment 6) Embodiment 6 of the present invention is shown in FIG. In this embodiment, unlike the first to fifth embodiments, an elliptical mirror having a relatively large eccentricity is used as the light-collecting reflecting means 47, and the liquid crystal optical element 30 and the light-collecting reflecting means 47 have the same space as in the fifth embodiment. It has a separate structure.

In this embodiment, the major axis of the cross section is 40 mm,
An elliptical mirror with a short diameter of 30 mm was used. The exit end of the incident side optical fiber and the entrance end of the exit side optical fiber were arranged at two focal positions.

An aspherical surface other than the ellipsoidal mirror may be used, as long as the light emitted from one optical fiber is reflected by the condensing reflecting means 47 and condensed at another focus. In order to prevent the interface reflection between the liquid crystal display element and air from entering the optical fiber on the exit side and causing the deterioration of the extinction ratio, a black paint having a diameter of about 5 mm is applied to the center of the surface of the liquid crystal display element to absorb the light. 70 is provided to reduce reflection at that portion.

Further, in order to improve the transmittance, both surfaces of the liquid crystal optical element 30 are coated with an antireflection film. Further, if the thickness of the light-incident side front substrate (substrate such as glass on which ITO is deposited) is about 1 mm or less,
It can be said that the frosting process is less necessary because the unnecessary regular reflection at the interface that causes the reduction of the extinction ratio is removed by the already formed light absorber 70. However, when the front substrate or the back substrate is thicker than that, it is preferable to remove the unnecessary interfacial reflection by frosting at least one electrode surface, preferably both electrode surfaces.

In this embodiment, the transmissive liquid crystal optical element 30 is used.
And the condensing reflection means 47 having an elliptic curved surface are separated. In this embodiment, N. A. When a fiber having a small size is used as the light guiding means or when light having a high directivity is guided and propagated, the light reflected by the interface of the liquid crystal optical element is less likely to directly enter the light guiding means 52. It is easy to obtain a high extinction ratio without forming the.

Further, in this embodiment, since the ellipsoidal mirror is used as the reflecting surface, each optical fiber can be installed at the first and second focal positions of the ellipsoidal mirror, which is preferable. That is,
When a space is required for installation of a connector or the like, a large space can be provided between the optical fiber on the incident side and the optical fiber on the emitting side, so that a complicated configuration can be dealt with.

In particular, when a single-line optical fiber is used, the diameter of the core, which is the optical transmission part, is 200 μm or less, while the outer shape of the connector is 5 to 10 mm. It is preferable to use an elliptical mirror surface. Compared with the case where the bundle fiber is used, the diameter of the opening of the light guide means is smaller by two digits, so that a high extinction ratio can be obtained even if the scattering ability of the liquid crystal optical element is the same.

Further, in this embodiment, the condensing reflection means 47 and the liquid crystal display element 30 are spatially separated. In this case, since the light-collecting / reflecting means 47 is made by a mold, it is cheaper and lighter in weight than the first embodiment of FIG. 1 in which the lens is diverted. On the other hand, it becomes difficult to install and adjust the optical fiber, the condensing reflection means 47, and the liquid crystal display element.

(Embodiments 7 to 8) FIG. 4 shows an embodiment 7 in which a parabolic curved surface, which is one of the quadric surfaces, is used as the reflecting surface of the condensing reflecting means. In this embodiment, the light emitted from the optical fiber 51 hits the condensing reflection means 48, is reflected there, and then goes to the liquid crystal optical element 30. The light transmitted through the liquid crystal optical element 30 is reflected by the plane reflection means 90, passes through the liquid crystal optical element 30 again, and reaches the optical fiber 52 for emission.

However, in the case of this configuration, the liquid crystal optical element 3
When each interface of 0 and the plane reflection means 90 are parallel, there is an unnecessary regular reflection that always enters the optical fiber 52 on the emission side. The interface reflection can be reduced by inclining each interface of the liquid crystal optical element with respect to the plane reflecting means 90 or forming fine irregularities for removing regular reflection. The condensing reflecting means 90 may have an aspherical shape other than the quadric surface in order to reduce aberrations and improve the converging property.

In this embodiment, a single wire optical fiber for optical communication is used as a light source, and the optical fibers 51 and 5 on the incident side and the emitting side are used.
2. Consists of a condensing reflecting means 48 having a curved surface of a paraboloid, a temperature controller (not shown), a liquid crystal optical element 30, and a plane reflecting means 90. Further, a drive circuit for driving the liquid crystal optical element in the liquid crystal optical element, an electronic circuit for driving and controlling the temperature controller, and the like are provided.

The pair of transparent electrode surfaces of the liquid crystal optical element 30 are frosted to form uneven surfaces (not shown). As the reflecting surface of the total reflection means 90, a glass substrate having optical flatness is used in which an optical interference multilayer film mirror that reflects the emission wavelength of a specific LD (laser diode) or LED that is incident light is formed. As an optical fiber, FC
Connector-type quartz fiber with a core diameter of 50μ
m stepped graded index optical fiber for multimode transmission was used.

Table 2 shows the results of measuring the optical characteristics of two examples of the liquid crystal optical device having such a basic structure. In Table 2, the relative light transmittance is 1 for Comparative Example.
It is set to 00%. Also, the measurement is performed in a constant temperature bath,
The temperature means the ambient temperature of the liquid crystal optical device, not the temperature of the liquid crystal display element, and the measured extinction ratio and response speed are -20 ° C.
In the temperature range of 60 ° C. to 60 ° C., the applied voltage values of 0 V and 100 V of the liquid crystal optical element were evaluated.

As Comparative Example 2, a liquid crystal optical element having a conventional configuration, in which the front electrode surface (and the back electrode surface) on the light incident side is a flat surface and a temperature regulator is not mounted, the same optical properties are obtained. The characteristic evaluation results are described.

[0077]

[Table 2]

From these results, it can be seen that the structure of the present invention achieves a dramatic improvement in the extinction ratio with almost no optical loss. Therefore, by using the present liquid crystal optical device as a variable optical attenuator for optical communication, the amount of emitted light corresponding to the applied voltage value can be adjusted arbitrarily and at high speed without large light amount loss.

The inclination angle α employed as the unnecessary light removing means in the present invention will be described. In the case of a single-wire fiber for optical communication, the core system is as thin as 200 μm or less, so that the inclination angle α in this case is preferably about 0.1 ° to 10 ° or less. On the other hand, in the case of the optical energy transmission fiber, the fiber system of the optical transmission unit is 2 to 2 because it is a bundle fiber or the like.
It becomes thick with about 20 mm, and the inclination angle α at this time is 1 °
It is preferably about 20 °.

Further, even when the inclination angle is large, the interface reflected light is removed, but most of the light obliquely enters the liquid crystal solidified composite layer, and haze is likely to occur due to index mismatch at the time of transparency. Transmittance decreases. Further, when the tilt angle α becomes large, the liquid crystal optical element becomes thick, and the size and weight of the entire device increase, so it is preferable to keep the tilt angle α within the above-mentioned small range.

The unevenness, which is another means, will be described. The size (pitch) of the irregularities is preferably about 2 to 200 μm, and the depth of the irregularities (+ point average roughness) R _z is 0.1 to 1
About 0 μm is preferable. As for the shape of the unevenness, the rectangular unevenness causes little change in the area of the regular reflection surface, and therefore the interface reflection noise light component incident on the emission side optical fiber is not significantly reduced. Therefore, the form of the irregularities is preferably Δ (serrated).

The embodiment has been described above. Next, the size of each part will be briefly described. When transmitting light energy, a halogen lamp as a light source,
Metal halide lamps, Xe lamps, etc. are used, and each has an emission length of about 2 to 10 mm. Therefore, in order to efficiently collect light by using a light collecting means and guide it to the fiber,
A fiber diameter on the order of 10 mm is required.

The size of the light source is 3 to 10 cm in length.
(10W-500W class) to 10-30cm (50
There is a width of about 0 W to 3 kW, and the size of the condenser mirror is also adjusted according to the type of the light source. Then, the size of the liquid crystal optical element depends on the condensing means (ellipse mirror, lens, etc.) used.
, The focal length, the effective diameter, and the N.V. of the fiber. A. However, when the above light source is used, the diagonal angle may be about 1 to 30 cm.

When used for the purpose of communication or optical measurement,
The light entrance diameter is 1 mm or less, and the diameter is 1 cm or less even if a lens is used to collect the divergent light of a laser die or LED. Since the core diameter of the optical transmission portion of the single fiber for optical communication is about 200 μm or less, the size of the liquid crystal optical element is about 1 to 5 cm. Even in this case, more precise light flux control can be achieved. When a bundle fiber is used, the liquid crystal panel size according to the effective area is used. Even with a large-area liquid crystal panel, uniform light flux control is possible.

[0085]

As described above, according to the present invention, the light emitted from the light source is converted into the liquid crystal by the liquid crystal optical element capable of electrically controlling the scattering state and the transmitting state, the light reflecting means and the light condensing means. Since the light passes through the light modulation portion of the optical element a plurality of times, the effective scattering ability is dramatically improved as compared with the case where the light is transmitted only once.

As an unnecessary regular reflected light reducing means,
A light absorber or unevenness is formed on a part of the light incident side surface of the liquid crystal optical element. Alternatively, the liquid crystal solidified composite layer and the reflecting surface are not made substantially parallel to each other and are inclined at a predetermined angle, so that unnecessary interface reflected light that is a main cause of background noise during transmission between input and output is eliminated. It is decreasing.

As a result, improvement of the extinction ratio and its dynamic range in the variable light function according to the applied voltage was achieved.

Then, the present optical device can be used for optical measurement as a lighting device with a light control function or a lighting device with a light shuttering function.

For example, as a light source for illumination having a high-speed shutter function, a strobe illumination can be used, that is, high-speed photographing can be performed. As a specific example, when the shutter speed is 1 ms, a moving average image of 1 cm is recorded by irradiating an object moving at a speed of 360 km / s.

If a high-speed moving object is photographed by continuously illuminating the shutter ring, the locus is recorded in steps. Examples of using the programmable characteristic that the shutter timing can be arbitrarily changed and have high-speed followability include, for example, advertisement lighting, exhibition lighting, floor lighting, shuttering in synchronization with the intensity or tone of BGM sound, or Dimming has enabled more active lighting.

The liquid crystal optical device of the present invention is used as a light source control for optical synchronous amplification detection (lock-in amplifier), and has a control function of a measurement light source which is turned on and off at a constant cycle and amplifies only signal light of the cycle. By the detection, it is possible to measure with a high S / N ratio even in a weak signal light or an environment with a lot of noise light.

As described above, the S / N ratio is improved by performing the shuttering in synchronization with the photodetector such as the optical chopper for the lock-in amplifier.

Also, in the field of optical communication, it has become possible to obtain an optical attenuator with variable attenuation by adjusting the applied voltage, instead of the optical attenuator having a fixed attenuation rate which has been used conventionally.

Further, the present invention is suitable for various applications as long as the effect is not lost.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the basic configuration of Examples 1 to 4 of the present invention.

FIG. 2 is a sectional view schematically showing Example 5 of the present invention.

FIG. 3 is a sectional view schematically showing Example 6 of the present invention.

FIG. 4 is a sectional view schematically showing Example 7 of the present invention.

FIG. 5 is a block diagram showing a configuration of Conventional Example 1.

FIG. 6 is a block diagram showing a configuration of Conventional Example 2.

[Explanation of symbols]

 30: Liquid Crystal Optical Element 31: Front Substrate 32: Back Substrate 30A: Front Electrode 30B: Liquid Crystal Solidified Complex Layer 30C: Back Electrode 45: Light Collecting Reflecting Means 51: First Light Guide Means 52: Second Conducting Means Light means

Claims (7)

[Claims] 1. A liquid crystal in which a liquid crystal is dispersed and held in a solidified matrix between a light source, a first light guide means, and a front substrate having a front electrode and a back substrate having a back electrode. The liquid crystal is controlled by the electric field generated between the electrodes by sandwiching the solidified composite, and when the refractive index of the liquid crystal does not match the refractive index of the solidified matrix, light is scattered and the refractive index of the liquid crystal changes to that of the solidified matrix. A liquid crystal optical element having a liquid crystal solidified composite layer that transmits light when the refractive index is substantially matched, a condensing reflecting means, and a second light guiding means are provided, and the first light guiding means is provided. The liquid crystal optical element is arranged between the second light guiding means and the light collecting reflecting means, and the light emitted from the light source and introduced into the first light guiding means is After passing through the liquid crystal optical element, it reaches the condensing reflection means, and by this condensing reflection means By being emitted, it passes through the liquid crystal optical element again and then exits from the liquid crystal optical element to pass through the liquid crystal solidified substance composite layer in the liquid crystal optical element twice, and then enters the second light guide means. Finally, the amount of light is controlled by the light scattering degree of the liquid crystal solidified composite layer, and the output end of the first light guide means and the input end of the second light guide means are
A liquid crystal optical device, wherein the liquid crystal optical device is arranged at a position that is mutually conjugated with respect to the reflection surface of the condensing reflection means. 2. A liquid crystal optical device according to claim 1, wherein an optical fiber is used as the first or second light guiding means. 3. A liquid crystal optical device according to claim 1, wherein a bundle fiber is used as the first or second light guide means. 4. The liquid crystal optical device according to claim 1, wherein a light absorber or unevenness is formed as a regular reflected light reducing means on a part of the surface of the liquid crystal optical element on the front substrate side. apparatus. 5. A concavo-convex pattern is formed on at least one of the electrode surfaces as a regular reflection light reducing means.
4. The liquid crystal optical device according to any one of items 4 to 4. 6. The liquid crystal according to claim 1, wherein the condensing reflecting means is one of a quadric curved mirror such as a spherical mirror, an elliptical mirror, a parabolic mirror or the like. Optical device. 7. An illuminating device using the liquid crystal optical device according to claim 1.