JPH06273718A - Liquid crystal optical device and illuminator using the same - Google Patents

Abstract

PURPOSE:To provide an efficient optical modulator. CONSTITUTION:This liquid crystal optical device is provided with optical fibers 51 and 52, rod lenses 55 and 56, prisms 2A and 2B, and a liquid crystal optical element 30 consisting of a front substrate 31, a front electrode 30A, a liquid crystal solidified composite layer 30B, a rear electrode 30C used as a reflecting means, and a rear substrate 32, and a sufficient gap between substrates is reserved to a rugged boundary face in the optical path or the liquid crystal solidified composite layer or a boundary face inclined at an angle alpha to the reflecting face is provided, and light passes the liquid crystal solidified composite layer 30B twice or more.

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 a transmission / scattering type liquid crystal optical element provided with an optical fiber and 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. FIG. 6 shows the basic arrangement as a conventional example. It is composed of an optical fiber 51 for incidence, an optical fiber 52 for emission, a convex lens 41, and a liquid crystal optical element 30 including a reflection type means and a liquid crystal solidified compound composite and showing a transmission / scattering type operation mode.
Then, with this configuration, light modulation can be achieved.

An optical variable attenuator having a similar arrangement to that of the prior art, but using low-loss thin-line optical fibers for optical communication information transmission on the light incident side and the light emitting side of a liquid crystal optical element is provided. Proposed. As described above, it is possible to reduce light loss by using a liquid crystal optical element having a liquid crystal solidified composite having a transmission / scattering 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.

[0005]

In this case, since the light passes through the liquid crystal solidified substance composite layer twice by adopting the reflection type structure, the light scattering ability of the liquid crystal solidified substance composite itself is only once. This is a dramatic improvement over the transmissive configuration that passes through.

However, a part of the interface reflection generated at the interface of the liquid crystal optical element and the interface of the condensing lens is always incident on the optical fiber on the light emitting side, so that when the liquid crystal solidified composite is in the scattering state, The amount of light emitted from the fiber was not reduced, and the extinction ratio of the light emitted by applying or not applying voltage to the liquid crystal solidified composite layer was not higher than that of the transmissive structure.

Therefore, the dynamic range of the change in the amount of light associated with the application of voltage to the liquid crystal optical element is hardly improved as compared with the transmissive element structure, and remains at a low characteristic value. In addition, when a light source that emits a large amount of light is used, the temperature rise of the liquid crystal optical element due to radiant heat or the like is remarkable, and various electro-optical characteristics (characteristics of applied voltage versus light transmittance,
The reproducibility of dynamic response characteristics, extinction ratio, etc.) became poor, making accurate dimming difficult.

[0008]

According to the present invention, a light source, a first light guide means, a first prism body, a front substrate having a front electrode and a back substrate having a back electrode are formed. When a liquid crystal solidified substance composite in which liquid crystal is dispersed and held in a solidified substance matrix is sandwiched, the liquid crystal is controlled by an electric field generated between both electrodes, and the refractive index of the liquid crystal does not match the refractive index of the solidified substance matrix. A liquid crystal optical element having a liquid crystal and solidified substance composite layer that transmits light when the refractive index of the liquid crystal is substantially matched with the refractive index of the solidified substance matrix, a light reflecting means, and a second prism. A body and a second light guiding means, and a light reflecting means is arranged in the optical path from the light source to the second light guiding means, and the liquid crystal solidified composite layer is on the reflecting surface side of the light reflecting means. Placed close to each other or closely attached to the reflective surface, The emitted light passes through the first light guide means and enters the inside of the liquid crystal optical element from the incident portion of the first surface of the liquid crystal optical element through the first prism body. The light is reflected once or more by the reflecting portion or the light reflecting means, and finally emitted from the emitting portion of the first surface,
Further, it is made incident on the second light guide means through the second prism body, and passed through the liquid crystal solidified composite layer 2 ⁿ times (an integer of 1 or more) from the incident portion to the emitting portion. At this time, the amount of light is controlled by the light transmittance of the liquid crystal solidified composite layer, and at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is provided with irregularities, or the liquid crystal optical element The distance d between the liquid crystal solidified composite layer and the light reflecting means is set to be 10 times or more the thickness t of the liquid crystal solidified composite layer, or at the interface intersecting the optical path inside the liquid crystal optical element. Provided is a liquid crystal optical device (1), wherein at least one of the interfaces is tilted by a predetermined angle α with respect to the reflecting surface of the light reflecting means.

Further, liquid crystal solidification in which liquid crystal is dispersed and held in a solidified matrix between the light source, the first light guide means, the front substrate on which the front electrode is formed and the back substrate on which the back electrode is formed. The liquid crystal is controlled by the electric field generated between the two electrodes by sandwiching the object complex, 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 becomes A liquid crystal optical element having a liquid crystal solidified composite layer through which light is transmitted when the refractive index is substantially matched,
A light reflecting means, a prism body having a second light guiding means and a reflecting surface are provided, and the light reflecting means is arranged in the optical path from the light source to the second light guiding means. The layer is arranged close to the reflection surface side of the light reflection means or is arranged in close contact with the reflection surface, and the light emitted from the light source is allowed to pass through the first light guide means and is incident on the prism body. The light is guided from the surface to the inside of the prism body, and is made to enter the inside of the liquid crystal optical element from the incident portion of the first surface of the liquid crystal optical element, and is reflected at least once by the reflecting surface of the prism body or the light reflecting means. Finally, the liquid crystal solidified composite layer is made to enter the second light guide means from the exit surface of the prism body, and 2 ⁿ times (n = 1 or more) between the entrance surface of the prism body and the exit surface of the prism body. Of the liquid crystal solidified compound. The amount of light is controlled by the light transmittance of the body layer, at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is provided with irregularities, or the liquid crystal solidified composite layer of the liquid crystal optical element and The distance d from the light reflecting means is 10 times or more the thickness t of the liquid crystal solidified composite layer, or at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is the optical path. Provided is a liquid crystal optical device (2) which is tilted by a predetermined angle α with respect to the central axis of the liquid crystal optical device (2).

Further, in the liquid crystal optical device of the above-mentioned liquid crystal optical device (1) or (2) in which the interface is provided with unevenness, the interface formed by the front electrode is provided with unevenness. Provide (3). In addition, in any one of the liquid crystal optical devices (1) to (3) described above, the liquid crystal optical device having irregularities on the interface, the irregularities are formed on the interface formed by the back electrode. A device (4) is provided.

Further, the above liquid crystal optical devices (1) to (3)
In any one of the liquid crystal optical device having an uneven surface, the light reflecting means is also used as a substantially flat back electrode of the liquid crystal optical element. . Further, the above liquid crystal optical device (1) to
The liquid crystal optical device (6) is characterized in that, in the liquid crystal optical device according to any one of (5), a temperature adjuster is further provided on the back substrate side. Further, there is provided an illuminating device equipped with any one of the above liquid crystal optical devices (1) to (6).

In the liquid crystal optical device of the present invention, fine irregularities are formed on the transparent electrode surface of the liquid crystal optical element as an unnecessary regular reflection light reducing means, or a liquid crystal solidified composite layer of the liquid crystal optical element is formed. The distance d from the light reflecting means is 10 times or more the thickness t of the liquid crystal solidified composite layer. The liquid crystal solidified composite layer of the liquid crystal optical element is provided with an inclination angle with respect to the reflecting surface of the light reflecting means. By these unnecessary reflection reducing means, of the regular reflections generated at the interface between the liquid crystal solidified composite layer and the substrate glass with the transparent electrode, the components incident on the second light guiding means are reduced.

Further, an integral structure is adopted so as to positively suppress the regular reflection light due to the interface between the prism body and the liquid crystal optical element, and it is compact and mechanically strong and optically excellent. A liquid crystal optical device is provided.

[0014]

According to the present invention, since light passes only through the solid medium and passes through the liquid crystal solidified composite layer at least twice, the effective scattering ability of the transmission / scattering type optical element is improved.
Then, when the transmission / scattering type liquid crystal optical element is installed between the light source and the optical fiber in the reflection type configuration, deterioration of the extinction ratio and the dynamic range due to the interface reflection of each optical element, which is a problem, is improved. As a result, a higher extinction ratio can be obtained as compared with an optical device using a transmission-scattering type liquid crystal optical element having a conventional transmissive element structure and a reflective element structure and an optical fiber.

Further, by forcibly controlling the temperature of the liquid crystal optical element from the back substrate side, the electro-optical characteristics of the liquid crystal optical element can be stabilized and the liquid crystal optical element can always be operated at a temperature at which the optimum electro-optical characteristic is obtained.

[0016]

【Example】

(Embodiment 1) Hereinafter, a specific description will be given with reference to an embodiment. Embodiment 1 of the present invention is shown in FIG. 1 and will be described with reference to this. In the liquid crystal optical device according to the first embodiment, light emitted from a light source installed outside as a light source is guided from the input optical fiber 51, passes through the input interface 55, and is input from the first prism body 2A on the input side to the liquid crystal optical device. It is introduced inside the element 30. The output side is also provided with the second prism body 2B, the output interface 56, and the output optical fiber 52, which are substantially symmetrical to the input side.

As the input-side and output-side optical fibers 51 and 52 used as the light guiding means, fibers having a numerical aperture (NA) of 0.57 and having a multi-component glass as a core are bundled to form a bundle having a diameter of 5 mm. A fiber was used.

A convex lens is used for the input interface 55 and the output interface 56, and the light emitted from the bundle fiber 51 is collimated by the convex lens 55,
The convex lens 56 focuses parallel light on the bundle fiber 52 on the output side. The input interface 5 in FIGS.
5, output interface 56 and light guide means 51 and 5
Although it is described as a structure in which 2 and the prism bodies 2A, 2B, 3 and 4 are joined, they may be guided through the space as described above.

In order to more firmly fix and reduce the interface reflection light loss, a gradient index rod lens is used as an input interface and an output interface as shown in FIGS.
It is preferable that the input interface and the output interface are joined to the light guide means and the prism body, respectively. The prism bodies 2A, 2B and the liquid crystal optical element 30 are preferably made of an optical material having a similar refractive index, and they are bonded together by an optical adhesive or a coupling oil having a similar refractive index.

When light is guided in the liquid crystal optical element by utilizing the total reflection on the surface of the front substrate 31 of the liquid crystal optical element 30, the structure is simple and a high reflectance of almost 100% can be obtained. However, in order for total reflection to occur, the incident angle within the front substrate (refractive index n) must be equal to or greater than the critical angle θ _c (°) described by the following equation (1). sin (θ _c ) = 1 / n (1)

Therefore, the angle formed between the inclined surfaces of the prism bodies 2A and 2B and the front substrate of the liquid crystal optical element 30 is (90)
° -θ _c ) or higher. On the other hand, when the reflective film is formed on the surface of the front substrate 31 of the liquid crystal optical element 30, there is no restriction as in the formula (1), and therefore the prism bodies 2A, 2
The allowable range for forming B is wide.

The liquid crystal optical element 30 comprises a front substrate 31, a transparent front electrode 30A, a liquid crystal resin composite layer 30B, a non-transparent back electrode 30C which reflects light and also serves as a reflection means, and a back substrate 32. A temperature controller is provided on the back substrate 32 side. Further, it includes a drive circuit for driving the liquid crystal optical element, an electronic circuit for driving and controlling the temperature adjuster, and the like.

In the case of this embodiment, the interface between the glass and the air of the front substrate 31 of the liquid crystal optical element is used as the total reflection surface, and the reflection is made between the front substrate 31 and the back electrode 30C which also serves as a reflection means. By repeatedly passing through the liquid crystal solidified composite layer four times or more, the scattering ability can be further improved and the extinction ratio can be improved.

At this time, as shown in FIG. 1, the reflection at the interface between the glass front substrate 31 and the air is such that total reflection determined by the refractive index of the glass occurs. Alternatively, a metal mirror of aluminum or silver or a mirror such as a multilayer dielectric film may be formed. As the regular reflection reducing means, the surface of the front substrate 31 on which the front electrode 30A is formed is a frosted surface having fine irregularities.

Next, 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 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 the ordinary refractive index (n
It is preferable to use a liquid crystal solidified resin composite which is made to substantially coincide with _o ). 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. 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 comprising 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, the individual microcapsules do not have to be completely independent,
Liquid bubbles of individual liquid crystals may be communicated 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 type or a 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 onto a substrate provided with a transparent electrode as an electrode without using a sealing material. Then, after that, the other electrode-attached substrate may 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, etc., so that the injection step is simple and the productivity is high. Very good.

The uncured mixture of the nematic liquid crystal and the curable compound contains ceramic particles for controlling the substrate gap, plastic particles, spacers such as glass fibers, pigments, dyes, viscosity modifiers and the like. 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.

Next, other components will be described. As the front electrode 30A of the liquid crystal optical element 30, a transparent electrode such as ITO is formed on the glass front substrate 31 which has been frosted by etching or polishing with an acid solution. The unevenness formed by the frosting process may have any shape as long as it reduces the regular reflection on the surface from finally reaching the light guide means 52 on the emission side.

Therefore, the rectangular unevenness having many planes parallel to the reflecting surface 30C is not suitable, and the Δ-shaped unevenness which is an aggregate of inclined surfaces having an inclination angle is preferable. This tilt angle is related to the effective diameter of the light guiding means 51, 52, the input interface 55, the output interface 56, the angle of incidence on the liquid crystal solidified composite layer, the number of reflections, etc. That is, unnecessary interface reflection is removed as sharp Δ-shaped irregularities.

However, since the surface area increases as the angle becomes sharper,
The rate of interfacial reflection increases and the available transmitted light decreases. Therefore, it is preferable to use Δ-shaped irregularities having many tilt components that can reduce unnecessary interface reflection without causing a significant decrease in transmittance. In addition, since the liquid crystal optical device of the present invention does not require the uniformity of in-plane characteristics, unlike the display element, the size of the unevenness (pitch)
Although there is no strict restriction on the above, in the characteristic of the amount of transmitted light with respect to the applied voltage, when a sharper rise is required as in the case of on-off operation, the smaller the unevenness size (pitch) is, the more preferable.

On the other hand, the application of a dimmer or the like for fine control of the intermediate light intensity requires the characteristic of the transmitted light intensity with respect to a gentle applied voltage. It is preferable that the thickness is dispersed. In order to further reduce the interfacial reflection intensity generated between the transparent electrode formed on the uneven surface and the liquid crystal solidified composite layer, a low refractive index layer such as SiO ₂ or MgF ₂ is formed on the transparent electrode layer. It is preferably formed as an antireflection film. Further, as the reflecting surface 30C, a glass-made back substrate 32 on which an aluminum film is formed also as an electrode is used. In addition to the metal film, a transparent electrode may be laminated on the dielectric multilayer film mirror.

When using the total reflection generated at the interface between the reflecting surface of the front substrate 31 and the air, foreign matter and dirt on the surface cause deterioration of the total reflection efficiency, so that the surface has a smaller refractive index than the front substrate material. It is preferable to form a film, for example, a polymer having a fluorine-containing alicyclic structure (trademark: Cytop) as a protective film.

Further, when the liquid crystal solidified composite layer is in a transparent state, the reflection surface region where the light is totally reflected by the front substrate 31 is only a part as shown in FIG. When the layer is in the scattering state, the scattered light is incident on a wider range of the interface of the front substrate 31 with the air. In order to efficiently remove such unnecessary scattered light, it is effective to form a light absorber such as a black paint in addition to the required total reflection area.

A heat radiating plate containing a temperature sensor and an electric heater was attached to the back side of the reflecting surface of the liquid crystal optical element. Furthermore, an air-cooling fan was attached behind this heat sink so that the temperature could be adjusted by an electric heater and an air-cooling fan while monitoring the temperature so that the liquid crystal optical element was maintained at the set temperature.

A visible light source such as a halogen lamp, a Xe lamp or a metal halide lamp was guided to the incident side optical fiber 51 to be incident light. 1 between the electrodes of the liquid crystal optical element 30
An AC voltage was applied to a rectangular wave of 00 Hz, the effective voltage value was modulated by an external circuit, and the transmission and scattering state of the liquid crystal optical element was changed to obtain a dimmer. The optical characteristics were measured using the liquid crystal optical device using the optical fiber of the present invention and the transmission / scattering type liquid crystal optical display element manufactured in such a configuration. The results are summarized in Table 1.

In Table 1, the relative light transmittance is set to 100% in the comparative example. Further, the measurement is carried out in a constant temperature bath, the temperature means not the temperature of the liquid crystal display element but the ambient temperature of the optical device, and the measured extinction ratio is the applied voltage value of the liquid crystal optical element in the temperature range of 0 ° C to 50 ° C. The range of the light amount value ratio of the output side fiber 52 with respect to 0V and 30V is shown. As a comparative example, of the liquid crystal optical element having the structure shown in Example 1, the same optical characteristic evaluation was performed on the liquid crystal optical element having the flat surface as the front electrode 30A surface, and the results are shown.

[0047]

[Table 1]

From these results, it can be seen that the structure of the present invention achieves a dramatic improvement in the extinction ratio and stability while the optical loss is almost small. Therefore, by using the present optical device as a dimmer, the amount of emitted light corresponding to the applied voltage value can be adjusted arbitrarily and at high speed with little loss of light amount.

Further, in the present liquid crystal optical device, the light emitting end of the light emitting side optical fiber is installed toward the object to be illuminated, and the electric signal of the photodetector such as the photomultiplier tube or the Si photodiode is set by the lock-in amplifier. It can be used as a fiber type optical chopper necessary for optical measurement with a high S / N ratio. Compared with the conventional rotating window type chopper or vibration type chopper, small size and high speed optical chopping becomes possible.

The reflecting surface 30C may be a metal reflecting mirror such as aluminum or an optical interference multilayer film reflecting mirror. In the former case, the reflecting surface also serves as an electrode, which facilitates manufacturing,
In addition, the device can be constructed without complicating the structure. In the latter case, it is 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 multilayer film, and for a specific semiconductor laser wavelength used in optical communication. There is a degree of freedom to form a mirror having a reflectance of 100%.

(Embodiment 2) This will be described with reference to FIG. In the present embodiment, unlike the configuration of the first embodiment, both the front electrode 30A and the back electrode 30C are transparent electrodes, and both are substantially flat surfaces. Further, by sufficiently opening the distance d between the liquid crystal solidified composite layer 30B and the reflection surface of the reflection means, the liquid crystal solidified composite layer 30B having a thickness t and the surfaces of the transparent front electrode 30A and back electrode 30B are separated. The optical path of the regular reflection light generated at the interface is shifted in the in-plane direction of the liquid crystal optical element so that the unnecessary interface reflection light does not reach the light guide means 52 on the emission side. You can

This shift amount δ depends on the liquid crystal solidified substance composite layer 3
It is described as δ = 2d · tan θ by the incident angle θ of the incident light on 0B and the distance d between the reflecting surface of the reflecting means. In order to prevent unnecessary interface reflected light from reaching the light guide 52 on the outgoing side, the shift amount δ may be equal to or larger than the irradiation width L of the incident light on the liquid crystal solidified composite layer 30B. In this way, if the shift amount δ required to remove the unnecessary interface reflected light is determined, the interval d is determined accordingly. Considering the function as the substrate on one side for holding the liquid crystal solidified composite layer, the thickness d needs to be a certain value or more. On the other hand, if d is a large value, the liquid crystal optical element becomes large, and therefore d = 0. 5-3
About 0 mm is preferable.

Further, in this embodiment, a silica type single mode optical fiber having a core diameter of 10 μm for optical communication information transmission is used as the light guiding means 51, 52, and a gradient index rod lens is used as an input interface. 5
5, used as the output interface 56. As the optical fiber guided light, semiconductor laser light with wavelengths of 1.3 μm and 1.5 μm in the near infrared region was used. Each of the prism bodies 2A and 2B includes an input interface 55, an output interface 56, and a front substrate 31 of the liquid crystal optical element 30 as shown in FIG.
It is joined with an optical adhesive.

A dielectric multilayer mirror that reflects 99% or more of light in the wavelength band of the guided light is formed only on the reflection surface portion of the surface of the front substrate 31 of the liquid crystal optical element 30, and the surface of another front substrate 31. A light absorber is applied to. In the present embodiment, since the reflection on the surface of the front substrate 31 is performed not by the total reflection but by the dielectric multilayer mirror, it is not necessary to satisfy the total reflection condition described by the equation (1).

Therefore, in order to prevent unnecessary guided light such as scattered light at the liquid crystal solidified composite layer 30B or light having a wavelength other than guided light from being totally reflected by the surface of the front substrate 31 and partly guided. , The tilt angles of the prism bodies 2A and 2B are set so that they are incident on the liquid crystal solidified substance composite layer 30B at an incident angle smaller than the critical angle θ _c determined by the equation (1), and unnecessary light is guided inside the liquid crystal optical element 30. Reduced the rate of waves.

In this embodiment, the liquid crystal solidified composite layer 30B is used.
And the front substrate 31 and the back substrate 32 were made of borosilicate glass having a thickness of about 1 mm. As a result, 1
A high extinction ratio of 0 ⁶ or more and a response speed of 2 msec or less were stably obtained.

(Embodiment 3) Description will be made with reference to FIG. In this embodiment, unlike the structure of the first embodiment, both the surface of the front electrode 30A and the surface of the back electrode 30C are substantially flat. Back substrate 32
Light is reflected by a dedicated light reflecting means 90 provided on the back side of the. In addition, the transparent front electrode 30A and the back electrode 30C, which are in contact with the liquid crystal solidified composite layer 30B, are the light reflecting means 9
By setting an appropriate inclination angle not parallel to 0, unnecessary interface reflection inside the liquid crystal optical element 30 can be removed.

In the case of the present invention in which light is transmitted in a one-to-one relationship without being focused, a flat surface precision of the substrate is not required so much. Therefore, a thin and inexpensive film substrate such as PET film is used. There is no problem even if it is used and a long film forming technique is used.

In this embodiment, the liquid crystal solidified substance composite layer 3 is formed.
The unnecessary regular reflection light of the interface at 0B is the output side optical fiber 5
2 so that the extinction ratio is not deteriorated by being incident on the front electrode 3
0A, the liquid crystal solidified composite layer 30B and the back electrode 30C, and the reflecting surface 90 of the light reflecting means are arranged so as to be inclined.

The inclination angle α is relative to the dispersion angle θ of parallel light incident on the liquid crystal solidified composite layer, which is determined by the effective diameters of the light guiding means 51 and 52 and the focal lengths of the input / output interfaces 55 and 56. If it is set to θ or more, unnecessary reflected light generated at the interface of the liquid crystal solidified composite layer is guided by the light guiding means 5.
It never hits 2.

In the case of a single wire fiber for optical communication, the core diameter is 2
N.O. A. Is also small, the inclination angle α
Is preferably in the range of 0.1 ° to 10 °. On the other hand, in the case of a fiber for optical energy transmission, since it is used as a bundle fiber and the like, the fiber diameter of the optical transmission part is as large as about 2 to 20 mm, so the inclination angle α is preferably in the range of 1 ° to 20 °.

Further, even when a large inclination angle α is set,
Although the interface reflected light is removed, most of the light obliquely enters the liquid crystal solidified composite layer, and the index
Haze easily occurs due to mismatching, and the effective transmittance is reduced. 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. Therefore, it is preferable to keep the tilt angle α within the above range.

In this embodiment, the same effective diameter as in Embodiment 1 is 5 m.
Since a bundle fiber of m and a convex lens with a focal length of 30 mm are used, the dispersion angle θ of the parallel light incident on the liquid crystal solidified composite layer is about 10.6 °, and the liquid crystal solidified composite layer is used as a light reflection means. It was tilted by 12 ° with respect to the reflecting surface.

In this embodiment, in order to perform temperature adjustment more accurately and to ensure reproducibility of optical characteristics even in a wide environment temperature, the reflecting mirror is a cold mirror and the temperature adjuster 60 is used.
An electronically controlled Peltier element and a heat sink with a temperature sensor embedded were used as.

When the optical characteristics were evaluated with the configuration of FIG.
The extinction ratio 320 was always obtained in a wide environment temperature of −20 ° C. to 80 ° C., and the applied voltage vs. optical output characteristics were stable with respect to temperature changes. Also, the cold mirror property is 10 compared to the aluminum product.
%, The relative light transmittance was higher than that of Comparative Example 1.

Further, in the liquid crystal optical device having the configuration of the above-described embodiment, the liquid crystal optical element 30 can be forcedly temperature-controlled from the reflection surface side (back side of the back substrate 32). As a forced temperature control method, a radiator plate is attached and cooled by an air cooling fan. Alternatively, a Peltier element, an electric heater and a temperature sensor may be attached to control the temperature by heating and cooling so that the temperature is maintained at a constant temperature.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, a single-line optical fiber for optical communication is used, an incident side optical fiber 51 and an emitting side optical fiber 52, a prism body 3 having a V-shaped total reflection surface, and a reflection type liquid crystal optical functioning as a light modulator. The element 30 and the temperature adjuster 60, and further a drive circuit for driving the liquid crystal optical element, an electronic circuit for driving and controlling the temperature adjuster 60, and the like.

Further, the liquid crystal optical element 30 and the prism body 3
And a first interface 55 consisting of a rod lens
Or a second interface 56 and the like,
Each optical element is bonded together with an optical adhesive.

The glass surface of the substrate 31 on which the transparent front electrode 30A (ITO or the like) on the light entrance surface or the exit surface side of the liquid crystal optical element 30 is formed is frosted. A specific LD (laser diode) that is incident light as the reflecting surface
A transparent electrode was formed on the back substrate 32 on which the optical interference multilayer mirror that reflects the emission wavelength of the LED or the LED was formed to form the counter substrate. As the optical fibers on the entrance side and the exit side of the liquid crystal optical element, an FC connector connection type silica fiber and a step type gradient index optical fiber for multimode transmission with a core diameter of 50 μm were used.

As an input interface and an output interface, wavelength = 1.8 mm, pitch = 1/4, lens length = 4.73 mm, wavelength 830 nmL.
Graded index type rod lens for D (NS
G: Selfoc lens) was used.

BK7 of optical glass is used as the prism body, and substantially parallel light emitted from the input interface 55 (rod lens) is used for one prism total reflection surface 3a.
After being reflected by the prism-type liquid crystal optical element 30, the regular reflection light reflected by the reflection means (also used as the back electrode 30C) is reflected by the other prism total reflection surface 3b. After that, the light is guided by the output interface. This light is further condensed on the end surface of the optical fiber 52 on the emission side and becomes emission light.

In this embodiment, as in the second embodiment, a heat radiating plate in which an electronically controlled Peltier element and a temperature sensor are embedded is used as the temperature controller 60, and stable optical characteristics can always be obtained in a wide environmental temperature. I did it. Table 2 shows the results of measurement of the optical characteristics of the liquid crystal optical device using the optical fiber of the present invention and the transmission / scattering type display element produced in such a configuration. In Table 2, the relative light transmittance is 100% for the comparative example.

The measurement is carried out in a constant temperature bath, and the temperature means not the temperature of the liquid crystal display element but the ambient temperature of the optical device, and the measured extinction ratio and the response speed are from -20 ° C to 60 ° C.
In the temperature range of 0V and 1 applied to the liquid crystal optical element
It evaluated with respect to 00V.

As a comparative example, the ITO electrode surface on the light incident side of the liquid crystal optical element having the conventional structure is flattened and the temperature adjuster 6 is used.
Similar optical characteristic evaluation results are also described for the structure in which 0 is not mounted.

[0075]

[Table 2]

From these results, it can be seen that the structure of the present invention achieves a dramatic improvement in extinction ratio and stability with almost no optical loss. Therefore, by using the present 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 with little light amount loss.

In this embodiment, the prism body 3 having a V-shaped total reflection surface is used, but another structure may be used. For example, the optical path may be bent by a spherical surface or an aspherical surface. The extinction ratio can be further improved by changing the shape of the total reflection surface of the prism body 3 and the ratio of the core diameter of the optical fiber.

(Fifth Embodiment) A fifth embodiment will be described with reference to FIG. In this embodiment, substantially parallel light emitted from the input optical fiber and the input interface 55 (rod lens) to the prism body 4 is incident on the reflection type liquid crystal optical element 30 by the trapezoidal prism body 4 at an appropriate incident angle. Then, the light is totally reflected by the back electrode 30C and is again totally reflected by the upper total reflection surface 4a of the prism body 4. When the prism body 4 is arranged at an appropriate position, the light is output to the output interface 56 on the emission side after the reflection is repeated a plurality of times by the reflection surface and the total reflection surface of the liquid crystal optical element.

With such a structure, the extinction ratio can be further improved by allowing light to pass through the liquid crystal solidified composite layer four times or more as compared with the structure in the conventional example in which light passes only twice. . Although FIG. 5 shows the case where the liquid crystal solidified composite layer passes through four times, the number of passing times can be changed by appropriately changing the length of the prism body 4 (the length in the left-right direction of the upper surface 4a) and the incident angle. It can be arbitrarily changed by a multiple of 2.

The reflective liquid crystal optical element 30 may have the same structure as that of the first embodiment, or it may be externally attached without contacting the liquid crystal solidified composite layer 30B to form a reflective surface as in the second or third embodiment. You may provide the light reflection means by a reflective surface. In this case, as the means for reducing regular reflection, both surfaces of the front electrode and the back electrode are frosted surfaces, or is the liquid crystal solidified composite layer provided with a space from the reflection surface of the light reflection means as in Example 2. 3, the reflective surface of the light reflecting means and the liquid crystal solidified substance composite layer 3
0B may be appropriately inclined (see FIG. 3) to remove the interface reflection between the liquid crystal solidified composite layer 30B and the electrode surface.

The size (pitch) of the irregularities is 2 to 200 μm.
The degree of unevenness (10-point average depth) R _Z is preferably about 0.1 to 10 μm. In addition, when light is obliquely incident on the liquid crystal-solidified composite layer in this way, the index matching with the liquid crystal at the time of transparent is the most optimal combination (that is, haze is reduced) at the light incident angle. It is preferable.

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. Etc., but when the above light source is used, it is considered that the diagonal is 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.

[0085]

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

As means for reducing the regular reflected light, irregularities are formed at the interface between the liquid crystal solidified composite layer and the transparent electrode, or the distance d between the liquid crystal solidified composite layer of the liquid crystal optical element and the light reflecting means. Is 10 with respect to the thickness t of the liquid crystal solidified composite layer.
Double or more, or the liquid crystal solidified composite layer and the reflecting surface are not parallel but inclined, and further, the interface reflection that directly enters the optical fiber at the device interface with air without passing through the liquid crystal solidified composite layer By applying black paint to the surface part, interface reflection light, which is the main cause of background noise, is reduced.

As a result, improvement of the extinction ratio and its dynamic range in the variable light function according to the applied voltage was achieved. In addition, since the temperature controller can be installed on one side of the liquid crystal optical element due to the configuration, by forced temperature control,
It has become possible to maintain the temperature at which the optimum characteristics of the liquid crystal optical element are always expressed regardless of the ambient environment temperature, and stable dimming and optical shuttering have been realized.

As a concrete example, there is stroboscopic illumination as a light source for illumination having a high-speed shutter function. That is, high-speed shooting becomes possible. For 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 continuously photographed with shuttering illumination, the locus is recorded in steps. As an example of using the programmable characteristic that the shutter timing can be arbitrarily changed and has high-speed followability, it is used as a measurement light source that turns on and off in a certain cycle, and only the signal light of that cycle is amplified and detected to be weak. S / even in high signal light or in environments with a lot of noise light
Measurement with a high N ratio is possible.

Further, in the present invention, the light does not pass through the air, but only the solid medium whose refractive index is close to each other optically passes through, so that the loss becomes small.

As a result, 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. In particular,
By performing shuttering in synchronization with a photodetector such as an optical chopper for lock-in amplifier, S / N
The ratio was improved. Also, in the field of optical communication, an optical attenuator having a fixed attenuation rate, which has been conventionally used, is now able to obtain an optical attenuator with variable attenuation by adjusting an applied voltage.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a liquid crystal optical device of Example 1 (uneven surface) of the present invention.

FIG. 2 is a schematic cross-sectional view of a liquid crystal optical device according to a second embodiment (thickness) of the present invention.

FIG. 3 is a schematic cross-sectional view of a liquid crystal optical device according to Example 3 (tilt) of the present invention.

FIG. 4 is a schematic view of a cross section of a liquid crystal optical device of Example 4 (V-type prism) of the present invention.

FIG. 5 is a schematic view of a cross section of a liquid crystal optical device of Example 5 (trapezoidal prism) of the present invention.

FIG. 6 is a plan view showing a configuration of a conventional example.

[Explanation of symbols]

 2A: Input side prism body 2B: Output side prism body 30: Liquid crystal optical element 30A: Front electrode 30B: Liquid crystal solidified compound layer 30C: Back electrode 31: Front substrate 32: Back substrate 51: Input side optical fiber 52: Output Side optical fiber 55: Input side interface 56: Output side interface 60: Temperature controller

Claims (7)

[Claims] 1. A liquid crystal in a solidified matrix between a light source, a first light guide means, a first prism body, and a front substrate on which a front electrode is formed and a back substrate on which a back electrode is formed. The liquid crystal and solidified substance complex held in the state of being sandwiched is sandwiched, and the liquid crystal is controlled by the electric field generated between both electrodes. When the refractive index of the liquid crystal does not match the refractive index of the solidified substance matrix, light is scattered, A liquid crystal optical element having a liquid crystal solidified material composite layer that transmits light when the refractive index substantially matches the refractive index of the solidified material matrix, a light reflecting means, a second prism body, and a second light guide. Means is provided, the light reflection means is arranged in the middle of the optical path from the light source to the second light guide means, and the liquid crystal solidified composite layer is arranged close to the reflection surface side of the light reflection means, Alternatively, the light emitted from the light source is placed close to the reflective surface The light is passed through the light guide means and is made incident on the inside of the liquid crystal optical element from the incident portion of the first surface of the liquid crystal optical element through the first prism body. It is reflected one or more times, and finally is emitted from the emission part of the first surface, and then is incident on the second light guide means via the second prism body, and the liquid crystal is solidified from the incidence part to the emission part. Two object complex layers
^After passing ⁿ times (an integer of 1 or more), the amount of light is controlled by the light transmittance of the liquid crystal solidified composite layer, and at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is controlled. Roughness is provided at the interface, or the distance d between the liquid crystal solidified composite layer of the liquid crystal optical element and the light reflecting means is set to 1 with respect to the thickness t of the liquid crystal solidified composite layer.
Or at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is inclined by a predetermined angle α with respect to the reflecting surface of the light reflecting means. Liquid crystal optical device. 2. Liquid crystal solidification in which liquid crystal is dispersed and held in a solidified matrix between a light source, a first light guide means, a front substrate having front electrodes and a back substrate having back electrodes. The liquid crystal is controlled by the electric field generated between the two electrodes by sandwiching the object complex, 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 becomes A liquid crystal optical element including a liquid crystal solidified composite layer that transmits light when the refractive index substantially matches, a light reflecting means, and a prism body including a second light guiding means and a reflecting surface are provided, The light reflection means is arranged in the middle of the optical path from the light source to the second light guide means, and the liquid crystal solidified composite layer is arranged close to the reflection surface side of the light reflection means or is in close contact with the reflection surface. The light emitted from the light source passes through the first light guide means. The light is guided from the incident surface of the prism body to the inside of the prism body, and further made to enter the inside of the liquid crystal optical element from the incident portion of the first surface of the liquid crystal optical element. Are reflected one or more times respectively, and finally are made to enter the second light guide means from the exit surface of the prism body, and the liquid crystal solidified compound composite layer is formed between the entrance surface of the prism body and the exit surface of the prism body. ^After passing ⁿ times (an integer of 1 or more), the amount of light is controlled by the light transmittance of the liquid crystal solidified composite layer, and at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is controlled. Roughness is provided at the interface, or the distance d between the liquid crystal solidified composite layer of the liquid crystal optical element and the light reflecting means is set to 1 with respect to the thickness t of the liquid crystal solidified composite layer.
Or at least one of the interfaces intersecting the optical path inside the liquid crystal optical element is inclined by a predetermined angle α with respect to the reflecting surface of the light reflecting means. Liquid crystal optical device. 3. The liquid crystal optical device according to claim 1 or 2, wherein the interface is provided with unevenness, wherein the interface formed by the front electrode is provided with unevenness. 4. The liquid crystal optical device according to any one of claims 1 to 3, wherein the interface is provided with irregularities, wherein the interface formed by the back electrode is provided with irregularities. 5. The liquid crystal optical device according to any one of claims 1 to 3, wherein the interface is provided with irregularities, wherein the light reflecting means is also used as a substantially flat back electrode of the liquid crystal optical element. Liquid crystal optical device. 6. The liquid crystal optical device according to claim 1, further comprising a temperature adjuster provided on the back substrate side. 7. An illuminating device comprising the liquid crystal optical device according to claim 1.