JP2001194635A - Focal position variable space modulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focal position variable space modulation device good in the image-formation performance. SOLUTION: The device is equiped with a refractive index variable material 30 disposed in the luminous flux, which deflects the incident light, a plurality of electrode pair 11, 21; 12, 22; 13, 23 disposed in the shape of a concentric circle, in the shape of a concentric ellipse, or in the shape of a partial power concentric ellipse, whose both sides are faced almost mutually on both sides of the refractive index variable material 30, and a voltage impressing means which applies the voltage between electrode pair 11, 21; 12, 22; 13, 23. About the refractive index variable material 30, space between the first area of the mutually opposing spacing of electrode P of the first electrode pair and the circumscription of it, and the second area of the mutually opposing spacing of electrode P of the second electrode pair adjacent to the first electrode pair and the circumscription of it, is devided, so that the influence of the other electric field is decreased mutually between the first and second areas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial light modulator having a variable focal position, and more particularly to a spatial light modulator having a variable focal position suitable for a liquid crystal lens.

[0002]

2. Description of the Related Art Conventionally, there have been plastic molded Fresnel plates, photographic dry plate type diffraction gratings, glass plate scribe type diffraction gratings, photographic dry plate type holograms, photoresist type holograms, but the transmission or reflection optical path is fixed during manufacturing. ing.

[0003] Techniques for deflecting the transmitted or reflected light path include, for example, the following.

Japanese Patent Application Laid-Open No. 10-62609 proposes a microlens whose focal length can be adjusted. This changes the focal position of one lens, and is applicable only to a lens having a small diameter pupil. In addition, if the size is simply increased, a necessary spherical surface (aspheric surface) cannot be obtained, and it is considered that practical use is difficult.

Japanese Unexamined Patent Publication No. 9-184965 discloses a technique in which a deflecting means for deflecting an incident optical path has power, but the lens power does not change and the pupil of the photographing lens is effectively used. Can not.

Laser Research, Vol. 25, No. 10, 68
7, "(Liquid Crystal Microlens)" (1997) discloses a technique for creating a microlens array and changing the focal position. However, several tens of micrometers in diameter
Can only be formed.

[0007] Japanese Patent No. 2628630 (Japanese Patent Laid-Open No. Sho 62-1)
Japanese Patent No. 70933) discloses a method in which electrodes are arranged concentrically and different voltages are sequentially applied to ring-shaped electrodes. However, this method is a method of controlling the alignment and refractive power between electrodes sandwiching a liquid crystal, and does not describe the alignment displacement and refractive power displacement between ring electrodes. The orientation also tilts between the ring electrodes due to the influence of the electrodes,
The refractive power also changes, and this part generates unnecessary refractive power, which causes a flare.

Japanese Patent Application Laid-Open No. Hei 9-304748 discloses a technique having a multi-ring structure, in which a radial electrode width is reduced from the center to the periphery from the center to the periphery to have a lens effect. . However, although it is designed to have a refractive power change only between the electrodes, the orientation between the multiple annular electrodes also tilts due to the effect of the electrodes, and the refractive power also changes, so this part is necessary. Generates refracting power that does not cause flare. Also,
Although the upper and lower electrodes are asymmetrical and only one type of electrode voltage is used, this is not the direction to solve the flare problem.

[0009]

Hitherto, it has been described that a liquid crystal is used as a variable focal point position (double focus lens system) with a small device. this is,
Electrodes are formed on two substrates and formed into a multi-ring shape, and a lens effect is provided by changing the refractive index of the liquid crystal between the electrodes sandwiching the liquid crystal. When no electric field is applied, the liquid crystal is oriented parallel to the substrate and has no lens effect. When an electric field is applied, the orientation angle of the liquid crystal changes,
We have used the fact that the refractive power changes.

However, although a method for controlling the alignment and refractive power between the electrodes sandwiching the liquid crystal has been described, the behavior regarding the alignment displacement and the refractive power displacement generated between the ring electrodes is not described. Actually, the orientation between the ring electrodes is tilted due to the influence of the electrodes, and the refractive index also changes. This portion generates unnecessary refractive power and causes flare.

The occurrence of flare causes erroneous sensing such as focus detection, and when used in a photographing system, the flare reduces image quality and cannot be said to have good lens performance.

Further, the refractive index between the electrodes sandwiching the liquid crystal is constant, and the refractive power of the entire device is a quantized refraction for each ring. These two factors do not result in a lens with good imaging performance.

Accordingly, a technical problem to be solved by the present invention is to provide a variable focal position spatial modulation device having good imaging performance.

[0014]

The present invention provides a variable focal position spatial modulation device having the following configuration to solve the above technical problems.

The variable focal position spatial modulation device comprises a variable refractive index material disposed in a light beam and capable of deflecting incident light, and concentric and concentric ellipses substantially opposed to each other on both sides of the variable refractive index material. A plurality of electrode pairs arranged at intervals in a shape or a concentric magnification ellipse, and voltage applying means for applying a voltage between the electrode pairs, and the refraction is performed by a voltage applied between the electrode pairs. This is a type in which the refractive index distribution of the variable index material changes and the focal position changes. For the variable refractive index material, a first region between and around the first pair of electrodes facing each other and a second region of the second electrode pair adjacent to the first pair of electrodes facing each other. The first and second regions are separated from each other and between the first and second regions so as to reduce the influence of the other electric field.

The term "magnification" refers to a case where the magnification in the orthogonal direction is not the same, and includes, for example, a case where the magnification differs in the X direction and the Y direction, a case where the magnification changes with distance, and the like.

In the above configuration, when a voltage is applied between the electrode pair by the voltage applying means, an electric field is generated. The refractive index variable material has a refractive index distribution corresponding to the electric field. The region of the variable refractive index material is divided for each electrode pair, and the influence of an electric field in an adjacent region in each region is reduced. This makes it easy to control the refractive index of the variable refractive index material, and makes it possible to obtain a desired refractive index distribution that improves the imaging performance.

For example, when the above-described configuration is applied to a liquid crystal lens, there is no luminous flux harmful to image formation and flare is reduced as compared with a conventional liquid crystal lens using only a change in the refractive index of an electrode region. Further, it becomes easy to obtain a refractive index distribution characteristic required as a lens, and it is possible to configure a focal position variable lens having good imaging performance.

Preferably, an electric field shielding material is disposed between the first region and the second region.

Thus, it is easy to eliminate the influence of the electric field in the adjacent region and achieve a desired refractive index distribution.

Preferably, an electric field reducing electrode is provided adjacent to at least one of the electrode pairs to reduce an electric field formed by the at least one electrode.

By appropriately applying a voltage to the electric field reducing electrode, the adverse effect of the electric field generated by the electrode pair on the adjacent region can be reduced. The electric field reducing electrode can be formed simultaneously with the electrode pair. Also, even if the refractive index variable material is not physically divided into regions,
It can be separated electromagnetically.

Preferably, the variable refractive index material is a liquid crystal.

The liquid crystal can obtain a refractive index distribution according to the electric field, and is easy to manufacture. Therefore, it is easy to configure a liquid crystal lens and the like.

Preferably, the variable refractive index material is a Pockels effect material or a Kerr effect material.

That is, the Pockels effect material whose refractive index is proportional to the electric field strength and the Kerr effect material whose refractive index is proportional to the square of the electric field strength have a desired refractive index distribution. This is preferable in the configuration for obtaining the same.

The present invention also provides a spatial light modulation device having the following configuration.

The variable focal position spatial modulation device comprises a variable refractive index material disposed in a light beam and capable of deflecting incident light, and concentric and concentric ellipses substantially opposite to each other on both sides of the variable refractive index material. A plurality of electrode pairs arranged at intervals in a shape or a concentric magnification ellipse, and voltage applying means for applying a voltage between the electrode pairs, and the refraction is performed by a voltage applied between the electrode pairs. This is a type in which the refractive index distribution of the variable index material changes and the focal position changes. A light-shielding mask for blocking a light beam that passes through a portion of the variable refractive index material that does not have a desired refractive index distribution is provided. Thereby, the light beam is transmitted only through a portion having a desired refractive index distribution in the variable refractive index material.

In the above configuration, when a voltage is applied between the electrode pair by the voltage applying means, an electric field is generated. The refractive index variable material has a refractive index distribution corresponding to the electric field.

A light beam that passes through a portion of the variable refractive index material that does not have the desired refractive index distribution is a light beam that does not contribute to the desired convergence or divergence performance, for example, a convergence opposite to the desired light,
Alternatively, the light flux may be a divergent light beam or a light beam causing a flare. This unnecessary light beam is cut by the light shielding mask. On the other hand, a light beam that passes through a portion having a desired refractive index distribution in the variable refractive index material is a light beam that contributes to a target convergence or divergence performance. Since this light beam passes through the variable refractive index material without being cut by the light shielding mask, it is possible to provide an image forming performance for obtaining one image or a virtual image forming performance. Since unnecessary light beams are cut, the aperture ratio decreases in terms of performance, but high imaging performance can be achieved at relatively low cost.

Preferably, the light-shielding mask includes an electrode facing region between the electrodes facing each other in each of the electrode pairs, and a substantially half of one side from a substantially center of the non-electrode facing region between the adjacent electrode facing regions. Blocks the light beam.

When a voltage is applied to each electrode pair, generally,
An electric field is formed substantially symmetrically between adjacent pairs of electrodes, whereby the refractive index distribution curve of the variable refractive index material becomes substantially symmetrical in a concave or convex shape. The refractive index distribution curve required is only half (on one side of the gradient). In general, the light-shielding mask having the above-described configuration transmits an electrode-facing region where a gradient of a refractive index does not occur or is small even if it occurs, and substantially half of a non-electrode-facing region having a refractive index distribution curve having a gradient opposite to a desired gradient. The light beam is blocked so that only the light beam having the desired lens performance passes.

Preferably, the light-shielding mask is disposed adjacent to any one of the electrode pairs.

Since the light beam that has passed through the variable refractive index material becomes convergent or divergent light, cutting off unnecessary light beams on only one side can reduce manufacturing errors and the effects of edges of the light-shielding mask.

Preferably, the variable refractive index material is a liquid crystal.

The liquid crystal can obtain a refractive index distribution according to the electric field, and is easy to manufacture. Therefore, it is easy to configure a liquid crystal lens and the like.

Preferably, the variable refractive index material is a Pockels effect material or a Kerr effect material.

That is, the Pockels effect material whose refractive index is proportional to the electric field strength and the Kerr effect material whose refractive index is proportional to the square of the electric field strength have a desired refractive index distribution. This is preferable in the configuration for obtaining the same.

More specifically, for example, the present invention does not use a substantially constant refractive index between the electrodes sandwiching the liquid crystal, but uses a gradually changing refractive index distribution between the ring electrodes to reduce the flare. The present invention provides a liquid crystal lens having good image forming performance by reducing the influence and eliminating image forming unevenness due to refractive power quantization.

That is, conventionally, for example, each prism element of a Fresnel lens is a collection of prisms formed of a plane, but in the present invention, each prism element of a Fresnel lens is a collection of lenses formed of a lens spherical surface. It can be said that.

According to the present invention, it can be said that a lens in which the refractive index distribution lens (Grin lens) is realized by liquid crystal and the refractive index distribution structure is like a Fresnel lens is realized.

The fields of application of the present invention are, for example, the following areas.

This is related to the case where sensing is performed using a light beam that has passed through the pupil of the objective lens on which light from a subject enters. For example, assume that the device is a camera and the sensing is focus detection.

More specifically, when the focus position is obtained by using the imaging area sensor of the digital camera, for example, in the case of the contrast method, the maximum contrast position is obtained, and the focus lens of the photographing lens is moved to output the contrast detection. Find the peak position of the curve and focus.

On the other hand, there is also a method of obtaining the focus position without moving the focus lens. The two image sensors are displaced in the direction of the optical axis of the photographing lens, and contrast outputs are compared to assume a focus position. In this case, the focus position is roughly predicted by interpolating (extrapolating or interpolating) the difference between the two output values. In this case, whether or not calculation is possible depends on the amount of defocus at the initial position of the lens. At this time, when the amount of blur is large, when the arrangement position of the two sensors in the optical axis direction (the amount of focus shift) is large, the focus position is easy to find. I want to set the position of the sensor in the optical axis direction (the amount of focus shift) small. At the time of large blur, the two sensors want to be largely separated in the direction of the optical axis.
I want to improve the accuracy of (end). In addition, it can be said that high-speed AF is possible even with large blur.

Thus, the conventional AF of the contrast method takes a long time. However, the present invention makes it possible to perform the AF quickly.

In addition, the number of types that can be used for sensing with an objective lens having a different pupil diameter increases. That is,
In contrast to sensing which is problematic due to the exit pupil, the luminous flux can be changed according to the pupil position, so that the sensing range increases.

Thus, for example, a lens whose focus can be detected only by a lens having a bright F-number can be used with the present invention to perform AF even with a dark lens.

Alternatively, since the focus sensing can be designed only to detect the light beam at a place where the F value is dark, the accuracy is lowered. However, the present invention enables high-precision AF.

Further, when the lens is used as a focus lens in a photographing lens, the focus can be adjusted. Conventionally, since the glass lens had to be moved by a considerable amount in the optical axis direction for focusing, it was necessary to increase the size of the photographing lens.

It should be noted that, in a general optical system design, in order to obtain a necessary focal position, it has been necessary to replace the lens itself or move one or more lenses in the present invention. Accordingly, the optical system can be easily formed in a small size.

In the conventional proposal of a liquid crystal lens, only the characteristic of a convergent lens is described, but application to a divergent lens is possible. By controlling the rate of change of the refractive index of the liquid crystal by the width of the electrode, an arbitrary refractive index distribution can be obtained, and the diverging lens (concave lens) characteristic can be configured.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, liquid crystal lenses according to embodiments of the present invention will be described with reference to the drawings.

First, a conventional liquid crystal lens will be described with reference to FIG.

As shown in the schematic sectional view of FIG. 1A, the liquid crystal lens 500 includes substrates 510 and 520 arranged in parallel.
The liquid crystal 530 is sealed with sealing materials 538 and 539, and electrodes 511, 512, 521 and 522, and an alignment film 5 are provided on opposite surfaces of the substrates 510 and 520.
18,528 are formed. Electrodes 511, 512;
The reference numerals 521 and 522 are formed concentrically with the optical axis O and opposed to each other. And
In the electrode facing region P between the facing electrodes, the orientation of the liquid crystal 530 can be changed by an electric field generated by applying a voltage to control the liquid crystal 530 at a specific refractive index. However, in the non-electrode facing region N where the adjacent electrode does not face, the light distribution of the liquid crystal 530 is not changed, and the liquid crystal 530 has no refracting power.

Therefore, the refractive index differs between the region N and the region P, and as shown in FIG. 1B, the refractive index of the liquid crystal lens 500 has an intermittent substantially rectangular distribution. In other words, as shown in FIG.
Corresponds to a Fresnel lens having a plurality of linear lens surface elements 540. Then, as shown in FIG. 1D, the light flux 552 that has passed through the electrode facing region P is
The light beam 554 that has passed through the non-electrode facing region N
Did not form an image at the focal point 550, and the image formability was low.

In practice, even if the orientation of the liquid crystal 530 does not change (even if it is horizontal), the liquid crystal 530 is refracted because it has a different refractive index from air. In addition, due to the electric field generated between the electrodes, the orientation is not changed only in the electrode facing region P, but is widened. In particular, due to the latter, in the non-electrode facing region N,
The refractive index gradually increases as the distance from the electrode facing region P increases, resulting in power.

In view of this, in contrast to the conventional method of controlling the refractive index of the electrode facing region P to form an image, the present invention controls the refractive index of the non-electrode facing region N as shown in FIG. , The image forming property is improved. In the figure, 10 and 20 are substrates,
Reference numerals 18 and 28 denote alignment films, 30 denotes a liquid crystal, 38 and 39 denote sealing materials, O denotes an optical axis, and L denotes an incident direction of a light beam.

That is, as shown in the schematic sectional view of FIG. 2A, the widths of the concentric ring-shaped electrodes 12, 13; 22, 23 formed on the substrates 10, 20 are made larger than the width of the non-electrode facing region P. And electric field cutoffs 32 and 34 are provided,
It is divided into ring-shaped cells. As a result, FIG.
As shown in (b), the refractive index is changed at a desired inclination in the non-electrode facing region N. As shown in FIG. 2C, the refractive index distribution includes a plurality of curved lens surface elements 4.
It is equivalent to a Fresnel lens having 0. And FIG.
As shown in (d), most of the light flux 54 passes through the non-electrode facing region N and forms an image at the focal point 50, so that the image forming property can be improved. Further, the light beam 52 passing through the electrode facing region P is also formed into an image at the focal point 50, so that the image forming property can be further improved.

The liquid crystal lens of the present invention can be specifically configured in various modes as described below.

When the cells are not separated as shown in the cross-sectional view of FIG. 3A, the refractive index repeats peaks as shown in FIG. 3B under the influence of electric field changes between adjacent electrodes. It becomes such a distribution. In order to obtain a desired image formability, it is necessary that one mountain-like refractive index distribution has a distribution including only one of the rising portion and the falling portion. For this purpose, the following configurations are possible.

FIG. 4A is a sectional view of a main part showing a configuration in which light shielding portions 62 to 65 for cutting unnecessary light beams are provided. In this configuration, the light shielding unit 62 to 65 blocks the light beams passing through the portion corresponding to the range does not contribute to imaging performance Q _T (see FIG. 3 (b)) of the refractive index distribution curve, contribute range Q Only the portion corresponding to _S allows the light beam to pass. The light shielding portions 62 to 65 can be easily formed by forming an opaque film, for example. However, in this method, as shown in FIG. 4B, one side of the mountain-shaped refractive index distribution curve is cut, so that the total light amount is reduced to approximately half.

FIG. 4 shows a convergent lens (convex lens).
However, in the case of a divergent lens (concave lens), the unused portion QT of the refractive index distribution curve is used, so the portion ( _T ) opposite to FIG. The light-transmitting portion) is masked.

As another configuration, the effective area is expanded by dividing into cells.

FIG. 5 shows the electric field shields 31, 33, 35,
37 is a configuration diagram in the case where cells are divided by 37. FIG. The electric field shields 31, 33, 35 and 37 are made of, for example, copper or a material used for a transparent electrode (indium oxide, tin oxide, ITO
That is, indium tin oxide or the like is used.

As shown in FIG. 7A, a desired refractive index distribution can be obtained by changing the distance between the electrodes.

That is, by increasing the distance between the electrodes near the center of the optical axis O and by narrowing the distance between the electrodes near the optical axis O, as shown in FIG. Make a difference.

In order to obtain a refraction distribution very similar to the shape of a so-called Fresnel zone plate, using the symbols in FIG.
The width of each cell, a>b>c> d > For e (1) the maximum refractive index of each _{cell, Q A> Q B> Q} C> Q D> Q E (2)

In this case, each of the electrodes 12-16, 22-
26 can be applied with the same voltage.

By dividing each cell, a light beam deflected in a direction opposite to a desired direction can be eliminated, and the transmittance can be improved. Further, the refractive index distribution characteristics of the non-electrode facing region can be improved, and the lens effect (imaging performance) can be improved. It is also possible to set an aspheric lens effect.

As shown in FIG. 8, a desired refractive index distribution can be obtained by changing the voltage applied to the electrodes.

In FIG. 8, for each of the cells A to F, the voltage applied to each of the electrodes X _{1 to} X ₆ is changed stepwise by resistors R _{1 to} R ₅ , and the maximum voltage V _A to each of the cells A to F is changed. V _{F
But, V F> V E> V} D> V C> V B> V A (3) The overall power is controlled in such a way as The power source V drives a voltage of, for example, 1 kHz and 5 V in AC. In this case, it is necessary to synchronize the light receiving means. Note that there is no need for synchronization in the case of a material that can maintain a constant refractive index with a DC power supply.

In this case, by setting the central portion of the optical axis O to a low voltage and the peripheral portion of the optical axis O to a high voltage, as shown in FIG.
The liquid crystal 30 in the cell near the center can be in a state close to horizontal alignment, that is, a high refractive index, and the liquid crystal 30 in the cell near the periphery can be in a state of strong alignment, that is, a low refractive index. The rate distribution effect can be exhibited.

[0074] That is, the distribution of the refractive index for each cell A~D, using the symbols shown in FIG. _{9 (a), Q A>} Q B> Q C> Q D (4) Q A '> Q B _' > Q _{C '} > Q _{D '} (5).

Also, an aspherical effect can be added, and the lens performance is improved.

Each cell can have various configurations as shown in FIGS.

FIG. 10 shows that each liquid crystal cell is formed of a concentric cylindrical wall W _1.
ＷW ₆ clearly separates each annular cell. Partition walls W ₁ to _W-6 consisting of an electromagnetic shielding material, it is possible to avoid the influence of the electrodes of adjacent cells, set high refractive power. However, an effective when the incident angle of the liquid crystal Seruhe is nearly perpendicular, wall W ₁ to _W-6 for separating the angles attaches it blocks the optical path, an adverse effect.

[0078] Figure 11, in order to set a high refractive power of each cell, a ground electrode _{S 2 ~S 6, T 2 ~T} 6 respectively in the vicinity of the electrodes _{X 2 ~X 6, Y 2 ~Y} 6 It is set.
It has the effect of eliminating the influence of the adjacent cell. Since control is performed from the ground, the control range of the potential difference is wide and can be set reliably.

FIG. 12 shows walls W ₁ to W 4 clearly separating cells.
Sets the W _5, on both sides of each wall W _i, respectively a pair of electrodes S _i and T _i, the construction of arranging the pair of X _i and Y _i.
The applied voltage controls the outside and inside of the ring-shaped cell with V and V2, makes it possible to finely control the electric field distribution and expand the effective area of the optical path deflection.

FIG. 13 shows the configuration of each cell itself, which is the same as that of FIG. 11. However, unlike FIG. 11, the electrodes Y _{1 to} Y ₆ are also grounded. The voltage V is changed by the microcomputer.

FIG. 14 shows the structure of each cell itself which is the same as that of FIG. 10, but differs from FIG. 11 in that the same voltage is applied to each electrode, and the magnitude can be changed by the variable resistor R.

FIG. 15 shows an example in the case of a concave lens.

In order to form a concave lens, an electric field seal
Do wall W_Two~ W₆And electrode X₁~ X₆, Y ₁~ Y₆The convex lens
It is arranged in the opposite positional relationship to the system, and the order of voltage magnitude is also reversed.
I do.

That is, by setting a high voltage near the central portion of the optical axis O and a low voltage near the peripheral portion of the optical axis O, as shown in FIG.
As shown in FIG. 5 (b), the refractive index distribution curve is concave, with a low refractive index near the center and a high refractive index near the periphery, so that a refractive index distribution effect as a concave lens can be exerted.

[0085] That is, the distribution of the refractive index for each cell A~F is the use of symbols in the _{figure, Q F> Q E> Q} D> Q C> Q B> Q A The _{(6) Q F '> Q} E'> Q D '> Q C'> Q B '> Q A' (7).

Whether the refractive index curve is concave or convex can be determined by the dimensional ratio of the width of the opposing electrodes X _i , Y _i (i = 1, 2,...). In FIG. 15, the electrodes Y _i (i = 1,
2,...) Are widened and the rise of the refractive index is made slow, thereby giving the character of a concave lens (diffusion lens) system. The electrodes X _i , Y _i (i = 1, 2,...)
If the widths are the same, the characteristics of the convex lens system (convergent lens) are provided as described above. This characteristic is determined at the time of design.

In the above description, a case was described in which a nematic liquid crystal having a positive dielectric anisotropy was used as a liquid crystal material. However, a transparent solid or liquid, which has a refractive index when an electric field is applied, is also used. Changing materials may be used.

Materials having a Pockels effect in which the change in the refractive index is proportional to the strength of the electric field (for example, BaTiO ₃ , KH ₂ PO)
₄ (KHP), KD ₂ PO ₄ (KDP), LiNbO ₃ , Zn
O), or a material utilizing the Kerr effect proportional to the square of the electric field (for example, CS ₂ ).

Note that, depending on the material, the distribution of the voltage applied near the center of the optical axis and the vicinity of the periphery may be reversed.

That is, the characteristics of the materials used have been described in connection with the embodiment in which the refractive index decreases as the electric field energy increases and the refractive index increases as the electric field energy decreases. In that case, for example, as shown in FIG.
The relationship of 2 to 34 is opposite to that of FIG.

Further, by setting the central portion of the optical axis at a high voltage and the peripheral portion at a low voltage, the lens characteristics can be improved. In this case, for example, as shown in FIG.

FIG. 18 shows an arrangement according to the characteristics of the material and the purpose of use. In this figure, is a case where the applied voltage is constant and is controlled only by the electrode interval,
Is a case where the voltage is changed to improve the lens characteristics.

The purpose of improving the convex lens characteristics is to reduce the refractive index of the peripheral portion. In the case of a concave lens, the refractive index of the peripheral portion is made high.

The liquid crystal lens of each embodiment described above can be a liquid crystal lens having good imaging performance by controlling the refractive index of the liquid crystal.

The present invention is not limited to the above embodiment, but can be implemented in various other modes.

For example, in the embodiments described above, since the electrodes are concentric rings, it is necessary that the wiring of each electrode has a multilayer structure. However, in order to reduce the cost, FIG. As described above, if a spiral electrode is used, the number of wiring layers can be reduced. In this case, the performance is lower than in the case of the concentric electrode, but the wiring becomes easier.

The device of the present invention is installed and used in a light beam of an optical lens as shown in FIG. 19, for example. FIG.
As shown in FIG. 9 (a), even when used as a device through which a light beam passes, as shown in FIG. 19 (b), a reflection surface is provided on the side opposite to the incident surface to be used as a device that reflects the light beam. Is also good.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a conventional liquid crystal lens.

FIG. 2 is an explanatory diagram of a liquid crystal lens of the present invention.

FIG. 3 is an explanatory view of a conventional liquid crystal lens.

FIG. 4 is an explanatory diagram of a liquid crystal lens of the present invention.

FIG. 5 is an explanatory diagram of a liquid crystal lens of the present invention.

FIG. 6 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 7 is an explanatory diagram of a liquid crystal lens of the present invention.

FIG. 8 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 9 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 10 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 11 is an explanatory diagram of a liquid crystal lens of the present invention.

FIG. 12 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 13 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 14 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 15 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 16 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 17 is an explanatory diagram of the liquid crystal lens of the present invention.

FIG. 18 is a table summarizing the configuration of the liquid crystal lens of the present invention.

FIG. 19 is an explanatory diagram of how to use the device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Substrate 11-16 Electrode (electrode pair) 18 Alignment film 20 Substrate 21-26 Electrode (electrode pair) 28 Alignment film 30 Liquid crystal (refractive index variable material) 31, 33, 35, 37 Electric field shield 32, 34 Partition 38, 39 Sealing material 40 Lens surface element 50 Focus 52, 54 Light flux 62-65 Light shielding part (light shielding mask) L Incident direction N Non-electrode facing area O Optical axis P Electrode facing area S ₁ -S ₆ electrode (Electric field reducing electrode) T ₁ through T ₆ electrode (field relief electrode) V, V ₂ supply (voltage applying means) W ₁ to _W-6 walls (field shielding material) X ₁ to X ₆ electrodes (an electrode pair) Y ₁ to Y ₆ electrode (electrode pairs )

Claims (10)

[Claims] 1. A variable-refractive-index material disposed in a light beam and capable of deflecting incident light, and concentrically, concentrically-elliptical, or concentrically magnified on both sides of the variable-refractive-index material substantially opposite to each other. A plurality of pairs of electrodes arranged at intervals in an elliptical shape, and voltage applying means for applying a voltage between the pair of electrodes, wherein the refractive index of the refractive index variable material is changed by the voltage applied between the pair of electrodes. In the variable focal position spatial modulation device in which the distribution changes and the focal position changes, the variable refractive index material includes a first region between the electrodes facing each other of the first electrode pair and around the first electrode pair, It separates between the opposing electrodes of the second electrode pair adjacent to the electrode pair and the second region around the electrodes, and the first and second regions are less affected by the other electric field. What I did Wherein, the focal position varying spatial modulation device. 2. The spatial light modulation device according to claim 1, wherein an electric field shielding material is disposed in at least a part between the first region and the second region. 3. The focal position according to claim 1, further comprising an electric field reducing electrode adjacent to at least one of said electrode pairs for reducing an electric field formed by said at least one electrode. Variable spatial modulation device. 4. The spatial light modulation device according to claim 1, wherein the variable refractive index material is a liquid crystal. 5. The spatial light modulation device according to claim 1, wherein the refractive index variable material is a Pockels effect material or a Kerr effect material. 6. A variable-refractive-index material disposed in a light beam and capable of deflecting incident light, and concentrically, concentrically-elliptical, or concentrically magnified on both sides of the variable-refractive-index material substantially opposite to each other. A plurality of pairs of electrodes arranged at intervals in an elliptical shape, and voltage applying means for applying a voltage between the pair of electrodes, wherein the refractive index of the refractive index variable material is changed by the voltage applied between the pair of electrodes. A focal position variable spatial modulation device in which the distribution changes and the focal position changes, comprising: a light-blocking mask that blocks a light beam that passes through a portion of the variable refractive index material that does not have a desired refractive index distribution. Variable position spatial modulation device. 7. The light-shielding mask includes a light flux for an electrode-facing region between electrodes facing each other in each of the electrode pairs and a half of one side from a substantially center of a non-electrode facing region between the adjacent electrode facing regions. 7. The device according to claim 6, wherein
13. The variable focal position spatial modulation device according to claim 1. 8. The focal position variable spatial modulation device according to claim 6, wherein the light shielding mask is arranged adjacent to one of the electrodes of the electrode pair. 9. The spatial light modulator according to claim 6, wherein the variable refractive index material is a liquid crystal. 10. The spatial light modulator according to claim 6, wherein the variable refractive index material is a Pockels effect material or a Kerr effect material.