JP3324083B2 - Optical element fabrication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element, and more particularly, to an optical element having birefringence and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an optical crystal such as calcite has been used as an optical element (hereinafter referred to as a birefringent optical element) having different characteristics depending on the polarization of incident light. When an optical crystal such as calcite is used, it is necessary to transmit an optical crystal on the order of centimeters (cm) to separate a light beam at intervals of several millimeters. Therefore, when an optical crystal is used for a two-dimensional optical switch that changes the transmission path of an optical signal by changing the direction of a light beam, as described above,
Since the beam separation ability is low, a large crystal is required,
There is a problem that the two-dimensional optical switch becomes large.

Also, there is a problem that the optical crystal is expensive even if it is small. For this reason, a birefringent optical element capable of realizing small size and low cost is desired.

As another birefringent optical element, an optical element in which a silicon substrate is processed into a diffraction grating structure showing structural birefringence has been developed (MICRO OPTICS NEWS).
7 (3) 1989, pp. 30-35).

FIG. 11 is a diagram showing a cross section of the birefringent diffraction grating. As shown in FIG. 11, this birefringent diffraction grating has a silicon substrate 801 with a diffraction grating structure having a period d _{1 and} a diffraction grating structure d _1.
> Is obtained by machining the structure period d ₂ is d _2. Bending light by structures diffraction effect of the period d _1, the structure of the period d ₂ causes a birefringence. When light whose polarization plane is perpendicular to the periodic direction of the grating is incident, the light is transmitted straight without diffraction, but when light whose polarization plane is parallel is incident, diffracted light is obtained.

[0006]

However, in the conventional birefringent diffraction grating, since the effect of the shape of the element is used, the element fabrication becomes complicated, the materials used are limited, and the cost is high. In particular, there is a problem that it is difficult to make the grating interval d ₁ of the diffraction grating small and increase the polarization angle of light.

In this device, since it has a simple shape, a plurality of orders of diffracted light are generated in principle. In addition, the optical path length amplitude cannot be made variable and the wavelength selectivity cannot be provided. Since it was difficult to form a complicated striped structure, it was impossible to reproduce an image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical element which can be easily manufactured.
It is to provide a technology that can be manufactured .

Another object of the present invention is to provide a large-area optical element.
It is to provide a technology that can be manufactured .

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0017]

In order to solve the above-mentioned object, the present invention provides a light-transmitting polymer resin having an optical axis in a specific direction.
With a structure in which multiple liquid crystal microscopic bodies are aligned
A method for manufacturing an element, wherein the light-transmitting polymer resin and the liquid
Using a lens group or hologram on the mixture with crystals
Irradiate the light condensed in a shape, the translucent polymer resin and the
The light intensity distribution in the mixture with the liquid crystal is made to have a sawtooth shape,
Curing with a structure according to the degree distribution, the optical path length distribution becomes a sawtooth shape
Characterized in that it.

[0018]

[0019]

[0020]

[0021]

[0022]

According to the method for producing an optical element of the present invention, a polymer tree
Use lens group or hologram for mixture of fat and liquid crystal
Irradiating the light condensed in stripes, the light-transmitting polymer resin
The light intensity distribution in the mixture of
By curing with a structure corresponding to the light intensity distribution of
An optical element having a sawtooth-like path length distribution was realized.

[0023]

[0024]

[0025]

[0026]

[0027]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and their repeated description will be omitted.

[0028] (Embodiment 1) FIG. 1 is a schematic diagram for explaining a reference example of the optical element of the present invention, FIG. 1 (a) is a perspective view showing a schematic configuration of the optical device, FIG. 1 ( (b) is a diagram for explaining the operation of this optical element. In FIG. 1A, 101 is a region of a light-transmitting substance, and 102 is an optically anisotropic region composed of liquid crystal molecules.
The anisotropic shape of the liquid crystal molecules 102 schematically represents the refractive index anisotropy.

As shown in FIG. 1A, the region of the light-transmitting substance
The optical element of the reference example is configured by repeatedly arranging the region 101 and the liquid crystal in a striped pattern. The liquid crystal is oriented so that the direction with the higher refractive index matches the direction of the stripes.
Further, the refractive indices of the translucent substance and the liquid crystal in the minor axis direction (direction in which the refractive index is small) were made to match. The optical path length of the optical element is as shown in the graph. The solid line indicates the optical path length for light whose polarization direction is parallel to the stripe, and the broken line indicates the optical path length for light perpendicular to the stripe.

As shown in FIG. 1B, a linearly polarized incident light beam whose polarization direction is perpendicular to the fringe is applied to this optical element.
Hit 103. Since the refractive indices of the region 101 and the region 102 match with respect to this polarized light, the optical element does not act as shown in the graph of FIG.
An emitted light beam (transmitted light) 104 is obtained. When the polarization direction of the incident light beam 103 is rotated by 90 degrees and the polarization direction and the direction of the stripe are matched, the refractive indices of the region 101 and the region 102 are not equal to each other with respect to this light, and the left and right sides of FIG. As shown in the graph, an optical path length distribution is formed, and the optical element behaves as a diffraction grating, so that a diffracted emitted light beam (diffracted light) 105 is obtained.

That is, it can be seen that different outgoing light directions can be changed depending on the polarization state of the incident light. That is, it has the same effect as an optical crystal having a refractive index.

The angle between the emitted light beam 104 and the emitted light beam 1105 is called a separation angle. The separation angle α is expressed as follows using the period d of the stripe and the wavelength λ of the light to be used.

[0033]

## EQU1 ## Here, n indicates the order of diffraction, and n = 0, 1, 2,...
And

The use of the formation method described later can reduce the interval between stripes. In particular, in the optical element of the present embodiment having a fringe period of 0.5 μm, 1
The separation angle of 45 degrees was realized as expected with the next diffraction light. If higher-order diffracted light is used, polarization at an even larger angle is possible.

In FIG. 1 (b), the number of outgoing light beams 105 is two for each of the upper and lower sides. However, as can be seen from equation (1), a large number of diffracted light beams are generally obtained. This means that the light beam is also split. It is obvious that the distribution ratio of the light amount to the divided light beam can be changed by changing the distribution of the liquid crystal or the thickness of the element in the light traveling direction.

When the plane of polarization of the incident light is in the above-mentioned intermediate position, it is equivalent to a combination of the above-mentioned two linearly polarized lights, so that the emitted light beam 104 and the emitted light beam 105 are superimposed simultaneously.

In this case, the resin is used, but any material may be used as long as it is translucent. Further, the liquid crystal is used, but is not limited to the liquid crystal, and may be any optically anisotropic body having a uniform optical axis. Further, the method of aligning the optical axes is not limited to directing the optical axes in a specific direction. For example, as long as the optical axis is limited to one plane, the region may be in a state showing birefringence.

Although FIG. 1 shows two types of regions, the present invention is not limited to this, and may be more than two types. Although the refractive index distribution in FIG. 1 is a rectangular wave, it may be an arbitrary distribution, and may have a distribution in the traveling direction of incident light.

The distribution of the refractive index is controlled by controlling the distribution of the light-transmitting substance and the optically anisotropic material, including the anisotropy.

FIG . 2 shows Embodiment 1 of the optical element according to the present invention.
FIG. 2A is a schematic diagram for explaining FIG.
The element is not completely separated from the light-transmissive material region and the optically anisotropic material region. This is an example in which a refractive index distribution is obtained by changing the refractive index distribution. Contrary to FIG. 2A, the region may be isolated on the light-transmitting substance side. Also,
The control may be performed based on not only the number density but also the size of the area. Further, it is not necessary for one of the regions to be isolated in an island shape, and both may be controlled continuously depending on the amount of appearance of the region.

FIG. 2B shows an example in which the same element is manufactured by using a mixture 108 of a transparent substance and an optically anisotropic substance. The line density in FIG. 2B schematically represents the density of the optically anisotropic body.

In the optical element of this embodiment, the refractive index distribution is obtained by changing the concentration of the optically anisotropic body.

Although the refractive index of the light-transmitting substance and the refractive index of the optically anisotropic substance with respect to ordinary light are made to match, they may be different. When the refractive index of the translucent material is between the maximum value and the minimum value of the refractive index of the optically anisotropic body, the incident light is directed in the direction in which the refractive indices of the translucent solid and the optically anisotropic body are equal. When the planes of polarization are matched, the element transmits the incident light without polarization. Further, the optically anisotropic body is uniaxial, but may be biaxial.

When the liquid crystal and the resin are used, for example, the optical element of the present invention is thin and highly flexible, so that it can be deformed into an arbitrary shape such as a curved surface or used in a movable portion. Becomes

FIG. 2C is an example in which a plurality of optical elements of the present invention are stacked. For example, as shown in FIG. 2C, two optical elements having different ratios of the light-transmitting substance and the optically anisotropic region are stacked. In this case, since the optical path lengths of the two superimposed images are asymmetric, the diffracted light 109 of a specific order can be converted into another diffracted light 105 or transmitted light 10.
Can be stronger than 4.

Here, the ratio between the translucent material and the optically anisotropic region was changed, but one or more of the grating period, the distribution of the stripes in the stripe structure, the element thickness, and the constituent materials were changed. May be overlapped.

(Embodiment 2) FIGS. 3A and 3B are schematic views for explaining Embodiment 2 of the optical element according to the present invention. FIG. 3A is a perspective view showing a schematic configuration of the optical element of Embodiment 2. () Is a diagram for explaining the operation of the optical element shown in (a).

The optical element of this embodiment is an optical element having a sawtooth optical path length distribution, and as shown in FIG.
For example, the region 20 made of a light-transmitting substance such as a light-transmitting resin
The optical path length was set to a sawtooth shape by the distribution of 1 and, for example, an optically anisotropic region 202 such as a liquid crystal. The refractive index of the light-transmitting resin is made to match the refractive index of the optically anisotropic body with respect to ordinary light, and the optical axis of the anisotropic body is made parallel to the direction of the stripes. The distribution of the optical path length is, as shown in the left graph of FIG. 3 (a), a sawtooth wave as shown by a solid line for light whose polarization direction is parallel to the stripe, and a constant as shown by a broken line for light perpendicular to the stripe. Become.

When the polarization plane of the incident light beam 203 is perpendicular to the direction of the stripes, the outgoing light becomes the outgoing light beam 204 as it is, similarly to the optical element of the first embodiment. Assuming that the polarization plane of the incident light beam 203 is parallel to the direction of the stripes, the optical element becomes a diffraction grating, and the outgoing light becomes a polarized outgoing light beam 205. A diffraction grating having a sawtooth optical path length distribution is generally called a blazed grating,
When the optical path length amplitude is L and the light wavelength is λ,

[0050]

L = nλ (n is a natural number) The diffracted light generated at a specific wavelength that satisfies (2) is
There is only the n-th order, and therefore, the number of luminous fluxes of emitted light is one. In general, the directivity of other wavelengths also increases. Therefore, this optical element is effective as an element that changes the direction of light with low loss, that is, a polarizing element.
The separation angle α at this time is:

[0051]

## EQU3 ## d tanα = nλ (3) If the polarization direction of the incident light is in the intermediate state, the outgoing light flux 204 and the outgoing light flux 205 can be superimposed. That is, the ratio of the amount of light between the emitted light beam 204 and the emitted light beam 205 can be continuously changed.

If the refractive index of the translucent substance and the refractive index of both axes of the optically anisotropic body are all different values, the transmission state like the outgoing light beam 204 in FIG. Figure 3
Switching between polarized light beams such as the outgoing light beam 206 and the outgoing light beam 207 as shown in FIG. That is, it can be used as a Y-branch switching element.

That is, if this optical element is used, since there is no unnecessary diffracted light, a birefringent optical element having no element loss due to light leakage can be realized.

Note that the method of aligning the optical axes is not limited to directing the optical axis in a specific direction. For example, as in the case where the optical axis is limited to one plane, the region exhibits birefringence. Should be fine. Although FIG. 3 shows two types of regions, the present invention is not limited to this, and may be more than two types, and a refractive index distribution may be realized in a concentration or a minute region. The optically anisotropic body may be uniaxial or biaxial.

(Embodiment 3) FIGS. 4A and 4B are schematic views for explaining Embodiment 3 of an optical element according to the present invention. FIG. 4A is a sectional view showing a schematic configuration of the optical element of Embodiment 3. ) Is a diagram for explaining the operation of the optical element shown in (a), (c) is a cross-sectional view showing a schematic configuration of a modification of the optical element of Example 3, (d)
FIG. 9 is a diagram for explaining the operation of the optical element shown in FIG.

The optical element of Example 3 has a refractive index distribution not only in the surface direction of the element but also in the thickness direction of the element as viewed from the incident light. As shown in FIG. For example,
It has an element structure in which translucent material regions 301 and optically anisotropic regions 302 such as liquid crystal are alternately laminated.

As shown in FIG. 4B, an incident light beam 303 is applied to an optical element 306 having the structure shown in FIG. The long axis direction of the liquid crystal (the direction with a large refractive index) is indicated by an arrow 307, and the refractive index of the liquid crystal in the short axis direction is made to match the refractive index of the translucent substance.
When the polarization direction of the incident light beam 303 is perpendicular to the arrow 307, the refractive index distribution of the optical element 306 becomes uniform with respect to the incident light, so that the outgoing light becomes the outgoing light beam 304 as it is. Assuming that the polarization direction of the incident light beam 303 is an arrow 307, since this light has a refractive index distribution, the reflected light 305 due to the interference effect is applied to light of a specific wavelength determined by the laminated structure.
Is obtained.

That is, the element of the present invention has an effect of acting as a birefringent optical element capable of transmitting or reflecting light depending on polarization.

In the third embodiment, the striped structure is a layer structure having an equal interval. However, as shown in FIG. 4C, a structure in which the interval is non-uniform depending on the location and the layer is not a plane may be used. . FIG. 4D shows the operation of this optical element. This optical element 308
, An incident light beam 303 is applied. Arrow 3 in the long axis direction of the liquid crystal
07, the refractive index of the liquid crystal in the minor axis direction is made to match the refractive index of the translucent substance. When the polarization direction of the incident light beam 303 is perpendicular to the arrow 307, the refractive index distribution of the optical element 308 is
Since the light becomes uniform with respect to the incident light, the outgoing light becomes the outgoing light flux 304 transmitted as it is. The direction of polarization of the incident light beam 303 is indicated by an arrow 30.
Assuming that there is a refractive index distribution for this light,
The real image 310 is formed by the reflected light 309 because of the dimensional striped structure, that is, the structure of the volume hologram.

That is, the optical element of the third embodiment has the effect of acting as a high-performance birefringent optical element that transmits light or reproduces an image depending on polarization.

FIGS. 5A and 5B are diagrams for explaining a modification in which two images are switched by overlapping two optical elements according to the third embodiment. The optical element of this modification is obtained by superposing the optical element 308 of Example 3 in which the major axis of the liquid crystal is parallel to the arrow 307 and the element 312 in which the major axis of the liquid crystal is perpendicular to the arrow 307. .

As shown in FIG. 5A, the polarization direction is
When an incident light beam 303 parallel to 7 is applied, a real image 310 is formed by the reflected light 309 by the element 308. On the other hand, as shown in FIG. 5B, an incident light beam 315 having a polarization direction perpendicular to the direction 307 is transmitted through the optical element 308, reflected by the element 312, and a real image 313 is formed by the reflected light 314. By recording different images on the optical element 308 and the optical element 312, the two images can be switched.

The reproduction of the hologram may be performed on the transmission side instead of the reflection side as shown in FIG. The wavelength selectivity caused by the structure in the thickness direction can be a function of the element.

As can be seen from the above description, the present embodiment 3
According to this optical element, a high-performance birefringent optical element for reproducing a real image can be obtained.

(Embodiment 4) FIGS. 6A and 6B are schematic views for explaining Embodiment 4 of an optical element according to the present invention, wherein FIG. 6A is a sectional view showing a schematic configuration of the optical element of Embodiment 4. () Is a diagram for explaining the operation of the optical element shown in (a).

As shown in FIG. 6A, the optical element of the fourth embodiment has a striped structure composed of a light-transmitting substance 401 similar to that described above and an optically anisotropic body 402 such as a liquid crystal. In this configuration, a portion is sandwiched between electrodes 406. The electrode 406 is formed using a material that transmits light having a wavelength. electrode
When a voltage is applied to the power supply 406 by extending the power supply 407, the alignment direction of the liquid crystal is changed, and the refractive index anisotropy can be changed. The refractive index of the liquid crystal in the minor axis direction is made to match the refractive index of the light-transmitting substance, and the alignment direction is made parallel to the direction of the stripes.

The optical path length amplitude is given by the following equation when no voltage is applied.
Suppose that (2) is satisfied. The optical path length is a sawtooth wave like a thin solid line for light whose polarization direction is parallel to the stripe as shown in the graph of (b), and the saw height decreases as the thick solid line increases when the voltage is increased, and is sufficiently large. The voltage becomes uniform as shown by the broken line. When the polarization plane is vertical, the polarization becomes uniform regardless of the voltage, as indicated by the broken line.

When the polarization plane of the incident light beam 403 is perpendicular to the direction of the stripes, the output light beam 403 exerts the action of the optical element because the refractive index of the element for this polarized light beam is uniform regardless of the voltage applied to the element. Transmitted as is without receiving. When the plane of polarization is made parallel to the stripes, the incident light beam 403 is affected by the optical element. As shown in FIG. 6B, in the case of the sawtooth-shaped optical path length distribution, the diffracted light becomes one light flux as shown in the second embodiment. When no voltage is applied, the difference between the refractive index of the liquid crystal and the refractive index of the translucent substance is large, and the optical path length amplitude is large.
The value of n in (3) is large, and the outgoing light beam 405 becomes higher-order diffracted light, and is obtained in the direction in which the separation angle α is large (arrow 405).

Here, n under this condition is set to n ₀ . When a voltage is applied, the refractive index of the liquid crystal in the direction of the stripe of the refractive index anisotropy and the dielectric anisotropy decreases, so that the optical path length amplitude decreases. When voltage is applied, the equation is obtained under the condition of n = n ₀ -1.
Satisfy (2). At this time, the outgoing light beam 408 shown in FIG.
Diffracted light is obtained in the direction of. When the voltage is further increased, emitted light having a small separation angle, such as the emitted light beam 409, is obtained under the condition of n = n ₀ -2. By controlling the applied voltage in this manner, the value of n satisfying the expression (2) can be changed, and the separation angle can be changed discretely. That is, this element has an effect that the switching destination of the output direction by polarized light can be electrically selected.

In particular, when the refractive index of the translucent substance is made equal to the refractive index of the liquid crystal in the minor axis direction, when a sufficiently large voltage is applied, the liquid crystal is oriented perpendicular to the element plane. Transmits light regardless of direction.

Here, the refractive index distribution is triangular,
The present invention is not limited to this, and any stripe structure including a three-dimensional structure may be used. In this case, control of the direction, intensity, and division ratio of the light beam can be performed electrically. Further, the refractive index distribution may be controlled not by the region but by the concentration or the like as described above.
Although liquid crystal is used, other light-transmitting substances may be used as long as they can electrically control the refractive index anisotropy.

By dividing and attaching the electrodes,
Even a single element of the present invention can have different functions depending on the location. If a deformable electrode is used, the deformability described in the first embodiment is not impaired.

In this way, it is possible to obtain an active birefringent optical element capable of electrically controlling the direction, intensity, and division ratio of a light beam.

(Embodiment 5) FIG. 7 is a schematic diagram for explaining Embodiment 5 of the optical element according to the present invention.

The optical element of the fifth embodiment is an optical element having a structure using a plurality of optical elements, and has an increased degree of freedom for electrically controlling the direction, intensity, and division ratio of a light beam. .

That is, as shown in FIG.
3 is incident on the optical element 501 and the optical element 509 of the fifth embodiment, which are two superimposed ones.

As the optical element 501, for example, the alignment of a liquid crystal having a sawtooth-shaped optical path length distribution as shown in the second embodiment, and the polarities of the refractive index anisotropy and the dielectric anisotropy coincide with each other. An optical element is used in which the direction is parallel to the stripe direction and the refractive index of the short axis of the liquid crystal matches the refractive index of the translucent solid. First,
First, a case where the optical element 509 in FIG. 7 transmits all light by applying a sufficiently large voltage to the electrode 508 will be described.

Assuming that the polarization of the incident light beam 503 is parallel to the stripe direction of the optical element 501, the element is in a transmission state with respect to this light, and an output light beam 504 is obtained. When the polarization direction of the incident light beam 503 is rotated by 90 degrees, the optical element 501 behaves as a blazed diffraction grating, and the emitted light is obtained in the direction of the emitted light beam 505. That is, by controlling the plane of polarization, the output light beam 50
A switching operation between 4 and the emitted light beam 505 can be performed. Here, when a voltage is applied to the electrode 508, the amplitude of the optical path of the blazed grating is reduced, and the direction of the diffraction angle is discretely changed in the direction of the output light beam 506 when a voltage is applied, and in the direction of the output light beam 507 when the voltage is further applied. Changes to Therefore, the output light beam 508
By controlling the voltage to be applied to the switch, switching between the output light beam 504 and the output light beam 506 or switching between the output light beam 504 and the output light beam 507 can be switched.

Further, the optical element 509 of the fifth embodiment is operated. The lattice spacing of the optical element 509 is made coarser than that of the optical element 501. If a sufficient voltage is applied to the electrode 511, the optical element 509 does not operate regardless of the polarization of the incident light. When the voltage is lowered, it acts as a diffraction grating and polarizes light. Optical element
Since the grid spacing of 509 is coarser than that of optical element 501,
The angle at which the light of 501 is polarized becomes smaller than that of the optical element 509. Therefore, for example, by controlling the voltage applied to the outgoing light beam 511, the switching performed between the outgoing light beam 504 and the outgoing light beam 507 can be performed between the outgoing light beam 504 and the outgoing light beam 510. In other words, by using a plurality of optical elements of the present invention, the resolution when selecting the switching destination can be increased.

That is, the device functions as an element that switches the direction of the emitted light at an arbitrary resolution and switches the direction according to the polarization of the incident light.

In the description so far, it is assumed that the grid stripe directions are the same.
In this example, the light can be controlled only in the vertical direction, that is, one-dimensionally. However, if the direction of the stripes of the lattice is different, for example, the optical element of the present invention rotated by 90 degrees is two-dimensionally controlled. The direction of light switching can be selected. Also, the number of sheets to be superimposed is not limited to two.

(Embodiment 6) FIG. 8 is a schematic view for explaining a method of manufacturing an optical element according to Embodiment 6 of the present invention.
(a) is a schematic diagram showing a schematic configuration of an apparatus for manufacturing an optical element of the sixth embodiment, and (b) is a schematic configuration of another apparatus for manufacturing an optical element of the sixth embodiment. FIG.

The manufacturing method of the optical element of the sixth embodiment is shown in FIG.
As shown in (a), for example, a coherent light source such as a laser
The light that has exited 601 is split into a plurality of light beams by a half mirror 602, and the light beams are caused to interfere on an element material 604 made of a mixture of a light-transmitting substance and an optically anisotropic substance, and a standing wave is formed as interference fringes. obtain. The interval and shape of the standing wave can be controlled by the position and shape of the mirror 603. If plane waves interfere with each other, standing waves at equal intervals can be obtained. The optical element is manufactured by fixing the difference in electric field strength of the generated standing wave or the material effect formed by the heat effect or light effect caused by the light with the light from the light source 601.

For example, a light-curing resin which is cured by light from the light source 601 as a light-transmitting substance, and a liquid crystal as an optically anisotropic substance are used.
An element material 604 is obtained by mixing or dissolving liquid crystal in a resin. Curing occurs at the antinode of the standing wave induced by the light of the light source 601, and the liquid crystal concentrates on the nodes, thereby forming a striped structure. Since the alignment direction of the liquid crystal is limited by the direction of the growth of the cured resin, the manufactured element shows a sub refraction.

As shown in FIG. 8B, a mixture of a light-transmitting substance which is not cured by light from the light source 601 and an optically anisotropic substance is used as the element material 606. Liquid crystal may be used as the optically anisotropic body, and resin may be used as the translucent substance. When the dielectric constant of the liquid crystal is larger than that of the resin, the liquid crystal gathers in a portion where the electric field intensity of the standing wave is large due to the light irradiation of the light source 601. Due to the dielectric anisotropy, the direction in which the dielectric constant is large and the direction of the electric field are aligned and aligned.

In this state, light 605 is used to cure the resin.
By irradiating the device, the structure is fixed and an element is manufactured. Instead of curing with the light 605, the optical element may be cured by heating. Conversely, the dielectric constant of the light-transmitting substance may be increased to collect the light-transmitting substances.

FIG. 9 is a view for explaining an example of a method for controlling the orientation direction by applying an electric field to the element material at the time of curing the element in the element manufacturing method shown in FIGS. 8A and 8B. FIG. The element material 607 is sandwiched between the electrodes 608. When a voltage is applied by the electric field 609, an electric field is generated inside the element material. Since the liquid crystal has dielectric anisotropy, the liquid crystal is oriented so that the direction having a large dielectric constant coincides with the direction of the electric field.

In particular, when a liquid crystal in which the polarity of the dielectric anisotropy is inverted depending on the frequency, that is, a so-called two-frequency liquid crystal, is used, the liquid crystal is driven at a voltage having a frequency different from that at the time of curing of the element, and the liquid crystal is shown in the fourth embodiment. As described above, the characteristics can be electrically controlled. Here, an electric field is applied at the time of curing, but the orientation may be controlled by a magnetic field. Further, the curing of the resin depends on the light of the light source 601 but is not limited to this.

In the method of manufacturing the optical element shown in FIGS. 8A, 8B, and 9, an object is placed at the position of the mirror 603.
By making the scattered light from the object interfere with the other light,
The interference fringes become holograms, and an optical element having a distribution in the thickness direction as described in the third embodiment can be manufactured.

In FIG. 9, light is incident on the element material from one direction, but light may be incident on both sides. Also, the incident light need not be two light beams. In particular, a non-sinusoidal standing wave may be formed by including an integral multiple of harmonic components. Alternatively, the structure may be grown from one side by using a substance which cures from the side irradiated with light.

By using this manufacturing method, a birefringent optical element having a fine structure on the order of the wavelength of light can be realized. In addition, since there is no manufacturing process other than light irradiation, it can be made easy and inexpensive.

(Embodiment 7) FIG. 10 is a schematic diagram showing a schematic configuration of an embodiment for explaining a method of manufacturing an optical element according to Embodiment 7 of the present invention.

In the manufacturing method of the optical element of the seventh embodiment, the parallel light flux 701 is obliquely incident on the non-cylindrical lens group 702. The transmitted light becomes stronger in the region 703 and has a sawtooth shape with the focal plane 704 at the tip. By placing the element material in a region 705 surrounded by a broken line with the focal plane 704 as one end surface,
The light intensity distribution in the element material has a sawtooth shape. By curing the element material with this light, the optical element of Example 2 can be obtained. The tips of the sawtooth portions 703 may be overlapped to reduce the sawtooth period or by moving the lens and exposing a plurality of times when the element material is thin.

[0094] Instead of the non-cylindrical lens group, a light intensity distribution may be formed by placing a hologram that converges in a stripe shape.

The light intensity distribution to be formed depends on the structure of the element to be manufactured, and is not limited to the sawtooth distribution as in the seventh embodiment.

In the manufacturing method of the optical element of the seventh embodiment, since light exposure is used, even if the area is large, it is divided into a plurality of regions, and each area is exposed to manufacture an optical element having a large area. Can be.

Although the present invention has been described in detail with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments and can be variously modified without departing from the scope of the invention. Absent.

[0098]

As described above, according to the present invention, the following effects can be obtained.

(1) The optical path length is obtained by using optical interference.
An optical element having a sawtooth distribution can be obtained.

(2) By using optical interference , the optical element
It is possible to easily manufacture the element and obtain an inexpensive optical element .

(3) Writing the element structure with light
Thus, an optical element having a large area can be obtained.

[0102]

[0103]

[0104]

[0105]

[0106]

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a reference example of an optical element of the present invention,

FIG. 2 illustrates a first embodiment of an optical element according to the present invention .
Schematic diagram for

FIG. 3 is a schematic diagram for explaining Example 2 of the optical element according to the present invention;

FIG. 4 is a schematic view for explaining Example 3 of the optical element according to the present invention;

FIG. 5 is a view for explaining a modification in which two images are switched by superposing two optical elements according to the third embodiment;

FIG. 6 is a schematic diagram for explaining Example 4 of the optical element according to the present invention;

FIG. 7 is a schematic diagram for explaining Example 5 of the optical element according to the present invention;

FIG. 8 is a schematic diagram for explaining a method for manufacturing an optical element of Example 6 according to the present invention;

FIG. 9 is a view for explaining an example of a method for controlling an alignment direction in the method for manufacturing the optical element shown in FIG.

FIG. 10 is a schematic diagram for explaining a method for manufacturing an optical element of Example 7 according to the present invention;

FIG. 11 is a schematic view showing a conventional birefringent diffraction grating.

[Explanation of symbols]

101, 201, 301, 401: translucent substance, 102, 107, 202, 302: optically anisotropic region, 103, 203, 303, 403, 503: incident light beam, 10
4,105,109,204,205,206,207,304,305,404,405408,409,5
04, 505, 506, 507, 510: outgoing light flux, 106: translucent solid region, 108: optical element of Example 1 whose refractive index distribution is controlled by optically anisotropic concentration, 306, 308, 312 ... three-dimensional distribution Optical element of the present invention having a structure, 307 ... direction, 309,314 ... reflected light, 310,313 ... real image, 311 ... incident light flux, 402 ... Cuboid, 406,608 ・ ・ ・ electrode, 40
7,609 power supply, 501 optical element of the present invention (first sheet), 50
8 ... Electrode of the optical element of the present invention (first sheet), 509 ... Electrode of the optical element of the present invention (second sheet), 511 ... Electrode of the optical element of the present invention (second sheet), 601 ... Coherent light source, 602 ... Semi-transparent mirror, 603
..Mirrors, 604, 606, 607... A mixture of a light-transmitting substance and an optically anisotropic body, 605... Area, 704: focal plane, 705: place where element material is placed, 801: silicon substrate.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenya Kato 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Shigenobu Sakai 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-63-262602 (JP, A) JP-A-63-4205 (JP, A) JP-A-4-355424 (JP, A) JP-A-3-31803 (JP, A) JP-A-5-80310 (JP, A) JP-A-62-237426 (JP, A) JP-A-62-238530 (JP, A) JP-A-61-201214 (JP, A) 58) Field surveyed (Int.Cl. ⁷ , DB name) G03H 1/00-1/30 G02B 5/18 G02B 5/30 G03F 1/1335

Claims (1)

(57) [Claims] An optical axis is set in a specific direction in a translucent polymer resin.
With a structure in which multiple liquid crystal microscopic bodies are aligned
A method for producing an element, wherein a mixture of the translucent polymer resin and the liquid crystal includes a lens.
Irradiates light condensed in stripes using groups or holograms
And the light intensity in the mixture of the translucent polymer resin and the liquid crystal.
The distribution is sawtooth-shaped and cured with a structure corresponding to the light intensity distribution, and the optical path length distribution is
A method for manufacturing an optical element, wherein the optical element has a sawtooth shape.