JP2009092905A - Optical element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which is capable of preventing a local deformation and damage of a quartz lamina, is excellent in light resistance and has no transmission wavefront aberration and focus fluctuation, and to provide a manufacturing method of the optical element. <P>SOLUTION: The optical element 100A includes: a substrate 110; the quartz lamina 120; and an adhesive 130 for joining the substrate 110 and the quartz lamina 120. The quartz lamina 120 includes: a thin-walled part 121 as optically effective area which exhibits optical characteristics; and a frame part 122 thickly formed on the outer periphery of the thin-walled part 121. The frame part 122 is protruded to the side in contact with the substrate 110 and is integrally formed in a cross-sectionally approximately Π shape. The frame part 122 has a joint surface 122A on the side in contact with the substrate 110, the joint surface 122A is joined to the substrate 110 via the adhesive 130 and, thereby, the optical element 100A is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element used in an image display device and the like and a manufacturing method thereof.

Conventionally, an optical element having optical anisotropy has been used to compensate for a phase shift of a liquid crystal panel that causes a decrease in contrast of the liquid crystal panel or the like.
In particular, for projectors and the like, in order to achieve higher brightness and higher contrast, optical compensation of liquid crystal panels using optical compensators made of optically anisotropic materials such as quartz and sapphire, which are inorganic materials with excellent heat resistance, is used. (For example, refer to Patent Document 1).

JP 2004-317752 A

In Patent Document 1, an adhesive is applied to the surface of glass, and crystal or the like is pasted on the adhesive. In addition, when quartz or the like is used as the optical compensation plate, it is necessary to make the optical compensation plate extremely thin.
However, a thin plate processed crystal is extremely weak in strength and may be locally deformed or damaged, so it needs to be handled with care and has poor workability and productivity. Furthermore, there is a problem that the thickness of the crystal is uneven due to the viscosity of the adhesive, and the quality as an optical element is lowered. Further, if the entire surface of the optical compensation plate is pasted, an adhesive is present in the optically effective area, and this adhesive is an organic substance, so that the light resistance is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical element that can prevent local deformation and breakage of a quartz flake, is excellent in light resistance, and has no transmitted wavefront aberration and non-uniform focal point, and a method for manufacturing the same.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Application Example 1]
This application example is an optical element including a quartz thin piece and a substrate, and the quartz thin piece includes an optical effective area and a frame portion thicker than the optical effective area around the optical effective area, The frame portion is bonded to the substrate.

According to this application example, in the optically effective area of the quartz thin piece, a space is formed between the substrate and the substrate. Thereby, even if the deformation amount of the substrate and the quartz crystal plate is different during deformation due to thermal expansion, the deformation amount is uniformly absorbed in the optically effective area. Therefore, there is no deformation of the locally concentrated quartz flakes that occur when the whole is bonded, so that the optical thickness is kept uniform. Therefore, transmitted wavefront aberration and focus unevenness do not occur, and the function as an optical element can be maintained for a long time.
Further, since the frame portion of the crystal thin piece is attached to the substrate, the substrate plays a role of supporting the crystal thin piece. Therefore, since the quartz flakes are not deformed, the quartz flakes can be prevented from being damaged.
Furthermore, since no organic substance such as an adhesive is present in the optically effective area, the light resistance is excellent.

[Application Example 2]
This application example is an optical element composed of a quartz flake and a substrate, and the substrate includes an optically effective area and a frame part thicker than the optically effective area around the optically effective area, A frame part is joined to the crystal flake.
According to this application example, a space is formed between the quartz crystal flakes in the optically effective area of the substrate. Therefore, the same operational effects as described above can be achieved.

[Application Example 3]
In this application example according to application example 1 or application example 2, it is preferable that both sides of the crystal flakes are sandwiched between the substrates.
According to this application example, since the optically effective area of the quartz flake does not directly contact the outside, the quartz flake is not accidentally damaged. Therefore, an optical element excellent in handling, maintenance, and reliability can be provided.

[Application Example 4]
In this application example according to Application Example 1 or Application Example 2, it is preferable that both surfaces of the substrate are sandwiched between the quartz crystal flakes.
According to this application example, since two crystal flakes are used, higher luminance and higher contrast can be realized, and only one substrate is used, so that the material cost can be reduced. it can.

[Application Example 5]
This application example is an optical element composed of a quartz thin piece and a substrate, and the outside of the optical effective area of the quartz thin piece and the substrate are bonded via a spacer.
According to this application example, the crystal thin piece and the substrate are bonded via the spacer, so that a space is formed between the crystal thin piece and the substrate. Therefore, since no stress is applied to the quartz flakes, the quartz flakes are not uneven or broken.
Moreover, it is preferable to use materials, such as a metal and plastics, such as stainless steel and a polycarbonate, as a material used for a spacer. By attaching the spacer to the quartz thin piece first, the quartz thin piece without the frame portion has a strength that can be handled in the manufacturing process of the optical element, and damage prevention during work and workability are improved.

[Application Example 6]
In this application example according to application example 1 to application example 5, it is preferable that an antireflection film is laminated on at least one side or both sides of the crystal thin piece and the substrate.
According to this application example, the light transmittance of the optically effective area is significantly improved by the antireflection film. Therefore, higher brightness and higher contrast, which are functions as an optical element, can be realized. Here, it is preferable that the antireflection film is laminated on both sides of both the quartz thin piece and the substrate.

[Application Example 7]
In this application example according to application example 1 to application example 6, the space between the optical effective area of the quartz flakes and the optical effective area of the substrate is sealed, and the dew point is −10 ° C. or lower in the space. The dry gas is preferably sealed.
Here, the dry gas may be air or an inert gas such as nitrogen or argon. The dry gas having such a dew point is obtained by boiling liquid nitrogen, for example. The dew point is preferably −20 ° C. or lower, more preferably −30 ° C. or lower.
According to this application example, it is possible to suppress the occurrence of condensation in the space formed between the quartz thin piece and the substrate. Therefore, changes in optical characteristics due to condensation can be prevented.

[Application Example 8]
In this application example according to application example 1 to application example 7, it is preferable that the surface of the quartz flake is coated with an organic material and / or an inorganic material.
According to this application example, the quartz flakes themselves can be reinforced with the coating material, so that the quartz flakes can be prevented from being damaged. As the organic material and / or the inorganic material, it is preferable to use a mixture such as ethyl silicate, for example.

[Application Example 9]
This application example is a method for manufacturing an optical element, which is characterized in that the quartz crystal piece or the substrate is etched.
According to this application example, the crystal flake or the substrate can be processed into a predetermined shape easily and accurately by etching. In particular, since there is little possibility of damage to a quartz flake with low strength, an optical element having the above-described effects can be produced effectively.
An optical element having the above-described effects can be manufactured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
<Configuration of Optical Element 100A>
FIG. 1 is a sectional view showing an optical element according to the first embodiment of the present invention.
As shown in FIG. 1, the optical element 100 </ b> A includes a substrate 110, a crystal thin piece 120, and an adhesive 130 that joins the substrate 110 and the crystal thin piece 120.

The substrate 110 is a flat thin plate and has a thickness of 50 μm or more, more preferably 100 μm or more. If the thickness of the substrate 110 is less than 50 μm, a sufficient reinforcing effect cannot be obtained.
Examples of the material used for the substrate 110 include lithium tantalate, lithium niobate, quartz, silicon, and borosilicate glass.

  The crystal flake 120 includes a thin portion 121 that forms an optically effective area that exhibits optical characteristics, and a frame portion 122 that is formed thick on the outer periphery of the thin portion 121. The frame portion 122 protrudes to the side in contact with the substrate 110, and the quartz crystal piece 120 is integrally formed with a substantially pie-shaped cross section. The frame portion 122 has a bonding surface 122A on the side in contact with the substrate 110, and the bonding surface 122A is bonded to the substrate 110 via the adhesive 130, thereby forming the optical element 100A.

The thickness of the thin portion 121 that is an optically effective area is 3 μm or more and 15 μm or less, preferably 5 μm or more and 10 μm or less. If the thickness of the thin portion 121 is smaller than 3 μm, the refractive index anisotropy of the liquid crystal display element cannot be canceled sufficiently, and the contrast compensation effect cannot be obtained. On the other hand, if it is larger than 15 μm, the refractive index anisotropy of the crystal becomes too large, resulting in overcompensation and a decrease in contrast.
In such an optical element 100 </ b> A, a space P is formed between the substrate 110 and the quartz crystal piece 120. The thickness of the space P is preferably 150 μm or less, more preferably 100 μm or less. If the thickness of the space P exceeds 150 μm, the amount of deformation of the quartz thin piece 120 increases, and thus the space P is easily damaged. Further, when the quartz crystal piece 120 is formed by etching, the amount of digging is increased, and the possibility that a defect is generated at the time of manufacturing increases, which is not practical.
From the above, the thickness of the frame portion 122 is preferably 165 μm or less, which is the sum of the thickness of the quartz crystal piece 120 and the thickness of the space P.

The adhesive 130 is for bonding the substrate 110 and the bonding surface 122 </ b> A of the frame portion 122 of the crystal thin piece 120.
As the adhesive 130, commonly used adhesives and pressure-sensitive adhesives can be used. For example, UV curing adhesives such as “UT20” (trade name) manufactured by Adel Co., Ltd. and acrylic pressure-sensitive adhesives Agents and the like.

Next, a method for manufacturing the optical element 100A will be described.
<Method for Manufacturing Optical Element 100A>
In order to manufacture the optical element 100A, first, the substrate 110 and the quartz crystal piece 120 are formed in a predetermined shape, thickness, and surface state, respectively. In the case of the present embodiment, the crystal flake 120 is formed with a flat plate whose surface is mirror-finished with the thickness of the frame portion 122, for example, about 110 μm. In addition, the thickness and surface state of the quartz thin piece 120 are not limited to this, and are appropriately set according to the application.

  The crystal flake 120 is formed with a film forming pattern on the surface thereof, and is processed into a substantially pie-shaped cross section by etching along the film forming pattern.

First, a method for forming a film formation pattern will be described.
FIG. 2 is a schematic cross-sectional view of a film forming jig 200 for forming a film forming pattern.
As shown in FIG. 2, the film forming jig 200 includes a base member 210, a mask member 220, and a magnet 230. FIG. 2 shows the crystal thin piece 120 sandwiched between the base member 210 and the mask member 220.
The base member 210 has a magnetic force because the magnet 230 is embedded on one side. The magnet 230 may be embedded on both surfaces of the base member 210.
A mask member 220 is disposed on the base member 210 via a quartz crystal piece 120.

The mask member 220 is made of a magnetic material, and is made of, for example, stainless steel having magnetism, and is disposed on the one surface 210A of the base member 210 at a position attracted by the magnetic force of the base member 210. The quartz crystal flake 120 disposed on the base member 210 is interposed between the base member 210 and the mask member 220, and its position is set by the magnetic force generated between the magnet 230 embedded in the base member 210 and the mask member 220. It is fixed.
The mask member 220 has a smaller outer shape than the crystal flake 120 in plan view, and a part of the crystal flake 120 is exposed from the mask member 220 over the entire circumference. Note that the size of the outer shape of the mask member 220 is determined by the shape of the film formation pattern formed on the quartz crystal piece 120.

  The crystal flakes 120 may be disposed on the surface of the base member 210 on the magnet 230 side, or may be disposed on both surfaces of the base member 210. When arranged on both sides, the mask member 220 is also arranged on both sides.

Then, a metal film such as Cr / Au is formed on the film-forming jig 200 having such a configuration by a vapor deposition apparatus or a sputtering apparatus (not shown) to form a film-forming pattern 125 as shown in FIG. Form.
Next, after removing the mask member 220, the crystal flake 120 is removed from the base member 210.
In this way, the crystal thin piece 120 is formed with a film forming pattern 125 having a frame shape that is connected to the entire periphery outside the central portion covered with the mask member 220.

  In the film-forming jig 200 having such a configuration, since the mask member 220 is attracted to one surface 210 </ b> A of the base member 210, the mask member 220 is not lifted from the crystal thin piece 120, and the crystal thin piece 120 is formed. Thus, the film formation pattern 125 having no outline blur can be formed.

  Then, a corrosion-resistant film 126 such as a Cr / Au film is formed on each surface of the quartz crystal piece 120 other than the surface on which the film formation pattern 125 is formed. As a result, as shown in FIG. 3A, the crystal thin piece 120 is masked by the film formation pattern 125 and the corrosion-resistant film 126 except for the central portion (optically effective area) of the crystal thin piece 120.

Next, a method for etching the crystal slice 120 will be described.
The quartz crystal thin piece 120 masked with the film formation pattern 125 and the corrosion-resistant film 126 is immersed in an etching solution such as hydrofluoric acid or hydrofluoric acid and ammonium fluoride. Then, etching is performed until the central portion (optical effective area) has a thickness of 150 μm or less, for example, about 100 μm. As a result, as shown in FIG. 3B, the central portion (optically effective area) of the quartz thin piece 120 is formed in a concave shape with the thin portion 121 and the frame portion 122.
As described above, the wall surface 122B of the quartz thin piece 120 is etched substantially smoothly because the film formation pattern 125 is not blurred and the outline 125A is sharply formed.

Then, the crystal flake 120 is immersed in a stripping solution to peel off the film formation pattern 125 and the corrosion-resistant film 126. After peeling, the crystal flake 120 is washed with pure water and dried. Thereby, the crystal | crystallization thin piece 120 provided with the thin part 121, ie, the thickness of the center part (optical effective area), can be obtained.
The stripping solution is a mixture of potassium nitrate and chloric acid when the film formation pattern 125 and the corrosion resistant film 126 are Cr, and a mixture of potassium iodide and chloric acid when the film formation pattern 125 and the corrosion resistant film 126 are Au. Can be used.

  The optical element 100A in which the space P is formed between the substrate 110 and the crystal thin piece 120 by applying the adhesive 130 to the bonding surface 122A of the crystal thin piece 120 processed by etching in this way and bonding the substrate 110 together. Can be obtained.

The first embodiment described above has the following effects.
In the first embodiment, since the space P is formed between the substrate 110 and the quartz thin piece 120, no stress is applied to the quartz thin piece 120. Therefore, deformation and breakage of the quartz flake 120 can be prevented, so that generation of transmitted wavefront aberration and focal spot unevenness can be suppressed and a long-life optical element can be provided.

Moreover, since there is no organic substance such as an adhesive between the substrate 110 and the quartz crystal piece 120 as in the prior art, the light resistance is excellent.
Furthermore, since the space P is substantially sealed, it is possible to prevent foreign matters from entering the space P.

  In the first embodiment, the crystal flake 120 is processed by etching. Since the quartz flake 120 has low strength, there is a risk of deformation or breakage during processing, but no stress is applied to the quartz flake 120 by etching. Therefore, there is no fear of deformation or breakage, and it can be processed into a predetermined shape. That is, work efficiency is good.

Next, a second embodiment of the present invention will be described.
[Second Embodiment]
FIG. 4 is a sectional view showing an optical element according to the second embodiment of the present invention.
As shown in FIG. 4, the optical element 100 </ b> B has the same configuration as that of the first embodiment except that an antireflection film 140 is provided on the surface of the substrate 110 and the quartz crystal piece 120, and thus description thereof is omitted.
The antireflection film 140 is provided at the interface between the substrate 110 and the quartz flake 120, respectively. The antireflection film 140 can be laminated by a vapor deposition apparatus, a sputtering apparatus, or the like.

In the second embodiment described above, the following effects can be obtained in addition to the effects of the first embodiment described above.
In the second embodiment, since the antireflection film 140 is provided, the light transmittance is greatly improved. Therefore, it is excellent in the function (high brightness, high contrast) as an optical element.

Next, a third embodiment of the present invention will be described.
[Third embodiment]
FIG. 5 is a sectional view showing an optical element according to the third embodiment of the present invention.
As shown in FIG. 5, since the optical element 100C has the same configuration as that of the first embodiment except that the space P is filled with nitrogen gas 150 having a dew point of −30 ° C. as a dry gas, the description thereof is omitted. .
In this case, the inside of the chamber is filled with dry nitrogen, and the substrate 110 and the frame portion 122 of the crystal thin piece 120 are pasted through the adhesive 130 without any gaps in this atmosphere.

In the third embodiment described above, the following effects can be obtained in addition to the effects of the first embodiment described above.
In the third embodiment, since nitrogen gas is filled, dew condensation inside the space P can be prevented. Therefore, the function as an optical element can be extended.

Next, a fourth embodiment of the present invention will be described.
[Fourth embodiment]
FIG. 6 is a sectional view showing an optical element according to the fourth embodiment of the present invention.
As shown in FIG. 6, the optical element 100 </ b> D has the same configuration as that of the first embodiment except that the coating material 160 is laminated on the surface of the quartz crystal piece 120, and thus the description thereof is omitted.
As the coating material 160, an organic material or an inorganic material can be used. For example, a mixture such as ethyl silicate is used.
In addition, the coating material 160 can be laminated | stacked on the surface of the crystal thin piece 120 with a vapor deposition apparatus, a sputtering apparatus, etc. FIG.

In the fourth embodiment described above, the following effects can be obtained in addition to the effects of the first embodiment described above.
In the fourth embodiment, since the quartz flake 120 is coated with the coating material 160, the quartz flake 120 itself is strengthened. Accordingly, since the quartz flake 120 is not easily damaged, an optical element having a long life can be provided.

Next, a fifth embodiment of the present invention will be described.
[Fifth embodiment]
FIG. 7 is a sectional view showing an optical element according to the fifth embodiment of the present invention.
As shown in FIG. 7, the optical element 100 </ b> E includes two substrates 115, a crystal flake 170 disposed between the two substrates 115, and an adhesive 130.
The board | substrate 115 is formed in flat form similarly to the board | substrate 110 of 1st embodiment.
The quartz crystal piece 170 is formed in a substantially H-shaped cross section, and includes a thin portion 171 that forms an optically effective area, and a thick frame portion 172 that is formed around the thin portion 171. The frame portion 172 is formed so as to protrude from both sides of the quartz crystal piece 170. Then, the bonding surfaces 172A of the respective frame portions 172 and the substrate 115 are bonded via the adhesive 130.

  The crystal thin piece 170 is formed into a substantially H-shaped cross section by forming film formation patterns on both sides of the crystal thin piece 170 and etching along the film formation pattern. Since the film forming pattern forming method and the etching method may be performed in the same manner as in the first embodiment, description thereof is omitted.

The fifth embodiment described above has the following effects in addition to the effects of the first embodiment described above.
In the fifth embodiment, since the crystal flakes 170 do not directly contact the outside, stress is not applied to the crystal flakes 170 or it is not accidentally touched. Therefore, the optical element 100E is excellent in handling, maintenance, and reliability.

Next, a sixth embodiment of the present invention will be described.
[Sixth embodiment]
FIG. 8 is a sectional view showing an optical element according to the sixth embodiment of the present invention.
As shown in FIG. 8, the optical element 100F includes a substrate 110, two quartz thin pieces 120 disposed with the substrate 110 interposed therebetween, an adhesive 130 that joins the substrate 110 and the quartz thin piece 120, It has.

The board | substrate 110 is formed in flat form similarly to 1st embodiment.
The two crystal flakes 120 are each formed in a substantially pie-shaped cross section as in the first embodiment, and have a thin portion 121 that is an optically effective area, and around the thin portion 121, than the thin portion 121. A thick frame portion 122 is provided.
The bonding surface 122A of the frame portion 122 and the substrate 110 are bonded via the adhesive 130. Since the substrate 110 is sandwiched between the two quartz slices 120, spaces P are formed on both surfaces of the substrate 110.

The sixth embodiment described above has the following effects in addition to the effects of the first embodiment described above.
In the sixth embodiment, since two crystal flakes are used, higher brightness and higher contrast can be realized. In addition, since only one substrate is used, the material cost can be reduced.

Next, a seventh embodiment of the present invention will be described.
[Seventh embodiment]
FIG. 9 is a sectional view showing a seventh embodiment of the present invention.
As shown in FIG. 9, the optical element 100G joins the substrate 110, the crystal thin piece 180, the spacer 190 provided between the substrate 110 and the crystal thin piece 180, and the substrate 110, the crystal thin piece 180, and the spacer 190. And an adhesive 130.

  The substrate 110 and the quartz crystal piece 180 are formed in a flat plate shape. The substrate 110 and the quartz crystal piece 180 are formed in substantially the same shape, and have a frame portion 182 around the thin portion 181 that is an optically effective area. The spacer 190 is provided around the thin portion 181 along the frame portion 182. As the spacer 190, one having high strength is preferable. For example, materials such as metal and plastic, specifically stainless steel and polycarbonate can be used.

Then, the quartz crystal piece 180 and the spacer 190 are joined with the adhesive 130, and then the substrate 110 and the spacer 190 are joined with the adhesive 130, the space P is formed.
The thickness of the spacer 190 is determined so that the thickness of the space P is 150 μm or less.
In the seventh embodiment, since it is not necessary to process the substrate 110 and the crystal thin piece 180, processing such as etching is not performed.

The seventh embodiment described above has the following effects in addition to the effects of the first embodiment described above.
In the seventh embodiment, the substrate 110 and the quartz crystal piece 180 are joined via the spacer 190. The spacer 190 is first bonded to the quartz flake 180. Accordingly, even when the crystal thin piece processed by polishing or the like cannot be used to provide the frame portion, it is possible to give the strength sufficient for handling in the manufacturing process.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the crystal flake 120 or 170 is formed in a substantially pie-shaped cross section to form the space P, but the substrate 110 or 115 is processed into a substantially pie-shaped cross section. Also good.

  The present invention can be used as an optical element such as an image display device.

Sectional drawing which shows the optical element concerning 1st embodiment of this invention. Sectional drawing which shows the formation method of the film-forming pattern in 1st embodiment of this invention. (A) is sectional drawing which shows the state before the etching in 1st embodiment of this invention. (B) is sectional drawing which shows the state after the etching in 1st embodiment of this invention. Sectional drawing which shows the optical element concerning 2nd embodiment of this invention. Sectional drawing which shows the optical element concerning 3rd embodiment of this invention. Sectional drawing which shows the optical element concerning 4th embodiment of this invention. Sectional drawing which shows the optical element concerning 5th embodiment of this invention. Sectional drawing which shows the optical element concerning 6th embodiment of this invention. Sectional drawing which shows the optical element concerning 7th embodiment of this invention.

Explanation of symbols

100A, 100B, 100C, 100D, 100E, 100F, 100G Optical element 110, 115 Substrate 120, 170 Crystal flake 130 Adhesive

Claims (9)

An optical element comprising a quartz flake and a substrate,
The crystal flake includes an optical effective area, and a frame portion thicker than the optical effective area around the optical effective area,
The optical element, wherein the frame portion is bonded to the substrate. An optical element comprising a quartz flake and a substrate,
The substrate includes an optical effective area, and a frame portion thicker than the optical effective area around the optical effective area,
The optical element, wherein the frame portion is bonded to the quartz crystal piece. The optical element according to claim 1 or 2,
An optical element characterized in that both sides of the quartz flake are sandwiched between the substrates. The optical element according to claim 1 or 2,
An optical element characterized in that both sides of the substrate are sandwiched between the quartz crystal flakes. An optical element comprising a quartz flake and a substrate,
An optical element characterized in that the outside of the optically effective area of the quartz flake and the substrate are bonded via a spacer. The optical element according to any one of claims 1 to 5,
An optical element, wherein an antireflection film is laminated on at least one side or both sides of the crystal thin piece and the substrate. The optical element according to any one of claims 1 to 6,
The space between the optical effective area of the quartz flake and the optical effective area of the substrate is sealed,
An optical element, wherein a dry gas having a dew point of −10 ° C. or lower is sealed in the space. The optical element according to any one of claims 1 to 7,
An optical element characterized in that the surface of the quartz flake is coated with an organic material and / or an inorganic material. A method for producing the optical element according to any one of claims 1 to 8,
A method of manufacturing an optical element, comprising etching the quartz crystal flakes or the substrate.

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