JP2007003870A - Method for manufacturing optical element, optical element and projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical element which is excellent in optical characteristics such as transmissivity and can be used suitably for a polarizing element or a diffraction grating. <P>SOLUTION: The method for manufacturing optical element is provided with: a step of forming a metal layer 2 on a substrate 11A made of a dielectric; a process of forming recesses 15 having a prescribed dot array pattern for the metal layer 2; a step of forming a laminate between the metal layer 2 and a metal oxide layer 2c having a linear groove pattern 15a by anodizing a part of the surface layer of the metal layer 2 while allowing the surface of the metal layer 2 on which the recesses 15 are formed to face a cathode; and a step of etching the metal layer 2 by using the metal oxide layer 2c as a mask to form a linear groove pattern 13 on the metal layer 2 and, thereby, forming a fine structure 12 made by laminating the metal layer 2(2a) and the metal oxide layer 2c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical element, an optical element, and a projection display device.

  A liquid crystal device is used as a light modulation device in a projection display device such as a projector. As such a liquid crystal device, one having a configuration in which a liquid crystal layer is sandwiched between a pair of opposed substrates is known, and a voltage is applied to the liquid crystal layer inside the pair of substrates. An electrode is formed. Further, an alignment film that controls the alignment of liquid crystal molecules when no voltage is applied is formed inside the electrode, and an alignment film that has been rubbed on the surface of a polyimide film is known.

On the other hand, a polarizing plate is disposed on the outside of the pair of substrates (a surface side different from the surface facing the liquid crystal layer) so that predetermined polarized light is incident on the liquid crystal layer. As a polarizing plate, a wire grid as disclosed in Patent Document 1 as well as a polarizing film manufactured by orienting iodine or a dichroic dye in a certain direction by stretching a resin film of an organic compound in one direction. A type of polarizing element is known.
Japanese Patent Application Laid-Open No. 2004-4621

  In the above-mentioned Patent Document 1, a dot row of recesses is formed on the surface of an aluminum film, and the aluminum surface on which the dot rows of the recesses are formed is anodized in a state of facing the cathode surface, thereby comprising aluminum oxide. A wire grid is formed. However, in Patent Document 1, since the wire grid formed on the glass substrate is made of a dielectric aluminum oxide film, the polarizing element used for a projector or the like has low optical characteristics such as transmittance and contrast. Optical properties are insufficient as a polarizing element for a projector.

  The present invention has been made to solve the above problems, and provides an optical element that is excellent in optical characteristics such as transmittance and can be suitably used as a polarizing element or a diffraction grating, and an efficient manufacturing method thereof. It is another object of the present invention to provide a projection display device including the optical element.

  In order to solve the above-described problems, a method for manufacturing an optical element according to the present invention includes a step of forming a metal layer on a substrate made of a dielectric, and a recess having a predetermined dot row pattern on the metal layer. A metal having a metal layer and a linear groove pattern by anodizing a part of a surface layer of the metal layer in a state where the surface of the metal layer in which the recess is formed is opposed to the cathode Forming a laminate with an oxide layer; and etching the metal layer using the metal oxide layer as a mask to form a linear groove pattern in the metal layer, thereby forming the metal layer and the metal oxide layer. And a step of forming a microstructure formed by laminating and.

According to such a manufacturing method, an optical element that does not use an organic material can be manufactured, and the manufactured optical element is extremely excellent in light resistance and heat resistance.
In addition, since a fine structure having a linear groove pattern made of a laminate of a metal layer as a conductor and a metal oxide layer is formed on a substrate made of a dielectric, the dielectric between the substrate and the metal layer is formed. Due to the difference in rate, when the optical element is used as a polarizing element of a projection display device such as a projector, the transmittance, contrast, and the like are favorable.
Furthermore, since the microstructure is formed by an anodic oxidation method, the groove width can be made uniform in the depth direction of the groove pattern of the microstructure, and the aspect ratio of the width and height of the microstructure Can be greatly increased. As a result, when the optical element is used as a polarizing element in a projection display device such as a projector, a polarizing element having excellent optical characteristics such as transmittance and contrast can be configured.
In addition, since the microstructure formed in the optical element manufactured by the method of the present invention is formed by laminating a metal oxide layer on the metal layer, when a light reflective material is employed as the metal layer, The oxide layer can prevent light reflection.
Furthermore, by forming a laminate of the metal layer and the metal oxide layer using the above anodic oxidation method, the boundary between the layers has a continuous crystal structure (that is, no discontinuous interface is formed). It is also possible to improve the reliability of the strength of the structure.

The optical element manufacturing method of the present invention may include a step of removing the metal oxide layer remaining on the groove bottom of the metal oxide layer by etching before etching the metal layer.
By performing etching in two stages as described above, the groove width and aspect ratio of the fine structure can be suitably controlled. In particular, if the metal oxide etching is performed wet, the width of the groove formed in the metal oxide layer can be increased.

Moreover, in the etching process of the metal layer, the metal layer can be anisotropically etched by performing the etching by dry etching.
By such anisotropic etching, the groove width and aspect ratio of the linear groove pattern formed in the metal layer can be suitably controlled.

Moreover, a nanoimprint method can be used in the step of forming a recess in the metal layer.
The nanoimprint method is a processing method using a mold having a convex portion of a dot row pattern on the surface, and a desired concave pattern can be efficiently formed.

  Next, in order to solve the above problems, an optical element of the present invention is an optical element in which a fine structure having a linear groove pattern is formed on a dielectric substrate, and the fine structure The body is composed of a laminate in which a metal layer and a metal oxide layer made of an oxide of the metal layer are laminated from the substrate side, and the boundary between the metal layer and the metal oxide layer is a continuous crystal. It is characterized by comprising a structure.

Since such an optical element does not use an organic material, it has excellent light resistance and heat resistance. In addition, since the stacking boundary between the metal layer and the metal oxide layer has a continuous crystal structure (that is, no discontinuous interface is formed), the microstructure has excellent strength and is extremely mechanically reliable. It is expensive.
In particular, a metal layer is laminated on a substrate made of a dielectric, and a metal oxide layer is laminated thereon. Therefore, when a light reflective material is adopted as the metal layer, the metal oxide layer reflects light. It becomes possible to prevent.

  In addition, as a metal material applicable to the metal layer of the present invention, for example, aluminum is preferable. In addition, silver, gold, copper, palladium, platinum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, Titanium, ruthenium, niobium, neodymium, ytterbium, yttrium, molybdenum, indium, bismuth, or an alloy thereof can be used.

  Next, in order to solve the above-described problem, a projection display device of the present invention includes a light source device, a light modulation device that modulates light emitted from the light source device, and light modulated by the light modulation device. A projection type display device comprising a projection device for projecting, wherein a polarizing element is provided on a light incident side and a light emitting side of the light modulation device, and the polarizing element is manufactured by the method described above. It is characterized by comprising an element.

  Such a projection display device is very reliable. In other words, the optical element manufactured by the above-described method has a structure that does not include an organic material, and thus is excellent in light resistance and heat resistance, and is configured by a fine structure made of aluminum that is uniform in the depth direction and has a large aspect ratio. Therefore, optical characteristics such as transmittance and contrast are excellent.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

[projector]
FIG. 1 is a schematic configuration diagram showing a main part of a projector as an embodiment of a projection display device of the present invention. The projector according to the present embodiment is a liquid crystal projector using a liquid crystal device as a light modulation device.

  In FIG. 1, 810 is a light source, 813 and 814 are dichroic mirrors, 815, 816 and 817 are reflection mirrors, 818 is an incident lens, 819 is a relay lens, 820 is an exit lens, and 822, 823 and 824 are liquid crystal devices. A modulation device, 825 is a cross dichroic prism, 826 is a projection lens, 831, 832, and 833 are incident-side polarizing plates (optical elements), and 834, 835, and 836 are output-side polarizing plates.

  The light source 810 includes a lamp 811 such as a metal halide and a reflector 812 that reflects the light of the lamp. As the light source 810, besides a metal halide, an ultrahigh pressure mercury lamp, a flash mercury lamp, a high pressure mercury lamp, a deep UV lamp, a xenon lamp, a xenon flash lamp, or the like can be used.

  The dichroic mirror 813 transmits red light contained in white light from the light source 810 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 817 and enters the red light liquid crystal light modulator 822 via the polarizing plate 831. The green light reflected by the dichroic mirror 813 is reflected by the dichroic mirror 814 and enters the liquid crystal light modulator 823 for green light via the polarizing plate 832. Further, the blue light reflected by the dichroic mirror 813 passes through the dichroic mirror 814. For blue light, in order to prevent light loss due to a long optical path, a light guide means 821 including a relay lens system including an incident lens 818, a relay lens 819, and an exit lens 820 is provided. The blue light is incident on the blue light liquid crystal light modulator 824 via the polarizing plate 833 via the light guide unit 821.

  The three color lights modulated by the respective light modulation devices 822 to 824 are incident on the cross dichroic prism 825 via the respective color polarizing plates 834 to 836. The cross dichroic prism 825 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

  Here, in the projector according to the present embodiment, the polarizing plates 831 to 836 employ those made of an inorganic material. Since the light source 810 composed of the metal halide lamp 811 emits high energy, the organic material may be decomposed or deformed by the high energy light. Therefore, the polarizing plates 831 to 836 are made of an inorganic material (including a metal material) having high light resistance and high heat resistance.

  2 is a perspective view showing a schematic configuration of polarizing plates 831 to 836 (hereinafter collectively referred to as polarizing plate 1), FIG. 3 is a schematic plan view of polarizing plate 1, and FIG. 4 is a schematic sectional view of polarizing plate 1. FIG. 5 and FIG. 5 are explanatory views showing the action when light passes through the polarizing plate 1.

  The polarizing plate 1 relates to the optical element of the present invention, and selects each color light emitted from the light source 810 for polarization and transmits only linearly polarized light. Specifically, as shown in FIG. 2, a plurality of non-organic materials (inorganic materials and / or metal materials) arranged in a stripe pattern on a translucent substrate 11A made of a dielectric material such as a glass substrate. The grating (fine structure) 12 is configured.

  As shown in FIG. 3, the pitch P of the grating 12 is a value smaller than the wavelength of the incident light, and is set to 140 nm or less, for example. The width of the grating 12 is set to, for example, 70 nm or less, which is convenient for manufacturing, but is more preferably about 1/10 of the wavelength of incident light. In addition, although the linear groove pattern 13 formed in the clearance gap between the grating | lattices 12 is made into space, it is good also as what inserts the translucent material different from the said grating | lattice 12, for example.

  Moreover, the grating | lattice 12 has a laminated structure as shown in FIG.2 and FIG.4. Here, a metal layer 2a made of aluminum as a conductor and a metal oxide layer 2c made of an oxide of aluminum (aluminum oxide) are stacked on the base 11A. Here, since the metal layer 2a has light reflectivity, the metal oxide layer 2 has light reflection preventing property. Therefore, the polarizing plate 1 of the present embodiment reflects selectively non-transmitted light. It has a function (antireflection function) that is not allowed.

  In addition, the height of the lattice (fine structure) 12 that is a laminate is approximately 10 nm to 50 nm. In addition to aluminum, the metal material constituting the metal layer 2a is silver, gold, copper, palladium, platinum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, titanium, ruthenium, niobium, neodymium, Ytterbium, yttrium, molybdenum, indium, bismuth, or alloys thereof can be used.

  Furthermore, the lattice 12 has a crystal structure in which the laminated boundary 2b between the metal layer 2a and the metal oxide layer 2c is continuous. That is, a discontinuous interface is not formed in the stacked boundary portion 2b, and aluminum forming the metal layer 2a and aluminum oxide forming the metal oxide layer 2c are formed with a continuous concentration distribution.

As shown in FIG. 5, the polarizing plate 1 has a refractive index n _A of the grating 12 and a refractive index n _B of the space 11 B interposed between the gratings 12. Polarization selection is performed according to the polarization direction. Specifically, linearly polarized light X having a polarization axis in a direction perpendicular to the extending direction of the grating 12 is transmitted, and linearly polarized light Y having a polarizing axis in a direction parallel to the extending direction of the grating 12 is reflected. Therefore, the polarizing plate 1 of the present embodiment has the same action as the light reflection type polarizer, that is, the action of transmitting the polarized light parallel to the optical axis (transmission axis) and reflecting the polarized light perpendicular thereto. .

  The linearly polarized light generated through the polarizing plate 1 is incident on the liquid crystal devices 822 to 824 serving as light modulation means. The liquid crystal devices 822 to 824 have a configuration as shown in FIG. 6, for example. FIG. 6 is a schematic cross-sectional view of the liquid crystal devices 822 to 824.

  The liquid crystal devices 822 to 824 are configured to include two substrates (element substrate 10 and counter substrate 20) made of a transparent substrate such as glass or plastic, and the liquid crystal layer 50 is interposed between the pair of substrates 10 and 20. It is pinched. A transparent electrode 9 made of ITO or the like is formed in a matrix on the liquid crystal layer 50 side of the element substrate 10, and further on the liquid crystal layer 50 side of the transparent electrode 9 is an alignment film 11 that regulates alignment of liquid crystal molecules. Is formed on the entire surface of the substrate.

  On the other hand, a solid transparent electrode 23 is formed on the entire surface of the counter substrate 20 on the liquid crystal layer 50 side, and further on the liquid crystal layer 50 side of the transparent electrode 23 is an alignment film 21 that regulates alignment of liquid crystal molecules. Is formed in a solid shape on the entire surface of the substrate.

  In the configuration of FIG. 6, a pair of substrates 10 and 20 are bonded together via a sealing material (not shown), and liquid crystal is sealed inside. In this case, a TN (Twisted Nematic) mode is employed as the liquid crystal mode of the liquid crystal layer 50, but an STN (Super Twisted Nematic) mode, an ECB (Electrically Controlled Birefringence) mode, and the like can also be employed.

The element substrate 10 is a translucent substrate such as glass or quartz, and includes a TFT element (not shown) that performs switching driving of voltage application to the pixel electrode 9. The pixel electrode 9 is made of a light-transmitting and conductive material such as ITO (indium tin oxide) and has a thickness of about 50 nm to 100 nm (for example, 85 nm). Further, the alignment film 11 is made of an oblique vapor deposition material of SiO ₂ and regulates the alignment of liquid crystal molecules. The alignment film 11 has a thickness of about 1 nm to 10 nm (for example, 5 nm).

On the other hand, the counter substrate 20 is composed of a light-transmitting substrate such as glass or quartz, like the element substrate 10, and has a light-transmitting and conductive property such as ITO (indium tin oxide) on the liquid crystal layer side. The common electrode 23 made of a material is formed with a film thickness of about 50 nm to 150 nm (for example, 140 nm). Further, an alignment film 21 made of an oblique vapor deposition material of SiO ₂ is formed on the liquid crystal layer side of the common electrode 23, and the film thickness thereof is about 1 nm to 10 nm (for example, 5 nm).

  In such liquid crystal devices 822 to 824, the phase control of linearly polarized light entering through the polarizing plates 831, 832, and 833 shown in FIG. 1 is performed. That is, the drive control of the liquid crystal layer 50 is performed by the voltage applied to the electrodes 9 and 23, and the phase of the incident light is controlled. The phase-controlled light is incident on the polarizing plates 834, 835, 836 disposed on the light exit side and modulated.

  Each color light modulated by the liquid crystal devices 822 to 824 and the polarizing plates 831 to 836 is formed by being incident on the cross dichroic prism 825 as described above. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

  In the present embodiment, no organic material is used for the polarizing plate 1 (831 to 836). That is, the polarizing plate 1 (831-836) is comprised from an inorganic material and / or a metal material, excluding the organic material which may be deteriorated with the high energy light supplied from a metal halide lamp. Moreover, since the said polarizing plate 1 (831-836) is manufactured by the method as shown below, manufacturing cost is also cheap and it has become very reliable.

[Production method of polarizing plate]
Hereinafter, an example of the manufacturing method of the polarizing plate 1 shown in FIGS. 2-4 is demonstrated. FIG. 7 is a schematic cross-sectional view showing a manufacturing process of the polarizing plate 1, and FIG. 8 is an explanatory diagram showing an outline of an apparatus used for anodization performed in the manufacturing process.
First, as shown in FIG. 7A, aluminum is formed on the entire surface of the substrate 11A made of SiO ₂ which is a light-transmitting dielectric material by sputtering, vacuum deposition, ion plating, or the like. Then, the aluminum layer 2 having a thickness of about 100 nm to 300 nm is formed.

  Next, as shown in FIG. 7B, a recess 15 having a predetermined dot row pattern is formed on the surface of the aluminum layer 2 by nanoimprinting. Here, a pressing member 30 made of a hard material such as SiC is prepared, and a convex portion 31 having a regular arrangement is formed on the surface thereof, and this is pressed against the surface of the aluminum layer 2 as a pressing mold. A concave portion 15 of a dot row pattern is formed. The arrangement pattern of the protrusions 31 is a dot column pattern corresponding to the pattern of the recesses 15 formed on the surface of the aluminum layer 2. Specifically, the arrangement pattern (or the row interval) in which the column interval is larger than the row interval. Is an arrangement pattern larger than the column spacing). Further, as the shape of the convex portion 31, a columnar shape (for example, a quadrangular column), a hemispherical shape, or a conical shape (for example, a quadrangular pyramid) can be adopted.

Next, as shown in FIG. 7C, the holes 15a corresponding to the dot rows are formed by oxidizing the aluminum layer 2 in which the dot rows of the recesses 15 (see FIG. 7B) are formed. To do.
Specifically, holes are formed by an anodic oxidation method using the anodizing apparatus shown in FIG. That is, as shown in FIG. 8, the surface of the Al film 2 as the anode and the surface of the cathode 40 made of platinum are arranged to face each other, and about 30 V in a sulfuric acid aqueous solution 41 having a concentration of about 5%. Is applied for about 20 minutes.
As a result, the aluminum oxide layer 2c having the fine holes 15a as shown in FIG. 7C is formed in a self-organized manner.

  Such an anodic oxidation process is performed in such a manner that a part of the aluminum layer 2 remains without being oxidized. That is, as a result of the anodic oxidation step, the aluminum oxide layer 2c is formed at the bottom of the hole 15a, and the aluminum layer 2 remains on the bottom of the substrate 11A.

Thereafter, as shown in FIG. 7 (d), wet etching is performed on the holes 15a corresponding to the dot rows formed by anodizing at about 30 ° C. using an aqueous solution containing about 5 wt% phosphoric acid. To enlarge. The etching is performed until at least the surface of the aluminum layer 2 is exposed from the hole 15a. The etching can also be performed by dry etching. As an etchant, for example, a mixed gas of Cl ₂ and BCl ₃ with Ar and N ₂ added as necessary can be used. The main etchant is a mixed gas of Cl ₂ and BCl ₃ , but the verticality is improved by adding Ar and N ₂ .

  At this time, in this embodiment, as described above, since the column spacing of the holes 15a has an arrangement pattern larger than the row spacing, the holes 15a, 15a adjacent in the row direction are connected to each other by expanding the holes 15a. A groove pattern is formed in the row direction. Therefore, it is possible to obtain a linear fine structure in which the aluminum oxide layer 2c extends in the column direction.

Subsequently, as shown in FIG. 7E, the aluminum layer 1 formed on the lower layer (substrate 11A side) of the aluminum oxide layer 2c is etched using the aluminum oxide layer 2c as a mask. Here, anisotropic etching by dry etching (etching gas: mixed gas of Cl ₂ and BCl ₃ ) is performed, and holes continuous from the holes 15 a of the aluminum oxide layer 2 c are formed in the aluminum layer 2. As a result, a lattice (fine structure) 12 having a linear groove pattern 13 as shown in FIG. 7E and FIGS. 2 to 4, that is, a metal layer (aluminum layer) 2a and a metal oxide layer (aluminum oxide layer). ) 2c and the polarizing plate 1 provided with the lattice 12 which is a linear microstructure formed by laminating.

  The hole 15a formed by such an anodic oxidation method has a uniform groove width in the depth direction of the groove, that is, a uniform duty ratio between the upper and lower portions of the groove. Further, by enlarging the holes 15a formed by the anodic oxidation method by wet etching, it is possible to more easily form a groove pattern in which the pores are linearly connected.

  Furthermore, after the wet etching, the aluminum layer 2 remaining at the bottom of the hole 15a is removed by anisotropic etching to obtain a groove pattern 13 that opens to the substrate 11A. The groove width becomes uniform in the depth direction of the groove, that is, the duty ratio between the upper part and the lower part of the groove becomes uniform. As a result, it is possible to make the effective refractive index good different between polarized light in a direction parallel to the direction in which the groove pattern 13 extends and polarized light in a direction orthogonal to the direction in which the groove pattern 13 extends, and thus good birefringence characteristics. It becomes possible to manufacture the polarizing plate 1 comprising: Furthermore, the aluminum layer 2a, which is a conductor, is formed on the substrate 11A made of a dielectric, so that the polarization characteristics are good and light transmission is achieved when used in a projection display device such as a projector. And the contrast of the projector is high.

  In this embodiment, an example in which an optical element having a fine structure is used as a polarizing element (polarizing plate) is shown, but it can also be used as a diffraction element, PBS (Polarized Beam Splitter), or a retardation plate. It is.

1 is a schematic diagram showing a schematic configuration of a projector according to an embodiment. The perspective view which shows typically one Embodiment of a polarizing plate. The top view which shows typically one Embodiment of a polarizing plate. Sectional drawing which shows typically one Embodiment of a polarizing plate. Explanatory drawing which shows the effect | action of a polarizing plate. FIG. 3 is a cross-sectional view schematically showing an embodiment of a liquid crystal device used as a light modulation device. Sectional drawing which shows an example of the manufacturing method of a polarizing plate typically. Explanatory drawing which shows an example of an anodizing apparatus typically.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,831-836 ... Polarizing plate, 2 ... Aluminum layer, 2a ... Metal layer, 2c ... Aluminum oxide layer (metal oxide layer), 11A ... Substrate, 12 ... Lattice (fine structure), 13 ... Groove pattern

Claims (7)

Forming a metal layer on a dielectric substrate;
Forming a recess having a predetermined dot row pattern for the metal layer;
In a state where the surface of the metal layer in which the recess is formed is opposed to the cathode, a part of the surface layer of the metal layer is anodized so that the metal layer and the metal oxide layer having a linear groove pattern are Forming a laminate of
Etching the metal layer using the metal oxide layer as a mask to form a linear groove pattern in the metal layer, thereby forming a fine structure in which the metal layer and the metal oxide layer are laminated. A process for producing an optical element comprising the steps of:   2. The optical element manufacturing method according to claim 1, further comprising a step of removing the metal oxide layer remaining at the bottom of the groove of the metal oxide layer by etching before etching the metal layer. Method.   3. The method of manufacturing an optical element according to claim 2, wherein the width of the groove formed in the metal oxide layer is expanded by performing the etching by wet etching in the etching step of the metal oxide layer.   4. The optical element manufacturing method according to claim 1, wherein the metal layer is anisotropically etched by performing the etching by dry etching in the metal layer etching step. Method.   5. The method of manufacturing an optical element according to claim 1, wherein a nanoimprint method is used in the step of forming a recess in the metal layer. An optical element in which a fine structure having a linear groove pattern is formed on a dielectric substrate,
The microstructure is composed of a laminate in which a metal layer and a metal oxide layer made of an oxide of the metal layer are laminated from the substrate side, and the boundary between the metal layer and the metal oxide layer is An optical element comprising a continuous crystal structure. A projection display device comprising: a light source device; a light modulation device that modulates light emitted from the light source device; and a projection device that projects light modulated by the light modulation device.
A polarizing element is provided on a light incident side and a light emitting side of the light modulation device, and the polarizing element is constituted by an optical element manufactured by the method according to any one of claims 1 to 5. A projection type display device characterized by comprising:

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