Variable-shape mirror
The shape-variable mirror design with multiple piezoelectric substrates and electrodes enhances deformation accuracy and amount, addressing precision challenges in existing mirrors for precise light control.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NAT UNIV CORP TOKAI NAT HIGHER EDUCATION & RES SYST
- Filing Date
- 2025-12-18
- Publication Date
- 2026-07-02
AI Technical Summary
Existing shape-variable mirrors face challenges in achieving high deformation accuracy and deformation amount of the reflection surface, limiting their performance in applications requiring precise control of light reflection.
A shape-variable mirror design comprising multiple piezoelectric substrates and electrodes, with alternating electrode configurations, allows for precise control of the reflective surface by applying voltages to each electrode, enhancing deformation accuracy and amount through layered deformation of the substrates.
The design achieves high-precision deformation of the reflective surface, enabling accurate tracking of target shapes and wavefront compensation for short-wavelength light, such as X-rays, with improved deformation accuracy and amount.
Smart Images
Figure JP2025044315_02072026_PF_FP_ABST
Abstract
Description
Shape-variable mirror
[0001] (Cross-reference to related applications) This application claims the priority of Japanese Patent Application No. 2024-227635 filed on December 24, 2024, and the entire content thereof is incorporated herein by reference.
[0002] (Technical field) This disclosure relates to a shape-variable mirror.
[0003] As an optical element, a shape-variable mirror capable of controlling the shape of a reflection surface is known. For example, a technique for precisely controlling the shape of a reflection surface has been proposed by providing a reflection electrode on a first surface of a piezoelectric single crystal substrate and a plurality of control electrodes on a second surface opposite to the first surface of the piezoelectric single crystal substrate (see, for example, Patent Document 1).
[0004] Japanese Patent No. 7587318
[0005] It is preferable to improve the deformation accuracy and deformation amount of the reflection surface.
[0006] This disclosure has been made in view of such problems, and one of its exemplary purposes is to provide a technique for improving the performance of a shape-variable mirror.
[0007] The shape-variable mirror according to an aspect of this disclosure includes a first piezoelectric substrate having a first surface and a second surface opposite to the first surface, a second piezoelectric substrate having a third surface and a fourth surface opposite to the third surface, a first electrode located on the first surface and having a reflection surface, a plurality of second electrodes located between the second surface and the third surface, a plurality of third electrodes located on the fourth surface, and a power source connected to the first electrode, the plurality of second electrodes, and the plurality of third electrodes for applying a voltage.
[0008] Any combination of the above components, or those obtained by mutually substituting the components and expressions of this disclosure between methods, systems, etc., are also effective as aspects of this disclosure.
[0009] According to this disclosure, the performance of the shape-variable mirror can be improved.
[0010] This is a schematic diagram showing the structure of a shape-variable mirror according to the first embodiment. This is a schematic diagram showing the structure of a shape-variable mirror according to the second embodiment. This is a schematic diagram showing the structure of a shape-variable mirror according to the third embodiment. This is a graph showing an example of the deformation amount of a shape-variable mirror. This is a schematic diagram showing the structure of a shape-variable mirror according to the fourth embodiment. This is a schematic diagram showing the structure of a shape-variable mirror according to the fifth embodiment.
[0011] The embodiments for implementing this disclosure will be described in detail below with reference to the drawings. In the description, the same elements will be denoted by the same reference numeral, and redundant explanations will be omitted as appropriate. In addition, to aid in understanding the description, the dimensional ratios of each component in each drawing do not necessarily correspond to the actual dimensional ratios.
[0012] (First Embodiment) Figure 1 is a schematic diagram showing the configuration of a shape-variable mirror 10 according to the first embodiment. The shape-variable mirror 10 has a reflective surface 12 to which light rays are incident, and is configured so that the shape of the reflective surface 12 is variable. The type of light rays incident on the reflective surface 12 and reflected is not particularly limited, but for example, infrared light, visible light, ultraviolet light, or X-rays.
[0013] The shape-changing mirror 10 comprises a first piezoelectric substrate 20, a second piezoelectric substrate 22, a first electrode 30, a plurality of second electrodes 32, a plurality of third electrodes 34, and a power supply 40.
[0014] In Figure 1, the thickness direction of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 is defined as the z-direction. The predetermined direction in which the multiple second electrodes 32 and the multiple third electrodes 34 are arranged is defined as the y-direction, and the direction perpendicular to the z-direction and the y-direction is defined as the x-direction. The coordinate axes shown are set up to aid in understanding the explanation and do not limit the orientation of the shape-variable mirror 10 when it is used.
[0015] The first piezoelectric substrate 20 has a first surface 51 and a second surface 52 opposite to the first surface 51. The second piezoelectric substrate 22 has a third surface 53 and a fourth surface 54 opposite to the third surface 53. The first piezoelectric substrate 20 and the second piezoelectric substrate 22 are stacked in the thickness direction and bonded to each other.
[0016] The first piezoelectric substrate 20 and the second piezoelectric substrate 22 are made of piezoelectric material, for example, piezoelectric single crystal materials such as lithium niobate (LN) or lithium tantalate (LT). As the piezoelectric substrate, for example, a 36-degree Y-cut LN substrate can be used.
[0017] The first piezoelectric substrate 20 deforms in response to the electric field applied between the first surface 51 and the second surface 52. The second piezoelectric substrate 22 deforms in response to the electric field applied between the third surface 53 and the fourth surface 54. The first piezoelectric substrate 20 and the second piezoelectric substrate 22 expand and contract in the thickness direction (z direction) in response to the electric field in the thickness direction (z direction), for example.
[0018] The first piezoelectric substrate 20 and the second piezoelectric substrate 22 may be made of the same material and have opposite polarization directions. For example, the first piezoelectric substrate 20 may expand in the thickness direction (z direction) due to an electric field in the +z direction from the first surface 51 to the second surface 52, and the second piezoelectric substrate 22 may contract in the thickness direction (z direction) due to an electric field in the +z direction from the third surface 53 to the fourth surface 54. Conversely, the first piezoelectric substrate 20 may contract in the thickness direction (z direction) due to an electric field in the +z direction from the first surface 51 to the second surface 52, and the second piezoelectric substrate 22 may expand in the thickness direction (z direction) due to an electric field in the +z direction from the third surface 53 to the fourth surface 54.
[0019] The first piezoelectric substrate 20 and the second piezoelectric substrate 22 may be made of the same material and have the same polarization direction. For example, the first piezoelectric substrate 20 may expand in the thickness direction (z direction) due to an electric field in the +z direction from the first surface 51 to the second surface 52, and the second piezoelectric substrate 22 may expand in the thickness direction (z direction) due to an electric field in the +z direction from the third surface 53 to the fourth surface 54. Conversely, the first piezoelectric substrate 20 may contract in the thickness direction (z direction) due to an electric field in the +z direction from the first surface 51 to the second surface 52, and the second piezoelectric substrate 22 may contract in the thickness direction (z direction) due to an electric field in the +z direction from the third surface 53 to the fourth surface 54.
[0020] The first piezoelectric substrate 20 and the second piezoelectric substrate 22 have the same thickness. The respective thicknesses t1 and t2 of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 are, for example, 0.1 mm or more, 0.2 mm or more, or 0.3 mm or more, and 5 mm or less, 2 mm or less, or 1 mm or less. The respective thicknesses t1 and t2 of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 may be about 0.5 mm. The first piezoelectric substrate 20 and the second piezoelectric substrate 22 may have different thicknesses. For example, the thickness t1 of the first piezoelectric substrate 20 may be greater than the thickness t2 of the second piezoelectric substrate 22. The thickness t1 of the first piezoelectric substrate 20 may be less than the thickness t2 of the second piezoelectric substrate 22.
[0021] The first electrode 30 is located on the first surface 51. The first electrode 30 is provided, for example, to cover the entire first surface 51. The first electrode 30 is provided, for example, over the entire y-direction on the first surface 51. The first electrode 30 does not have to be provided over the entire x-direction on the first surface 51, but may be provided only in the central part in the x-direction. The first electrode 30 has a reflective surface 12. The first electrode 30 can be made of a metal layer comprising nickel (Ni), chromium (Cr), rhodium (Rh), platinum (Pt), gold (Au), etc. The first electrode 30 may be made of a metal layer of a single material, or it may be made as a laminate of multiple metal layers of different materials. The first electrode 30 may have, for example, an adhesive layer of Cr or Ti that contacts the first surface 51, and a reflective layer of Rh, Pt, Au, etc. formed on the adhesive layer. The reflective layer may provide the reflective surface 12. The reflective layer may comprise a multilayer film to increase reflectivity, a dielectric multilayer film, or a multilayer film in which heavy metal elements and light metal elements are alternately layered. The first electrode 30 can be formed using a vapor deposition method or a sputtering method. The thickness of the first electrode 30 is, for example, 10 nm or more, 50 nm or more, or 100 nm or more, and 1 mm or less, 100 μm or less, or 1 μm or less.
[0022] Multiple second electrodes 32 are located between the second surface 52 and the third surface 53. Multiple second electrodes 32 are located between the first piezoelectric substrate 20 and the second piezoelectric substrate 22. Multiple second electrodes 32 are joined to the second surface 52 and the third surface 53, and connect the first piezoelectric substrate 20 and the second piezoelectric substrate 22. Multiple second electrodes 32 are arranged with spacing in a predetermined direction (y direction). The width w1 of each of the multiple second electrodes 32 in the predetermined direction is, for example, 0.5 mm or more, 1 mm or more, or 2 mm or more, and 10 mm or less, 5 mm or less, or 3 mm or less. The spacing d1 of the multiple second electrodes 32 in the predetermined direction is, for example, 0.1 mm or more, 0.5 mm or more, or 1 mm or more, and 5 mm or less, 3 mm or less, or 2 mm or less. The width w1 of the multiple second electrodes 32 may be the same as the spacing d1 between the multiple second electrodes 32, may be greater than the spacing d1, or may be smaller than the spacing d1.
[0023] The multiple second electrodes 32 are configured such that the pitch p1 (sum of width w1 and spacing d1) in a predetermined direction is constant. For example, the multiple second electrodes 32 are configured such that the width w1 and spacing d1 in a predetermined direction are constant. At least one of the width w1, spacing d1, and pitch p1 of each of the multiple second electrodes 32 may be configured to be different from one another. The pitch p1 of the multiple second electrodes 32 is greater than the thickness t1 of the first piezoelectric substrate 20. The pitch p1 of the multiple second electrodes 32 may be the same as the thickness t1 of the first piezoelectric substrate 20, or it may be less than the thickness t1 of the first piezoelectric substrate 20.
[0024] The multiple second electrodes 32 are made of a metallic material and can be composed of a metal layer containing, for example, nickel (Ni), chromium (Cr), copper (Cu), silver (Ag), gold (Au), etc. The multiple second electrodes 32 can be formed, for example, by forming a first metal layer on a second surface 52 and a second metal layer on a third surface 53 using a vapor deposition method or a sputtering method, and then joining the first metal layer and the second metal layer. The method of joining the first metal layer and the second metal layer is not particularly limited, and any metal joining technique can be used. As an example, solid-phase joining techniques such as room-temperature joining or diffusion joining can be used. In addition, a binder material such as a conductive adhesive or metal nanoparticles may be used to join the first metal layer and the second metal layer. The thickness of the multiple second electrodes 32 is not particularly limited, but for example, it can be 10 nm or more, 50 nm or more, or 100 nm or more, and 1 mm or less, 100 μm or less, or 1 μm or less.
[0025] A bonding material (not shown) for joining the second surface 52 and the third surface 53 may be provided between the multiple second electrodes 32 (the portion with a gap d1). The gap d1 between the multiple second electrodes 32 may be filled with the bonding material. The bonding material may be an adhesive such as epoxy resin, or inorganic nanoparticles such as silica nanoparticles. For example, the second surface 52 and the third surface 53 can be joined with silica nanoparticles by applying a liquid in which silica nanoparticles are dispersed in water between the second surface 52 and the third surface 53, joining them, and then heating to evaporate the water. By joining with inorganic nanoparticles, the bonding strength between the second surface 52 and the third surface 53 can be increased, and the amount and accuracy of deformation of the laminate of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 can be improved.
[0026] Multiple third electrodes 34 are located on the fourth surface 54. Multiple third electrodes 34 are arranged at intervals in a predetermined direction (y-direction). The width w2 of each of the multiple third electrodes 34 in the predetermined direction is, for example, 0.5 mm or more, 1 mm or more, or 2 mm or more, and 10 mm or less, 5 mm or less, or 3 mm or less. The spacing d2 between the multiple third electrodes 34 in the predetermined direction is, for example, 0.1 mm or more, 0.5 mm or more, or 1 mm or more, and 5 mm or less, 3 mm or less, or 2 mm or less. The width w2 of the multiple third electrodes 34 may be the same as the spacing d2 between the multiple third electrodes 34, may be greater than the spacing d2, or may be less than the spacing d2.
[0027] The multiple third electrodes 34 are configured such that the pitch p2 (sum of width w2 and spacing d2) in a predetermined direction is constant. For example, the multiple third electrodes 34 are configured such that the width w2 and spacing d2 in a predetermined direction are constant. At least one of the width w2, spacing d2, and pitch p2 of each of the multiple third electrodes 34 may be configured to be different from one another. The pitch p2 of the multiple third electrodes 34 is greater than the thickness t2 of the second piezoelectric substrate 22. The pitch p2 of the multiple third electrodes 34 may be the same as the thickness t2 of the second piezoelectric substrate 22, or it may be less than the thickness t2 of the second piezoelectric substrate 22.
[0028] The multiple third electrodes 34 are made of a metallic material and can be composed of a metallic layer containing, for example, nickel (Ni), chromium (Cr), copper (Cu), silver (Ag), or gold (Au). The multiple third electrodes 34 can be formed on the fourth surface 54 using, for example, a vapor deposition method or a sputtering method. The thickness of the multiple third electrodes 34 is not particularly limited, but for example, it is between 10 nm and 1 μm.
[0029] Multiple second electrodes 32 and multiple third electrodes 34 are arranged in a staggered pattern such that their positions in a predetermined direction (y-direction) alternate. The center position of each of the multiple second electrodes 32 in the predetermined direction is offset from the center position of each of the multiple third electrodes 34 in the predetermined direction. Each of the multiple second electrodes 32 is positioned to overlap with at least one of the multiple third electrodes 34 in the thickness direction. Similarly, the multiple third electrodes 34 are positioned to overlap with at least one of the multiple second electrodes 32 in the thickness direction.
[0030] Each of the plurality of second electrodes 32 has two ends 62, 63 located at both ends in a predetermined direction, and a central portion 64 located between the two ends 62, 63. Similarly, each of the plurality of third electrodes 34 has two ends 66, 67 located at both ends in a predetermined direction, and a central portion 68 located between the two ends 66, 67. The ends 62, 63 of the plurality of second electrodes 32 can overlap with any of the ends 66, 67 of the plurality of third electrodes 34 in the thickness direction. The central portion 64 of the plurality of second electrodes 32 does not overlap with any of the plurality of third electrodes 34, but overlaps with the spacing d2 of the plurality of third electrodes 34 in the thickness direction. Similarly, the central portion 68 of the plurality of third electrodes 34 does not overlap with any of the plurality of second electrodes 32, but overlaps with the spacing d1 of the plurality of second electrodes 32 in the thickness direction.
[0031] In the example shown in Figure 1, both ends 62 and 63 of the multiple second electrodes 32 overlap with any of the multiple third electrodes 34 in the thickness direction. In a modified example, only one of the two ends of the multiple second electrodes 32 (for example, end 62) overlaps with any of the multiple third electrodes 34 in the thickness direction, and the other end of the multiple second electrodes 32 (for example, end 63) does not need to overlap with any of the multiple third electrodes 34. Similarly, in a modified example, only one of the two ends of the multiple third electrodes 34 (for example, end 66) overlaps with any of the multiple second electrodes 32 in the thickness direction, and the other end of the multiple third electrodes 34 (for example, end 67) does not need to overlap with any of the multiple second electrodes 32.
[0032] In the example shown in Figure 1, the center position of each of the multiple second electrodes 32 in a predetermined direction coincides with the center position of the interval d2 between the multiple third electrodes 34. Also, the center position of each of the multiple third electrodes 34 in a predetermined direction coincides with the center position of the interval d1 between the multiple second electrodes 32. In the modified example, the center position of each of the multiple second electrodes 32 in a predetermined direction may be offset in a predetermined direction from the center position of the interval d2 between the multiple third electrodes 34. In the modified example, the center position of each of the multiple third electrodes 34 in a predetermined direction may be offset in a predetermined direction from the center position of the interval d1 between the multiple second electrodes 32.
[0033] The power supply 40 is connected to the first electrode 30, a plurality of second electrodes 32, and a plurality of third electrodes 34, and is configured to apply voltage. The power supply 40 may include, for example, a first power supply 42 that applies voltage between the first electrode 30 and the plurality of second electrodes 32, and a second power supply 44 that applies voltage between the first electrode 30 and the plurality of third electrodes 34. The first electrode 30 is connected to, for example, ground 48. In Figure 1, to avoid complexity in the drawing, the first power supply 42 is connected to only one second electrode 32 and the second power supply 44 is connected to only one third electrode 34, but the first power supply 42 is connected to each of the plurality of second electrodes 32, and the second power supply 44 is connected to each of the plurality of third electrodes 34. The first power supply 42 can independently control the applied voltage to each of the plurality of second electrodes 32. The second power supply 44 can independently control the applied voltage to each of the plurality of third electrodes 34.
[0034] The first power supply 42 controls the electric field applied between the first surface 51 and the second surface 52 by controlling the voltage applied to the plurality of second electrodes 32, thereby controlling the amount of deformation of the first piezoelectric substrate 20. The first power supply 42 controls the amount of deformation of the first piezoelectric substrate 20 at positions corresponding to each of the plurality of second electrodes 32, thereby variably controlling the shape of the reflective surface 12.
[0035] The second power supply 44 controls the electric field applied between the first surface 51 and the fourth surface 54 by controlling the voltage applied to the plurality of third electrodes 34, thereby controlling the amount of deformation of the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The second power supply 44 controls the amount of deformation of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 at positions corresponding to each of the plurality of third electrodes 34, thereby variably controlling the shape of the reflective surface 12.
[0036] According to this embodiment, since the multiple second electrodes 32 and the multiple third electrodes 34 are arranged alternately in a predetermined direction, the shape of the reflective surface 12 can be changed not only at positions corresponding to the multiple second electrodes 32, but also at positions between the multiple second electrodes 32. In other words, the shape of the reflective surface 12 can be changed even at positions between the multiple second electrodes 32, where it is difficult to apply an electric field in the thickness direction. As a result, the reflective surface 12 can be deformed at a higher spatial frequency compared to a single-layer configuration without a second piezoelectric substrate 22 and multiple third electrodes 34. Furthermore, according to this embodiment, by deforming both the first piezoelectric substrate 20 and the second piezoelectric substrate 22, the maximum deformation amount of the reflective surface 12 can be increased compared to a single-layer configuration. Therefore, according to this embodiment, both the deformation accuracy and deformation amount of the reflective surface 12 can be improved, and the reflective surface 12 can be made to follow the target shape with high accuracy. As a result, the performance of the shape-variable mirror 10 can be improved.
[0037] According to this embodiment, the maximum deformation amount of the reflective surface 12 can be set to 10 nm or more, and the error between the reflective surface 12 and the target shape can be reduced to 1 nm or less. This makes it possible to accurately track the reflective surface 12 to the target shape. According to this embodiment, a high-precision focusing mirror can be provided for light rays with extremely short wavelengths, such as X-rays. According to this embodiment, a high-precision wavefront compensation device can be provided that enables wavefront compensation with an accuracy of 1 / 10 or less or 1 / 100 or less of the wavelength λ for infrared light, visible light, or ultraviolet light.
[0038] (Second Embodiment) Figure 2 is a schematic diagram showing the configuration of the shape-changing mirror 10A according to the second embodiment. The shape-changing mirror 10A according to the second embodiment differs from the first embodiment described above in that it further comprises a third substrate 24. The second embodiment will be described focusing on the differences from the above embodiment, and the common points will be omitted from the explanation as appropriate.
[0039] The shape-variable mirror 10A comprises a first piezoelectric substrate 20, a second piezoelectric substrate 22, a third substrate 24, a first electrode 30, a plurality of second electrodes 32, a plurality of third electrodes 34A, and a power supply 40. The first piezoelectric substrate 20, the second piezoelectric substrate 22, the first electrode 30, the plurality of second electrodes 32, and the power supply 40 can be configured in the same manner as in the first embodiment.
[0040] The third substrate 24 has a fifth surface 55 and a sixth surface 56 opposite to the fifth surface 55. The third substrate 24 is laminated in the thickness direction with the first piezoelectric substrate 20 and the second piezoelectric substrate 22 and bonded to each other. The third substrate 24 may be a third piezoelectric substrate made of a piezoelectric material, or it may be made of a piezoelectric single crystal material such as lithium niobate (LN) or lithium tantalate (LT). The third substrate 24 may be made of the same material as the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The third substrate 24 may be made of a different material from the first piezoelectric substrate 20 and the second piezoelectric substrate 22, and may be made of quartz, sapphire, or the like.
[0041] The third substrate 24 has a larger thickness t3 than the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The thickness t3 of the third substrate 24 is, for example, 1.5 times or more, 3 times or more, or 5 times or more, and 100 times or less, 50 times or less, or 10 times or less, the thickness t1, t2 of the first piezoelectric substrate 20 or the second piezoelectric substrate 22. The thickness t3 of the third substrate 24 is, for example, 1 mm or more, 2 mm or more, or 3 mm or more, and 20 mm or less, 15 mm or less, or 10 mm or less. The third substrate 24 fixes the first piezoelectric substrate 20 and the second piezoelectric substrate 22 from the back side, making deformation of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 more easily apparent on the reflective surface 12. By providing the third substrate 24, the maximum deformation amount of the reflective surface 12 can be increased compared to when the third substrate 24 is not provided.
[0042] Multiple third electrodes 34A are located between the fourth surface 54 and the fifth surface 55. Multiple third electrodes 34A are located between the second piezoelectric substrate 22 and the third substrate 24. Multiple third electrodes 34A are joined to the fourth surface 54 and the fifth surface 55, and join the second piezoelectric substrate 22 and the third substrate 24. Multiple third electrodes 34A can be joined to the fourth surface 54 and the fifth surface 55 by the same joining method as multiple second electrodes 32.
[0043] A bonding material (not shown) for joining the fourth surface 54 and the fifth surface 55 may be provided between the plurality of third electrodes 34A (in the portion of the interval d2). The interval d2 between the plurality of third electrodes 34A may be filled with the bonding material. The bonding material may be an adhesive such as an epoxy resin, or may be inorganic nanoparticles such as silica nanoparticles. The bonding material may be the same as the bonding material provided between the plurality of second electrodes 32 (in the portion of the interval d1).
[0044] According to the present embodiment, by fixing the first piezoelectric substrate 20 and the second piezoelectric substrate 22 to the third substrate 24, the amount of deformation of the fourth surface 54 due to the expansion and contraction in the thickness direction of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 can be reduced, and the amount of deformation of the reflecting surface 12 can be increased. For example, compared with a single-layer configuration using only the first piezoelectric substrate 20, the maximum deformation amount can be increased to three times or more. Thereby, the performance of the shape-variable mirror 10A can be improved.
[0045] (Third Embodiment) FIG. 3 is a diagram schematically showing the configuration of a shape-variable mirror 10B according to the third embodiment. The shape-variable mirror 10B according to the third embodiment is different from the above-described first embodiment in that it further includes a third piezoelectric substrate 24B and a fourth electrode 36. Regarding the third embodiment, the description will be centered on the differences from the above-described embodiments, and the description of the common points will be omitted as appropriate.
[0046] The shape-variable mirror 10B includes a first piezoelectric substrate 20, a second piezoelectric substrate 22, a third piezoelectric substrate 24B, a first electrode 30, a plurality of second electrodes 32, a plurality of third electrodes 34A, a fourth electrode 36, and a power supply 40B. The first piezoelectric substrate 20, the second piezoelectric substrate 22, the first electrode 30, the plurality of second electrodes 32, and the plurality of third electrodes 34A can be configured in the same manner as in the first embodiment or the second embodiment.
[0047] The third piezoelectric substrate 24B has a fifth surface 55 and a sixth surface 56 opposite to the fifth surface 55. The third piezoelectric substrate 24B is laminated in the thickness direction with the first piezoelectric substrate 20 and the second piezoelectric substrate 22 and bonded to each other. The third piezoelectric substrate 24B is made of a piezoelectric material and may be made of a piezoelectric single crystal material such as lithium niobate (LN) or lithium tantalate (LT).
[0048] The third piezoelectric substrate 24B may be made of the same material as the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The polarization direction of the third piezoelectric substrate 24B may be the same as that of the first piezoelectric substrate 20 or the second piezoelectric substrate 22, or may be opposite to that of the first piezoelectric substrate 20 or the second piezoelectric substrate 22. For example, the polarization direction of the third piezoelectric substrate 24B may be the same as that of the first piezoelectric substrate 20 and opposite to that of the second piezoelectric substrate 22. For example, the polarization direction of the third piezoelectric substrate 24B may be opposite to both the first piezoelectric substrate 20 and the second piezoelectric substrate 22.
[0049] The third piezoelectric substrate 24B has a thickness t3 greater than that of the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The thickness t3 of the third piezoelectric substrate 24B is, for example, 1.5 times or more, 3 times or more, or 5 times or more the thicknesses t1, t2 of the first piezoelectric substrate 20 or the second piezoelectric substrate 22, and is 100 times or less, 50 times or less, or 10 times or less. The thickness t3 of the third piezoelectric substrate 24B is, for example, 1 mm or more, 2 mm or more, or 3 mm or more, and is 20 mm or less, 15 mm or less, or 10 mm or less.
[0050] The fourth electrode 36 is located on the sixth surface 56. The fourth electrode 36 is provided, for example, so as to cover the entire sixth surface 56. The fourth electrode 36 is made of a metal material and can be composed of a metal layer including, for example, nickel (Ni), chromium (Cr), copper (Cu), silver (Ag), gold (Au), etc. The fourth electrode 36 can be formed on the sixth surface 56 using, for example, a vapor deposition method or a sputtering method. The thickness of the fourth electrode 36 is not particularly limited, but is, for example, 10 nm or more and 1 μm or less.
[0051] The fourth electrode 36 is connected to the power supply 40B. The fourth electrode 36 can have the same potential as the first electrode 30 and can be connected to the ground 48. Instead of being connected to the ground 48, the fourth electrode 36 may be connected to a third power supply (not shown) different from the first power supply 42 and the second power supply 44. The fourth electrode 36 may have a potential different from that of the first electrode 30.
[0052] The first power supply 42 controls the amount of deformation of the first piezoelectric substrate 20 by controlling the voltage applied to the plurality of second electrodes 32, thereby controlling the electric field applied between the first surface 51 and the second surface 52. The first power supply 42 controls the amount of deformation of the second piezoelectric substrate 22 and the third piezoelectric substrate 24B by controlling the voltage applied to the plurality of second electrodes 32, thereby controlling the electric field applied between the third surface 53 and the sixth surface 56. The first power supply 42 controls the amount of deformation of the first piezoelectric substrate 20, the second piezoelectric substrate 22 and the third piezoelectric substrate 24B at positions corresponding to each of the plurality of second electrodes 32, thereby variably controlling the shape of the reflective surface 12.
[0053] The second power supply 44 controls the electric field applied between the first surface 51 and the fourth surface 54 by controlling the voltage applied to the plurality of third electrodes 34A, thereby controlling the amount of deformation of the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The second power supply 44 controls the electric field applied between the fifth surface 55 and the sixth surface 56 by controlling the voltage applied to the plurality of third electrodes 34A, thereby controlling the amount of deformation of the third piezoelectric substrate 24B. The second power supply 44 controls the amount of deformation of the first piezoelectric substrate 20, the second piezoelectric substrate 22 and the third piezoelectric substrate 24B at positions corresponding to each of the plurality of third electrodes 34A, thereby variably controlling the shape of the reflective surface 12.
[0054] According to this embodiment, by making the third piezoelectric substrate 24B deformable, the maximum deformation amount of the reflective surface 12 can be increased compared to the case where only the first piezoelectric substrate 20 and the second piezoelectric substrate 22 are deformable. Furthermore, by increasing the deformation amount with the thicker third piezoelectric substrate 24B and combining it with the thinner first piezoelectric substrate 20 and second piezoelectric substrate 22, the deformation amount can be precisely varied. As a result, both the deformation accuracy and deformation amount of the reflective surface 12 can be improved, and the performance of the shape-variable mirror 10B can be improved.
[0055] Figure 4 is a graph showing an example of the deformation amount of the shape-variable mirror 10B. Figure 4 shows the deformation amount of the reflective surface 12 when a voltage is applied to any one of the multiple second electrodes 32 or any one of the multiple third electrodes 34A. The horizontal axis of the graph shows the y-direction position of the reflective surface 12, and the vertical axis of the graph shows the z-direction deformation amount of the reflective surface 12. The upper part of the graph schematically shows the y-direction positions of the second electrodes 32L, 32R and the third electrode 34A. The second electrode 32L is located in the range of 1 mm to 3 mm on the horizontal axis of the graph. The second electrode 32R is located in the range of 4 mm to 6 mm on the horizontal axis of the graph. The third electrode 34 is located in the range of 2.5 mm to 4.5 mm on the horizontal axis of the graph. The widths w1 and w2 of the multiple second electrodes 32 and the multiple third electrodes 34 are 2 mm, and the spacing d1 and d2 is 1 mm. The thicknesses t1 and t2 of the first piezoelectric substrate 20 and the second piezoelectric substrate 22 are 0.5 mm, respectively, and the thickness t3 of the third piezoelectric substrate 24A is 4 mm.
[0056] Graph 70 shows the case where 500V is applied only to the second electrode 32L, and it can be seen that a deformation of approximately +15 nm is obtained at the position corresponding to the second electrode 32L. Graph 72 shows the case where 500V is applied only to the second electrode 32R, and it can be seen that a deformation of approximately +15 nm is obtained at the position corresponding to the second electrode 32R. Graph 74 shows the case where 500V is applied only to the third electrode 34A, and it can be seen that a deformation of approximately -15 nm is obtained at the position corresponding to the third electrode 34. From the graphs in Figure 4, it can be seen that local deformation can be generated on the reflective surface 12 at positions corresponding to the second electrodes 32L, 32R, or the third electrode 34A. In particular, by using the third electrode 34A, it can be seen that the reflective surface 12 can be deformed even at positions between adjacent second electrodes 32L and 32R, thereby improving the deformation accuracy of the reflective surface 12.
[0057] (Fourth Embodiment) Figure 5 is a schematic diagram showing the structure of the shape-variable mirror 10C according to the fourth embodiment. The shape-variable mirror 10C according to the fourth embodiment differs from the first embodiment described above in that it further comprises a third piezoelectric substrate 24C, a fourth piezoelectric substrate 26C, a fourth electrode 36C, and a fifth electrode 38C. The fourth embodiment will be described focusing on the differences from the above embodiments, and the common points will be omitted from the explanation as appropriate.
[0058] The shape-variable mirror 10C comprises a first piezoelectric substrate 20, a second piezoelectric substrate 22, a third piezoelectric substrate 24C, a fourth piezoelectric substrate 26C, a first electrode 30, a plurality of second electrodes 32C, a plurality of third electrodes 34C, a fourth electrode 36C, a fifth electrode 38C, and a power supply 40C. The first piezoelectric substrate 20, the second piezoelectric substrate 22, and the first electrode 30 can be configured in the same manner as in the first or second embodiment.
[0059] The third piezoelectric substrate 24C has a fifth surface 55 and a sixth surface 56 opposite to the fifth surface 55. The third piezoelectric substrate 24C is located between the first piezoelectric substrate 20 and the second piezoelectric substrate 22 and is coupled to the first piezoelectric substrate 20 and the second piezoelectric substrate 22. The third piezoelectric substrate 24C is made of a piezoelectric material and may be made of a piezoelectric single crystal material such as lithium niobate (LN) or lithium tantalate (LT). The third piezoelectric substrate 24C may be made of the same material as the first piezoelectric substrate 20, but with opposite polarization directions. The thickness t3 of the third piezoelectric substrate 24C is the same as the thickness t1 of the first piezoelectric substrate 20. The thickness t3 of the third piezoelectric substrate 24C may be greater than or less than the thickness t1 of the first piezoelectric substrate 20.
[0060] The fourth piezoelectric substrate 26C has a seventh surface 57 and an eighth surface 58 opposite to the seventh surface 57. The fourth piezoelectric substrate 26C is laminated with the second piezoelectric substrate 22 in the thickness direction and bonded to the second piezoelectric substrate 22. The fourth piezoelectric substrate 26C is made of a piezoelectric material and may be made of a piezoelectric single crystal material such as lithium niobate (LN) or lithium tantalate (LT). The fourth piezoelectric substrate 26C may be made of the same material as the second piezoelectric substrate 22, but with opposite polarization directions. The thickness t4 of the fourth piezoelectric substrate 26C is the same as the thickness t2 of the second piezoelectric substrate 22. The thickness t4 of the fourth piezoelectric substrate 26C may be greater than or less than the thickness t2 of the second piezoelectric substrate 22.
[0061] Multiple second electrodes 32C are located between the second surface 52 and the fifth surface 55. Multiple second electrodes 32C are located between the first piezoelectric substrate 20 and the third piezoelectric substrate 24C. Multiple second electrodes 32 are joined to the second surface 52 and the fifth surface 55, and join the first piezoelectric substrate 20 and the third piezoelectric substrate 24C. Multiple second electrodes 32C can join the second surface 52 and the fifth surface 55 by the same joining method as the multiple second electrodes 32 according to the first embodiment described above. Joining material (not shown) for joining the second surface 52 and the fifth surface 55 may be provided between the multiple second electrodes 32C (the portion with a gap d1).
[0062] Multiple third electrodes 34C are located between the fourth surface 54 and the seventh surface 57. Multiple third electrodes 34C are located between the second piezoelectric substrate 22 and the fourth piezoelectric substrate 26C. Multiple third electrodes 34C are joined to the fourth surface 54 and the seventh surface 57, and join the second piezoelectric substrate 22 and the fourth piezoelectric substrate 26C. Multiple third electrodes 34C can join the fourth surface 54 and the seventh surface 57 by the same joining method as multiple second electrodes 32C. Joining material (not shown) for joining the fourth surface 54 and the seventh surface 57 may be provided between the multiple third electrodes 34C (the portion with a gap d2).
[0063] The fourth electrode 36C is located between the sixth surface 56 and the third surface 53. The fourth electrode 36C is located between the third piezoelectric substrate 24C and the second piezoelectric substrate 22. The fourth electrode 36C is bonded to the sixth surface 56 and the third surface 53, and bonds the third piezoelectric substrate 24C and the second piezoelectric substrate 22. The fourth electrode 36C is provided, for example, to cover the entire sixth surface 56 and the third surface 53. The fourth electrode 36C can bond the sixth surface 56 and the third surface 53 by the same bonding method as for multiple second electrodes 32C or multiple third electrodes 34C.
[0064] The fifth electrode 38C is located on the eighth surface 58. The fifth electrode 38C is provided, for example, to cover the entire eighth surface 58. The fifth electrode 38C is made of a metallic material and can be composed of a metallic layer containing, for example, nickel (Ni), chromium (Cr), copper (Cu), silver (Ag), gold (Au), etc. The fifth electrode 38C can be formed on the eighth surface 58 using, for example, a vapor deposition method or a sputtering method. The thickness of the fifth electrode 38C is not particularly limited, but for example, it is 10 nm or more and 1 μm or less.
[0065] The fourth electrode 36C and the fifth electrode 38C are connected to the power supply 40C. The fourth electrode 36C and the fifth electrode 38C may have the same potential as the first electrode 30 and may be connected to ground 48. At least one of the fourth electrode 36C and the fifth electrode 38C may be connected to a third power supply (not shown) different from the first power supply 42 and the second power supply 44 instead of being connected to ground 48. At least one of the fourth electrode 36C and the fifth electrode 38C may have a different potential than the first electrode 30.
[0066] The first power supply 42 controls the amount of deformation of the first piezoelectric substrate 20 by controlling the voltage applied to the plurality of second electrodes 32C, thereby controlling the electric field applied between the first surface 51 and the second surface 52. The first power supply 42 controls the amount of deformation of the third piezoelectric substrate 24C by controlling the voltage applied to the plurality of second electrodes 32C, thereby controlling the electric field applied between the fifth surface 55 and the sixth surface 56. The first power supply 42 controls the amount of deformation of the first piezoelectric substrate 20 and the third piezoelectric substrate 24C at positions corresponding to each of the plurality of second electrodes 32C, thereby variably controlling the shape of the reflective surface 12.
[0067] The second power supply 44 controls the amount of deformation of the second piezoelectric substrate 22 by controlling the voltage applied to the plurality of third electrodes 34C, thereby controlling the electric field applied between the third surface 53 and the fourth surface 54. The second power supply 44 controls the amount of deformation of the fourth piezoelectric substrate 26C by controlling the voltage applied to the plurality of third electrodes 34C, thereby controlling the electric field applied between the seventh surface 57 and the eighth surface 58. The second power supply 44 controls the amount of deformation of the second piezoelectric substrate 22 and the fourth piezoelectric substrate 26C at positions corresponding to each of the plurality of third electrodes 34C, thereby variably controlling the shape of the reflective surface 12.
[0068] According to this embodiment, by inserting a fourth electrode 36C between a plurality of second electrodes 32C and a plurality of third electrodes 34C, the deformation caused by the voltage applied to the plurality of second electrodes 32C and the deformation caused by the voltage applied to the plurality of third electrodes 34C can be made independent. That is, the first piezoelectric substrate 20 and the third piezoelectric substrate 24C can be selectively deformed by the voltage applied to the plurality of second electrodes 32C, and the second piezoelectric substrate 22 and the fourth piezoelectric substrate 26C can be selectively deformed by the voltage applied to the plurality of third electrodes 34C. As a result, the shape of the reflective surface 12 can be controlled more precisely.
[0069] According to this embodiment, by reversing the polarization directions of the first piezoelectric substrate 20 and the third piezoelectric substrate 24C, the voltage applied to the multiple second electrodes 32C can cause the first piezoelectric substrate 20 and the third piezoelectric substrate 24C to expand and contract in the same direction. Furthermore, by reversing the polarization directions of the second piezoelectric substrate 22 and the fourth piezoelectric substrate 26C, the voltage applied to the multiple third electrodes 34C can cause the second piezoelectric substrate 22 and the fourth piezoelectric substrate 26C to expand and contract in the same direction. This improves the amount of deformation of the reflective surface 12.
[0070] (Fifth Embodiment) Figure 6 is a schematic diagram showing the structure of the shape-changing mirror 10D according to the fifth embodiment. The shape-changing mirror 10D according to the fifth embodiment differs from the fourth embodiment described above in that it further comprises a fifth substrate 28. The fifth embodiment will be described focusing on the differences from the embodiments described above, and the common points will be omitted from the explanation as appropriate.
[0071] The shape-variable mirror 10D comprises a first piezoelectric substrate 20, a second piezoelectric substrate 22, a third piezoelectric substrate 24C, a fourth piezoelectric substrate 26C, a fifth substrate 28, a first electrode 30, a plurality of second electrodes 32C, a plurality of third electrodes 34C, a fourth electrode 36C, a fifth electrode 38D, and a power supply 40C. The first piezoelectric substrate 20, the second piezoelectric substrate 22, the third piezoelectric substrate 24C, the fourth piezoelectric substrate 26C, the first electrode 30, the plurality of second electrodes 32C, the plurality of third electrodes 34, the fourth electrode 36C, and the power supply 40C can be configured in the same manner as in the embodiments described above.
[0072] The fifth substrate 28 has a ninth surface 59 and a tenth surface 60 opposite to the ninth surface 59. The fifth substrate 28 is laminated in the thickness direction with the fourth piezoelectric substrate 26C and bonded to the fourth piezoelectric substrate 26C. The fifth substrate 28 may be a fifth piezoelectric substrate made of a piezoelectric material, or it may be made of a piezoelectric single crystal material such as lithium niobate (LN) or lithium tantalate (LT). The fifth substrate 28 may be made of the same material as the other piezoelectric substrates. The fifth substrate 28 may be made of a different material from the piezoelectric substrates, and may be made of quartz, sapphire, or the like.
[0073] The fifth substrate 28 has a greater thickness than the other piezoelectric substrates. The thickness t5 of the fifth substrate 28 is, for example, 1.5 times or more, 3 times or more, or 5 times or more, and 100 times or less, 50 times or less, or 10 times or less, the thickness t1, t2 of the first piezoelectric substrate 20 or the second piezoelectric substrate 22. The thickness t5 of the fifth substrate 28 is, for example, 1 mm or more, 2 mm or more, or 3 mm or more, and 20 mm or less, 15 mm or less, or 10 mm or less. The fifth substrate 28 fixes the laminate of the first piezoelectric substrate 20 to the fourth piezoelectric substrate 26C from the back side, making it easier for deformation of the first piezoelectric substrate 20 to the fourth piezoelectric substrate 26C to be reflected on the reflective surface 12. By providing the fifth substrate 28, the maximum deformation amount of the reflective surface 12 can be increased compared to when the fifth substrate 28 is not provided.
[0074] The fifth electrode 38D is located between the eighth surface 58 and the ninth surface 59. The fifth electrode 38D is located between the fourth piezoelectric substrate 26C and the fifth substrate 28. The fifth electrode 38D is joined to the eighth surface 58 and the ninth surface 59, and joins the fourth piezoelectric substrate 26C and the fifth substrate 28. The fifth electrode 38D can be joined to the eighth surface 58 and the ninth surface 59 by the same joining method as the fourth electrode 36C.
[0075] According to this embodiment, by fixing the laminate of the first piezoelectric substrate 20 to the fourth piezoelectric substrate 26C to the fifth substrate 28, the amount of deformation of the eighth surface 58 due to expansion and contraction in the thickness direction of the first piezoelectric substrate 20 to the fourth piezoelectric substrate 26C can be reduced, and the amount of deformation of the reflective surface 12 can be increased. As a result, the maximum amount of deformation of the reflective surface 12 can be further increased, and the performance of the shape-variable mirror 10D can be improved.
[0076] The present disclosure has been described above based on embodiments. Those skilled in the art will understand that the present disclosure is not limited to the above embodiments, that various design changes are possible, and that various modifications are possible, and that such modifications are also within the scope of the present disclosure.
[0077] According to this disclosure, the performance of shape-variable mirrors can be improved.
[0078] 10...Shape-changing mirror, 12...Reflective surface, 20...First piezoelectric substrate, 22...Second piezoelectric substrate, 30...First electrode, 32...Second electrode, 34...Third electrode, 40...Power supply, 51...First surface, 52...Second surface, 53...Third surface, 54...Fourth surface.
Claims
1. A shape-changing mirror comprising: a first piezoelectric substrate having a first surface and a second surface opposite to the first surface; a second piezoelectric substrate having a third surface and a fourth surface opposite to the third surface; a first electrode located on the first surface and having a reflective surface; a plurality of second electrodes located between the second surface and the third surface; a plurality of third electrodes located on the fourth surface; and a power supply connected to the first electrode, the plurality of second electrodes, and the plurality of third electrodes for applying voltage.
2. The shape-variable mirror according to claim 1, wherein the plurality of second electrodes are arranged in a predetermined direction along the second surface, the plurality of third electrodes are arranged in the predetermined direction along the fourth surface, and the positions of the plurality of second electrodes and the plurality of third electrodes alternate in the predetermined direction.
3. The shape-variable mirror according to claim 2, wherein the center positions of the plurality of second electrodes in the predetermined direction coincide with the center positions of the spacing between the plurality of third electrodes in the predetermined direction.
4. The shape-variable mirror according to claim 2, wherein the center positions of the plurality of second electrodes in the predetermined direction are offset from the center positions of the spacing between the plurality of third electrodes in the predetermined direction.
5. The shape-variable mirror according to claim 2, wherein each of the plurality of third electrodes overlaps with at least one of the plurality of second electrodes in the thickness direction.
6. The shape-variable mirror according to claim 1, wherein the second piezoelectric substrate is coupled to the first piezoelectric substrate via the plurality of second electrodes.
7. The shape-variable mirror according to claim 6, wherein the second piezoelectric substrate is coupled to the first piezoelectric substrate via a bonding material located between the plurality of second electrodes.
8. The shape-changing mirror according to claim 7, wherein the bonding material includes inorganic nanoparticles.
9. A shape-shifting mirror according to any one of claims 1 to 8, further comprising a third substrate having a fifth surface and a sixth surface opposite to the fifth surface, wherein the plurality of third electrodes are located between the fourth surface and the fifth surface.
10. A shape-changing mirror according to any one of claims 1 to 8, further comprising: a third piezoelectric substrate having a fifth surface and a sixth surface opposite to the fifth surface; and a fourth electrode provided on the sixth surface, wherein the plurality of third electrodes are located between the fourth surface and the fifth surface.
11. A shape-changing mirror according to any one of claims 1 to 5, further comprising a third piezoelectric substrate having a fifth surface and a sixth surface opposite to the fifth surface, wherein the third piezoelectric substrate is located between the first piezoelectric substrate and the second piezoelectric substrate, and the plurality of second electrodes are located between the second surface and the fifth surface, further comprising a fourth piezoelectric substrate having a seventh surface and an eighth surface opposite to the seventh surface, wherein the plurality of third electrodes are located between the fourth surface and the seventh surface, and further comprising a fourth electrode located between the sixth surface and the third surface, and a fifth electrode located on the eighth surface, wherein the power supply is connected to the fourth electrode and the fifth electrode.
12. The shape-shifting mirror according to claim 11, further comprising a fifth substrate having a ninth surface and a tenth surface opposite to the ninth surface, wherein the fifth electrode is located between the eighth surface and the ninth surface.