Composite heat balance piezoelectric deformation reflector and processing technology thereof

Abstract

The invention discloses a composite heat balance piezoelectric deformation reflector and a processing technology thereof, and belongs to the field of optical devices, the composite heat balance piezoelectric deformation reflector comprises a mirror surface substrate layer, the center of the mirror surface substrate layer is provided with an analysis aperture area, and the front surface of the mirror surface substrate layer is provided with an annular heat balance layer; and a mirror surface multi-degree-of-freedom control electrode array for realizing high-order optical modal actuation and a mirror surface structure modal reconstruction electrode array for realizing low-order mirror surface structure modal sensing are sequentially arranged on the back surface of the mirror surface substrate layer from inside to outside. According to the composite heat balance piezoelectric deformable mirror and the processing technology thereof, the front and back surfaces of the mirror surface substrate layer are covered with different materials, so that complete heat balance of the deformable mirror structure can be realized, namely extremely small deformation in an aperture is effectively analyzed under the condition of temperature change, and the heat stability of the structure is ensured; and meanwhile, by additionally arranging the auxiliary electrode and the multi-channel charge amplifier array, modal sensing of relative surface shape change can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of optical devices, and in particular to a composite thermal balance piezoelectric deformable reflector and a processing technology thereof. Background Art

[0002] Wavefront distortion caused by atmospheric turbulence can cause serious degradation and degradation of images acquired by optical imaging systems. To solve the above problems, the prior art has developed an adaptive optics (AO) technology to improve the performance of optical systems. The principle is as follows: after the light enters the analysis aperture of the observation device, it is measured by a wavefront sensor to detect the distortion of the wavefront, and the wavefront information is fed back to the controller; after receiving the feedback, the controller uses the corrector to provide the opposite wavefront to compensate the optical system, thereby producing a clear image. In this process, the deformable mirror is mainly responsible for processing high-order optical modes, while the tilt mirror is specifically used to correct the tilt of the wavefront. It can be seen that in the above adjustment, the deformable reflector plays a key role. It achieves precise control of the shape of the reflector by installing an actuator array on the back of the reflector, thereby compensating for the optical path difference caused by the wavefront distortion.

[0003] Most existing deformable mirrors are composite layer adaptive optical piezoelectric deformable mirrors, which are made of a thin silicon-based material as the mirror substrate, with an electric field-controlled strain material (such as piezoelectric material or electrostrictive material) attached to the back, and then the lateral strain actuation of the mirror area is achieved by arranging an electrode array, thereby achieving optical surface and wavefront conjugation. It can be seen that composite layer adaptive optical piezoelectric deformable mirrors have the following defects:

[0004] 1. The wavefront control capability of the existing composite layer adaptive optical piezoelectric deformable mirror is greatly affected by the environmental temperature change. The thermal strain difference caused by the thermal environment change between the mirror substrate layer and the actuation layer material is usually greater than the mirror deformation caused by the piezoelectric actuation lateral strain;

[0005] 2. The piezoelectric actuation layer usually needs to be loaded with an electric field along the polarization direction to maintain the spontaneous polarization of piezoelectric materials in various complex environments. The conventional technical solution to this problem is to electrically load the piezoelectric layer with pressure bonding, that is, to connect the thin plate mirror layer and the piezoelectric layer with pressure through a conductive adhesive, and at the same time apply a bias electric field to the piezoelectric material throughout the bonding process; the shortcoming of this solution is that the bonding electrode pressure is mainly applied to the surface shape control within the effective analysis aperture of the mirror, resulting in uncorrectable high-order distortion of the mirror shape during the processing process.

[0006] 3. Conventional composite single-pressure deformable mirrors only have surface actuation and cannot realize real-time sensing of relative surface shape changes in isolation. Currently, only electromagnetic actuation / capacitive sensing large-aperture deformable mirrors can partially realize this function, but there is no practical application in lightweight single-pressure deformable mirrors. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a composite thermally balanced piezoelectric deformable mirror and a processing technology thereof. By covering different materials on the front and back sides of the mirror substrate layer, the deformable mirror structure can be completely thermally balanced, that is, the deformation within the aperture can be effectively analyzed under temperature changes to ensure the thermal stability of the structure. At the same time, by adding auxiliary electrodes and a multi-channel charge amplifier array, modal sensing of relative changes in surface shape can be achieved.

[0008] To achieve the above-mentioned purpose, the present invention provides a composite thermal balance piezoelectric deformable mirror, comprising a mirror substrate layer, an analysis aperture region is reserved in the center of the mirror substrate layer, an annular thermal balance layer is arranged on the front side of the mirror substrate layer, and a mirror multi-degree-of-freedom control electrode array for realizing high-order optical modal actuation and a mirror structure modal reconstruction electrode array for realizing low-order mirror structure modal sensing are arranged on the back side of the mirror substrate layer in sequence from inside to outside;

[0009] The mirror multi-degree-of-freedom control electrode array is arranged inside the analysis aperture area, and the mirror structure mode reconstruction electrode array is arranged outside the analysis aperture area.

[0010] Preferably, the mirror multi-degree-of-freedom control electrode array comprises a plurality of control electrodes arranged in a hexagonal honeycomb pattern, and the plurality of control electrodes are electrically connected to a multi-channel voltage amplifier via a bus;

[0011] The mirror structure modal reconstruction electrode array comprises a plurality of auxiliary electrodes arranged in a keystone shape, and the plurality of auxiliary electrodes are electrically connected to a multi-channel charge amplifier via a bus.

[0012] Preferably, the mirror multi-degree-of-freedom control electrode array and the mirror structure modal reconstruction electrode array are both made of piezoelectric materials.

[0013] Preferably, the material of the annular heat balance layer is aluminum;

[0014] The mirror substrate layer is a silicon-based circular plate, the material of the silicon-based circular plate is silicon, silicon carbide or an organic polymer material, and the organic polymer material is polyethylene terephthalate PET or polyimide PI;

[0015] The piezoelectric material is PZT polarized and covered with copper-nickel electrodes.

[0016] Preferably, the annular heat balance layer and the mirror structure modal reconstruction electrode array are arranged symmetrically with respect to the mirror substrate layer.

[0017] Preferably, the lower surface of the mirror structure modal reconstruction electrode array is provided with three supporting points arranged in an equilateral triangle.

[0018] The processing technology of the composite thermal balance piezoelectric deformable reflector includes the following steps:

[0019] S1. Covering the annular heat balance layer on the front side of the mirror substrate layer by magnetic sputtering or by using a conductive adhesive bonding method;

[0020] S2, bonding the mirror multi-degree-of-freedom control electrode array and the mirror structure modal reconstruction electrode array on the back side of the mirror substrate layer using a conductive adhesive;

[0021] S3, Electrical loading pressure bonding:

[0022] A top flexible filling medium and an inverted boss contact panel are sequentially placed on the upper surface of the annular heat balance layer, and the center of the inverted boss contact panel is in contact with the mirror substrate layer, and the edge of the inverted boss contact panel is in contact with the upper surface of the top flexible filling medium;

[0023] At the same time, a bottom flexible filling medium and a support base are sequentially arranged on the lower surface of the mirror multi-degree-of-freedom control electrode array, and the lower surface of the bottom flexible filling medium is located at the central groove position of the support base, and the edge of the support base is provided with telescopic electrical contacts arranged in a multi-layer ring shape, and the contacts of the telescopic electrical contacts are in contact with the lower surface of the mirror structure modal reconstruction electrode array;

[0024] Then, evenly apply downward pressure to the upper surface of the inverted boss contacting the panel until pressure bonding occurs.

[0025] The present invention has the following beneficial effects:

[0026] 1. By covering the front and back sides of the mirror substrate layer with different materials, the deformable mirror structure can be completely thermally balanced, that is, the deformation within the aperture can be effectively analyzed to be minimal under temperature changes, thus ensuring the thermal stability of the structure;

[0027] 2. Modal sensing of relative changes in surface shape can be achieved by adding auxiliary electrodes and multi-channel charge amplifier arrays;

[0028] 3. Based on the electric loading pressure bonding process, the electric loading point is arranged outside the analysis aperture area of ​​the mirror substrate layer to reduce the influence of the main mechanical structure contact in the pressure bonding process on the surface shape inside the analysis aperture, thereby reducing the influence of the processing technology on the mirror accuracy;

[0029] 4. During the pressure bonding process, the upper and lower surfaces of the deformable mirror are composed of a contact surface and a flexible filling medium with low stiffness (Young's modulus is on the order of 1MPa-5MPa), which only generates low-order correctable surface errors.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A cross-sectional view of a composite thermally balanced piezoelectric deformable reflector according to the present invention;

[0032] Figure 2 A bottom view of a composite thermally balanced piezoelectric deformable reflector of the present invention;

[0033] Figure 3 A circuit wiring diagram of a composite thermally balanced piezoelectric deformable reflector of the present invention;

[0034] Figure 4 A processing state diagram of a processing technology of a composite thermal balance piezoelectric deformable reflector of the present invention;

[0035] Figure 5 This is a temperature variation diagram of the deformable mirror surface under a 20K temperature variation condition described in the simulation experiment of the present invention;

[0036] Figure 6 This is a diagram showing the finite element pre-calculation result of deformation of the deformable reflector under 20K temperature change conditions.

[0037] Figure 7 The relationship between the internal deformation amplitude and the thickness of the annular heat balance layer under the set analysis aperture (80 mm) described in the simulation experiment of the present invention;

[0038] Figure 8 This is a graph showing the relationship between the longitudinal displacement and the thickness of the annular thermal balance layer under the set analysis aperture (80 mm) described in the simulation experiment of the present invention.

[0039] Reference numerals

[0040] 1. Annular thermal balance layer; 2. Mirror substrate layer; 3. Mirror structure modal reconstruction electrode array; 4. Mirror multi-degree-of-freedom control electrode array; 5. Support point. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0042] It should be noted that the terms "include", "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or devices.

[0043] Like reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0044] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0045] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] like Figure 1-Figure 3 As shown, a composite thermal balance piezoelectric deformable mirror comprises a mirror substrate layer 2, an analysis aperture region is reserved in the center of the mirror substrate layer 2, an annular thermal balance layer 1 is arranged on the front side of the mirror substrate layer 2 to compensate for the deformation caused by the thermal expansion difference between the mirror substrate layer 2 and the piezoelectric material under temperature change conditions, and a mirror multi-degree-of-freedom control electrode array 4 for realizing high-order optical modal actuation and a mirror structure modal reconstruction electrode array 3 for realizing low-order mirror structure modal sensing are arranged on the back side of the mirror substrate layer 2 in sequence from the inside to the outside; the mirror multi-degree-of-freedom control electrode array 4 is arranged inside the analysis aperture region, and the mirror structure modal reconstruction electrode array 3 is arranged outside the analysis aperture region.

[0047] Mirror deformation will cause changes in the electric field distribution inside the mirror multi-degree-of-freedom control electrode array 4 and the mirror structure modal reconstruction electrode array 3, thereby generating charges. The generated charges are then collected through the electrode array and transmitted to the multi-channel charge amplifier array, which converts the charge signal into a voltage signal and further processes it into a digital signal. By analyzing the digital signal, the modal information of the mirror deformation can be obtained, including the amplitude and direction of the deformation.

[0048] The mirror multi-degree-of-freedom control electrode array 4 includes a plurality of control electrodes arranged in a hexagonal honeycomb shape, and the plurality of control electrodes are electrically connected to a multi-channel voltage amplifier via a bus to realize the generation of complex surface shapes (or decoupled optical modes); the mirror structure modal reconstruction electrode array 3 includes a plurality of auxiliary electrodes arranged in a keystone shape, and the plurality of auxiliary electrodes are electrically connected to a multi-channel charge amplifier via a bus, so that relative deformation prediction and dynamic parameter inversion can be realized through local stress measurement.

[0049] The mirror multi-degree-of-freedom control electrode array 4 and the mirror structure modal reconstruction electrode array 3 are both made of piezoelectric materials. The material of the annular thermal balance layer 1 is aluminum. In this embodiment, the relationship between the thickness of the aluminum layer, the thickness of the mirror substrate layer 2 and the electrode array can be fitted based on the electromechanical coupling finite element pre- and post-processing platform of MATLAB, thereby assisting in the design of the thickness of the aluminum layer; the mirror substrate layer 2 is a silicon-based circular plate, and the material of the silicon-based circular plate is silicon, silicon carbide or an organic polymer material, and the organic polymer material is polyethylene terephthalate PET or polyimide PI; the piezoelectric material is a polarized PZT (lead zirconate titanate piezoelectric ceramic material) covered with copper-nickel electrodes.

[0050] The annular heat balance layer 1 and the mirror structure modal reconstruction electrode array 3 are arranged symmetrically with respect to the mirror substrate layer 2 .

[0051] The lower surface of the mirror structure modal reconstruction electrode array 3 is provided with three supporting points 5 arranged in an equilateral triangle.

[0052] like Figure 4 As shown, the processing technology of the composite thermal balance piezoelectric deformable reflector includes the following steps:

[0053] S1, using magnetic sputtering or conductive adhesive bonding method to cover the front side of the mirror substrate layer 2 with an annular heat balance layer 1;

[0054] S2, using a conductive adhesive to adhere the mirror multi-degree-of-freedom control electrode array 4 and the mirror structure modal reconstruction electrode array 3 to the back of the mirror substrate layer 2;

[0055] S3, Electrical loading pressure bonding:

[0056] A top flexible filling medium and an inverted boss contact panel are sequentially placed on the upper surface of the annular heat balance layer 1, and the center of the inverted boss contact panel is in contact with the mirror substrate layer 2, and the edge of the inverted boss contact panel is in contact with the upper surface of the top flexible filling medium;

[0057] At the same time, a bottom flexible filling medium and a supporting base are sequentially arranged on the lower surface of the mirror multi-degree-of-freedom control electrode array 4, and the lower surface of the bottom flexible filling medium is located at the central groove position of the supporting base, and the edge of the supporting base is provided with telescopic electrical contacts arranged in a multi-layer ring shape, and the contacts of the telescopic electrical contacts are in contact with the lower surface of the mirror structure modal reconstruction electrode array 3;

[0058] Then, evenly apply downward pressure to the upper surface of the inverted boss contacting the panel until pressure bonding occurs.

[0059] Simulation experiment

[0060] In this simulation experiment, the deformable mirror has a mirror size of 152.4 mm (6-inch wafer), the hexagonal side length of the mirror multi-degree-of-freedom control electrode array is 9.5 mm, the mirror substrate layer material is silicon (thickness: 800 μm), the piezoelectric material is PZT ceramic (thickness: 150 μm), and the annular thermal balance layer material is aluminum (thickness: 80 μm); the diameter of the analysis aperture here is 80 mm; Figure 5-Figure 8 As shown, it can be seen that the deformation of the mirror surface of the deformable reflector of the present invention changes very little with temperature, thereby proving the effectiveness of the present invention.

[0061] Therefore, the present invention adopts the above-mentioned composite thermal balance piezoelectric deformable mirror and its processing technology. By covering different materials on the front and back sides of the mirror substrate layer, the deformable mirror structure can be completely thermally balanced, that is, the deformation within the aperture can be effectively analyzed under temperature changes to ensure the thermal stability of the structure. At the same time, by adding auxiliary electrodes and a multi-channel charge amplifier array, modal sensing of relative changes in surface shape can be achieved.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A composite thermally balanced piezoelectric deformable mirror, comprising a mirror substrate layer, with an analysis aperture region reserved in the center of the mirror substrate layer, characterized in that: The front side of the mirror substrate layer is provided with an annular heat balance layer, and the back side of the mirror substrate layer is provided with a mirror multi-degree-of-freedom control electrode array for realizing high-order optical modal actuation and a mirror structure modal reconstruction electrode array for realizing low-order mirror structure modal sensing in sequence from inside to outside; The mirror multi-degree-of-freedom control electrode array is arranged inside the analysis aperture area, and the mirror structure mode reconstruction electrode array is arranged outside the analysis aperture area.

2. The composite thermally balanced piezoelectric deformable mirror according to claim 1, characterized in that: The mirror multi-degree-of-freedom control electrode array includes a plurality of control electrodes arranged in a hexagonal honeycomb pattern, and the plurality of control electrodes are electrically connected to a multi-channel voltage amplifier via a bus; The mirror structure modal reconstruction electrode array comprises a plurality of auxiliary electrodes arranged in a keystone shape, and the plurality of auxiliary electrodes are electrically connected to a multi-channel charge amplifier via a bus.

3. The composite thermally balanced piezoelectric deformable mirror according to claim 2, characterized in that: The mirror multi-degree-of-freedom control electrode array and the mirror structure modal reconstruction electrode array are both made of piezoelectric materials.

4. The composite thermally balanced piezoelectric deformable mirror according to claim 3, characterized in that: The material of the annular heat balance layer is aluminum; The mirror substrate layer is a silicon-based circular plate, the material of the silicon-based circular plate is silicon, silicon carbide or an organic polymer material, and the organic polymer material is polyethylene terephthalate PET or polyimide PI; The piezoelectric material is PZT polarized and covered with copper-nickel electrodes.

5. The composite thermally balanced piezoelectric deformable mirror according to claim 4, characterized in that: The annular heat balance layer and the mirror structure modal reconstruction electrode array are symmetrically arranged with respect to the mirror substrate layer.

6. The composite thermally balanced piezoelectric deformable mirror according to claim 1, characterized in that: The lower surface of the mirror structure modal reconstruction electrode array is provided with three supporting points arranged in an equilateral triangle.

7. The processing technology of the composite thermally balanced piezoelectric deformable mirror according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Covering the annular heat balance layer on the front side of the mirror substrate layer by magnetic sputtering or by using a conductive adhesive bonding method; S2, bonding the mirror multi-degree-of-freedom control electrode array and the mirror structure modal reconstruction electrode array on the back side of the mirror substrate layer using a conductive adhesive; S3, Electrical loading pressure bonding: A top flexible filling medium and an inverted boss contact panel are sequentially placed on the upper surface of the annular heat balance layer, and the center of the inverted boss contact panel is in contact with the mirror substrate layer, and the edge of the inverted boss contact panel is in contact with the upper surface of the top flexible filling medium; At the same time, a bottom flexible filling medium and a support base are sequentially arranged on the lower surface of the mirror multi-degree-of-freedom control electrode array, and the lower surface of the bottom flexible filling medium is located at the central groove position of the support base, and the edge of the support base is provided with telescopic electrical contacts arranged in a multi-layer ring shape, and the contacts of the telescopic electrical contacts are in contact with the lower surface of the mirror structure modal reconstruction electrode array; Then, evenly apply downward pressure to the upper surface of the inverted boss contacting the panel until pressure bonding occurs.

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