Nanopositioning device with high thermal performance

Abstract

This invention provides a nanopositioning device capable of positioning objects with nanometer-level precision. The nanopositioning device includes a bracket assembly and an actuator coupled to the bracket assembly via a shaft for precisely controlling the position of the bracket assembly relative to the actuator. The bracket assembly includes a front clamp and a rear clamp. The bracket assembly is displaceable relative to a shaft attached to a base. The actuator includes a piezoelectric stack and a shaft extending from the piezoelectric stack to be coupled to the front and rear clamps for stick-slip actuation of the bracket assembly. The shaft includes multiple ceramic plates. Each of the multiple ceramic plates is polished and made of a ceramic material. The multiple ceramic plates contact the front and rear clamps to create a frictional interface for actuating the bracket assembly.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 426,795, filed November 21, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to the field of precision engineering. Specifically, this disclosure relates to a nanopositioner that operates reliably under ambient conditions and extreme environments. Background Technology

[0004] Nanopositioners have become key tools in many scientific and commercial fields due to their ability to position objects with nanometer precision. Nanopositioners play an important role in scanning probe microscopes, optical microscopes, life science instruments, and other devices used in the semiconductor and data storage industries. Most existing nanopositioners operate using a stick-slip mechanism, in which a piezoelectric component drives a dynamic translator. The movement of the translator is caused by alternating sliding or sticking motions between two elements actuated by the extension and contraction of the piezoelectric element [1], [2].

[0005] In this operation, the shaft is fixed to the base and coupled to the bracket assembly via a friction interface formed between the surfaces of the shaft and the bracket. The piezoelectric stack and metal rod constituting the shaft extend or contract when a voltage is applied. At slower speeds, the inertial force is less than the maximum static friction, causing the clamp to move with the shaft. However, when the piezoelectric element extends or contracts rapidly, the inertial force of the bracket exceeds the static friction, causing slippage between the clamp and the shaft. This "stick-slip" mechanism then facilitates linear axial displacement of the bracket.

[0006] Many applications also require "closed-loop" position sensors for feedback and control. To date, piezoresistive or thin-film elements have been frequently used. While their integration is cost-effective, these types of sensors offer relatively low measurement accuracy and cause energy dissipation during operation. In contrast, capacitive sensors offer unparalleled accuracy, long-term stability, and linearity, with virtually no energy dissipation. This makes them particularly suitable for extreme conditions and applications where energy dissipation must be avoided, such as cryogenic environments.

[0007] Each step of the stick-slip motion is determined by a variety of factors, including clamping force, coefficient of friction, and load weight, and these parameters are very susceptible to environmental conditions such as temperature and pressure.

[0008] Operating stick-slip actuators in vacuum and cryogenic environments presents additional challenges. The performance of piezoelectric actuators degrades at lower temperatures, requiring increased drive voltages to achieve the same linear displacement. For example, at a cryogenic temperature of 4K, a piezoelectric actuator only achieves 5% of the displacement at room temperature. This leads to increased power dissipation (proportional to the square of the drive voltage) and potentially harmful heating effects. Thermal shrinkage alters the spatial dimensions of the nanopositioner assembly, affecting the contact forces between the bracket and base at the friction surfaces. Furthermore, friction between the bracket and base typically increases in a vacuum without the lubrication of air and moisture. Therefore, achieving consistently reliable nanopositioners under diverse environmental conditions presents a significant challenge.

[0009] Therefore, material selection becomes particularly critical at low temperatures. Many materials, especially electrical insulators such as alumina (Al₂O₃), exhibit poor thermal conductivity at these temperatures and prevent objects from effectively heating to ambient temperature, especially at lower temperatures below 1 K. Additional measures are needed to achieve efficient heat transfer, such as installing an external copper braid layer.

[0010] Existing commercial nanopositioners face several drawbacks. They rely on an alumina shaft rigidly connected to a fixed base via piezoelectric elements. When the surface roughness of the alumina shaft is not optimized to the nanoscale, a thin surface coating is required to reduce friction. However, such coatings are typically made of graphite or molybdenum disulfide, which absorb moisture when adsorbed on the surface freezes, inhibiting reliable movement under vacuum or cryogenic conditions.

[0011] Commercial nanopositioners are not well-suited for operation over a wide temperature range due to the mismatch in the thermal expansion coefficients of the materials. This can lead to unreliability at low temperatures, particularly below 1 K.

[0012] Existing position readout mechanisms based on resistance reading consume significant amounts of power, limiting their use in low-temperature conditions. Including a readout mechanism significantly increases the footprint of commercially available nanopositioners, potentially excluding their use in space-constrained applications.

[0013] Therefore, there is a need in the art for a nanopositioner that provides reliable operation under ambient conditions and extreme environments, efficient heat transfer through the positioning device, and accurate and dissipation-free position readout. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and appended claims, taken in conjunction with the accompanying drawings and the background art of this disclosure. Summary of the Invention

[0014] This paper presents a nanopositioner that operates reliably under ambient conditions and extreme environments.

[0015] In certain aspects of this disclosure, a nanopositioning device is provided capable of positioning objects with nanometer-level precision. The nanopositioning device includes a bracket assembly and an actuator coupled to the bracket assembly for precisely controlling the position of the bracket assembly relative to the actuator. The bracket assembly includes a front clamp and a rear clamp. The actuator includes a piezoelectric stack and a shaft extending from the piezoelectric stack to be coupled to the front and rear clamps for stick-slip actuation of the bracket assembly. The shaft includes a plurality of ceramic plates. Each of the plurality of ceramic plates is polished and made of a ceramic material. The plurality of ceramic plates contact the front and rear clamps to achieve a frictional interface for actuating the bracket assembly.

[0016] In one embodiment, multiple ceramic plates are adhesively attached to the shaft to reduce dissipative frictional losses during stick-slip motion and to enhance thermal conductivity.

[0017] In one embodiment, the shaft and bracket assembly are made of materials having substantially the same coefficient of thermal expansion, such that the pressure exerted on the bracket assembly on the multiple ceramic plates and shaft is independent of temperature.

[0018] In one embodiment, the multiple ceramic plates are flat, solid plates with a thickness ≤250 μm. The diameter of the shaft is 2 mm to 10 mm, so the mismatch in the coefficients of thermal expansion between the multiple ceramic plates and the shaft can be ignored, making the coefficient of friction of the friction interface formed by the bracket assembly and the multiple ceramic plates independent of temperature.

[0019] In one embodiment, multiple ceramic plates, shafts, and bracket assemblies are made of a material with relatively high thermal conductivity to provide efficient heat transfer through the nanopositioning device.

[0020] In one embodiment, the front clamp and the rear clamp each include a plurality of inner surfaces. Each of the plurality of inner surfaces is a polished metal surface for engaging with a plurality of ceramic plates to form a friction interface.

[0021] In one embodiment, the nanopositioning device further includes a base and one or more metal rods for performing position feedback. The base includes one or more rod holders and a capacitive sensor. Front and rear clamps include one or more through-holes located aligned with the one or more rod holders for receiving the one or more metal rods. The capacitive sensor is configured to determine the geometric capacitance between the one or more metal rods and the bracket assembly for calculating the relative position of the bracket assembly relative to the base.

[0022] In one embodiment, each of the one or more metal rods is a vertical rod having a circular or polygonal cross-section.

[0023] In this embodiment, the capacitive sensor is a Sigma-Delta (Σ-Δ) capacitive-to-digital converter.

[0024] In one embodiment, one or more metal rods are fixedly connected to one or more rod bases via an insulating plate to electrically insulate the one or more metal rods from the base or bottom plate. The insulating plate is a ceramic insulator made of aluminum nitride (AlN) or sapphire.

[0025] In one embodiment, the base further includes a base body and a base plate. A piezoelectric laminate is adhesively or gluingly attached to the base plate. An insulating plate is adhesively attached to the base body or base plate within one or more rod holders.

[0026] In one embodiment, the base body further includes a plurality of cable channels configured to connect a plurality of cables to a piezoelectric stack. The piezoelectric stack is configured to receive a sawtooth voltage signal.

[0027] In one embodiment, the bracket assembly is configured to follow the movement of the shaft when a slowly rising or falling voltage signal is applied to the piezoelectric stack. The shaft is configured to slide when a rapidly rising or falling voltage signal is applied to the piezoelectric stack to cause a stick-slip motion of the bracket assembly relative to the base body.

[0028] In one embodiment, the shaft further includes an extension extending from the bottom end of the shaft in a direction parallel to the shaft. The extension is a thin metal sheet rigidly connected to the base plate to achieve a threaded engagement between the shaft and the base.

[0029] In one embodiment, the nanopositioning device further includes a base, which is a support structure placed below the bracket assembly. The bracket assembly, shaft, and base are made of a metallic material selected from the group consisting of molybdenum (Mo), beryllium copper (BeCu), and phosphor bronze (PhBr); and the ceramic material is AlN or sapphire.

[0030] In one embodiment, the friction interface between the bracket assembly and the shaft uses a stick-slip mechanism to achieve bidirectional linear inertial motion of the bracket assembly relative to the base.

[0031] In one embodiment, the shaft is a cuboid shaft with a rectangular cross-section, and the shaft can be inserted into the rectangular hole gap formed when the current clamp and the rear clamp abut against each other.

[0032] In one embodiment, the front clamp and the rear clamp each include two screw slots. The front clamp and the rear clamp are adjustablely connected by two spring-loaded screws via the screw slots to control the clamping force applied to the shaft by the bracket assembly.

[0033] This summary is provided to present a simplified description of the selected concepts, which will be further described in the detailed embodiments below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to assist in determining the scope of the claimed subject matter. Other aspects and advantages of the invention will be disclosed through the examples described below. Attached Figure Description

[0034] The accompanying drawings contain figures that further illustrate and clarify the above and other aspects, advantages, and features of this disclosure. It should be understood that these drawings depict only certain embodiments of the disclosure and are not intended to limit its scope. It should also be understood that these drawings are shown for simplicity and clarity and are not necessarily drawn to scale. This disclosure will now be described and explained with additional specificity and detail using the accompanying drawings, in which:

[0035] Figure 1 This is a perspective view of a nanopositioning device according to certain embodiments of the present disclosure.

[0036] Figure 2 yes Figure 1 A top view of the nano-positioning device.

[0037] Figure 3 yes Figure 1 An exploded view of the nanopositioning device.

[0038] Figure 4 It is a nano-positioning device along Figure 2 A sectional view of axis A-A' in the diagram.

[0039] Figure 5 This is an exploded view of another embodiment of a nanopositioning device with a threaded joint according to certain embodiments of the present disclosure. Detailed Implementation

[0040] The following detailed description is merely exemplary in nature and is not intended to limit the scope of this disclosure or its application and / or use. It should be understood that numerous variations exist. The detailed description will enable those skilled in the art to implement exemplary embodiments of this disclosure without excessive experimentation, and it should be understood that various changes or modifications can be made to the functionality and structure described in the exemplary embodiments without departing from the scope of this disclosure as set forth in the appended claims.

[0041] Benefits, advantages, solutions to problems, and any elements that may lead to or make more apparent any benefit, advantage, or solution should not be construed as key, essential, or necessary features or elements in any or all of the claims. The invention is defined solely by the appended claims, including any modifications made during the pending period of this application and all equivalents of those claims.

[0042] In the context of describing this invention (particularly in the context of the appended claims), the terms “a” and “an,” “the,” and “at least one,” and similar indicators, should be interpreted to cover both singular and plural, unless otherwise stated herein or clearly contradicted by the context. The terms “comprising,” “having,” and “including,” or any other variations thereof, should be interpreted as open-ended terms (i.e., meaning “including but not limited to”), unless otherwise stated. The use of any and all example or exemplary language (e.g., “such as”) provided herein is intended only to better illustrate the invention and does not constitute a limitation on the scope of the invention, unless otherwise required. No language in the specification should be construed as indicating that any unclaimed element is necessary for the practice of this invention.

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used in the embodiments of this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0044] When referring to coefficients of thermal expansion, the term "substantially identical" as used herein describes two materials having the same or nearly identical coefficients of thermal expansion, making their thermal expansion comparable. The term "perpendicular" as used herein means substantially perpendicular to the plane extending from the base of the device.

[0045] Given the background, there is a need to provide a nanopositioner that operates reliably over a wide temperature and pressure range. In particular, space technology, the semiconductor industry, microscopy applications, and quantum sensing require reliable and precise nanoscale positioning under ultra-high vacuum and cryogenic conditions, with positioning capabilities below 1 x 10⁻⁶. -9 Operating at pressures of mbar and temperatures as low as -273°C.

[0046] This disclosure relates to a nanopositioning device 100 capable of positioning objects with nanometer-level precision. Figure 1 and Figure 2 A perspective view and a top view of a nanopositioning device 100 according to an embodiment of the present invention are shown. Figure 3 An exploded view of the nanopositioning device 100 is shown. Based on the stick-slip actuation principle, the nanopositioning device 100 is capable of operation in ambient and ultra-high vacuum conditions over a wide temperature range from above room temperature to below 1 K. Specifically, the geometry of the nanopositioning device 100, along with its components, and the materials used to manufacture the nanopositioning device 100 and its components, are optimized to maximize efficient heat transfer through the nanopositioning device 100 and to facilitate reliable operation of the nanopositioning device 100 under ambient conditions, in ultra-high vacuum conditions, and across a large temperature window from below 1 K to above room temperature.

[0047] The nanopositioning device 100 includes a base 102, an actuator 103, and a bracket assembly 101 having a front clamp 110 and a rear clamp 120, the front clamp 110 and the rear clamp 120 abutting each other to form an octagonal shape with a rectangular aperture gap. The actuator 103 is coupled to the bracket assembly 101 for precise control of the position of the bracket assembly 101, wherein the actuator 103 includes a piezoelectric stack 145 and a shaft 142. The shaft 142 is preferably cuboid in shape and axially inserted into the base 102 through the rectangular aperture gap, such that the shaft 142 extends from the piezoelectric stack 145 to couple to the front clamp 110 and the rear clamp 120 to drive the bracket assembly 101 with a stick-slip motion. Therefore, the bracket assembly 101 can perform bidirectional linear inertial motion along a vertical axis defined by the shaft 142. In some embodiments, the bracket assembly 101 can be displaced relative to the shaft 142 attached to the base 102. The front clamp 110 and the rear clamp 120 each include two screw slots 136. The front clamp 110 and the rear clamp 120 are adjustably connected via the screw slots 136 by two spring-loaded screws (not shown). Specifically, the two spring-loaded screws are screwed into the two screw slots 136 to secure the front clamp 110 to the rear clamp 120. The spring-loaded screws provide a constant force, ensuring consistent pressure. By adjusting the position of the spring-loaded screws through the screw slots 136, the clamping force applied by the bracket assembly 101 to the shaft 142 can be controlled. This method provides a reliable means for securely mounting the front clamp 110 and the rear clamp 120 of the bracket assembly 101, while allowing precise adjustment to achieve the desired clamping level.

[0048] The bracket assembly 101, formed by the front clamp 110 and the rear clamp 120, contacts the shaft 142, which includes a plurality of ceramic plates 141. In some embodiments, the shaft 142 has a polygonal cross-section. More preferably, the shaft 142 is a cuboid shaft with a rectangular cross-section and can be inserted into a rectangular hole gap. Each of the plurality of ceramic plates 141 is polished and made of a ceramic material. The plurality of ceramic plates 141 contact the front clamp 110 and the rear clamp 120 to form a friction interface for driving the bracket assembly 101. The plurality of ceramic plates 141 are flat, solid plates adhesively attached to the shaft 142. Preferably, the ceramic material is aluminum nitride (AlN) or sapphire. Advantageously, compared to using a shaft made entirely of alumina (amorphous Al2O3), the ceramic plates 141 reduce dissipative frictional losses in stick-slip motion and enhance thermal conductivity. As shown in the embodiment illustrated, the plurality of ceramic plates 141 include four flat, solid plates adhesively attached to the four sides of the cuboid shaft. Two of the plurality of ceramic plates 141 contact the front clamp 110, and the other two of the plurality of ceramic plates 141 contact the rear clamp 120. The shaft 142 employs a stick-slip mechanism to enable the bracket assembly 101 to perform bidirectional linear inertial motion relative to the base 102, thus allowing the bracket assembly 101 to move along the vertical axis defined by the shaft 142. In one embodiment, the diameter of the shaft 142 is 2 mm to 10 mm, and the thickness of the plurality of ceramic plates 141 is ≤250 μm. The mismatch in the coefficients of thermal expansion between the plurality of ceramic plates 141 and the shaft 142 is negligible, making the coefficient of friction of the friction interface formed between the bracket assembly 101 and the plurality of ceramic plates 141 temperature-independent.

[0049] Both the front clamp 110 and the rear clamp 120 include a plurality of inner surfaces 135. Each of the plurality of inner surfaces 135 is a polished metallic surface for engaging with a plurality of ceramic plates 141 to form a friction interface. In some embodiments, each of the plurality of inner surfaces 135 has a surface roughness minimized by electropolishing or mechanical surface treatment. The plurality of inner surfaces 135 and the plurality of ceramic plates 141 together form a friction interface between the front clamp 110 (or rear clamp 120) and the shaft 142, wherein the frictional force acting on the friction interface can be controlled by adjusting the clamping force applied to the shaft 142 using a spring-loaded screw-adjustable bracket assembly 101.

[0050] The rear clamp 120 also includes one or more screw holes 131 for securing a load to the rear clamp 120 of the bracket assembly 101. Screws are rotatably inserted into one or more screw holes 131. The load can be displaced relative to the base 102 via bidirectional movement along axis 142, which is a stable platform for the nanopositioning device 100.

[0051] The piezoelectric stack 145 comprises multiple thin piezoelectric elements stacked together. When a voltage is applied to the piezoelectric stack 145, each piezoelectric element will expand or contract slightly. The overall effect of the piezoelectric stack 145 is due to displacement amplification caused by the parallel operation of the multiple piezoelectric elements.

[0052] The base 102 is a support structure positioned below the bracket assembly 101. In some embodiments, the base 102 includes a base body 160 and / or a base plate 180. The base body 160 and the base plate 180 are mounted together using one or more screws or other connectors through a plurality of threaded holes 182. A piezoelectric stack 145 is glued or otherwise adhesively attached to the base plate 180 at piezoelectric stack grooves 181. The base body 160 also includes a plurality of cable channels 167 arranged for connecting a plurality of cables (not shown) to the piezoelectric stack 145.

[0053] In some embodiments, the piezoelectric stack 145 is configured to receive a sawtooth voltage signal. When a slowly rising or falling voltage signal is applied to the piezoelectric stack 145, the bracket assembly 101 is configured to follow the movement of the shaft 142. On the other hand, when a rapidly rising or falling voltage signal is applied to the piezoelectric stack 145, the length of the piezoelectric stack 145 will change rapidly. Due to the inertia of the bracket assembly 101, the shaft 142 will slide to cause a stick-slip motion of the bracket assembly 101 relative to the base 102.

[0054] By applying a voltage to the piezoelectric stack 145, the piezoelectric material expands or contracts, causing the shaft 142 to move up or down. The bracket assembly 101, to which a load is attached, can be moved along the shaft 142 via the screw holes 131 to allow the load to be precisely positioned.

[0055] The nanopositioning device 100 also includes one or more metal rods 150 for obtaining position feedback. The front clamp 110 and rear clamp 120 include one or more through holes 132 that allow the placement of one or more metal rods 150. In the illustrated embodiment, the front clamp 110 has one through hole 132, and the rear clamp 120 has another through hole 132. (Reference) Figure 4 In the cross-sectional view, one or more through holes 132 are provided at positions aligned with one or more rod seats 163 provided on the base 102. One or more metal rods 150 are used to determine the relative position of the bracket assembly 101 for positioning purposes. In some embodiments, the geometric capacitance between the bracket assembly 101 and the one or more metal rods 150 is determined, which depends on the vertical positions of the front clamp 110 and the rear clamp 120. This can be used as a position readout. Specifically, the geometric capacitance (C) C-R The formula for calculating ) is:

[0056]

[0057] in:

[0058] L is the length of the geometric overlap between the metal rod 150 and the bracket assembly 101;

[0059] b is the aperture of each of the one or more through holes 132; and

[0060] a is the rod diameter of each of the one or more metal rods 150.

[0061] Using typical dimensions L = 5mm, b = 2.2mm, ε = 8.85x10 -12 Fm -1 With a = 2 mm, the geometric capacitance is 2.92 pF. The capacitance value depends on the relative position of the bracket assembly 101 with respect to one or more metal rods 150 and can be determined by external sensing circuitry. In some embodiments, the capacitance sensor is a sigma-delta (Σ-Δ) capacitance-to-digital converter. For example, the capacitance sensor could be an AD7745 or AD7746, which can resolve capacitances as small as 4 aF. The capacitance sensor is a built-in capacitance sensor implemented within the footprint of the nanopositioning device 100. Obviously, the capacitance sensor can be positioned in locations other than the base 102. Contact cables are used to connect to one or more metal rods 150 at the upper contact cable slot 137 and the lower contact cable slot 151 for capacitance measurement.

[0062] Each of the one or more metal rods 150 is a vertical rod having a circular or polygonal cross-section. The one or more metal rods 150 are received in one or more through holes 132. The surfaces of the one or more metal rods 150 are electrically isolated relative to the front clamp 110 and the rear clamp 120 by a clearance space. At the lowermost end of the one or more through holes 132, the one or more metal rods 150 are also electrically isolated from the base body 160 by an insulating plate 152. In some embodiments, the one or more metal rods 150 are fixedly connected to the base 102 at one or more rod holders 163 via the insulating plate 152 to electrically insulate the one or more metal rods 150 from the base 102 or the base plate 180. Specifically, for electrical insulation, the insulating plate 152 is a ceramic insulator made of AlN or sapphire, which are electrical insulators. Obviously, the insulating plate 152 can be made of other electrical insulators without departing from the scope and spirit of this disclosure. By using two metal rods 150, as demonstrated in the illustrated embodiment, a position readout accuracy better than 10 nm can be achieved over a total travel distance of L = 5 mm. Therefore, the disclosed capacitive readout design provides excellent readout accuracy, reduced heat dissipation during the readout process, and a reduced geometric footprint for the nanopositioning device 100.

[0063] Another aspect of this disclosure provides high operational performance of the nanopositioning device 100 over a wide temperature range. The bracket assembly 101, shaft 142, and base 102 are made of the same metallic material selected from the group consisting of molybdenum (Mo), beryllium copper (BeCu), and phosphor bronze (PhBr). This is to maintain the operational performance of the stick-slip mechanism of the nanopositioning device 100 under temperature variations. Due to the material-specific coefficient of thermal expansion, the degree of thermal expansion and contraction of the spatial dimensions of an object depends on its material. In some embodiments, the bracket assembly 101, shaft 142, and base 102 are made of the same material or materials having substantially the same coefficient of thermal expansion. Therefore, the effect of thermal contraction and thermal expansion on the spatial dimensions of the bracket assembly 101, shaft 142, and base 102 is negligible. Therefore, the pressure of the bracket assembly 101 on the plurality of ceramic plates 141 and shaft 142 is temperature-independent. On the other hand, the plurality of ceramic plates 141 are made of AlN or sapphire. Because the multiple ceramic plates 141 have a thickness of ≤250 μm, there is a possible mismatch in their coefficients of thermal expansion (e.g., Mo is approximately 5 × 10⁻⁶). -6 / K, AlN is approximately 4.5 × 10 -6 / K) is negligible. This allows the stick-slip mechanism to operate reliably over a wide temperature window, from <1K to above room temperature.

[0064] Another aspect of this disclosure provides high thermal conductivity in the nanopositioning device 100, making it ideally suited for applications requiring efficient removal of excess heat load or sufficient cooling power on the nanopositioning device 100. Specifically, the plurality of ceramic plates 141, shaft 142, and bracket assembly 101 are made of materials with relatively high thermal conductivity to provide efficient heat transfer through the nanopositioning device 100. The relatively high thermal conductivity of these materials (Mo, BeCu, and PhBr) facilitates efficient heat transfer through the nanopositioning device 100. Because the plurality of ceramic plates 141 have a thickness ≤100 μm, their relatively poor thermal conductivity at temperatures less than 1 K minimizes the impact on the overall thermal conductivity through the nanopositioning device 100. For example, excess heat generated by objects attached to the bracket assembly 101 will be efficiently transferred through the entire nanopositioning device 100 to the support structure rigidly connected to the base plate 180. Therefore, the nanopositioning device 100 of this disclosure features reliable operation at a minimum temperature of 100 mK and during processes where excess heat load must be eliminated.

[0065] In one embodiment, the rigid connection between the shaft 142 and the base 102 is established via an adhesive interface or a threaded joint, which is based on a thin metal sheet extending in a direction parallel to the shaft 142. Using a threaded joint is advantageous because it establishes a metal interface between the shaft 142 and the base 102, maximizing heat transfer while the thin metal sheet does not impede the piezoelectric effect of the actuator 103.

[0066] refer to Figure 5 Another embodiment of the nanopositioning device 100 with a threaded connector 143 is provided. The shaft 142 also includes an extension 144 extending from the bottom end of the shaft 142 in a direction parallel to the shaft 142 to provide heat conduction. Preferably, the extension 144 can be a thin metal sheet rigidly connected to the base plate 180 via the threaded connector 143. This threaded connector 143 enables metal-to-metal contact, which further maximizes efficient heat load transfer through the nanopositioning device 100 from the bracket 101 to the base 102 compared to the adhesive interface between the shaft 142 and the piezoelectric stack 145.

[0067] Therefore, the nanopositioning device 100 of the present invention can achieve reliable operation over a wide temperature range and under internal and external ultra-high vacuum conditions. This illustrates the basic structure of the nanopositioning device 100 according to the present disclosure. It is obvious that variations and other features and functions or alternatives thereof disclosed above can be combined into many other different methods or devices. Therefore, this embodiment is to be considered illustrative rather than restrictive in all respects. The scope of this disclosure is indicated by the appended claims rather than by the foregoing description, and is therefore intended to include all changes falling within the meaning and scope of the equivalents of the claims.

[0068] References

[0069] The following references are cited in this specification. The contents of these references are incorporated herein by reference in their entirety.

[0070] [1] N DWPohl, "Dynamic piezoelectric translation devices," Review ofScientific Instruments, vol.58, p.54-57, 1987, https: / / doi.org / 10.1063 / 1.1139566.

[0071] [2]Ph.Niedermann, R.Emch, P.Descouts, "Simple piezoelectric translation device," Review of Scientific Instruments, vol.59, p.368-369, 1988, https: / / doi.org / 10.1063 / 1.1140206.

Claims

1. A nanopositioning device capable of positioning objects with nanometer-level precision, comprising: A bracket assembly, the bracket assembly including a front clamp and a rear clamp; An actuator coupled to the bracket assembly for precisely controlling the position of the bracket assembly relative to the actuator, wherein the actuator includes a piezoelectric stack and a shaft extending from the piezoelectric stack to be coupled to the front clamp and the rear clamp for stick-slip driving of the bracket assembly; Base; as well as One or more metal rods used to perform position feedback. in: The shaft includes a plurality of ceramic plates, each of which is polished and made of ceramic material, and the plurality of ceramic plates contact the front clamp and the rear clamp to achieve a friction interface for driving the bracket assembly; The base includes one or more rod holders and a capacitive sensor; The front clamp and the rear clamp each include one or more through holes, which are positioned aligned with the one or more rod holders to accommodate the one or more metal rods; and The capacitive sensor is configured to determine the geometric capacitance between the one or more metal rods and the bracket assembly, for calculating the relative position of the bracket assembly relative to the base.

2. The nanopositioning device according to claim 1, wherein, The plurality of ceramic plates are adhesively attached to the shaft to reduce dissipative frictional losses during stick-slip motion and to enhance thermal conductivity.

3. The nanopositioning device according to claim 2, wherein, The shaft and the bracket assembly are made of materials having substantially the same coefficient of thermal expansion, such that the pressure exerted by the bracket assembly on the plurality of ceramic plates and the shaft is independent of temperature.

4. The nanopositioning device according to claim 2, wherein, The plurality of ceramic plates are flat solid plates with a thickness of ≤250μm; and the diameter of the shaft is 2mm to 10mm. Therefore, the mismatch in the coefficients of thermal expansion between the plurality of ceramic plates and the shaft can be ignored, making the coefficient of friction of the friction interface formed by the bracket assembly and the plurality of ceramic plates independent of temperature.

5. The nanopositioning device according to claim 2, wherein, The plurality of ceramic plates, the shaft, and the bracket assembly are made of a material with relatively high thermal conductivity to provide efficient heat transfer through the nanopositioning device.

6. The nanopositioning device according to claim 2, wherein, The front clamp and the rear clamp each include a plurality of inner surfaces, wherein each of the plurality of inner surfaces is a polished metal surface for engaging with the plurality of ceramic plates to form the friction interface.

7. The nanopositioning device according to claim 1, wherein, Each of the one or more metal rods is a vertical rod with a circular or polygonal cross-section; and wherein the relative positions of the bracket assemblies are based on the geometric capacitance ( The determination is as follows: in: L It is the length of the metal rod that geometrically overlaps with the bracket assembly; b It is the diameter of each of the one or more through holes; and It is the rod diameter of each of the one or more metal rods; ε It is the dielectric constant.

8. The nanopositioning device according to claim 1, wherein, The capacitive sensor is a Sigma-Delta (Σ-Δ) capacitive-to-digital converter.

9. The nanopositioning device according to claim 1, wherein, The one or more metal rods are fixedly connected to the one or more rod bases by an insulating plate for electrically insulating the one or more metal rods from the base, wherein the insulating plate is a ceramic insulator made of aluminum nitride (AlN) or sapphire.

10. The nanopositioning device according to claim 9, wherein, The base also includes a base body and / or a base plate, wherein the piezoelectric laminate is adhesively attached to the base plate; and wherein the insulating plate is adhesively attached to the base body or the base plate within one or more rod holders.

11. The nanopositioning device according to claim 10, wherein, The base body or the base plate also includes a plurality of cable channels configured to connect a plurality of cables to the piezoelectric stack; and wherein the piezoelectric stack is configured to receive a sawtooth voltage signal.

12. The nanopositioning device according to claim 11, wherein, The bracket assembly is configured to follow the movement of the shaft when a slowly rising or falling voltage signal is applied to the piezoelectric stack; and wherein the shaft is configured to slide when a rapidly rising or falling voltage signal is applied to the piezoelectric stack to cause a stick-slip movement of the bracket assembly relative to the base body or the base plate.

13. The nanopositioning device according to claim 10, wherein, The shaft also includes an extension extending from the bottom end of the shaft in a direction parallel to the shaft, wherein the extension is a thin metal sheet rigidly connected to the base plate to achieve a threaded engagement between the shaft and the base.

14. The nanopositioning device according to claim 1, wherein, The base is a support structure placed below the bracket assembly, wherein the bracket assembly, the shaft, and the base are made of a metallic material selected from the group consisting of molybdenum (Mo), beryllium copper (BeCu), and phosphor bronze (PhBr); and wherein the ceramic material is aluminum nitride (AlN) or sapphire.

15. The nanopositioning device according to claim 14, wherein, The friction interface between the bracket assembly and the shaft uses a stick-slip mechanism to achieve bidirectional linear inertial motion of the bracket assembly relative to the base.

16. The nanopositioning device according to claim 1, wherein, The shaft is a cuboid shaft with a rectangular cross-section, and the shaft can be inserted into the rectangular hole gap formed when the front clamp and the rear clamp abut against each other.

17. The nanopositioning device according to claim 1, wherein, The front clamp and the rear clamp each include two screw slots, and the front clamp and the rear clamp are adjustablely connected by two spring-loaded screws via the screw slots for controlling the clamping force applied by the bracket assembly.

18. A nanopositioning device capable of positioning objects with nanometer-level precision and possessing high thermal conductivity, comprising: A bracket assembly, the bracket assembly including a front clamp and a rear clamp; An actuator coupled to the bracket assembly for precisely controlling the position of the bracket assembly, wherein the actuator includes a piezoelectric stack and a shaft extending from the piezoelectric stack to the bracket assembly; Base; as well as One or more metal rods used to perform position feedback. in: The shaft includes a plurality of ceramic plates with a thickness ≤250μm. The plurality of ceramic plates are flat solid plates adhesively attached to the shaft to reduce dissipative frictional losses in stick-slip motion when the bracket assembly moves along a vertical axis defined by the shaft. Furthermore, the diameter of the shaft is sufficiently larger than the thickness of the plurality of ceramic plates, so that the mismatch in the coefficients of thermal expansion between the plurality of ceramic plates and the shaft can be ignored. The base includes one or more rod holders and a capacitive sensor; The front clamp and the rear clamp each include one or more through holes, which are positioned aligned with the one or more rod holders to accommodate the one or more metal rods; and The capacitive sensor is configured to determine the geometric capacitance between the one or more metal rods and the bracket assembly, for calculating the relative position of the bracket assembly relative to the base.

19. The nanopositioning device according to claim 18, wherein, The base is a support structure placed below the bracket assembly, wherein the bracket assembly, the shaft, and the base are made of a metallic material selected from the group consisting of molybdenum (Mo), beryllium copper (BeCu), and phosphor bronze (PhBr); and wherein the plurality of ceramic plates are made of aluminum nitride (AlN) or sapphire.

20. The nanopositioning device according to claim 19, wherein, The shaft also includes an extension extending from the bottom end of the shaft in a direction parallel to the shaft, wherein the extension is a thin metal sheet rigidly connected to the base to achieve a threaded engagement between the shaft and the base.

21. The nanopositioning device according to claim 18, wherein, The shaft is a cuboid shaft with a rectangular cross-section, and the shaft can be inserted into the rectangular hole gap formed when the front clamp and the rear clamp abut against each other.

22. The nanopositioning device according to claim 21, wherein, The plurality of ceramic plates include four flat, solid plates that are adhesively attached to the four sides of the cuboid axis.

23. The nanopositioning device according to claim 18, wherein, The plurality of ceramic plates have polished surfaces to form friction interfaces with the plurality of inner surfaces of the front clamp and the rear clamp.

24. The nanopositioning device according to claim 23, wherein, The coefficient of friction of the friction interface formed by the bracket assembly and the plurality of ceramic plates becomes independent of temperature.

25. The nanopositioning device according to claim 23, wherein, The friction interface between the bracket assembly and the shaft uses a stick-slip mechanism to achieve bidirectional linear inertial motion of the bracket assembly relative to the base.

Images