A sub-nanometer high-precision micro-displacement device and application for precision laser interferometry calibration

Abstract

The present invention provides a sub-nanometer high-precision micro-displacement device and application for precision laser interferometry calibration. By using differential capacitance micrometer feedback and electrostatic suspension drive for closed-loop control, it realizes real-time monitoring of high-precision micro-displacement at the sub-nanometer level and can be used as a reference benchmark for high-precision micro-displacement at the sub-nanometer level. At the same time, an active vibration isolation table is used to isolate the vibration influence of ground vibration noise on the sub-nanometer high-precision micro-displacement device. A corner cube reflector is ingeniously embedded on the floating substrate as the moving mirror of the precision laser interferometry system, and another fixed corner cube reflector is used as the static mirror. The electrostatic suspension drive moves the floating substrate to drive the corner cube reflector to generate a quantitative micro-displacement at the sub-nanometer level. The precision laser interferometry system is used to measure the quantitative micro-displacement of the corner cube reflector, and a quantitative calibration relationship between the measurement result and the micro-displacement is established to complete the sub-nanometer displacement measurement calibration of the precision laser interferometry system.

Description

Technical Field

[0001] The present invention relates to the technical field of precision laser interferometry, and in particular to a sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration and its application. Background Art

[0002] Precision laser interferometry uses a laser as the light source, takes the laser wavelength or laser frequency as the reference, and utilizes the interference principle of light to achieve high-precision measurements with a position accuracy (such as positioning accuracy, repeat positioning accuracy, etc.) at the nanometer level, sub-nanometer level, or even picometer level. It has a wide range of applications in industries such as numerical control precision machining, basic metrology measurement, precision positioning and ranging, and high-end manufacturing, as well as in aerospace fields such as earth gravity field testing, gravitational gradient measurement, deep space laser communication, and space gravitational wave detection. As a high-precision precision micro-displacement measurement system, although laser interferometry mainly takes the laser wavelength or laser frequency as the measurement reference, the measurement accuracy of the entire system is also affected by other components of the measurement system. How to achieve quantitative calibration of sub-nanometer level micro-displacement measurement in laser interferometry is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0003] The first object of the present invention is to provide a sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration in view of the deficiencies in the prior art.

[0004] To achieve the above object of the present invention, the following technical solutions are adopted:

[0005] A sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration, characterized in that: the sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration includes a fixed bottom plate, a fixed top plate, and a floating substrate arranged in the space surrounded by the fixed bottom plate and the fixed top plate. A differential capacitance sensor is provided between the fixed bottom plate and the fixed top plate. The differential capacitance sensor includes a fixed capacitance upper plate, a fixed capacitance lower plate, and a movable capacitance plate. The fixed capacitance upper plate is arranged on the lower surface of the fixed top plate, the fixed capacitance lower plate is arranged on the upper surface of the fixed bottom plate, and a circle of movable capacitance plates is coated on the outer surface of the floating substrate;

[0006] A corner cube reflector is provided on the floating substrate, and the position of the corner cube reflector is such that the light incident on the corner cube reflector can return without obstruction.

[0007] While adopting the above technical solutions, the present invention can also adopt or combine the following technical solutions:

[0008] As a preferred technical solution of the present invention: a support vertical plate is provided between the fixed bottom plate and the fixed top plate, and both the fixed bottom plate and the fixed top plate are located on the same side of the support vertical plate.

[0009] As a preferred technical solution of the present invention: the fixed bottom plate is arranged on the active vibration isolation table.

[0010] As a preferred technical solution of the present invention: the position of the floating substrate where the corner cube mirror is provided is hollowed out, and it is ensured that the weight of the hollowed-out part of the floating substrate is the same as the weight of the corner cube mirror.

[0011] As a preferred technical solution of the present invention: the vertical projection of the moving capacitor plate includes and is larger than the vertical projections of the fixed capacitor lower plate and the fixed capacitor upper plate, and the vertical projections of the fixed capacitor lower plate and the fixed capacitor upper plate coincide.

[0012] As a preferred technical solution of the present invention: the floating substrate is processed and formed from a carbon fiber material with light weight and good stiffness.

[0013] As a preferred technical solution of the present invention: the corner cube mirror is made of BK7 glass material, and a high-reflectivity film is deposited based on the ion beam sputtering coating process by selecting the coating material with the best match with the lattice constant of the substrate.

[0014] Another object of the present invention is to provide the application of the sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration described above in the quantitative calibration of a precision laser interferometry system.

[0015] While adopting the above technical solutions, the present invention can also adopt or combine the following technical solutions:

[0016] As a preferred technical solution of the present invention: the application specifically includes the following steps:

[0017] S1. Apply a driving voltage amplified by high voltage to the three capacitor plates of the differential capacitance sensor to generate an electrostatic force. Adjusting the driving voltage applied to the three capacitor plates can change the electrostatic force between adjacent plates. After breaking the balance state, the floating substrate can be ensured to form a horizontal suspension in the space surrounded by the fixed bottom plate and the fixed top plate under the action of the electrostatic force.

[0018] S2. After the floating substrate is horizontally suspended, continuously adjusting the relative magnitudes of the driving voltages applied to the three capacitor plates can cause the floating substrate to translate up and down in the vertical direction by a sub-nanometer magnitude.

[0019] S3. After the floating substrate undergoes a position translation in the vertical direction, the distances between the moving capacitive electrode plate and the lower and upper fixed capacitive electrode plates will all change accordingly, resulting in changes in the capacitance values of the upper and lower capacitive sensors that make up the differential capacitive sensor. By using the upper and lower capacitive sensors of the differential capacitive sensor, based on the differential capacitance micrometry technology, the tiny displacement generated by the electrostatic levitation drive of the floating substrate can be monitored in real time with high precision at the sub-nanometer level. Using the differential capacitance micrometry as real-time displacement feedback and cooperating with the electrostatic levitation drive for closed-loop control, it can ensure that the floating substrate can achieve high-precision displacement at the sub-nanometer level under the electrostatic levitation drive, and can be used as a displacement calibration reference benchmark for precision laser interferometry measurement.

[0020] S4. During the calibration of precision laser interferometry measurement, the corner cube reflector on the floating substrate is used as the moving mirror of the laser interferometry measurement system, and another fixed corner cube reflector is used as the static mirror. The electrostatic levitation drive moves the floating substrate to drive the corner cube reflector to generate a quantitative micro-displacement at the sub-nanometer level. The precision laser interferometry measurement system is used to measure the quantitative micro-displacement of the corner cube reflector, and a quantitative calibration relationship between the measurement result and the micro-displacement is established to complete the sub-nanometer level displacement measurement calibration of the precision laser interferometry measurement system.

[0021] The present invention provides a sub-nanometer level high-precision micro-displacement device and application for precision laser interferometry measurement calibration. The sub-nanometer level high-precision micro-displacement device for precision laser interferometry measurement calibration uses differential capacitance micrometry feedback and electrostatic levitation drive for closed-loop control to achieve real-time monitoring of high-precision micro-displacement at the sub-nanometer level, and can be used as a reference benchmark for high-precision micro-displacement at the sub-nanometer level. At the same time, an active vibration isolation table is used to isolate the vibration influence of ground vibration noise on the sub-nanometer level high-precision micro-displacement device. A corner cube reflector is ingeniously embedded on the floating substrate of the sub-nanometer level high-precision micro-displacement device as the moving mirror of the precision laser interferometry measurement system, and another fixed corner cube reflector is used as the static mirror. The electrostatic levitation drive moves the floating substrate to drive the corner cube reflector to generate a quantitative micro-displacement at the sub-nanometer level. The precision laser interferometry measurement system is used to measure the quantitative micro-displacement of the corner cube reflector, and a quantitative calibration relationship between the measurement result and the micro-displacement is established to complete the sub-nanometer level displacement measurement calibration of the precision laser interferometry measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural diagram of the sub-nanometer level high-precision micro-displacement device for precision laser interferometry measurement calibration provided by the present invention.

[0023] Figure 2 It is a schematic block diagram of the closed-loop control of differential capacitance micrometry feedback and electrostatic levitation drive.

[0024] Figure 3Schematic diagram of the application of the sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration in the quantitative calibration of a precision laser interferometry system provided by the present invention. Detailed implementation manners

[0025] The present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.

[0026] As Figure 1 shown, a sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration includes a fixed bottom plate 1, a support vertical plate 2, a fixed top plate 3, a floating substrate 4, a differential capacitance sensor 5, a corner cube reflector 6, and an active vibration isolation table 7; the outer contour dimensions of the fixed bottom plate 1 and the fixed top plate 3 are the same, both are parallel to the horizontal plane and are vertically installed at the upper and lower ends of the vertically placed support vertical plate 2 and are on the same side of the support vertical plate 2; the width of the floating substrate 4 is slightly smaller than the width of the fixed top plate 3, and after suspension, it is ensured that the floating substrate 4 is parallel to the fixed top plate 3 and has no contact with the support vertical plate 2, the length is greater than the length of the fixed top plate 3, and after suspension, it is ensured that the lengths of the two parts extending left and right in the length direction of the floating substrate 4 are the same; the differential capacitance sensor 5 is plated between the fixed bottom plate 1, the fixed top plate 3, and the floating substrate 4; the corner cube reflector 6 is embedded in the middle position of the right-side extended part of the floating substrate 4, and the light incident on the corner cube reflector 6 can return without obstruction; the fixed bottom plate 1 is placed on the active vibration isolation table 7.

[0027] The fixed bottom plate 1, the support vertical plate 2, and the fixed top plate 3 are processed from aluminum alloy materials, and the floating substrate 4 is processed from lightweight and high-rigidity carbon fiber materials. The fixed capacitance lower electrode plate 5-1 and the fixed capacitance upper electrode plate 5-2 that make up the differential capacitance sensor 5 are respectively plated on the upper surface of the fixed bottom plate 1 and the lower surface of the fixed top plate 3 by a gold plating process, and the moving capacitance electrode plate 5-3 is plated in a circle on the surface of the floating substrate 4 by a gold plating process. The vertical projections of the two fixed capacitance electrode plates are the same, and the vertical projection of the moving capacitance electrode plate includes and is greater than the vertical projections of the two fixed capacitance electrode plates. The corner cube reflector 6 is made of BK7 glass material, and the coating material with the best lattice constant matching with the substrate is selected, and a high-reflectivity film is plated based on the ion beam sputtering coating process. The active vibration isolation table 7 is selected to be realized by the best commercially available vibration isolation table with vibration isolation performance on the current market.

[0028] By using the upper and lower two capacitance sensors of the differential capacitance sensor 5, real-time displacement monitoring at the sub-nanometer level can be realized based on the differential capacitance micrometry technology. Based on the differential capacitance micrometry feedback, combined with the electrostatic suspension drive of the floating substrate 4 for closed-loop feedback control, high-precision micro-displacement at the sub-nanometer level can be realized as a displacement reference benchmark.

[0029] The fixed base plate 1 is placed on the active vibration isolation table 7. The active vibration isolation table 7 is used to isolate the vibration influence of the ground vibration noise on the sub-nanometer-level high-precision micro-displacement reference benchmark, ensuring the accuracy of the micro-displacement.

[0030] As Figure 1 shown, the middle position of the extended part on the right side of the floating substrate 4 is hollowed out, and a corner cube mirror 6 is inlaid at the hollowed-out position. The weight of the corner cube mirror 6 is precisely controlled so that its weight is the same as the weight of the hollowed-out part of the floating substrate 4, ensuring that the floating substrate 4 can still maintain static balance after the corner cube mirror 6 is inlaid and the light incident on the corner cube mirror 6 can return unobstructed.

[0031] As Figure 3 shown, the Figure 1 sub-nanometer-level high-precision micro-displacement device shown is combined with the precision laser interferometry system. Using the corner cube mirror 6 inlaid on the extended part on the right side of the floating substrate 4 as the moving mirror of the precision laser interferometry system, high-precision displacement calibration of sub-nanometer level for the precision laser interferometry can be achieved.

[0032] The application of the sub-nanometer-level high-precision micro-displacement device for precision laser interferometry calibration in the quantitative calibration of the precision laser interferometry system specifically includes the following steps:

[0033] S1. As Figure 1 shown, a fixed capacitor lower plate 5-1 is plated on the upper surface of the fixed base plate 1, a fixed capacitor upper plate 5-2 is plated on the lower surface of the fixed top plate 3, and a fixed capacitor plate 5-3 is plated in a circle on the surface of the floating substrate 4. Two capacitive sensors are formed between the three capacitor plates. The upper and lower two capacitive sensors form a differential capacitive sensor 5. Applying a driving voltage amplified by high voltage to the three capacitor plates of the differential capacitive sensor 5 can generate an electrostatic force. As Figure 2 shown, considering the gravity of the floating substrate, the driving voltage applied to the fixed capacitor upper plate 5-2 is U 0 +U, the driving voltage applied to the fixed capacitor lower plate 5-1 is U 0 -U, and the driving voltage applied to the moving capacitor plate 5-3 of the floating substrate 4 is 0, where U 0 is the reference bias driving voltage, U is the control driving voltage, taking U 0 = 1000V, and U is variable between 300 and 700V. Adjusting the driving voltages applied to the two capacitor plates of the fixed capacitor lower plate 5-1 and the fixed capacitor upper plate 5-2 can change the electrostatic force between adjacent plates. After breaking the balance state, the floating substrate 4 can be ensured to be horizontally suspended under the action of the electrostatic force;

[0034] S2. After the floating substrate 4 is horizontally suspended, continuously adjusting the relative magnitudes of the driving voltages applied to the two capacitor plates of the fixed capacitor lower plate 5-1 and the fixed capacitor upper plate 5-2 can cause the floating substrate 4 to translate vertically by a sub-nanometer magnitude;

[0035] S3. After the floating substrate 4 translates vertically, the distances between the moving capacitor plate 5-3 and the fixed capacitor lower plate 5-1 and between the moving capacitor plate 5-3 and the fixed capacitor upper plate 5-2 will correspondingly change, thereby causing the capacitance values of the upper and lower two capacitance sensors C 上 and C 下 constituting the differential capacitance sensor 5 to change. As Figure 2 shown, by using the upper and lower two capacitance sensors of the differential capacitance sensor 5, based on the differential capacitance micrometer technology, the minute displacement generated by the electrostatic suspension drive of the floating substrate 4 can be monitored in real time with high precision at the sub-nanometer magnitude; further using the differential capacitance micrometer as the real-time displacement feedback and cooperating with the electrostatic suspension drive for closed-loop control to ensure that the floating substrate 4 can achieve a high-precision displacement at the sub-nanometer magnitude under the electrostatic suspension drive, which can be used as the displacement calibration reference for precise laser interferometry measurement;

[0036] S4. As Figure 3 shown, during the calibration of precise laser interferometry measurement, the corner cube reflector 6 embedded on the right side of the floating substrate 4 is used as the moving mirror of the laser interferometry measurement system, and another fixed corner cube reflector is used as the static mirror. The electrostatic suspension drives the floating substrate 4 to drive the corner cube reflector 6 to generate a quantitative minute displacement at the sub-nanometer magnitude, and the precise laser interferometry measurement system is used to measure the quantitative minute displacement of the corner cube reflector 6, and a quantitative calibration relationship between the measurement result and the minute displacement is established, thereby completing the sub-nanometer magnitude displacement measurement calibration of the precise laser interferometry measurement system.

[0037] The above specific embodiments are used to explain and illustrate the present invention, which are only the preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration, characterized in that: The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration includes a fixed bottom plate, a fixed top plate, and a floating substrate arranged in the space surrounded by the fixed bottom plate and the fixed top plate. A differential capacitance sensor is provided between the fixed bottom plate and the fixed top plate. The differential capacitance sensor includes a fixed capacitance upper plate, a fixed capacitance lower plate, and a movable capacitance plate. The fixed capacitance upper plate is arranged on the lower surface of the fixed top plate, the fixed capacitance lower plate is arranged on the upper surface of the fixed bottom plate, and a circle of movable capacitance plates is coated on the outer surface of the floating substrate; A corner cube reflector is provided on the floating substrate, and the position of the corner cube reflector is such that the light incident on the corner cube reflector can return without obstruction.

2. The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1, characterized in that: A support vertical plate is provided between the fixed bottom plate and the fixed top plate, and both the fixed bottom plate and the fixed top plate are located on the same side of the support vertical plate.

3. The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1, characterized in that: The fixed bottom plate is arranged on an active vibration isolation table.

4. The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1, characterized in that: The position of the floating substrate where the corner cube reflector is provided is hollowed out, and the weight of the hollowed-out part of the floating substrate is ensured to be the same as the weight of the corner cube reflector.

5. The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1, characterized in that: The vertical projection of the movable capacitance plate includes and is larger than the vertical projections of the fixed capacitance lower plate and the fixed capacitance upper plate, and the vertical projections of the fixed capacitance lower plate and the fixed capacitance upper plate coincide.

6. The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1, characterized in that: The floating substrate is processed and formed from a carbon fiber material with light weight and good stiffness.

7. The sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1, characterized in that: The corner cube reflector is made of BK7 glass material, and the coating material with the best match with the lattice constant of the substrate is selected, and a high-reflectivity film is deposited based on the ion beam sputtering coating process.

8. Application of the sub-nanometer high-precision micro-displacement device for precision laser interferometry calibration according to claim 1 in quantitative calibration of a precision laser interferometry system.

9. The application according to claim 8, characterized in that: The application includes the following steps: S1. Apply a drive voltage amplified by high voltage to the three capacitance plates of the differential capacitance sensor to generate an electrostatic force. Adjusting the drive voltage applied to the three capacitance plates can change the electrostatic force between adjacent plates. After breaking the balance state, the floating substrate can be ensured to form a horizontal suspension in the space surrounded by the fixed bottom plate and the fixed top plate under the action of the electrostatic force; After the floating substrate is horizontally suspended, continuously adjusting the relative magnitudes of the driving voltages applied to the three capacitor plates can cause the floating substrate to translate vertically by a sub-nanometer magnitude. After the floating substrate undergoes a position translation in the vertical direction, the distances between the moving capacitor plate and the lower fixed capacitor plate and between the moving capacitor plate and the upper fixed capacitor plate will correspondingly change, thereby causing the capacitance values of the upper and lower capacitor sensors that make up the differential capacitance sensor to change. By using the upper and lower capacitor sensors of the differential capacitance sensor and based on the differential capacitance micrometer technology, the tiny displacement generated by the electrostatic suspension drive of the floating substrate can be monitored in real time with high precision at the sub-nanometer level. Using the differential capacitance micrometer as the real-time displacement feedback and cooperating with the electrostatic suspension drive for closed-loop control can ensure that the floating substrate can achieve a high-precision displacement at the sub-nanometer level under the electrostatic suspension drive, which can be used as a displacement calibration reference benchmark for precise laser interferometry measurement. During the calibration of the precise laser interferometry measurement, the corner cube reflector on the floating substrate is used as the moving mirror of the laser interferometry system, and another fixed corner cube reflector is used as the static mirror. The electrostatic suspension drives the floating substrate to drive the corner cube reflector to generate a quantitative micro-displacement at the sub-nanometer level. The precise laser interferometry system is used to measure the quantitative micro-displacement of the corner cube reflector, and a quantitative calibration relationship between the measurement result and the micro-displacement is established to complete the sub-nanometer level displacement measurement calibration of the precise laser interferometry system.

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