Construction method of digital reference surface shape and long-range surface shape instrument system

Abstract

The invention belongs to the technical field of ultrahigh-precision surface shape detection, and provides a construction method of a digital reference surface shape and a long-range surface shape instrument system. The construction method comprises the following steps: fixing one end of a reference mirror to form a cantilever structure, and applying a series of acting forces Fi; obtaining the deformation Xi of the suspended end under Fi or the inclination angle Ai of the end face; calculating the deformation X'i of the reference mirror under Fi or the inclination angle A'i of the end face based on finite element simulation; and adjusting parameters of analog calculation to enable X'i to be consistent with Xi or enable the inclination angle A'i to be consistent with Ai, thereby obtaining accurate deformation values of the lower mirror body under Fi, and enabling differences between the deformation values to become a series of surface shape numerical value groups so as to obtain a digital reference surface shape. The digital reference surface serves as a standard surface shape, and the calibration problem depending on entity reference mirror surface precision can be solved. The digital standard mirror surface is used for simultaneous measurement or calibration, so that reliable and higher-precision test results can be obtained in the surface shape measurement of the large-scale reflecting mirror.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-high precision surface shape detection, and in particular to a method for constructing a digital reference surface shape and a long-range surface shape meter system. Background Art

[0002] For the measurement of large-size reflectors, the long-range profilometer is a commonly used measuring instrument. The basic principle of the long-range profilometer is to introduce a thin beam of light with a fixed incident angle to scan the optical device to be measured point by point. Since the normal directions of different points on the optical device are different, the reflected light is reflected at different angles to the angle detection system of the long-range profilometer for angle measurement, so as to obtain the surface information of the optical device along the scanning direction by measuring the relative change values ​​of the angles at different points.

[0003] With the improvement of measurement accuracy, a solution of using calibration devices to solve the accuracy and precision problems of the system has been formed in the process of gradual iteration of the measurement system. That is, a calibration device is used to calibrate the measurement surface accuracy.

[0004] In the related technology, some typical measurement methods use standard parts as comparison measurements to achieve high-precision measurements through comparison measurements. And the related measurement system lacks the calibration link, because long-scale standard mirrors are difficult to obtain. In large-scale reflectors, due to the influence of time, gravity, etc., the surface accuracy of the fixed reference mirror itself will also be a problem. Summary of the invention

[0005] The present invention provides a method for constructing a digital reference profile and a long-range profiler system, which are used to solve the defect of low measurement accuracy of the long-range profiler in the prior art.

[0006] A first aspect of the present invention provides a method for constructing a digital reference surface shape, comprising the following steps: Fix one end of the reference mirror to form a cantilever structure, and apply a series of forces F to the suspended end. i ; Get the force F i The deformation of the suspended end of the reference mirror is X i Or the inclination angle A of the end face i ; Based on the finite element simulation calculation, the force F i The deformation of the reference mirror is X' i Or the inclination angle A' of the end face i ; Adjust the physical properties and boundary condition parameters of the simulation calculation so that X' i Compared with the measured X i A' i Compared with the measured Ai Consistent, and then get a series of different forces F i The following are some deformation values ​​of the reference mirror X' i Or some inclination angle value A' i ; Based on several deformation values ​​X' i The difference between them is used as a deformation series of surface shape value groups, and a digital reference surface shape is obtained based on the deformation series of surface shape value groups; or, based on a number of tilt angle values ​​A' i The difference between them is used as a series of inclination angle surface shape value groups, and a digital reference surface shape is obtained based on the series of inclination angle surface shape value groups.

[0007] According to the method for constructing a digital reference surface shape provided by the present invention, the force F i The deformation of the suspended end of the reference mirror is X i Or the inclination angle A of the end face i , including the following steps: Construct a bending deformation measurement system; The bending deformation measurement system is used to apply a series of forces F to one end of the reference mirror. i and record the measured deformation values ​​X through the bending deformation measurement system i .

[0008] According to the method for constructing a digital reference surface shape provided by the present invention, the construction of a compression bending deformation measurement system comprises the following steps: One end of the reference mirror is fixed, and the other end of the reference mirror is freely extended as a suspended end; A displacement detection module is arranged above or below the suspended end to detect the up and down displacement of the suspended end, and the up and down displacement is used as the deformation amount X i ; An end face reflector is arranged on the end face of the suspended end, and an angle measuring instrument is arranged on one side of the end face reflector. The angle measuring instrument can output a measuring beam to measure the angle change of the reference mirror, and obtain the inclination angle A of the end face based on the angle change. i .

[0009] According to the method for constructing a digital reference surface provided by the present invention, based on finite element simulation calculation, the force F i The deformation of the reference mirror is X' i Or the inclination angle A' of the end face i , including the following steps: Establish the cantilever structure model of the reference mirror; Obtain the physical parameters of the reference mirror, and based on the physical parameters and the force F i, calculate the corresponding deformation X' i Or the inclination angle A' of the end face i .

[0010] A second aspect of the present invention provides a long-range profilometer system, comprising: an optical head, a guide rail, a reflector to be measured and a digital reflector system; the optical head is provided with two beam output ends, the two beam output ends respectively output a first sampling beam and a second sampling beam; the optical head is slidably disposed on the guide rail; the reflector to be measured is arranged at one side of the guide rail, and the reflector to be measured is parallel to the guide rail; the digital reflector system adopts any of the above-mentioned methods for constructing a digital reference profilometer to obtain a digital reference mirror, and the digital reference mirror is arranged at one side of the guide rail and is parallel to the guide rail; wherein the first sampling beam acts on the reflector to be measured, and the second sampling beam acts on the digital reference mirror for calibration.

[0011] According to the long-range profilometer system provided by the present invention, an electrically controlled gate is provided between the optical head and the reflector to be measured and the digital reference mirror, and the electrically controlled gate is connected to a controller to control the electrically controlled gate to modulate the passing light beam.

[0012] According to the long-range profilometer system provided by the present invention, the reflector to be measured and the digital reference mirror are respectively located on both sides of the guide rail.

[0013] The long-range profilometer system provided by the present invention further comprises a driving device, which is transmission-connected to the optical head and is used to drive the optical head to move along the guide rail.

[0014] The long-range profilometer system provided by the present invention further includes a rotating platform, which is slidably connected to the guide rail, and the optical head is installed on the rotating platform so as to drive the optical head to rotate through the rotating platform.

[0015] According to the long-range profilometer system provided by the present invention, a level is provided on the rotating platform, and the level is used to monitor the rotation accuracy of the rotating platform.

[0016] The present invention provides a method for constructing a digital reference surface shape, by i Or the inclination angle A of the end face i , adjust the simulation calculation parameters so that the calculated deformation X' i Compared with the measured X i Consistent or calculated end face tilt angle A' i The measured end face inclination angle A i Consistent, it can be obtained that in a series of F iThe exact deformation value of the mirror under the force. The difference between these mirror deformation values ​​can become a series of surface value groups that are independent of the actual reference mirror shape. In this way, we get the digital reference surface shape from finite element calculation and boundary conditions, which embodies the concept of digital reference surface shape. Using such a digital reference surface as a standard surface shape can get rid of the problem of the influence of the accuracy of the physical reference mirror surface. By using the simultaneous measurement or calibration of the digital standard mirror, the surface shape measurement of large-scale reflectors can obtain reliable and higher-precision test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic flow chart of the method for constructing a digital reference surface shape provided by the present invention.

[0019] Figure 2 It is a structural schematic diagram of a medium-pressure bending deformation measurement system of a digital reference surface shape provided by the present invention.

[0020] Figure 3 It is a schematic diagram of a specific process of constructing a compression bending deformation measurement system in the method for constructing a digital reference surface shape provided by the present invention.

[0021] Figure 4 A schematic structural diagram of a long-range profilometer system provided by the present invention.

[0022] Figure 5 A schematic diagram of the measurement structure during actual measurement in the long-range profilometer system provided by the present invention.

[0023] Reference numerals: 1. Guide rail; 2. Optical head; 21. First sampling beam; 22. Second sampling beam; 3. Reflector to be measured; 4. Digital reflector system; 5. Reference mirror; 6. Displacement detection module; 7. Angle measuring instrument; 71. Measuring beam; 8. End reflector. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0026] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" 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 an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0027] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0029] Long-range profilometers are mainly used to measure the geometric shape and error of mirrors or other surfaces. In order to achieve high-precision measurement, the relevant tests mainly use correction methods to improve the measurement accuracy. The correction methods currently used include the following correction methods.

[0030] One is to use an autocollimator to monitor the angular error of the optical head motion scanning to compensate for the measurement data. However, the angle measurement of the autocollimator should be in-situ or a comparison of a shorter displacement distance in principle. The comparison between the autocollimator readings after a longer distance change, and even the readings when the reflectors have different reflectivities, cannot be strictly compared. This makes this method difficult to use in long-distance measurements.

[0031] Another is the UTM (Universal Test Mirror) system proposed by Germany's BESSY, but the UTM system takes a long time to test, and random errors can affect the calibration data. The equipment calibration system is not synchronized with the measurement, which affects the accuracy of the calibration.

[0032] Another common method is to calibrate through standard parts. In related technologies, standard parts themselves lack effective calibration solutions, which makes it difficult to obtain long-scale standard mirrors. In addition, in large-scale reflectors, due to the influence of time, gravity and other factors, the surface accuracy of the fixed standard mirror itself will also be problematic. As a result, the production accuracy of the standard mirror itself affects the final comparison results, resulting in the measurement accuracy not being guaranteed.

[0033] Regarding the problems in related technologies, such as Figure 1 As shown, the present invention provides a method for constructing a digital reference surface shape, comprising the following steps: Step S100: fix one end of the reference mirror 5 to form a cantilever structure, and apply a series of forces F to the suspended end. i , obtain the force F i The deformation of the suspended end of the reference mirror is X iOr the inclination angle A of the end face i Specifically, the reference mirror 5 is a long strip structure, one end of the reference mirror 5 is fixed, and the other end of the reference mirror 5 is freely extended as a suspended end to form a cantilever structure, and a series of different forces are applied to a certain position of the suspended end through a pressure device.

[0034] In a specific implementation, a reference mirror with uniform texture and accurate size is selected to construct a bending deformation measurement system; a force F is applied to one end of the reference mirror 5 by using the bending deformation measurement system. i The actual deformation X is recorded by the bending deformation measurement system i The bending deformation measurement system is used to apply pressure to the deformation of the reference mirror 5 and measure and record the deformation.

[0035] Step S200: Calculate the force F based on finite element simulation. i The deformation of the reference mirror is X' i Or the inclination angle A' of the end face i , and adjust the physical properties and boundary condition parameters of the simulation calculation so that X' i Compared with the measured X i A' i Compared with the measured A i Consistent, and then get a series of different forces F i The following are some deformation values ​​of the reference mirror X' i Or some inclination angle value A' i The theoretical deformation value X' of this model is obtained by finite element simulation software analysis and calculation. i Or the theoretical inclination angle A' of the end face i .

[0036] Specifically, firstly, a model is established according to the actual structure of the bending deformation measurement system, then the physical properties and boundary condition parameters of the model are defined according to the material of the actual reference mirror 5, and finally, the finite element simulation software (such as Anasys) is imported to reasonably set the grid size and the bending force size as F. i , calculate the corresponding theoretical deformation X' i Theoretical inclination angle A' of the end face i Adjust the simulation parameters so that the calculated deformation X' i Compared with the measured X i Consistent or calculated end face tilt angle A' i The measured end face inclination angle A i Consistent, it can be obtained that in a series of F i The exact deformation value of the mirror body under the force. Among them, the deformation value is the deformation value X' i and the tilt angle value A'i It is understood that after adjusting the physical properties and boundary condition parameters, the value X' i and X i The values ​​are the same, so all subsequent calculations are accurate values ​​and no distinction is made in the markings.

[0037] Step S300: Based on a number of deformation values ​​X' i The difference between them is used as a deformation series surface shape value group, and a digital reference surface shape is obtained based on the deformation series surface shape value group; or, based on a number of tilt angle values ​​A' i The difference between them is used as the tilt angle series surface shape value group, and the digital reference surface shape is obtained based on the tilt angle series surface shape value group. Specifically, based on the finite element simulation calculation under the action force F i The shape change and deformation of the lower reference mirror X i Or the inclination angle A of the end face i ; Based on the deformation X i Or the inclination angle A of the end face i , adjust the simulation calculation parameters so that the calculated deformation X' i Compared with the measured X i Consistent or calculated end face inclination angle A' i The measured end face inclination angle A i Consistent, it can be obtained that in a series of F i The accurate deformation value of the mirror under the force. The difference between these mirror deformation values ​​can become a series of surface value groups that are independent of the actual reference mirror surface shape. In this way, we get the digital reference surface shape guaranteed by finite element calculation and boundary conditions, which embodies the digital reference surface shape.

[0038] In specific applications, the deformation measurement system can be built manually. After the construction is completed, the deformation of the reference mirror 5 is measured by setting the measuring components, and the measured structure can be automatically sent to the data processing system. The data processing system can automatically record the actual deformation X1. Then, the model is built through Anasys software, and the measured deformation X2 is obtained by simulation calculation by inputting the physical parameters. The calculated deformation X2 is the theoretical deformation of the bending system. By adjusting the physical parameters of the simulation calculation to make X2 consistent with X1, a series of different forces F are repeatedly applied. i A numerical value group can be obtained. By subtracting the measured specific values, a numerical value group of the deformation variation or a numerical value group of the inclination angle variation can be obtained. This numerical value group of the variation can form a digital reference deformation that is independent of the initial surface shape of the reference mirror 5, and the numerical reference surface shape can be used as a standard mirror for calibration measurement.

[0039] It is understandable that the reference mirror 5 adopts a relatively simple cantilever structure with a single end fixed, and is bent by applying a force through a force-applying device at the other end (i.e., the suspended end). The bending deformation measurement system can realize accurate measurement of the actual deformation of the reference mirror 5. Based on the various physical parameters of the reference mirror 5, complete data of the force deformation of the reference mirror 5 can be obtained through finite element simulation analysis. In other words, the scheme is to measure the surface shape changes caused by the force difference, which can be considered as a series of ideal digital reference surface shapes that can be accurately calculated and are independent of the initial surface shape of the reference mirror 5. Since the force can be adjusted continuously, the deformation along the long axis direction of the reference mirror 5 is also continuous. As long as the size and material of the reference mirror 5 are uniform, the surface shape difference produced by the two force parameters is a high-precision digital reference surface shape that is independent of the initial surface shape of the reference mirror 5 surface.

[0040] Specifically, the difference in deformation of the reference mirror 5 under various forces can be accurately calculated by finite element calculation, and the value group can become a digital virtual standard mirror. At this time, after applying the same force to the reference mirror 5, a series of corresponding actual values ​​can be measured, and then the actual value difference of the deformation amount or tilt angle can be calculated by the corresponding force difference, so that the initial surface shape accuracy of the physical reference mirror 5 is no longer a big problem, and is recorded as the digital reference surface shape in this embodiment.

[0041] For example, forces F1 and F2 are applied to the suspended end of the reference mirror 5. The actual deformation measured by the bending deformation measurement system under the force F1 is X1, and the actual deformation measured under the force F2 is X2. Based on the above, it can be seen that the actual measured results and theoretical results need to be calibrated. The calibration is achieved by adjusting the physical parameters so that the calculated values ​​of the finite element simulation software are consistent with the measured values. The parameters calculated after calibration are X1" and X2", and the difference between the two calibrated values ​​is ΔX i =X1"-X2", by changing the magnitude of the applied force, measure and calculate multiple ΔX i The formed value group can be used as a digital reference surface shape, which has nothing to do with the initial surface shape of the physical reference mirror 5, and gets rid of the problem that the reference mirror 5 surface is affected by the processing and manufacturing accuracy. By comparing with this digital reference surface shape at the same time, a high-precision and reliable result can be obtained.

[0042] According to the specific embodiment provided by the present invention, Figure 2 , Figure 3 As shown in the figure, building a bending deformation measurement system includes the following steps: Step S110, fix one end of the reference mirror 5, and let the other end of the reference mirror 5 extend freely as a suspended end. Specifically, set a fixed platform, fix one end of the long reference mirror 5 on the fixed platform, and let the other end of the reference mirror 5 extend freely.

[0043] Step S120: a displacement detection module 6 is arranged above or below the suspended end to detect the vertical displacement of the suspended end. Specifically, a displacement sensor is arranged above the reference mirror 5. The displacement sensor can act on the surface of the reference mirror 5. The suspended end of the reference mirror 5 can be displaced in the vertical direction under the action of the pressure device. The displacement sensor can monitor the displacement in real time. The displacement measured can represent the deformation X. i .

[0044] Step S130, an end reflector 8 is arranged on the end surface of the suspended end, and an angle measuring instrument 7 is arranged on one side of the end reflector 8, the angle measuring instrument 7 can output a measuring beam 71 to measure the angle change of the reference mirror 5; based on the angle change, the tilt angle A can be characterized. i One end of the reference mirror 5 is fixed, so that the reference mirror 5 will have a certain curvature change when it is deformed. By measuring the curvature change and the displacement, an accurate deformation value can be obtained.

[0045] It is understandable that the accuracy of the actual measurement value will affect the accuracy of the digital reference surface shape. In this embodiment, by setting the measurement of the vertical displacement or the measurement of the angle change during the bending process, the accurate deformation amount can be obtained, thereby improving the measurement accuracy of the deformation amount.

[0046] In a specific configuration, the pressure device is disposed below the reference mirror 5, and the pressure device applies a force F to drive the reference mirror 5 to deform, and can achieve a deformation amount or a change angle (that is, a tilt angle) corresponding to the force F. The displacement sensor and the angle measuring instrument 7 in the above system are used to measure the deformation amount.

[0047] A second aspect of the present invention provides a long-range profilometer system, such as Figure 4As shown, it includes an optical head 2, a guide rail 1, a reflector 3 to be measured and a digital reflector system 4; the optical head 2 is provided with two beam output ends, and the two beam output ends output a first sampling beam 21 and a second sampling beam 22 respectively; the optical head 2 is slidably arranged on the guide rail 1; the reflector 3 to be measured is arranged on one side of the guide rail 1, and the reflector 3 to be measured is parallel to the guide rail 1; the digital reflector system 4 adopts any of the above-mentioned digital reference surface construction methods to obtain a digital reference mirror 5, and the digital reference mirror 5 is arranged on one side of the guide rail 1 and is parallel to the guide rail 1; wherein, the first sampling beam 21 acts on the reflector 3 to be measured, and the second sampling beam 22 acts on the digital reference mirror 5 for calibration. When measuring the relationship between the force and the deformation of the mirror to be measured, it is necessary to ensure the accuracy of the measurement. In this embodiment, the optical head 2 can generate and output two sampling beams, one of which is used as a digital reference mirror 5, and the digital reference mirror 5 is used to determine whether a measurement error occurs during the measurement process, so that the measurement accuracy can be higher and the data has a higher credibility.

[0048] It is understandable that in the construction of digital surface shape, the measurement accuracy of the reference mirror 5 (i.e., the reflector) is a key factor affecting the accuracy of the final digital surface shape. In this embodiment, two light beams are generated by the optical head 2, one of which can correspond to the digital reference mirror 5 in real time, so that the change of this segment of data is used as a reference to realize the calibration of the reflector 3 to be measured, so that the measurement data is more reliable and more accurate. That is, the optical head 2 in this embodiment can solve the problem of measuring the standard reference and the calibration of the measurement system at the same time by outputting light beams in both directions.

[0049] Specifically, the optical head 2 can project two beams of light, a first sampling beam 21 and a second sampling beam 22. By projecting the first sampling beam 21 onto a digital reference mirror, a reference object can be provided for the system, and at the same time, the second sampling beam 22 is projected onto the reflector to be measured. The matching result of the first sampling beam 21 can be used to reflect the measurement result, so that the measurement result of the reflector 3 to be measured is more reliable and more accurate.

[0050] In specific operation, the first sampling beam 21 is projected onto the reflector to be measured, and the second sampling beam 22 is projected onto the digital reflector system 4. During measurement, the force F of the digital reflector system 4 is adjusted to make the first sampling beam 21 the same as the second sampling beam 22. At this time, it means that the surface deflection angle of a certain position of the reflector 3 to be measured is the same as the deflection angle in the digital reflector system 4, so that the surface shape of the position can be known, and then the optical head 2 is driven to move to realize the mirror scanning of the reflector 3 to be measured, so as to realize the measurement of the reflector 3 to be measured. Specifically, the first sampling beam and the second sampling beam are calibrated by the deflection angle of their reflection to determine whether they are the same. That is, the projected first sampling beam 21 has a deflection angle after being reflected back from the reflector 3 to be measured. At this time, the digital reflector system 4 is adjusted so that the second sampling beam 22 reflected back by the digital reflector system 4 has the same deflection angle. At this time, it can be considered that the first sampling beam 21 and the second sampling beam 22 are the same in this state.

[0051] In a specific example, Figure 4 As shown, the reflector 3 to be measured and the digital reference mirror 5 are respectively located on both sides of the guide rail 1. The optical head 2 can be translated along the guide rail 1, and is parallel to the reflector 3 to be measured and the digital reference mirror 5 during the translation process, which is conducive to translational scanning of various points on the reflector 3 to be measured, and realizes the measurement of the force deformation of the reflector 3 to be measured.

[0052] For example, the first sampling beam 21 emitted from the optical head 2 is projected onto the reflector 3 to be measured, and the second sampling beam 22 is projected onto the digital reference mirror 5, wherein the digital reference mirror 5 includes a physical mirror body and a data processing system, and then a force F is applied to the reflector 3 to be measured. At this time, if the deformation change generated by the mirror body in the digital reference mirror 5 matches the virtual digital reference surface shape in the data processing system, it means that the measurement of the entire system is relatively accurate, and the numerical value obtained by the measurement can be used as a reliable result. If, during the measurement process of the reflector 3 to be measured, the deformation change generated by the mirror body in the digital reference mirror 5 does not match the virtual digital reference surface shape in the data processing system, it means that there is a problem in the measurement system at this time, and the measurement result at this time is invalid and cannot be used. In this way, the relationship between the deformation of the reflector 3 to be measured and the force can be accurately measured, so that the final digital reference surface shape (i.e., the standard part in the measurement method, such as the standard resistor in the bridge, the standard plane mirror in the interferometer) is more credible, has higher accuracy, and has a more reliable reference value.

[0053] According to the specific implementation provided by the present invention, a driving device is included, which is transmission-connected to the optical head 2, and the driving device is used to drive the optical head 2 to move along the guide rail 1. By driving the optical head 2 to move by the driving device, a comprehensive scanning measurement of the long strip reflector 3 to be measured can be achieved, thereby improving the overall measurement capability.

[0054] In a specific example, the long-range profilometer system further includes a rotating platform, which is slidably connected to the guide rail 1, and the optical head 2 is mounted on the rotating platform so as to drive the optical head 2 to rotate. The setting of the rotating platform can realize self-calibration of the measurement system and improve the overall calibration quality.

[0055] It is understandable that the rotating platform is slidably connected to the guide rail 1, the driving device is transmission-connected to the rotating platform, the driving device can drive the rotating platform to slide along the laying direction of the guide rail 1, and the rotating platform has a rotating driving member. The rotating driving member can drive the optical head 2 installed on the rotating platform to rotate.

[0056] Furthermore, if Figure 4 As shown, when the optical head 2 rotates 180 degrees, the first sampling beam 21 is projected onto the digital reference mirror, and the second sampling beam 22 is projected onto the reflector 3 to be measured, thereby realizing switching between the reflector 3 to be measured and the digital reference mirror, so that comparative measurements can be performed simultaneously, thereby improving the accuracy of the measurement and the credibility of the measurement data.

[0057] In a specific implementation, a level is provided on the rotating platform, and the level is used to monitor the rotation accuracy of the rotating platform. The rotating platform needs to control the rotation angle when rotating, and the accuracy of the rotation angle will affect the subsequent measurement results. In this example, the setting of the level can monitor the rotation accuracy of the rotating platform, monitor the accuracy after the exchange of positions, and improve the accuracy of comparative measurement.

[0058] It can be understood that in this embodiment, the reference mirror 5 (the reflector 3 to be measured and the digital reference mirror) and the optical head 2 are both duplicated, and the displacement sensor in the two optical heads 2 is shared by one. The symmetry of the twin system design is utilized to simultaneously solve the problem of measuring the standard reference object and the calibration of the measurement system. For example, during the entire measurement process, the reflector 3 to be measured and the "digital reference mirror" are compared and measured simultaneously, which can eliminate various interferences in the measurement process. The system has strong robustness, ensures the accuracy of the measurement results of the measured mirror, and does not require very high environmental conditions. In addition, the dual measuring heads and the rotating platform method that can exchange the position of the measured mirror surface can realize the simultaneous comparative measurement of the two reference mirrors 5 and realize the self-calibration of the device during translation.

[0059] According to an example provided by the present invention, an electrically controlled gate is provided between the optical head 2 and the reflector 3 to be measured and the digital reference mirror 5, and the electrically controlled gate is connected to the controller to control the electrically controlled gate to modulate the light beam passing through. In the actual measurement system, in order to realize the simultaneous measurement of two sampling light beams on the optical head 2, a displacement sensor is used to receive the signal, and when the sensor receives the signal, it mainly converts the light signal into a point signal for transmission. In this embodiment, in order to solve the problem of optical-electronic mixing, the light beam is modulated by the electrically controlled gate, and then the circuit system is used to separate / identify the signals from the two paths AB, so as to realize simultaneous measurement without interference.

[0060] In a specific example, first, the angle change of the reference mirror 5 during the pressure application process is matched with the corresponding electrical signal data in the sensor through the micro-angle generating device, and the linear range is determined, so that in the subsequent measurement process, it is necessary to measure within the linear range. That is, it is necessary to select the force within the range. If it exceeds the range, the measurement accuracy may be low, resulting in low credibility of the data.

[0061] Then, two sets of bending deformation measurement systems are built, and the optical head 2 is installed on the rotating platform. The bending deformation measurement system is used to apply pressure within a specified range, and the two reference mirrors 5 are translated and measured to obtain the corresponding digital reference surface shape.

[0062] Then, the rotating platform can be driven to rotate to switch the optical heads 2 used for the two deformable reference mirrors 5, forming a self-calibrated "digital reference mirror" and a surface measurement system to obtain accurate measurement data and extreme detection results. At this time, an accurate digital reference mirror that can be used as a "standard part" is obtained through the above method. That is, the light beams projected by the two optical heads 2 act on the digital reference mirror to achieve self-calibration of the "standard part", which can suppress system errors and improve the accuracy of the measurement system.

[0063] Finally, during actual measurement, by replacing one of the digital reference mirrors with the reflector 3 to be measured, and performing a comparative measurement of the reflector 3 to be measured and the digital reference mirror at the same time, calibration is achieved and used as a reference for the reliability of the measurement data. It can be understood that in this embodiment, the reflector to be measured and the digital reference mirror are used alternately in the measurement system, and the system error is suppressed by comparison.

[0064] In general, firstly, by configuring both reflectors as digital reference mirrors, the self-calibration of the entire system can be achieved, which can avoid the factors affecting the measurement results due to the installation errors of the optical head 2 and the installation errors of various components. That is, other errors can be reduced through the self-calibration process of the two digital reference mirrors, and during measurement, one of the digital reference mirrors can be replaced with the reflector 3 to be measured, so as to achieve high-precision measurement of the reflector 3 to be measured and suppress system errors.

[0065] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment provides a high-precision digital reference surface shape to solve the bottleneck of high-precision calibration, and get rid of the problem that the reference mirror 5 is affected by the processing and manufacturing accuracy. High-precision and reliable results are obtained by simultaneous comparison with the digital reference mirror. Further, the long-range profilometer system can be set up to compare and measure the reflector 3 to be measured with the "digital reference mirror" at the same time during the entire measurement process, which can eliminate various interferences in the measurement process. The system has strong robustness, ensures the accuracy of the measurement results of the measured mirror, and does not require very high environmental conditions. The dual measuring head (that is, capable of projecting the first sampling beam 21 and the second sampling beam 22) and the rotating platform method that can exchange the position of the measured mirror surface can realize the simultaneous comparison measurement of the two digital reference mirrors and realize the self-calibration of the device during translation.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a digital reference surface shape, characterized in that: The following steps are involved: Fix one end of the reference mirror to form a cantilever structure, and apply a series of forces F to the suspended end. i ; Get the force F i The deformation of the suspended end of the reference mirror is X i Or the inclination angle A of the end face i ; Based on the finite element simulation calculation, the force F i The deformation of the reference mirror is X' i Or the inclination angle A' of the end face i ; Adjust the physical properties and boundary condition parameters of the simulation calculation so that X' i Compared with the measured X i A n Compared with the measured A' i Consistent, and then get a series of different forces F i The following are some deformation values ​​of the reference mirror X' i Or some inclination angle value A' i ; Based on several deformation values ​​X' i The difference between them is used as a deformation series of surface shape value groups, and a digital reference surface shape is obtained based on the deformation series of surface shape value groups; or, based on a number of tilt angle values ​​A' i The difference between them is used as a series of inclination angle surface shape value groups, and a digital reference surface shape is obtained based on the series of inclination angle surface shape value groups.

2. The method for constructing a digital reference surface shape according to claim 1, characterized in that: Get the force F i The deformation of the suspended end of the reference mirror is X i Or the inclination angle A of the end face i , including the following steps: Construct a bending deformation measurement system; The bending deformation measurement system is used to apply a series of forces F to one end of the reference mirror. i and record the measured deformation values ​​X through the bending deformation measurement system i .

3. The method for constructing a digital reference surface shape according to claim 2, characterized in that: The construction of the bending deformation measurement system comprises the following steps: One end of the reference mirror is fixed, and the other end of the reference mirror is freely extended as a suspended end; A displacement detection module is arranged above or below the suspended end to detect the up and down displacement of the suspended end, and the up and down displacement is used as the deformation amount X i ; An end face reflector is arranged on the end face of the suspended end, and an angle measuring instrument is arranged on one side of the end face reflector. The angle measuring instrument can output a measuring beam to measure the angle change of the reference mirror, and obtain the inclination angle A of the end face based on the angle change. i .

4. The method for constructing a digital reference surface shape according to claim 1, characterized in that: Based on the finite element simulation calculation, the force F i The deformation of the reference mirror is X' i Or the inclination angle A' of the end face i , including the following steps: Establish the cantilever structure model of the reference mirror; Obtain the physical parameters of the reference mirror, and based on the physical parameters and the force F i , calculate the corresponding deformation X' i Or the inclination angle A' of the end face i .

5. A long-range profilometer system, characterized in that: include: An optical head, wherein the optical head is provided with two beam output ends, and the two beam output ends respectively output a first sampling beam and a second sampling beam; A guide rail, on which the optical head is slidably arranged; A reflector to be measured, wherein the reflector to be measured is arranged on one side of the guide rail, and the reflector to be measured is parallel to the guide rail; A digital reflector system, wherein the digital reflector system adopts the method for constructing a digital reference surface shape as described in any one of claims 1 to 4 to obtain a digital reference mirror, and the digital reference mirror is arranged on one side of the guide rail and parallel to the guide rail; The first sampling light beam acts on the reflector to be measured, and the second sampling light beam acts on the digital reference mirror for calibration.

6. The long-range profilometer system according to claim 5, characterized in that: An electrically controlled gate is provided between the optical head, the reflector to be measured and the digital reference mirror. The electrically controlled gate is connected to a controller to control the electrically controlled gate to modulate the light beam passing through.

7. The long-range profilometer system according to claim 5, characterized in that: The reflective mirror to be measured and the digital reference mirror are respectively located on two sides of the guide rail.

8. The long-range profilometer system according to claim 5, characterized in that: It also includes a driving device, which is transmission-connected to the optical head and is used to drive the optical head to move along the guide rail.

9. The long-range profilometer system according to claim 5, characterized in that: It also includes a rotating platform, which is slidably connected to the guide rail, and the optical head is installed on the rotating platform so that the optical head is driven to rotate through the rotating platform.

10. The long-range profilometer system according to claim 9, characterized in that: The rotating platform is provided with a level, and the level is used to monitor the rotation accuracy of the rotating platform.

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