Compensation optical path structure for improving measurement accuracy

Abstract

The present disclosure describes a compensation optical path structure for improving measurement accuracy. The reconstruction device includes a measurement optical path structure and a compensation optical path structure for obtaining the initial height of a target point. The compensation optical path structure includes a first generation module, a spectroscopic module, an interference objective lens, and a data processing module. The first generation module is used to generate a compensation light beam with a bandwidth not greater than a first preset value. The spectroscopic module includes a first spectroscopic unit and a second spectroscopic unit. The first spectroscopic unit is configured to receive the compensation light beam and reflect the compensation light beam to the interference objective lens. The compensation light beam forms a compensation reflection light beam in the interference objective lens. The data processing module compensates the initial height based on the compensation reflection light beam to obtain a comprehensive measurement height. According to the present disclosure, a compensation optical path structure can be provided that compensates for the measurement height of a target point to improve the measurement accuracy of the target point.

Description

Technical Field

[0001] The present disclosure relates to an intelligent manufacturing equipment industry, and in particular to a compensating optical path structure for improving measurement accuracy. Background Art

[0002] With the increasing development of ultra-precision machining technology, ultra-precision detection technology has become increasingly important. Optical measurement methods are widely used in the field of optical measurement due to their low cost and high precision. Among them, the optical measurement system based on the principle of interference has the advantages of high precision and high resolution, and is often used for the precise measurement of physical quantities.

[0003] White light interferometer is an ultra-precision measuring device based on white light interferometry technology. In the prior art, white light interferometer usually uses a single white light source to measure the height of the object to be measured. During the measurement scan, if the optical path difference between the measuring light and the reference light is less than the coherence length of the white light source, the two beams of light can interfere to produce a white light interference signal. When the optical path difference between the measuring light and the reference light is zero, the intensity of the interference signal reaches the maximum. Therefore, the height information of the object to be measured can be obtained through the zero optical path difference position.

[0004] However, the measurement precision and accuracy of white light interferometer are obviously affected by the environment. Generally speaking, environmental impacts include industrial environmental impacts and natural environmental impacts. Among them, industrial environmental impacts refer to the vibrations caused by people and the surrounding environment, which cause low-frequency vibrations on the ground and are then transmitted to the interferometer; natural environmental impacts refer to changes in the natural environment, such as air flow, temperature changes, etc., which cause the interferometer to produce certain vibrations. The above two types of vibrations caused by environmental impacts are both environmental vibrations. When there is environmental vibration, the white light interference fringes generated by the white light interferometer are prone to jitter, such as the interference fringes images overlapping, deforming, trimming, blurring or burring, resulting in large errors in the measurement results; even worse, if the amplitude of the interference pattern fringes fluctuates greatly, the interference fringes cannot be observed and cannot be measured. Summary of the invention

[0005] The present disclosure is proposed in view of the above-mentioned prior art conditions, and its purpose is to provide a compensation optical path structure that can compensate for the measured height of a target point to improve the measurement accuracy of the target point.

[0006] The present disclosure provides a compensation optical path structure for improving measurement accuracy, which is a compensation optical path structure for improving the measurement accuracy of a reconstruction device when measuring the height of a target point. The reconstruction device includes a measurement optical path structure for obtaining an initial height of the target point and the compensation optical path structure. The compensation optical path structure includes a first generating module, a spectroscopic module, an interference objective lens, and a data processing module. The first generating module is used to generate a compensation light beam with a bandwidth not greater than a first preset value. The spectroscopic module includes a first spectroscopic unit and a second spectroscopic unit. The first spectroscopic unit is configured to receive the compensation light beam and reflect the compensation light beam to the interference objective lens. The compensation light beam forms a compensation reflection light beam at the interference objective lens. The data processing module compensates for the initial height based on the compensation reflection light beam to obtain a comprehensive measurement height.

[0007] In this case, the vibration information of the target point caused by the environmental vibration can be obtained, and the above vibration information can be calculated in a visual form, and then the initial height of the target point can be compensated based on the above vibration information to obtain the comprehensive measurement height. In addition, the reconstruction device involved in this embodiment can reconstruct the three-dimensional shape of the object to be measured based on the comprehensive measurement height of the target point, thereby improving the reconstruction accuracy of the object to be measured by the reconstruction device.

[0008] In addition, in the compensation optical path structure involved in the present disclosure, optionally, it also includes a first receiving module connected to the data processing module signal, and the first receiving module is configured to receive the compensation reflection light beam reflected by the second splitting unit and form a compensation interference signal. Thus, the compensation optical path structure can compensate the initial height of the target point based on the compensation interference signal. In this case, the data processing module can perform signal processing based on the compensation reflection light beam to calculate the compensation information generated by the environmental vibration of the target point and compensate for the initial height. Thus, the measurement accuracy of the height of the target point by the reconstruction device can be improved.

[0009] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the first receiving module includes a first receiving unit and a first lens unit, and the first lens unit is arranged between the first receiving unit and the second light splitting unit. In this case, the first lens unit can focus the compensation reflection light beam on the first receiving unit, and the first receiving unit can convert the received compensation reflection light beam into a compensation interference signal.

[0010] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the data processing module is configured to obtain compensation information based on the compensation interference signal, and compensate the initial height based on the compensation information to obtain the comprehensive measurement height. In this case, the data processing module can perform signal processing based on the compensation reflected light beam to calculate the compensation information generated by the target point due to the environmental vibration, and compensate the initial height. Thereby, the measurement accuracy of the height of the target point by the reconstruction device can be improved.

[0011] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the interference objective lens includes a third beam splitter unit and a reference unit, the third beam splitter unit is configured to receive the compensation beam and decompose the compensation beam into a first compensation beam reflected to the reference unit and a second compensation beam transmitted to the target point; the first compensation target beam is reflected to the reference unit via the third beam splitter unit and reflected by the reference unit to form a first compensation reflection beam, the second compensation target beam is transmitted to the target point via the third beam splitter unit and reflected by the target point to form a second compensation reflection beam, and the first compensation reflection beam and the second compensation reflection beam form a compensation reflection beam. In this case, after the compensation beam reaches the interference objective lens, it can be decomposed into a first compensation beam and a second compensation beam, wherein the first compensation beam can be reflected to the reference unit via the third reflection unit, and the second compensation beam can be transmitted to the target point via the third reflection unit. Since the first compensation beam and the second compensation beam arrive at different places, the first compensation reflection beam and the second compensation reflection beam formed by the reflection of the first compensation beam and the second compensation beam can have an optical path difference.

[0012] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the measurement optical path structure includes a second generating module, the spectroscopic module, the interference objective lens, the data processing module, and a second receiving module, the second generating module is used to generate a measurement beam with a bandwidth not less than a second preset value, the first preset value is not greater than the second preset value, the first spectroscopic unit is also configured to receive the measurement beam and reflect the measurement beam to the interference objective lens, the measurement beam forms a measurement reflection beam in the interference objective lens, the second receiving module is configured to receive the measurement reflection beam transmitted through the second spectroscopic unit, and the data processing module obtains the initial height of the target point based on the measurement reflection beam. In this case, in the measurement optical path structure, the first measurement reflection beam and the second measurement reflection beam can interfere to form a measurement interference signal, and the data processing unit can obtain the initial height of the target point based on the generated measurement interference signal.

[0013] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the reconstruction device further includes a coupling unit, and the coupling unit is configured to receive the compensation beam and the measurement beam and couple the compensation beam and the measurement beam. In this case, the compensation beam and the measurement beam can be coupled by the coupling unit into a beam and sent to the first spectroscopic unit, so that the compensation beam and the measurement beam can synchronously arrive at the interference objective lens, synchronously form the compensation reflection beam and the measurement reflection beam, which is conducive to obtaining compensation information that more accurately matches the initial height of the target point.

[0014] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the measuring device also includes a timing synchronization unit, and the timing synchronization unit is configured to send a control signal to the first receiving module and the second receiving module so that the first receiving module and the second receiving module synchronously receive the compensation reflected beam and the measurement reflected beam.

[0015] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the time for the first receiving module to respond to an optical signal is not greater than the response time for the second receiving module to respond to an optical signal. In this case, the first receiving module and the second receiving module can synchronously receive the optical signal, thereby, the compensation information monitored by the compensation optical path structure can be synchronized with the measurement information of the measurement optical path structure, further improving the comprehensive measurement accuracy of the reconstruction device.

[0016] In addition, in the compensation optical path structure involved in the present disclosure, optionally, the reconstruction device further includes a driving module, and the driving module is configured to adjust the relative position of the interference objective lens and the target point. In this case, the relative position of the interference objective lens and the target point can be changed, so that the initial height of the target point can be obtained based on the measurement reflected light beam, and the target point can be compensated based on the compensation reflected light beam to obtain the comprehensive measurement height.

[0017] According to the present disclosure, a compensation optical path structure can be provided for compensating the measured height of a target point to improve the measurement accuracy of the target point. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present disclosure will now be explained in further detail, by way of example only, with reference to the accompanying drawings.

[0019] Figure 1 It is a schematic diagram showing an application scenario of the reconstruction device involved in the present disclosure.

[0020] Figure 2 is a structural block diagram showing the compensation optical path structure involved in the present disclosure.

[0021] Figure 3 Schematic diagram showing the compensation optical path structure involved in the present disclosure.

[0022] Figure 4 It is a schematic diagram showing the internal optical path structure of the interference objective lens involved in the present disclosure.

[0023] Figure 5 is a schematic diagram showing the compensation interference signal and the scanning stroke involved in the present disclosure.

[0024] Figure 6 is a structural block diagram showing the measurement optical path structure involved in the present disclosure.

[0025] Figure 7 Schematic diagram showing the measurement optical path structure involved in the present disclosure.

[0026] Figure 8 is a schematic diagram showing the measurement interference signal and the scanning stroke involved in the present disclosure.

[0027] Fig. 9 It is a schematic diagram showing the overall optical path structure involved in the present disclosure.

[0028] Fig.10 It is a schematic diagram showing the synchronous reception of optical signals by the measurement optical path structure and the compensation optical path structure involved in the present disclosure. DETAILED DESCRIPTION

[0029] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same symbols are assigned to the same components, and repeated descriptions are omitted. In addition, the accompanying drawings are only schematic diagrams, and the ratio of the dimensions of the components or the shapes of the components may be different from the actual ones.

[0030] It should be noted that the terms "including" and "having" and any variations thereof in the present disclosure, such as a process, method, apparatus, product or equipment that includes or has a series of steps or units, are not necessarily limited to those steps or units clearly listed, but may include or have other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0031] In addition, the subheadings and the like involved in the following description of the present disclosure are not intended to limit the content or scope of the present disclosure, but are merely used as a reminder for reading. Such subheadings should neither be understood as being used to divide the content of the article, nor should the content under the subheading be limited to the scope of the subheading.

[0032] The present disclosure relates to a compensating optical path structure for improving measurement accuracy, which may sometimes be referred to as a compensating optical path structure below. In some examples, the compensating optical path structure for improving measurement accuracy involved in the present disclosure may also be referred to as a compensating optical path structure for obtaining vibration information, or an optical path structure for obtaining compensation information.

[0033] According to the compensation optical path structure involved in the present disclosure, the vibration information (also called compensation information) generated by the target point due to the environmental vibration can be obtained, and the above compensation information can be calculated in a visual form, and then the initial height of the target point can be compensated based on the above compensation information to obtain the comprehensive measurement height. In addition, the reconstruction device involved in this embodiment can reconstruct the three-dimensional morphology of the object to be measured based on the comprehensive measurement height of the target point, thereby improving the reconstruction accuracy of the reconstruction device for the object to be measured.

[0034] The compensation optical path structure involved in this embodiment is described in detail below with reference to the accompanying drawings.

[0035] Figure 1 FIG2 is a schematic diagram showing an application scenario of the reconstruction device 10 involved in the present disclosure. FIG2 is a structural block diagram showing a compensation optical path structure 100 involved in the present disclosure. Figure 3 is a schematic diagram showing a compensation optical path structure 100 involved in the present disclosure.

[0036] See also Figure 1 The compensation optical path structure 100 of the present disclosure can be applied to Figure 1 In some examples, the reconstruction device 10 may be a device for measuring the surface height of the object 20 to be measured and reconstructing the three-dimensional shape of the object 20 to be measured based on the surface height (see Figure 3 ).

[0037] In some examples, the object to be tested 20 (described later) may be referred to as a sample. The sample may be a semiconductor, a 3C electronic glass screen, a micro-nano material, an automobile component, or an ultra-precision device such as a MEMS device. In some examples, the sample may be a device used in the fields of aerospace and the like.

[0038] In some examples, the measurement point when the reconstruction device 10 measures the object to be measured 20 can be called a target point 21. That is, the reconstruction device 10 can be used to measure the height of the target point 21. The target point 21 can be a point, a line, or an area. In some examples, the object to be measured 20 can include at least one target point 21. Measuring one target point 21 can obtain the height of one target point 21, and measuring multiple target points 21 can obtain the heights of multiple target points 21. In this case, if only the height of one target point 21 needs to be obtained, the reconstruction device 10 only needs to measure one target point 21; when the reconstruction device 10 measures multiple target points 21 of the object to be measured 20, the three-dimensional surface morphology of the object to be measured 20 can be reconstructed based on the heights of the multiple target points 21. In some examples, the above height can be the surface height of the object to be measured 20.

[0039] In some examples, the compensation optical path structure 100 can be used to improve the measurement accuracy of the reconstruction device 10 when measuring the height of the target point 21. As a result, the height data of the target point 21 can be more accurate.

[0040] In some examples, the reconstruction device 10 may include a compensation optical path structure 100. In some examples, the reconstruction device 10 may include a measurement optical path structure 200 (described later). The measurement optical path structure 200 may be used to obtain an initial height of the target point 21. In the measurement optical path, the initial height of the target point 21 may be obtained based on a measurement interference signal generated by the measurement beam L20.

[0041] In some examples, the reconstruction device 10 may include a compensation optical path structure 100. The compensation optical path structure 100 may be used to obtain compensation information of the target point 21 due to environmental vibration. In some examples, the reconstruction device 10 may compensate the initial height with the compensation information to obtain the comprehensive measurement height of the target point 21. Thus, the measurement accuracy of the target point 21 by the reconstruction device 10 can be improved. In some examples, the reconstruction device 10 may reconstruct the object 20 to be measured based on the comprehensive measurement accuracy of multiple target points 21 to obtain a more accurate three-dimensional surface morphology.

[0042] In some examples, the measuring beam L20 may be white light. In some examples, the wavelength of the measuring beam L20 may be 400 nm-700 nm, for example, 400 nm, 450 nm, 500 nm, 550 nm, 6000 nm, 650 nm or 700 nm. In this case, the reconstruction device 10 can obtain clearer image information of the surface of the object to be measured 20 when measuring the information of the object to be measured 20.

[0043] In some examples, the compensation optical path structure 100 can compensate the initial height based on the compensation interference signal generated by the compensation beam L10. In some examples, the compensation beam L10 can be infrared light. The wavelength of the compensation beam L10 can be no less than 900nm. For example, the wavelength of the compensation beam L10 can be 950nm, 980nm, or 1000nm. In this case, the wavelength band spanned by the measuring beam L20 and the compensation beam L10 has a sufficiently long interval so that the measuring beam L20 and the compensation beam L10 can have a higher isolation, thereby reducing the influence of the compensation beam L10 on the measuring beam L20 during the measurement process.

[0044] In some examples, the bandwidth of the compensation beam L10 may be no greater than a first preset value. The bandwidth of the measurement beam L20 may be no less than a second preset value, and the first preset value may be no greater than the second preset value. For example, the first preset value may be 50 nm, and the second preset value may be 100 nm.

[0045] See also Figure 2 and Figure 3 In this embodiment, the compensation optical path structure 100 may include a first generating module 110 , a spectroscopic module 120 , an interference objective lens 130 , and a data processing module 140 .

[0046] The first generating module 110 can be used to generate the compensation beam L10. The light splitting module 120 can be used to change the propagation direction of the compensation beam L10. The interference objective lens 130 can be used to form the compensation reflection beam L10'. The data processing module 140 can compensate the initial height based on the compensation reflection beam L10' to obtain the comprehensive measurement height.

[0047] As described above, the first generating module 110 can be used to generate the compensation light beam L10. In some examples, the compensation light beam L10 can be a narrowband light whose bandwidth is not greater than the first preset value. Therefore, the first generating module 110 can be a narrowband light source. In some examples, the compensation light beam L10 generated by the first generating module 110 can be changed in propagation direction by the light splitting module 120.

[0048] In some examples, the light splitting module 120 may include a first light splitting unit 121. The first light splitting unit 121 may be used to receive the compensation light beam L10. The first light splitting unit 121 may be used to reflect the compensation light beam L10. In some examples, the first light splitting unit 121 may be used to receive the compensation light beam L10 and reflect the compensation light beam L10. Thus, the compensation light beam L10 can change the propagation direction based on the setting of the first light splitting unit 121.

[0049] In some examples, the compensation optical path structure 100 may further include a beam adjustment module 160. The beam adjustment module 160 may be used to adjust the convergence of the compensation beam L10. In some examples, the beam adjustment module 160 may be disposed between the first generating module 110 and the first light splitting unit 121 to adjust the convergence of the compensation beam L10.

[0050] In some examples, the beam adjustment module 160 may include a converging unit 161 and a collimating unit 162. The converging unit 161 may be used to converge the compensation beam L10 into a beam. The collimating unit 162 may be used to convert the compensation beam L10 from divergent light into collimated light. In this case, the compensation beam L10 can be converged into a beam after passing through the first lens unit 152 and then sent to the collimating unit 162. The collimating unit 162 converts the converged compensation beam L10 into collimated light and sends it to the first beam splitting unit 121, thereby reducing the divergence of the compensation beam L10 and thus reducing the energy loss of the compensation beam L10.

[0051] In some examples, the compensation optical path structure 100 may not include the beam adjustment module 160 .

[0052] In some examples, the compensation light beam L10 reflected by the first light splitting unit 121 may be sent to the interference objective lens 130 . The compensation light beam L10 may form a compensation reflection light beam L10 ′ in the interference objective lens 130 .

[0053] In some examples, the light splitting module 120 may further include a second light splitting unit 122. The second light splitting unit 122 may be used to change the propagation direction of the compensation reflected light beam L10'.

[0054] Figure 4 Schematic diagram showing the internal optical path structure of the interference objective lens 130 involved in the present disclosure.

[0055] See also Figure 4 In some examples, the interference objective lens 130 may include a third beam splitting unit 131 and a reference unit 132. The third beam splitting unit 131 may be configured to receive the compensation beam L10 and decompose the compensation beam L10 into a first compensation beam L11 and a second compensation beam L12. In some examples, the third beam splitting unit 131 may also be configured to reflect the first compensation beam L11 to the reference unit 132 and transmit the second compensation beam L12 to the target point 21.

[0056] In some examples, the first compensation target beam L30 can be reflected to the reference unit 132 via the third splitter unit 131 and reflected by the reference unit 132 to form a first compensation reflection beam L10′. In some examples, the second compensation beam L12 can be transmitted to the target point 21 via the third splitter unit 131 and reflected by the target point 21 to form a second compensation reflection beam L10′. In some examples, the first compensation reflection beam L10′ and the second compensation reflection beam L10′ can form a compensation reflection beam L10′. Specifically, the third splitter unit 131 can also be configured to synthesize the first compensation beam L11 and the second compensation beam L12 to form a compensation reflection beam L10′. In other words, the compensation reflection beam L10′ can include the first compensation reflection beam L10′ and the second compensation reflection beam L10′. In this case, the compensation beam L10 can be decomposed into a first compensation beam L11 and a second compensation beam L12 after reaching the interference objective lens 130, wherein the first compensation beam L11 can be reflected to the reference unit 132 via the third splitting unit 131, and the second compensation beam L12 can be transmitted to the target point 21 via the third splitting unit. Since the first compensation beam L11 and the second compensation beam L12 arrive at different places, the first compensation beam L11 and the second compensation beam L12 formed by reflection can have an optical path difference.

[0057] Figure 5 is a schematic diagram showing the compensation interference signal and the scanning stroke involved in the present disclosure, wherein I can be the light intensity and z can be the scanning stroke.

[0058] As described above, the third light splitting unit 131 can be configured to synthesize the first compensation beam L11 and the second compensation beam L12 to form the compensation reflection beam L10'. In some examples, the first compensation beam L11 and the second compensation beam L12 included in the compensation reflection beam L10' can have an optical path difference. Thus, the first compensation beam L11 and the second compensation beam L12 can interfere to generate a compensation interference signal.

[0059] In some examples, the direction of the relative displacement between the interference lens 130 and the object 20 to be measured may be referred to as a scanning direction. Figure 3 , the scanning direction can be as follows Figure 3 In some examples, the relative displacement between the interference lens 130 and the object 20 when the reconstruction device 10 measures a target point 21 can be referred to as a scanning stroke.

[0060] In some examples, the scanning stroke may be not less than the coherence length of the measuring beam L20. In some examples, the compensation beam L10 having a bandwidth not greater than the first preset value is called a narrowband beam. A narrowband beam has a longer coherence length. Thus, in the entire scanning stroke of measuring a target point 21, the first compensation reflection beam L10 ′ and the second compensation reflection beam L10 ′ included in the compensation reflection beam L10 ′ can interfere to generate a compensation interference signal. Figure 5 In some examples, the compensation interference signal may be a sinusoidal wave signal, and the compensation interference signal may be formed throughout the entire scanning stroke.

[0061] In some examples, the vibration of the target point 21 can be monitored based on the compensation beam L10. In other words, the compensation information (vibration information) generated by the environmental vibration of the target point 21 during the measurement process can be obtained based on the compensation beam L10. Thus, the initial height can be compensated based on the compensation beam L10. In some examples, the compensation information of the target point 21 during the measurement process can be obtained based on the compensation interference signal. The compensation interference signal can be a sine wave signal. In some examples, the compensation interference signal of the compensation optical path can be called a vibration monitoring signal.

[0062] As described above, the spectroscopic module 120 may further include a second spectroscopic unit 122. The second spectroscopic unit 122 may be arranged in the same direction as the first spectroscopic unit 121. The second spectroscopic unit 122 may be a dichroic spectroscopic plate. In some examples, the compensating reflected light beam L10′ may reach the second spectroscopic unit 122 via the first spectroscopic unit 121 after being emitted by the interference objective lens 130. In other words, the second spectroscopic unit 122 may be configured to receive the compensating reflected light beam L10′ transmitted via the first spectroscopic unit 121. In some examples, the second receiving unit 221 may reflect the compensating reflected light beam L10′ to the first receiving module 150.

[0063] In some examples, the first receiving module 150 can be configured to receive the compensation reflected light beam L10' reflected by the second light splitting unit 122 and form a compensation interference signal. Thus, the compensation optical path structure 100 can compensate the initial height of the target point 21 based on the compensation interference signal.

[0064] In some examples, the first receiving module 150 may include a first receiving unit 151 and a first lens unit 152. The first lens unit 152 may be disposed between the first receiving unit 151 and the second light splitting unit 122. In some examples, the first receiving unit 151 may be a photodetector. Preferably, the first receiving unit 151 may be a point photodetector. Thus, the first receiving unit 151 can convert the received compensation reflection light beam L10′ into a compensation interference signal. In some examples, the point photodetector may have the advantages of high speed and large dynamic range of receiving signals. In this case, using the point photodetector as the first receiving unit 151 enables the reconstruction device 10 to quickly and accurately receive the light intensity change information of the target point 21 during the process of measuring the target point 21. Thus, more accurate compensation information can be obtained. In some examples, the first lens unit 152 may be a converging lens with a converging light beam function. In this case, the first lens unit 152 can focus the compensation reflection light beam L10′ on the first receiving unit 151. In some examples, the first receiving module 150 may not include the first lens unit 152.

[0065] In some examples, multiple first receiving units 151 may be included. In some examples, the number of first receiving units 151 may be no less than 3. For example, 3, 4, 5, etc. first receiving units 151 may be included. In some examples, when the reconstruction device 10 includes multiple first receiving units 151, the multiple first receiving units 151 may monitor the vibration information of multiple target points 21, and then the vibration surface may be synthesized based on the multiple vibration information. In this case, the reconstruction device 10 can not only realize the function of compensating the initial height of the target point 21, but also realize the function of compensating the angle change of the target point 21.

[0066] In some examples, the first receiving module 150 may be signal-connected to the data processing module 140. The data processing module 140 may compensate the initial height based on the compensation reflected light beam L10′ to obtain a comprehensive measured height. In this case, the data processing module 140 may perform signal processing based on the compensation reflected light beam L10′ to calculate compensation information generated by the target point 21 due to environmental vibration and compensate the initial height. Thus, the measurement accuracy of the height of the target point 21 by the reconstruction device 10 can be improved.

[0067] Specifically, the data processing module 140 can be connected to the first receiving module 150 by signal. More specifically, it is connected to the first receiving unit 151 by signal. Thus, the first receiving module 150 can send the compensation interference signal to the data processing module 140. The data processing module 140 can be configured to obtain compensation information based on the compensation interference signal, and compensate the initial height based on the compensation information to obtain the comprehensive measurement height. In this case, the data processing module 140 can obtain the compensation information of the target point 21 due to the environmental vibration based on the compensation interference information, and after compensating the initial height based on the compensation information, the measurement error caused by the environmental vibration can be reduced, thereby improving the measurement accuracy of the reconstruction device 10.

[0068] In some examples, a data acquisition unit 170 may be provided between the data processing module 140 and the first receiving unit 151. The compensation interference signal may be sent to the data processing module 140 via the data acquisition unit 170.

[0069] In some examples, the compensation information may refer to a measurement error caused by environmental vibration, that is, the vibration information mentioned above.

[0070] In summary, according to the compensation optical path structure 100 involved in the present disclosure, the measurement error caused by the environmental vibration during the measurement of the height of the target point 21 can be obtained. In the present disclosure, the measurement error caused by the environmental vibration can become compensation information or vibration information. And the compensation optical path structure 100 involved in the present disclosure can also correct (compensate) the initial height based on the compensation information to obtain the comprehensive measurement height of the target point 21, thereby improving the measurement accuracy of the reconstruction device 10.

[0071] Figure 6 is a structural block diagram showing a measurement optical path structure 200 involved in the present disclosure. Figure 7 is a schematic diagram showing a measurement optical path structure 200 involved in the present disclosure.

[0072] As described above, the reconstruction device 10 can obtain the initial height of the target point 21 based on the measurement optical path structure 200. In some examples, the measurement optical path structure 200 can include a second generation module 210, a light splitting module 120, an interference lens 130, a data processing module 140, and a second receiving module 220.

[0073] The second generating module 210 can be used to generate a measuring beam L20 with a bandwidth not less than a second preset value. The first light splitting unit 121 can also be configured to receive the measuring beam L20 and reflect the measuring beam L20 to the interference objective lens 130 , where the measuring beam L20 forms a measuring reflected beam L20 ′.

[0074] Specifically, as described above, the interference objective 130 may include a third spectroscopic unit 131 and a reference unit 132. The third spectroscopic unit 131 may also be configured to receive the measuring beam L20 and decompose the measuring beam L20 into a first measuring beam and a second measuring beam. In some examples, the third spectroscopic unit 131 may also be configured to reflect the first measuring beam to the reference unit 132 and transmit the second measuring beam to the target point 21. In some examples, the first measuring target beam may be reflected to the reference unit 132 via the third spectroscopic unit 131 and reflected by the reference unit 132 to form a first measuring reflected beam. In some examples, the second measuring beam may be transmitted to the target point 21 via the third spectroscopic unit 131 and reflected by the target point 21 to form a second measuring reflected beam. In some examples, the first measuring reflected beam and the second measuring reflected beam may form a measuring reflected beam L20′. Specifically, the third spectroscopic unit 131 may also be configured to synthesize the first measuring beam and the second measuring beam to form a measuring reflected beam L20′. In other words, the measuring reflected beam L20′ may include the first measuring reflected beam and the second measuring reflected beam. In this case, after the measuring beam L20 reaches the interference objective lens 130, it can be decomposed into a first measuring beam and a second measuring beam, wherein the first measuring beam can be reflected to the reference unit 132 via the third spectroscopic unit 131, and the second measuring beam can be transmitted to the target point 21 via the third spectroscopic unit 131. Since the first measuring beam and the second measuring beam arrive at different places, the first measuring beam and the second measuring beam formed by the reflection can have an optical path difference (the specific principle can be referred to Figure 4 ).

[0075] As described above, the measuring beam L20 may be white light. The bandwidth of the measuring beam L20 may be not less than the second preset value. In some examples, the measuring beam L20 having a bandwidth not less than the second preset value is referred to as broadband white light.

[0076] Figure 8 is a schematic diagram showing the measurement interference signal and the scanning stroke involved in the present disclosure.

[0077] In some examples, the first measurement reflected beam and the second measurement reflected beam may form interference. Therefore, the reconstruction device 10 may obtain the initial height of the target point 21 based on the measurement interference signal of the first measurement reflected beam and the second measurement reflected beam. Since the coherence length of broadband white light is short, when the optical path difference between the first measurement reflected beam and the second measurement reflected beam is not greater than the coherence length of the measurement beam L20, the first measurement reflected beam and the second measurement reflected beam may interfere and generate interference fringes. In some examples, when the optical path difference between the first measurement reflected beam and the second measurement reflected beam is zero, the interference fringes are most obvious, the intensity of the measurement interference signal may reach a maximum value, and the reconstruction device 10 may obtain the initial height of the target point 21 based on the measurement interference signal at this time. Therefore, the initial height of the target point 21 may be obtained by locating the position of zero optical path difference.

[0078] See also Figure 8 In some examples, the measurement interference signal collected by the measurement optical path structure 200 can be a sine wave signal modulated by a Gaussian envelope. Specifically, at the zero optical path difference position, an interference peak appears in the measurement interference signal. Based on the interference peak, the initial height of the target point 21 can be obtained. When the optical path difference between the first measurement reflection beam and the second measurement reflection beam is greater than the coherence length of the measurement beam L20, the first measurement reflection beam and the second measurement reflection beam will not interfere and thus no measurement interference signal will be generated.

[0079] In some examples, when the optical path difference between the first measuring reflected beam and the second sub-measuring reflected beam L20 ′ is zero, the vertical distance between the reference unit 132 and the third light splitting unit 131 and the vertical distance between the third light splitting unit 131 and the target point 21 may be equal.

[0080] As described above, the scanning stroke may be not less than the coherence length of the measuring light beam L20. In this case, the measuring interference signal generated by the interference of the measuring reflected light beam L20′ during the scanning stroke can be fully displayed, the peak value of the measuring interference signal can be accurately determined, and compensation information can be obtained based on the compensation interference signal of the compensation reflected light beam L10′ during the entire scanning stroke.

[0081] In some examples, the measurement optical path structure 200 may further include a second receiving module 220. The second receiving module 220 may be configured to receive the measurement reflected light beam L20′ transmitted through the second light splitting unit 122. In some examples, the second receiving module 220 may include a second receiving unit 221 and a second lens unit 222. The second lens unit 222 may be a lens unit having the same function as the first lens unit 152.

[0082] In some examples, the second receiving unit 221 may be a CDD camera or a CMOS camera. Thus, the second receiving unit 221 can convert the received measurement reflection beam L20 ′ into a measurement interference signal.

[0083] In some examples, the data processing module 140 may obtain the initial height of the target point 21 based on the measured reflected light beam L20′. Specifically, the second receiving unit 221 may be connected to the data processing module 140 by signal. The data processing module 140 may obtain the initial height of the target point 21 based on the interference signal.

[0084] In some examples, the measurement optical path structure 200 may also include a beam adjustment module 160 , that is, may include a converging unit 161 and a collimating unit 162 . In some examples, the measurement optical path structure 200 may also not include the converging unit 161 and the collimating unit 162 .

[0085] In this case, in the measuring optical path structure 200 , the first measuring reflected light beam and the second measuring reflected light beam can interfere with each other to form a measuring interference signal, and the data processing unit can obtain the initial height of the target point 21 based on the generated measuring interference signal.

[0086] Fig. 9 Schematic diagram showing the overall optical path structure 300 involved in the present disclosure.

[0087] As described above, the reconstruction device 10 may include a measurement optical path structure 200 and a compensation optical path structure 100. Fig. 9 In some examples, the measuring optical path structure 200 and the compensating optical path structure 100 may be combined into a total optical path structure 300. That is, the total optical path structure 300 may include any one of the above modules or units.

[0088] In some examples, the reconstruction device 10 may further include a driving module (not shown), which may be configured to adjust the relative position of the interference objective lens 130 and the target point 21. In some examples, the driving module may adjust the interference objective lens 130 away from or close to the target point 21. In other examples, the driving module may adjust the target point 21 away from or close to the interference objective lens 130. In this case, the relative position of the interference objective lens 130 and the target point 21 can be changed, so that the initial height of the target point 21 can be obtained based on the measurement reflected light beam L20′, and the target point 21 can be compensated based on the compensation reflected light beam L10′ to obtain the comprehensive measurement height.

[0089] In some examples, the reconstruction device 10 may further include a carrier module. The carrier module may be used to carry the object to be measured 20. That is, the above-mentioned driving module may drive the relative position between the interference objective lens 130 and the carrier module to change. In some examples, the driving module may be configured to adjust the relative distance between the carrier module and the interference objective lens 130 so that the optical path difference between the multiple target points 21 included on the surface of the object to be measured 20 and the reference unit 132 of the interference objective lens 130 is successively zero. In this case, the reconstruction device 10 can obtain the heights of the multiple target points 21 based on the measured interference signals of the multiple target points 21, and compensate the heights of the multiple target points 21 based on the measured interference signals of the multiple target points 21, thereby being able to reconstruct a more accurate three-dimensional surface morphology of the object to be measured 20.

[0090] In some examples, if the measuring optical path structure 200 and the compensating optical path structure 100 are combined into a total optical path structure 300, the reconstruction device 10 may further include a coupling unit 310, which may be configured to receive the compensating beam L10 and the measuring beam L20 and couple the compensating beam L10 and the measuring beam L20. At this time, the coupling unit 310 may be arranged at 45° to the emission direction of the compensating beam L10. In other words, it may be arranged at 45° to the emission direction of the measuring beam L20 (see Fig. 9 In this case, the compensation beam L10 and the measuring beam L20 can be coupled by the coupling unit 310 into a beam and sent to the first light splitting unit 121, so that the compensation beam L10 and the measuring beam L20 can synchronously arrive at the interference objective lens 130, and synchronously form the compensation reflection beam L10′ and the measurement reflection beam L20′, which is conducive to obtaining compensation information that more accurately matches the initial height of the target point 21.

[0091] In some examples, the compensation beam L10 and the measurement beam L20 coupled by the coupling unit 310 can be used as the target beam L30. The first beam splitting unit 121 receives the target beam L30 and reflects the target beam L30 to the interference objective lens 130. Then, the target beam L30 forms a target reflected beam L30′ in the interference objective lens 130 (for details on how to form the target reflected beam L30′, please refer to Figure 4, which will not be described in detail here). Then, the target reflected light beam L30′ emitted by the interference objective lens 130 can be transmitted to the second spectroscopic unit 122 through the first spectroscopic unit 121. The second spectroscopic unit 122 can receive the target light beam L30′ and decouple the target light beam L30′ into a compensation reflected light beam L10′ matching the compensation light beam L10 and a measurement reflected light beam L20′ matching the measurement light beam L20. Then the second spectroscopic unit 122 reflects the compensation reflected light beam L10′ to the first receiving module 150, and transmits the measurement reflected light beam L20′ to the second receiving module 220. In addition, the first receiving unit 151 and the second receiving unit 221 can synchronously receive the compensation reflected light beam L10′ and the measurement reflected light beam L20′. Finally, the data processing module 140 obtains the initial height of the target point 21 based on the measurement reflected light beam L20′, obtains the compensation information of the target point 21 based on the compensation reflected light beam L10′, and compensates the initial height to obtain the comprehensive measurement height.

[0092] Fig.10 Schematic diagram showing the measurement optical path structure 200 and the compensation optical path structure 100 involved in the present disclosure synchronously receiving optical signals.

[0093] In some examples, the reconstruction device may further include a timing synchronization unit 320, which may be configured to send a control signal to the first receiving module 150 and the second receiving module 220 so that the first receiving module 150 and the second receiving module 220 may synchronously receive the compensation reflected light beam L10′ and the measurement reflected light beam L20′. In this case, the first receiving module 150 and the second receiving module 220 may synchronously receive the optical signal, thereby the compensation information monitored by the compensation optical path structure 100 may be synchronized with the measurement information of the measurement optical path structure 200, further improving the comprehensive measurement accuracy of the reconstruction device 10.

[0094] Specifically, the timing synchronization unit 320 can be connected to the first receiving unit 151 signal, and the timing synchronization unit 320 can be connected to the second receiving unit 221 signal. The timing synchronization unit 320 can send a frame synchronization pulse to the first receiving unit 151 signal and the second receiving unit 221 signal. In addition, the time interval of each frame can be the same. Each frame can obtain a data information of the target point 21 (i.e., the white light interference signal and the compensation interference signal). In other examples, each frame can obtain multiple data information of the target point 21. In some examples, N frames of data can be collected to reconstruct the three-dimensional surface morphology of the object to be tested 20. N can be an even number.

[0095] In some examples, in order to reduce the impact of environmental vibration on measurement accuracy, the rate at which the first receiving unit 151 and the second receiving unit 221 receive optical signals can be increased as much as possible. As described above, the first receiving unit 151 can be a photodetector. The second receiving unit 221 can be a CDD camera or a CMOS camera. Then the frame rate of the first receiving unit 151 can be 1MHZ-1GHZ. The frame rate of the second receiving unit 221 can be 50HZ-1KHZ. Therefore, the sampling rate of the first receiving unit 151 can be much greater than the sampling rate of the second receiving unit 221. That is, the time for the first receiving unit 151 to respond to an optical signal can be no greater than the response time for the second receiving unit 221 to respond to an optical signal. Let the time for the first receiving unit 151 to receive an optical signal be τ1, and the time for the second receiving unit 221 to receive an optical signal be τ2. Combined with the above-mentioned frame synchronization pulses (Frame1, Frame2, Frame3...), the time schematic diagram of the synchronous acquisition of optical signals by the measurement optical path structure 200 and the compensation optical path structure 100 can be shown in Figure 10. In this case, the sampling integration time of the first receiving unit 151 can be much lower than the sampling integration time of the second receiving unit 221, so that the vibration information monitored by the compensation optical path structure 100 can more accurately reflect the environmental vibration.

[0096] In some examples, the same timing synchronization unit 320 is used to control the synchronous trigger sampling of the first receiving unit 151 and the second receiving unit 221, so that the interference signals of the compensation optical path structure 100 and the measurement optical path structure 100 can be synchronized, and the vibration information monitored by the compensation optical path structure 100 can be synchronized with the initial height obtained by the measurement optical path structure 200.

[0097] Hereinafter, it is specifically described how to obtain compensation information based on the compensation optical path structure 100 and to compensate the initial height to obtain the comprehensive measurement height.

[0098] In some examples, the intensity model of the compensation interference signal formed by the compensation reflection light beam L10′ can be expressed as formula (1):

[0099] I(t)=A+B cos[θ+φ(t)] (1)

[0100] Where, θ can be the wavefront phase, φ(t) can be the time-varying phase shift, A and B can be the DC term coefficient and AC term coefficient, respectively. I(t) can be the light intensity, and t is the scanning time.

[0101] If the first receiving unit 151 collects the compensation interference signal from the kth frame to the pth frame, the interference light intensity of the kth frame and the pth frame can be respectively expressed as formula (2) and formula (3):

[0102] Ik =A+B cos(θ) (2)

[0103]

[0104] Among them, I k It can be the light intensity of the compensation reflected light beam L10′ in the kth frame, I p It can be the light intensity of the compensation reflected light beam L10′ in the pth frame, Can be a phase increment.

[0105] In some examples, formula (2) and formula (3) may be further derived to obtain the wavefront phase θ of the target point 21 of the object to be measured 20, and the wavefront phase θ may satisfy formula (4):

[0106]

[0107] In some examples, the phase shift increment between two frames can be taken as (“Four-step phase shift method”), then the wavefront phase θ:

[0108]

[0109] In some examples, the phase true value of the first receiving unit 151 at the target point 21 can be θ. Since the range of the tangent function is [-π / 2, +π / 2], the function period is π, according to the light intensity sequence (I1, I2, I3, LI N ) can calculate the interferometric phase shift of adjacent frames:

[0110] Frame 1-2: θ1 = θ + δ1

[0111] Frames 3-4: θ2 = Mod π (θ+π+δ2)=θ+δ2

[0112] Frames 5-6: θ3 = Mod π (θ+2π+δ3)=θ+δ3

[0113] …

[0114] Frames k-1 to k: θ k =Mod π (θ+2π+δ k / 2 )=θ+δ k / 2

[0115] …

[0116] Frames N-1 to N: θ N / 2 =Mod π (θ+2π+δ N / 2 )=θ+δ N / 2

[0117] Where k = 1, 2, ..., N / 2, δ k is the additional phase shift caused by vibration noise between the 2k-1 to 2k frames.

[0118] In some examples, the above N / 2 equations may be added and averaged to obtain equation (6):

[0119]

[0120] When the frame rate of the acquisition is high enough, the averaged vibration component can be close to zero:

[0121]

[0122] Therefore, the wavefront phase of the surface of the first receiving unit 151 corresponding to the target point 21 of the object to be measured 20 can be expressed by formula (7):

[0123]

[0124] Where N is the total number of frames collected, θ k represents the phase change of the target point in adjacent frames (frames 2k-1 to 2k), Thereby, an accurate wavefront phase can be obtained.

[0125] In some examples, the error caused by environmental vibration can be calculated based on the accurate wavefront phase. In some examples, the error caused by environmental vibration can also be called vibration interference.

[0126] In some examples, the phase shift amount added by the vibration noise in each frame j can be calculated based on formula (8):

[0127]

[0128] Among them, I j is the intensity of the compensating interference signal in the jth frame, I j-1 is the light intensity of the compensation interference signal in the j-1th frame, A is the DC term coefficient of the intensity model of the compensation interference signal, and θ is the wavefront phase of the second receiving unit 720 corresponding to the target point 21.

[0129] In some examples, the first frame is an initial frame, and the phase change caused by vibration may be zero, that is, δ j = 0. Therefore, the phase change of the target point 21 due to vibration in each frame can be obtained based on formula (8).

[0130] In some examples, when multiple (≥3) first receiving units 151 are arranged, different Z-direction translation amounts can be detected at multiple target points 21 at the same time, and then can be fitted into a vibration plane. In addition to characterizing the translation noise of the target point 21, the angular swing noise of the target point 21 can also be characterized.

[0131] In some examples, the initial height of the target point 21 may also be compensated based on formula (8). In some examples, the vibration of each frame j may be calculated based on the monitoring signal, and the phase change caused by the vibration of the jth frame is δ j , correspondingly, the displacement caused in the z direction can be expressed by formula (9):

[0132]

[0133] Among them, λ monitor It can be the central wavelength of the compensation beam L10.

[0134] Assume that the measured interference signal of the reflected beam L20′ is measured in the jth frame, in the z-direction position sequence z j The sampling data of the target point 21 is (z j ,I j ), considering the displacement caused by environmental vibration, the actual sampling position (position of the object to be measured 20) can be z j +ε j , therefore, the sampled data can be corrected to:

[0135]

[0136] From the above, it can be seen that the uncompensated target point 21 sampling data can be a regular position sequence (initial height) or time series. However, by calculating the error caused by environmental vibration and compensating the error to the initial height, an irregular but accurate position sequence (comprehensive measurement height) or time series sampling can be obtained.

[0137] In summary, the present disclosure can obtain the initial height of the target point 21 based on the measurement interference signal generated by the measurement reflection light beam L20′. The initial height can be compensated based on the compensation interference signal of the compensation reflection light beam L10′ in the entire scanning stroke. The compensated initial height can be a comprehensive measurement height. In some examples, the comprehensive measurement heights of multiple target points 21 can be obtained based on the compensation optical path structure 100 of the present disclosure.

[0138] In this embodiment, the heights of the multiple target points 21 can be obtained by obtaining measurement interference signals of the multiple target points 21 of the object to be measured 20 based on the above-mentioned disclosed content, and the heights of the multiple target points 21 can be compensated based on the measurement interference signals of the multiple target points 21, so as to reconstruct a more accurate three-dimensional surface morphology of the object to be measured 20.

[0139] Although the present disclosure is specifically described above in conjunction with the accompanying drawings and examples, it is to be understood that the above description does not limit the present disclosure in any form. Those skilled in the art may modify and change the present disclosure as needed without departing from the essential spirit and scope of the present disclosure, and these modifications and changes all fall within the scope of the present disclosure.

Claims

1. A compensating optical path structure for improving measurement accuracy, which is a compensating optical path structure for improving the measurement accuracy of a reconstruction device when measuring the height of multiple target points, characterized in that: The reconstruction device includes a measuring optical path structure for obtaining the initial heights of the plurality of target points and the compensation optical path structure, the compensation optical path structure includes a first generating module, a spectroscopic module, an interference objective lens, and a data processing module, the first generating module is used to generate a compensation light beam with a bandwidth not greater than a first preset value, the spectroscopic module includes a first spectroscopic unit and a second spectroscopic unit, the first spectroscopic unit is configured to receive the compensation light beam and reflect the compensation light beam to the interference objective lens, the compensation light beam forms a compensation reflection light beam at the interference objective lens; a first receiving module is connected to the data processing module by signal, the first receiving module includes a plurality of first receiving units and a first lens arranged between the plurality of first receiving units and the second spectroscopic unit Unit, the multiple first receiving units are configured to receive the compensation reflection light beam reflected by the second splitting unit and form a compensation interference signal, the compensation light beam is configured to form a narrow-band light beam of the compensation interference signal in the entire scanning stroke, the data processing module calculates the error caused by the environmental vibration based on the compensation interference signal of the compensation reflection light beam to obtain the vibration information of the multiple target points, synthesizes the vibration surface based on the multiple vibration information, and compensates the initial height based on the vibration information to directly obtain the comprehensive measurement height, and compensates for the angle change of the target point based on the vibration surface; the reconstruction device is also configured to synchronize the compensation information of the compensation optical path structure with the measurement information of the measurement optical path structure.

2. The compensation optical path structure according to claim 1, characterized in that: The interference objective lens includes a third light splitting unit and a reference unit. The third beam splitting unit is configured to receive the compensation beam and split the compensation beam into a first compensation beam reflected to the reference unit and a second compensation beam transmitted to the target point; The first compensation target light beam is reflected to the reference unit via the third light splitting unit and is reflected by the reference unit to form a first compensation reflected light beam. The second compensation target beam is transmitted to the target point via the third light splitting unit and is reflected by the target point to form a second compensation reflection beam. The first compensation reflection beam and the second compensation reflection beam form a compensation reflection beam.

3. The compensation optical path structure according to claim 2, characterized in that: The measuring optical path structure includes a second generating module, the light splitting module, the interference objective lens, the data processing module, and a second receiving module. The second generating module is used to generate a measuring light beam with a bandwidth not less than a second preset value, and the first preset value is not greater than the second preset value. The first light splitting unit is further configured to receive the measuring light beam and reflect the measuring light beam to the interference objective lens, where the measuring light beam forms a measuring reflected light beam. The second receiving module is configured to receive the measurement reflected light beam transmitted through the second light splitting unit, and the data processing module obtains the initial height of the target point based on the measurement reflected light beam.

4. The compensation optical path structure according to claim 3, characterized in that: The reconstruction device further includes a coupling unit configured to receive the compensation beam and the measurement beam and couple the compensation beam and the measurement beam.

5. The compensation optical path structure according to claim 3, characterized in that: The reconstruction device further includes a timing synchronization unit configured to send a control signal to the first receiving module and the second receiving module so that the first receiving module and the second receiving module synchronously receive the compensation reflected light beam and the measurement reflected light beam.

6. The compensation optical path structure according to claim 5, characterized in that: The time taken by the first receiving module to respond to an optical signal is no longer than the time taken by the second receiving module to respond to an optical signal.

7. The compensation optical path structure according to claim 1, characterized in that: The reconstruction device further includes a driving module configured to adjust a relative position of the interference objective lens and the target point.

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