Confocal measurement system and its measurement method

Abstract

The present invention provides a confocal measurement system and a measurement method. The confocal measurement system includes a measurement unit, a position measurement unit, and an angle measurement unit. The measurement unit includes a laser light source, a collimating lens, a first beam splitter, a focusing lens, a second beam splitter, and a data processing component, which are sequentially arranged along the optical path. Through the confocal measurement system and the measurement method provided by the present invention, the surface profile information and the surface inclination information of the object to be measured can be obtained simultaneously, the measurement in a large angle range can be realized, and the structure of the confocal measurement system provided by the present invention is simple and easy to implement, the measurement method is easy to operate, and both accuracy and rapidity are taken into account at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and particularly relates to a confocal measurement system and a measurement method thereof. Background Art

[0002] In the field of ultra-precision manufacturing of optical elements, in order to achieve high-precision detection of parameters such as the shape and surface type of a processed free-form mirror, it is required that the measurement probe used in the measurement device not only has a high spatial resolution of nanometers, but also has technical characteristics such as non-contact. Confocal microscopes and differential confocal microscopes are widely used in industry and are very ideal optical probes for three-dimensional contour detection of free-form surfaces.

[0003] However, the existing confocal measurement can only provide the spatial position information of the surface to be measured, and cannot simultaneously provide the two-dimensional inclination angles and spatial position information of all discrete points on the surface to be measured.

[0004] In the differential confocal optical path used by DUI Company in the Netherlands, in the return optical path, a beam splitter and a PSD detector structure are added to achieve simultaneous measurement of position and two-dimensional angle. However, due to the principle and structure problems of the PSD itself, factors such as material inhomogeneity, electrode shape, and edge effect exist, resulting in an almost linear relationship between the position estimation and the true position when the light spot is in the central region. After a slightly larger offset occurs, a large non-linear error will be generated, which requires heavy calibration and algorithm compensation. At the same time, the common PSD sizes on the market are usually small, and the linear effective area is even smaller, which cannot meet the system structure using a larger beam. Therefore, this method requires a small light spot or the displacement of the light spot on the PSD to be one order of magnitude smaller than the light spot diameter.

[0005] If the two-dimensional inclination angle and spatial position information of discrete points are separately obtained through confocal measurement and laser differential confocal microscopy measurement, there will be two aspects of cumulative errors and accurate three-dimensional data of the free-form surface cannot be provided. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the prior art and propose a confocal measurement system and a measurement method.

[0007] To achieve the above purpose, the present invention adopts the following specific technical solutions:

[0008] The confocal measurement system proposed by the present invention includes a measurement unit, a position measurement unit, and an angle measurement unit; wherein,

[0009] The measurement unit includes a laser light source, a collimating lens, a first beam splitter, a focusing lens, a second beam splitter, and a data processing component sequentially arranged along the optical path;

[0010] The position measurement unit is a confocal microscope assembly or a differential confocal assembly;

[0011] The beam emitted by the laser light source is collimated by the collimating lens and then transmitted to the first beam splitter. After passing through the first beam splitter, it is transmitted to the focusing lens for focusing. The focused beam is incident on the surface of the object to be measured. After being reflected by the surface of the object to be measured, it passes through the focusing lens and then is incident on the first beam splitter. After being reflected by the first beam splitter, it is transmitted to the second beam splitter for splitting. One part of the beam is reflected as the angle measurement beam and is incident on the angle measurement unit, and the other part is transmitted as the position measurement beam and is incident on the position measurement unit. The position measurement unit obtains the position information of the object to be measured through confocal microscopy measurement method or differential confocal measurement method; the angle measurement unit reduces the angle measurement beam to one-dimensional spectral data and then transmits it to the data processing component. The data processing component obtains the tilt angle of the surface of the object to be measured according to the one-dimensional spectral data, and combines the position information of the surface of the object to be measured obtained by the position measurement unit to simultaneously obtain the surface profile information and the surface tilt angle information of the object to be measured.

[0012] Further, the measurement unit includes a diaphragm;

[0013] The beam focused by the focusing lens passes through the diaphragm and is incident on the surface of the object to be measured. After being reflected by the surface of the object to be measured, it passes through the diaphragm and the focusing lens and then is incident on the first beam splitter.

[0014] Further, the position measurement unit is a confocal microscopy measurement component or a differential confocal measurement component.

[0015] Further, the angle measurement unit includes a third beam splitter, a first angle measurement unit, and a second angle measurement unit;

[0016] The angle measurement beam is incident on the third beam splitter for splitting. One part of the beam is transmitted as the first angle measurement beam to be reduced in dimension and is incident on the first angle measurement unit, and the other part of the beam is reflected as the second angle measurement beam to be reduced in dimension and is incident on the second angle measurement unit. The first angle measurement unit and the second angle measurement unit respectively transmit the one-dimensional spectral data to the data processing component.

[0017] Further, the first angle measurement unit includes a first cylindrical lens and a first linear array detector;

[0018] The second angle measurement unit includes a second cylindrical lens and a second linear array detector;

[0019] The first angle measurement beam is incident on the first cylindrical lens. After being reduced in dimension by the first cylindrical lens, it is incident on the first linear array detector

[0020] Both the first cylindrical mirror and the second cylindrical mirror are plano-convex cylindrical lenses, and the convex surfaces face the first linear array detector and the second linear array detector respectively.

[0021] Furthermore, the first cylindrical mirror and the second cylindrical mirror are arranged perpendicular to each other.

[0022] The present invention also proposes a measurement method for a confocal measurement system, which realizes measurement based on the confocal measurement system, and includes the following steps:

[0023] S1. Build a confocal measurement system, including a laser light source, a collimating lens, a first beam splitter, a focusing lens, a diaphragm, a second beam splitter, a third beam splitter, a first cylindrical mirror, a first linear array detector, a second cylindrical mirror, a second linear array detector, a data processing component, a confocal microscopic measurement component or a differential confocal measurement component arranged in sequence along the optical path;

[0024] The pixels of the first linear array detector and the second linear array detector correspond one-to-one to the received beam intensity values;

[0025] The beam emitted by the laser light source is transmitted through the collimating lens, the first beam splitter, the focusing lens, and the diaphragm in sequence to the surface of the object to be measured, and the beam reflected by the surface of the object to be measured returns along the original optical path to the first beam splitter. The beam is reflected by the first beam splitter to the second beam splitter for beam splitting. The reflected beam and the transmitted beam after beam splitting are used as the angle measurement beam and the position measurement beam for measurement respectively;

[0026] The angle measurement beam is incident on the third beam splitter for beam splitting. The transmitted beam is used as the first angle measurement beam with reduced dimension and is incident on the first cylindrical mirror and the first linear array detector in sequence. The reflected beam is used as the second angle measurement beam with reduced dimension and is incident on the second cylindrical mirror and the second linear array detector in sequence. The data processing component collects the signals of the first linear array detector and the second linear array detector for analysis to obtain the tilt angle information of the surface of the object to be measured;

[0027] The position measurement beam is incident on the confocal microscopic measurement component or the differential confocal measurement component. The data processing component collects the signals of the confocal microscopic measurement component or the differential confocal measurement component for analysis to obtain the position information of the object to be measured;

[0028] Furthermore, the surface shape information and the surface inclination angle information of the object to be measured are obtained simultaneously.

[0029] S2.

[0030] The method for the data processing component to obtain the position information of the object to be measured is: confocal microscopy measurement method or differential confocal measurement method;

[0031] The method for the data processing component to obtain the tilt angle information of the surface of the object to be measured is: a one-dimensional curve is formed on the target surfaces of the first linear array detector and the second linear array detector respectively, and the one-dimensional curves respectively represent the pixel distribution curves of the first angle measurement beam intensity and the second angle measurement beam intensity received. The peak pixel extraction is performed on the one-dimensional curves formed by the first linear array detector and the second linear array detector respectively by the modified peak clustering extraction method, and the corresponding relationship between the two peak positions and the tilt angle is obtained through polynomial fitting, thereby completing the two-dimensional tilt angle measurement.

[0032] Further, the specific process of the modified peak clustering extraction method is as follows:

[0033] S201. Obtain the initial peak P by using the centroid method 0 , and set the allowable error ε;

[0034] S202. Calculate the mean-shift vector corresponding to the current peak pixel according to formula (1):

[0035]

[0036] where I is the corresponding light intensity sequence, h is the kernel radius, P hi is the data point position of the kernel radius at the current position, μ is an adjustable parameter, and P i is the pixel sequence of the linear array detector corresponding to the current position;

[0037] S203. Compare the calculated mean-shift vector corresponding to the current peak pixel with the allowable error;

[0038] When ||M h,G (P 0 )||>ε, let M h,G (P 0 ) = P 0 , and repeat step S202 until ||M h,G (P 0 )||≤ε, then the currently obtained M h,G (P 0 ) vector value is the pixel position where the corrected peak is located;

[0039] When ||M h,G (P 0 )||≤ε, the currently obtained M h,G (P 0 ) vector value is the pixel position where the corrected peak is located.

[0040] Further, before using the modified peak clustering extraction method, a preprocessing step is also included, which is specifically as follows:

[0041] The data processing component converts the signals collected by the first linear array detector and the second linear array detector into gray values, numbers each pixel, and makes the pixels on the first linear array detector and the second linear array detector correspond to the light intensity values one by one.

[0042] Further, in step S2, the corresponding relationship between the two peak positions and the tilt angle is obtained by polynomial fitting, and the specific steps are as follows:

[0043] Using the method of polynomial least squares fitting, a fitting function model of the tilt angle and the two peak positions is constructed, and then the actually measured tilt angle is obtained through the peak positions.

[0044] The present invention can achieve the following technical effects:

[0045] 1. Through the confocal measurement system and measurement method provided by the present invention, the surface shape information and the surface inclination angle information of the object to be measured can be obtained simultaneously;

[0046] 2. Through the confocal measurement system and measurement method provided by the present invention, a peak pixel extraction algorithm for modified peak clustering is proposed, which can reduce the error brought by the existing peak extraction algorithm;

[0047] 3. Through the confocal measurement system and measurement method provided by the present invention, measurement in a large angle range can be realized;

[0048] 4. The structure of the confocal measurement system provided by the present invention is simple and easy to implement, the measurement method is easy to operate, and both accuracy and rapidity are taken into account at the same time. Description of the Drawings

[0049] Figure 1 is a schematic structural diagram of a confocal measurement system according to an embodiment of the present invention;

[0050] Figure 2 is a flowchart of a confocal measurement method according to an embodiment of the present invention.

[0051] The reference numerals therein include:

[0052] 1 laser light source, 2 collimating lens, 3 first beam splitter, 4 focusing lens, 5 aperture, 6 object to be measured, 7 second beam splitter, 8 position measurement unit, 9 third beam splitter, 10 first cylindrical lens, 11 second cylindrical lens, 12 first linear array detector, 13 second linear array detector, 14 board, 15 host computer. Detailed Embodiment

[0053] In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, their detailed descriptions will not be repeated.

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0055] The following will be combined with Figure 1 to describe in detail the specific working mode of the confocal measurement system according to the embodiments of the present invention:

[0056] Figure 1 The structural schematic diagram of the confocal measurement system according to the embodiments of the present invention is shown.

[0057] On the one hand, the embodiments of the present invention provide a confocal measurement system, as Figure 1 shown, including a measurement unit, a position measurement unit and an angle measurement unit.

[0058] The measurement unit includes a laser light source 1, a collimating lens 2, a first beam splitter 3, a focusing lens 4, a diaphragm 5, a second beam splitter 7, and a data processing component arranged in sequence along the optical path. The position measurement unit 8 is a confocal microscope component or a differential confocal component. In the embodiments of the present invention, the angle measurement unit includes a third beam splitter 9, a first angle measurement unit and a second angle measurement unit. The first angle measurement unit includes a first cylindrical lens 10 and a first linear array detector 12. The second angle measurement unit includes a second cylindrical lens 11 and a second linear array detector 13.

[0059] The laser light source 1 used in the embodiments of the present invention is a single-wavelength light source in the visible band with a wavelength of 400-700 nm. The beam emitted by the laser light source 1 is collimated by the collimating lens 2 and then transmitted to the first beam splitter 3. After being transmitted through the first beam splitter 3, it is focused by the focusing lens 4. The focused beam passes through the diaphragm 5 and is incident on the surface of the object to be measured 6. After being reflected by the surface of the object to be measured 6, it passes through the diaphragm 5 and the focusing lens 4 and then is incident on the first beam splitter 3. After being reflected by the first beam splitter 3, it is transmitted to the second beam splitter 7 for beam splitting. The beam reflected by the surface of the object to be measured 6 not only carries the position information of this point on the surface to be measured, but also carries the tilt angle information, that is, it carries information in two dimensions of the transverse (X-axis direction) and the longitudinal (Y-axis direction). When the surface to be measured is tilted, its position information does not change, but its surface inclination angle information changes. The diaphragm 5 used in the embodiments of the present invention can filter out stray light and prevent it from affecting the main optical path.

[0060] After being split by the second beam splitter 7, a part of the light beam is reflected as an angle measurement light beam and incident on the third beam splitter 9 for splitting. The light beam transmitted by the third beam splitter 9 is incident on the first cylindrical lens 10 as the first angle measurement light beam. After being dimensionally reduced by the first cylindrical lens 10, it is incident on the first linear array detector 12. The light beam reflected by the third beam splitter 9 is incident on the second cylindrical lens 11 as the second angle measurement light beam. After being dimensionally reduced by the second cylindrical lens 11, it is incident on the first linear array detector 12. The first linear array detector 12 and the second linear array detector 13 respectively transmit the one-dimensional spectral data to the data processing component. In the embodiment of the present invention, both the first cylindrical lens 10 and the second cylindrical lens 11 are plano-convex cylindrical lenses, and the convex surfaces are respectively facing the first linear array detector 12 and the second linear array detector 13. The first cylindrical lens 10 and the second cylindrical lens 11 are arranged perpendicular to each other. In the technical solution of the embodiment of the present invention where the first cylindrical lens 10 and the second cylindrical lens 11 are arranged perpendicular to each other, the error introduced by the inclination angles of the two cylindrical lenses themselves can be avoided. In the actual use process, if the first cylindrical lens 10 and the second cylindrical lens 11 are not perpendicular, calibration processing can be performed by calibrating the standard surface. The embodiment of the present invention does not limit this and can be selected according to the actual situation. The detectors used in the embodiment of the present invention are linear array detectors, which can improve the response speed of the confocal measurement system.

[0061] In the embodiment of the present invention, by setting the surface types and orientations of the two cylindrical lenses, the two-dimensional information of the inclination angle of the object to be measured 6 can be dimensionally compressed from two directions, and integrated separately in the horizontal and vertical directions, that is, the first angle measurement light beam and the second angle measurement light beam carrying the tilt angle information are respectively incident on the convex surfaces of the first cylindrical lens 10 and the second cylindrical lens 11. After the converging action of the two cylindrical lenses, the first angle measurement light beam and the second angle measurement light beam respectively form one-dimensional curves in the horizontal and vertical directions on the target surface of the linear array detector, completing the horizontal and vertical measurements respectively. Then, by decoupling the one-dimensional signals in the two directions, the two-dimensional angle measurement is completed.

[0062] Another part is transmitted as a position measurement light beam and incident on the position measurement unit 8. The position measurement unit 8 in the embodiment of the present invention is a laser confocal microscope measurement component or a differential confocal microscope measurement component. The existing laser confocal microscope measurement component or differential confocal microscope measurement component in the prior art can be used and can be selected according to the actual situation. The embodiment of the present invention does not limit this. The data processing component uses the confocal microscopic measurement method or the differential confocal measurement method in the prior art according to the corresponding selected position measurement unit 8 to obtain the position information of the object to be measured 6. Among them, obtaining the position information of the object to be measured 6 can be realized by using the methods in the prior art, and the present invention does not limit this.

[0063] The data processing component obtains the tilt angle of the surface of the object 6 to be measured based on the one-dimensional spectral data, combines the position information of the surface of the object 6 obtained by the position measurement unit 8, and simultaneously obtains the surface profile information and the surface tilt angle information of the object 6.

[0064] Figure 2 The flowchart of the confocal measurement method according to an embodiment of the present invention is shown.

[0065] An embodiment of the present invention also provides a measurement method for a confocal measurement system, which realizes measurement based on the confocal measurement system, as Figure 2 shown, including the following steps:

[0066] S1. Set up a confocal measurement system, including a laser light source 1, a collimating lens 2, a first beam splitter 3, a focusing lens 4, a diaphragm 5, a second beam splitter 7, a third beam splitter 9, a first cylindrical lens 10, a first linear array detector 12, a second cylindrical lens 11, a second linear array detector 13, a data processing component, a confocal microscopic measurement component or a differential confocal measurement component arranged in sequence along the optical path. The first cylindrical lens 10 and the second cylindrical lens 11 are arranged perpendicular to each other, and the first linear array detector 12 and the second linear array detector 13 are arranged perpendicular to each other. The pixels of the first linear array detector 12 and the second linear array detector 13 correspond one by one to the received beam intensity values. In the embodiment of the present invention, the data processing component uses a board 14 and a host computer 15 in the prior art for data acquisition and data arithmetic processing.

[0067] The beam emitted by the laser light source 1 is transmitted through the collimating lens 2, the first beam splitter 3, the focusing lens 4, and the diaphragm 5 in sequence to the surface of the object 6 to be measured. The beam reflected by the surface of the object 6 returns along the original optical path to the first beam splitter 3. The beam is reflected by the first beam splitter 3 to the second beam splitter 7 for beam splitting. The reflected beam and the transmitted beam after beam splitting are used as the angle measurement beam and the position measurement beam for measurement respectively; the angle measurement beam is incident on the third beam splitter 9 for beam splitting. The transmitted beam is used as the first angle measurement beam with reduced dimension and is incident on the first cylindrical lens 10 and the first linear array detector 12 in sequence. The reflected beam is used as the second angle measurement beam with reduced dimension and is incident on the second cylindrical lens 11 and the second linear array detector 13 in sequence. The data processing component collects the signals of the first linear array detector 12 and the second linear array detector 13 for analysis to obtain the tilt angle information of the surface of the object 6 to be measured.

[0068] The position measurement beam is incident on the confocal microscopic measurement component or the differential confocal measurement component. The data processing component collects the signals of the confocal microscopic measurement component or the differential confocal measurement component for analysis to obtain the position information of the object 6 to be measured; and then the surface profile information and the surface tilt angle information of the object 6 to be measured are obtained simultaneously.

[0069] S2.

[0070] The method for the data processing component to obtain the position information of the object 6 to be measured is: the confocal microscopy measurement method or the differential confocal measurement method in the prior art.

[0071] The method for the data processing component to obtain the tilt angle information of the surface of the object 6 to be measured is: a one-dimensional curve is respectively formed on the target surfaces of the first linear array detector 12 and the second linear array detector 13. The one-dimensional curves respectively represent the pixel distribution curves of the first angle measurement beam intensity and the second angle measurement beam intensity received. The peak pixels are extracted from the one-dimensional curves formed by the first linear array detector 12 and the second linear array detector 13 respectively by the improved peak clustering extraction method, and the corresponding relationship between the two peak positions and the tilt angle is obtained through polynomial fitting, so as to complete the two-dimensional tilt angle measurement.

[0072] The pixels of the first linear array detector 12 and the second linear array detector 13 correspond one by one to the received beam intensity values. The one-dimensional curve data on the first linear array detector 12 and the second linear array detector 13 are transmitted to the board 14 for gray value conversion. The light intensity corresponds to 0-255 respectively, and each pixel on each linear array detector corresponds to its own light intensity value, so that the pixels on the first linear array detector 12 and the second linear array detector 13 correspond one by one to the light intensity values. Each of the two linear array detectors forms an intensity pixel distribution curve. Therefore, the improved peak clustering extraction method is used subsequently to extract the peak pixels, and finally the relationship between the two peak positions and the tilt angle is obtained through the polynomial fitting formula. Therefore, each two-dimensional tilt angle corresponds to the two peak pixel numbers on the two linear array detectors.

[0073] The present invention provides a preferred embodiment, and the improved peak clustering extraction method is specifically as follows:

[0074] S201. Obtain the initial peak P by using the centroid method 0 , and set the allowable error ε.

[0075] S202. Calculate the mean-shift vector corresponding to the current peak pixel according to formula (1):

[0076] The main idea of mean-shift is to search for the peak along the rising direction of the probability density gradient. The mean-shift vector always points to the direction of increasing probability density. When the mean-shift vector is 0, the kernel density estimation reaches the maximum value. The peak searching based on the mean-shift vector is an iterative process.

[0077] Set the pixel sequence of the linear array detector as P, and I as the corresponding light intensity sequence (or the gray value of the linear array detector). First, use the centroid method to calculate the initial peak P 0, given the allowable error ε, calculate the meanshift vector corresponding to the current peak pixel using formula 1, and the direction indicated by this vector is the position of the pixel where the true peak is located:

[0078]

[0079] where I is the corresponding light intensity sequence, h is the kernel radius, and P hi is the data point position of the kernel radius at the current position, μ is an adjustable parameter, and P i is the pixel sequence of the linear array detector corresponding to the current position.

[0080] S203. Compare the calculated meanshift vector corresponding to the current peak pixel with the allowable error;

[0081] When ||M h,G (P 0 )|| > ε, let M h,G (P 0 ) = P 0 , and repeat step S202 until ||M h,G (P 0 )|| ≤ ε, then the currently obtained M h,G (P 0 ) vector value is the pixel position where the corrected peak is located.

[0082] When ||M h,G (P 0 )|| ≤ ε, the currently obtained M h,G (P 0 ) vector value is the pixel position where the corrected peak is located.

[0083] The present invention provides a preferred embodiment, which uses the method of polynomial least squares fitting to construct a fitting function model of the tilt angle and the positions of two peaks, and then obtains the actually measured tilt angle through the peak positions, that is, obtains the inclination angle information of the surface of the object to be measured 6.

[0084] In the embodiment of the present invention, binary quadratic polynomial least squares fitting is used to construct the function model.

[0085] First, measure the object to be measured 6 at different tilt angles (θ 1 , θ 2 ), and find out its peak positions (P 1 , P 2 ). A total of N groups of samples are collected, and the tilt angle of each group of samples is recorded as (θ 1_i , θ 2_i ), and the peak positions are recorded as (P 1_i , P 2_i ).

[0086] Using the method of least squares fitting of binary quadratic polynomials, the relationship between (θ 1 , θ 2 ) and (P 1 , P 2 ) is fitted and recorded as:

[0087]

[0088] where a 0 , a 1 , a 2 , a 3 , a 4 , a 5 , b 0 , b 1 , b 2 , b 3 , b 4 , b 5 are undetermined constants.

[0089] The purpose of fitting is to find the constants a 0 , a 1 , a 2 , a 3 , a 4 , a 5 such that is minimized, and to find the constants b 0 , b 1 , b 2 , b 3 , b 4 , b 5 such that is minimized. Where E 1 , E 2 are the error functions respectively.

[0090] To minimize E 1 , it should be made that where j = 0, 1,..., 5, and we can get:

[0091]

[0092] Solving this system of equations can obtain a 0 , a 1 , a 2 , a 3 , a 4 , a 5 .

[0093] To minimize E 2 , it should be made that where j = 0, 1,..., 5, and we can get

[0094]

[0095] Solving this system of equations can obtain b 0 , b 1 , b 2 , b 3 , b 4 , b 5 .

[0096] By measuring the positions of two peaks (P 1 , P 2 ), inputting the fitted functions f(P 1 , P 2 ) and g(P 1 , P 2 ), the tilt angles (θ 1 , θ 2 ) of the surface of the object to be measured 6 can be obtained.

[0097] In the embodiments provided by the present invention, a modified peak clustering extraction method is used to extract the peak positions. It not only has strong robustness, but also can quickly extract peaks and perform corrections while extracting peaks. The modified peak clustering extraction method in the embodiments provided by the present invention realizes a faster speed increase and a smaller system variance by using a triangular kernel function and an adaptive weight function. Compared with the maximum search, centroid algorithm, and model-based Gaussian fitting algorithm, which are commonly used peak position extraction methods in the prior art, it improves the extraction speed and the accuracy of the algorithm while improving the extraction speed.

[0098] In summary, the data processing component in the embodiments of the present invention obtains the tilt angle of the surface of the object to be measured according to the one-dimensional spectral data, and combines the position information of the surface of the object to be measured obtained by the position measurement unit to simultaneously obtain the surface shape information and the surface inclination angle information of the object to be measured.

[0099] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example 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 can be combined in any one or more embodiments or examples in a suitable manner. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0100] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0101] The above specific embodiments of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A confocal measurement system, characterized in that, it includes a measurement unit, a position measurement unit and an angle measurement unit; wherein, the measurement unit includes a laser light source, a collimating lens, a first beam splitter, a focusing lens, a second beam splitter, and a data processing component arranged in sequence along the optical path; the position measurement unit includes a confocal microscope component or a differential confocal component; the beam emitted by the laser light source is collimated by the collimating lens and then transmitted to the first beam splitter, transmitted through the first beam splitter to the focusing lens for focusing, the focused beam is incident on the surface of the object to be measured, after being reflected by the surface of the object to be measured, it passes through the focusing lens and then is incident on the first beam splitter, reflected by the first beam splitter to the second beam splitter for beam splitting, a part of the beam is reflected as an angle measurement beam and incident on the angle measurement unit, and the other part is transmitted as a position measurement beam and incident on the position measurement unit, and the position measurement unit obtains the position information of the object to be measured through confocal microscopy measurement method or differential confocal measurement method; the angle measurement unit reduces the angle measurement beam to one-dimensional spectral data and then transmits it to the data processing component; the data processing component obtains the tilt angle of the surface of the object to be measured according to the one-dimensional spectral data, combines the position information of the surface of the object to be measured obtained by the position measurement unit, and simultaneously obtains the surface profile information and the surface tilt angle information of the object to be measured.

2. The confocal measurement system according to claim 1, characterized in that, the measurement unit includes a diaphragm; the beam focused by the focusing lens passes through the diaphragm and is incident on the surface of the object to be measured, after being reflected by the surface of the object to be measured, it passes through the diaphragm and the focusing lens and then is incident on the first beam splitter.

3. The confocal measurement system according to claim 1, characterized in that, the position measurement unit is a confocal microscopy measurement component or a differential confocal measurement component.

4. The confocal measurement system according to claim 1, characterized in that, the angle measurement unit includes a third beam splitter, a first angle measurement unit and a second angle measurement unit; the angle measurement beam is incident on the third beam splitter for beam splitting, a part of the beam is transmitted as the first angle measurement beam to be reduced in dimension and incident on the first angle measurement unit, and the other part of the beam is reflected as the second angle measurement beam to be reduced in dimension and incident on the second angle measurement unit, and the first angle measurement unit and the second angle measurement unit respectively transmit the one-dimensional spectral data to the data processing component.

5. The confocal measurement system according to claim 4, characterized in that, the first angle measurement unit includes a first cylindrical lens and a first linear array detector; the second angle measurement unit includes a second cylindrical lens and a second linear array detector; the first angle measurement beam is incident on the first cylindrical lens, and after being reduced in dimension by the first cylindrical lens, it is incident on the first linear array detector; both the first cylindrical lens and the second cylindrical lens are plano-convex cylindrical lenses, and the convex surfaces are respectively facing the first linear array detector and the second linear array detector.

6. The confocal measurement system according to claim 5, characterized in that, the first cylindrical mirror and the second cylindrical mirror are arranged perpendicular to each other.

7. A measurement method for a confocal measurement system, characterized in that, measurement is realized based on the confocal measurement system, including the following steps: S1. Set up the confocal measurement system, including a laser light source, a collimating lens, a first beam splitter, a focusing lens, a diaphragm, a second beam splitter, a third beam splitter, a first cylindrical mirror, a first linear array detector, a second cylindrical mirror, a second linear array detector, a data processing component, a confocal microscopic measurement component or a differential confocal measurement component arranged in sequence along the optical path; the pixels of the first linear array detector and the second linear array detector correspond one by one to the received beam intensity values; the beam emitted by the laser light source is transmitted through the collimating lens, the first beam splitter, the focusing lens, and the diaphragm to the surface of the object to be measured in sequence, and the beam reflected by the surface of the object to be measured returns along the original optical path to the first beam splitter. The beam is reflected by the first beam splitter to the second beam splitter for beam splitting. The reflected beam and the transmitted beam after beam splitting are used as the angle measurement beam and the position measurement beam for measurement respectively; the angle measurement beam is incident on the third beam splitter for beam splitting. The transmitted beam is used as the first angle measurement beam after dimension reduction and is incident on the first cylindrical mirror and the first linear array detector in sequence. The reflected beam is used as the second angle measurement beam after dimension reduction and is incident on the second cylindrical mirror and the second linear array detector in sequence. The data processing component collects the signals of the first linear array detector and the second linear array detector for analysis to obtain the tilt angle information of the surface of the object to be measured; the position measurement beam is incident on the confocal microscopic measurement component or the differential confocal measurement component. The data processing component collects the signals of the confocal microscopic measurement component or the differential confocal measurement component for analysis to obtain the position information of the object to be measured; furthermore, the surface profile information and the surface tilt angle information of the object to be measured are obtained simultaneously; S2、 the method for the data processing component to obtain the position information of the object to be measured is: confocal microscopic measurement method or differential confocal measurement method; the method for the data processing component to obtain the tilt angle information of the surface of the object to be measured is: a one-dimensional curve is respectively formed on the target surfaces of the first linear array detector and the second linear array detector. The one-dimensional curves respectively represent the pixel distribution curves of the received first angle measurement beam intensity and the second angle measurement beam intensity. The peak pixels are extracted from the one-dimensional curves formed by the first linear array detector and the second linear array detector respectively by the modified peak clustering extraction method, and the corresponding relationship between the two peak positions and the tilt angle is obtained through polynomial fitting, and then the two-dimensional tilt angle measurement is completed.

8. The measurement method according to claim 7, characterized in that, the specific process of the modified peak clustering extraction method is as follows: S201. Obtain the initial peak value P using the centroid method 0 , and set the allowable error ε; S202. Calculate the mean-shift vector corresponding to the current peak pixel according to formula (1): where I is the corresponding light intensity sequence, h is the kernel radius, P hi is the data point position of the kernel radius at the current position, μ is an adjustable parameter, P i is the pixel sequence of the linear array detector corresponding to the current position; S203. Compare the mean - shift vector corresponding to the currently calculated peak pixel with the allowable error; When ||M h,G (P 0 )|| > ε, let M h,G (P 0 ) = P 0 , repeat step S202 until ||M h,G (P 0 )|| ≤ ε, then the currently obtained vector value of M h,G (P 0 ) is the pixel position where the corrected peak is located; When ||M h,G (P 0 )|| ≤ ε, the currently obtained M h,G (P 0 ) vector value is the pixel position where the corrected peak is located.

9. The measurement method according to claim 7, wherein, before using the modified peak clustering extraction method, it further includes a pre - processing step, specifically as follows: The data processing component converts the signals collected by the first linear array detector and the second linear array detector into gray - scale values, numbers each pixel, and makes the pixels on the first linear array detector and the second linear array detector correspond to the light intensity values one by one.

10. The measurement method according to claim 9, wherein, in step S2, obtain the corresponding relationship between the two peak positions and the tilt angle through polynomial fitting, and the specific steps are as follows: Using the method of polynomial least - squares fitting, construct a fitting function model of the tilt angle and the two peak positions, and then obtain the actually measured tilt angle through the peak positions.

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