Confocal measurement system and measurement method thereof

Abstract

The present invention provides a confocal measurement system and a measurement method. The confocal measurement system measures position distances through a differential confocal measurement component in a position measurement unit. By adding an angle measurement unit to the differential confocal optical path and thereby constructing an angle measurement optical path, it is possible to measure the tilt angle while measuring the position. The technical solution provided by the present invention solves the problem in the prior art that differential confocal microscopy cannot measure the tilt angle simultaneously. The optical path of the optical system is simple and easy to implement. The angle measurement component has a simple structure and low cost in terms of spectroscopic angle measurement. It is possible to obtain tilt angle information of the position to be measured while performing differential confocal distance measurement, thereby achieving higher accuracy in optical morphology measurement, especially in identifying tiny surface defects.

Description

Technical Field

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

[0002] The rapid development of science and technology, coupled with the rise of nanoscale technologies such as ultra-precision machining, has posed new challenges to the accuracy of ultra-precision testing. The demand for submicron and even nanometer-level measurement accuracy makes traditional contact measurement technology unsuitable due to its shortcomings, such as poor real-time performance, easy damage to measuring components, and low response frequency.

[0003] Among the current ultra-precision measurement methods in the optical field, confocal microscopy-based technology has been highly developed. However, it also has significant drawbacks. Factors such as light source power fluctuations and stray light contamination can significantly affect measurement accuracy. Furthermore, the measured confocal response signal has limitations such as intensity dependence and positional ambiguity. Consequently, the resulting differential confocal microscopy system, while fully utilizing the unique axial response of confocal microscopy, can achieve more precise focus positioning, offering advantages such as high sensitivity and a wide linear range while reducing noise interference and measurement uncertainty. However, when the machined surface is tilted, that is, when the normal of a point on the measurement surface does not coincide with the axis of the collimated beam emitted by the probe, the return beam cannot return along its original path, and the confocal axial response signal is affected to a certain extent. Similarly, the focus error signal ultimately obtained by the differential confocal microscopy system faces the same problem, which significantly affects detection accuracy. However, current theoretical and technological research in this area is still relatively lacking, both domestically and internationally. Therefore, when performing ultra-precision measurements based on the confocal microscopy principle, it is necessary to consider calibration at different tilt angles of the measured surface to compensate for changes in resolution, linear range, etc.

[0004] Photoelectric autocollimators are irreplaceable in the field of ultra-precision measurement, enabling the measurement of small angles using linear position measurements. With the advent of CCDs and PSDs, the photodetector, the core component of the autocollimator, is no longer a diode, enabling high precision, high resolution, a large measurement range, excellent dynamic performance, and portability. However, existing photoelectric autocollimators can only measure the overall tilt angle of a horizontal surface; they are unable to scan the specific distance position of each point on the surface being measured, nor can they determine the normal tilt angle at each point. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and to provide a confocal measurement system and a measurement method.

[0006] To achieve the above objectives, the present invention adopts the following specific technical solutions:

[0007] The present invention provides a confocal measurement system, comprising a laser light source, a first beam splitter, a second beam splitter, a focusing lens, a position measurement unit and an angle measurement unit; wherein,

[0008] The position measurement unit is a differential confocal measurement component;

[0009] The angle measurement unit includes a third beam splitter, a first cylindrical mirror, a first linear array detector, a second cylindrical mirror and a second linear array detector;

[0010] The light beam emitted by the laser light source is split by the first beam splitter and transmitted to the focusing lens for focusing. The focused light beam is incident on the surface of the object to be measured, is reflected by the surface of the object to be measured, passes through the focusing lens, and is incident on the first beam splitter. After being reflected by the first beam splitter, it is incident on the second beam splitter for splitting. A portion of the light beam is transmitted as an angle measurement beam and is incident on the angle measurement unit for angle measurement, and the other portion is reflected as a position measurement beam and is incident on the position measurement unit for position measurement.

[0011] The angle measurement beam is incident on the third beam splitter for splitting, the transmitted beam is incident on the first cylindrical mirror and the first linear array detector in sequence as the first angle measurement beam, and the reflected beam is incident on the second cylindrical mirror and the second linear array detector in sequence as the second angle measurement beam, data from the first linear array detector and the second linear array detector are collected, and the tilt angle information of the object to be measured is obtained by analyzing the data;

[0012] The differential confocal measurement component obtains position information of the object to be measured according to the differential confocal measurement method;

[0013] The surface information and the inclination angle information of the object to be measured are simultaneously acquired by combining the position information and the inclination angle information.

[0014] Furthermore, the first cylindrical mirror and the second cylindrical mirror are both plano-convex cylindrical lenses, and the convex surfaces thereof are respectively directed toward the first linear array detector and the second linear array detector.

[0015] Furthermore, the first cylindrical mirror and the second cylindrical mirror are arranged perpendicular to each other.

[0016] Furthermore, the differential confocal measurement assembly includes a transmission assembly, a fourth beam splitter, a front-focus focusing lens, a front-focus pinhole, a front-focus photodetector, a back-focus focusing lens, a back-focus pinhole, and a back-focus photodetector; wherein,

[0017] The transmission assembly is fixedly connected to the focusing lens, and the transmission assembly controls the focusing lens to move back and forth along the direction of the laser beam to control the imaging position of the surface to be measured. The interferometer is used to measure the displacement value of the focusing lens; the object plane of the pre-focus focusing lens is located before the focus, and the pre-focus photodetector is set on its image plane; the object plane of the post-focus focusing lens is located after the focus, and the post-focus photodetector is set on its image plane;

[0018] The position measurement beam is incident on the fourth beam splitter for splitting, and a portion of the beam is reflected as a pre-focus measurement beam, which passes through the pre-focus focusing lens and the pre-focus pinhole in sequence and is incident on the pre-focus photodetector; the other portion of the beam is transmitted as a post-focus measurement beam, which passes through the post-focus focusing lens and the post-focus pinhole in sequence and is incident on the post-focus photodetector.

[0019] The present invention also provides a measurement method of a confocal measurement system, which implements measurement based on the confocal measurement system, comprising the following steps:

[0020] S1. Build a confocal measurement system, including a laser light source, a first beam splitter, a focusing lens, 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, and a differential confocal measurement component, which are arranged in sequence along the optical path;

[0021] The pixels of the first linear array detector and the second linear array detector correspond one-to-one to the intensity values of the received light beams;

[0022] The light beam emitted by the laser light source is sequentially transmitted through the first beam splitter, the focusing lens, and the aperture to the surface of the object to be measured. The light beam reflected by the surface of the object to be measured returns to the first beam splitter along the original optical path. The light beam is reflected by the first beam splitter to the second beam splitter for splitting. The reflected light beam and the transmitted light beam after splitting are respectively used as the angle measurement beam and the position measurement beam for measurement;

[0023] The angle measurement beam is incident on the third beam splitter for splitting, the transmitted beam is incident on the first cylindrical mirror and the first linear array detector as a first angle measurement beam with reduced dimension, and the reflected beam is incident on the second cylindrical mirror and the second linear array detector as a second angle measurement beam with reduced dimension, and the data processing component collects signals from 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;

[0024] The position measurement beam is incident on the confocal microscopy measurement component or the differential confocal measurement component, and the data processing component collects and analyzes the signal of the confocal microscopy measurement component or the differential confocal measurement component to obtain the position information of the object to be measured;

[0025] Then, the surface shape information and the inclination angle information of the object to be measured are obtained simultaneously.

[0026] S2,

[0027] The method for obtaining the position information of the object to be measured is: differential confocal measurement method;

[0028] The method for obtaining the inclination angle information of the surface of the object to be measured is: a one-dimensional curve is formed on the target surface of the first linear array detector and the second linear array detector respectively, and the one-dimensional curve represents the pixel distribution curve of the intensity of the received first angle measurement beam and the pixel distribution curve of the intensity of the second angle measurement beam respectively. The centroid pixel of the one-dimensional curve formed by the first linear array detector and the second linear array detector is extracted respectively by the centroid method, thereby completing the two-dimensional inclination angle measurement.

[0029] Furthermore, the method for obtaining the tilt angle information in step S2 is specifically as follows:

[0030] S201a, numbering the pixels on the first linear array detector and the second linear array detector as 1 to n, and recording the signal data collected on each corresponding pixel as I ij , where i = x, y, j = 1, 2…n, x, y represent two sets of signal data in the horizontal and radial directions respectively;

[0031] S202a, collecting two sets of voltage signal data of the first angle measurement beam and the second angle measurement beam incident on the first linear array detector and the second linear array detector, processing the data using the centroid method according to formula (1), and obtaining pixel number coordinates corresponding to the centroids of the first angle measurement beam and the second angle measurement beam in the horizontal direction and the vertical direction; formula (1) is as follows:

[0032]

[0033] S203a, obtaining the tilt angle of the surface of the object to be measured using formula (2) according to the pixel sizes of the first linear array detector and the second linear array detector;

[0034]

[0035] Wherein, d is the pixel size, f is the focal length of the focusing lens, and θ1 and θ2 are the tilt angles of the surface of the object to be measured in two dimensions, respectively.

[0036] Furthermore, before step S201a, a pre-calibration step is also included:

[0037] S200a. Replace the object to be measured with a plane reflector with a zero tilt angle. First, focus the object using a differential confocal measurement assembly. Then, collect two sets of voltage signal data from the first angle measurement beam and the second angle measurement beam incident on the first linear array detector and the second linear array detector. Use the centroid method to obtain the coordinates of the corresponding transverse and longitudinal centroids of the first linear array detector and the second linear array detector to complete the calibration.

[0038] Furthermore, the differential confocal measurement method in step S2 is specifically as follows:

[0039] S201b, driving the focusing lens to move by the transmission component, respectively collecting the light signal intensities I of the pre-focus photodetector and the post-focus photodetector vf , I vb ;

[0040] S202b, when the light intensity of the pre-focus photodetector is equal to the light signal intensity of the post-focus photodetector, obtaining a differential confocal signal curve I diff , the curve is shown in formula (3):

[0041]

[0042] S203b, measuring the focusing lens displacement value corresponding to the zero-crossing position of the differential confocal signal curve by the interferometer, and thereby obtaining the position information of the to-be-measured point on the surface of the object to be measured.

[0043] The present invention can achieve the following technical effects:

[0044] 1. The confocal measurement system and measurement method provided by the present invention can simultaneously obtain the surface shape information and surface inclination information of the object to be measured;

[0045] 2. The confocal measurement system and measurement method provided by the present invention propose that angle measurement can be performed based on a differential confocal optical path through an angle measurement unit;

[0046] 3. The confocal measurement system and measurement method provided by the present invention can achieve measurement over a wide angle range;

[0047] 4. The confocal measurement system provided by the present invention has a simple structure and is easy to implement, and the measurement method is easy to operate, while taking into account both accuracy and speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1is a schematic structural diagram of a confocal measurement system according to an embodiment of the present invention;

[0049] Figure 2 is a flow chart of a confocal measurement method according to an embodiment of the present invention;

[0050] Figure 3 FIG. 4 is a schematic diagram of the principle of angle measurement of a confocal measurement system according to an embodiment of the present invention.

[0051] Reference numerals include:

[0052] 1 laser light source, 2 first beam splitter, 3 focusing lens, 4 object to be measured, 5 second beam splitter, 6 fourth beam splitter, 7 post-focus focusing lens, 8 pre-focus focusing lens, 9 post-focus pinhole, 10 pre-focus pinhole, 11 post-focus photoelectric detector, 12 pre-focus photoelectric detector, 13 third beam splitter, 14 first cylindrical mirror, 15 second cylindrical mirror, 16 first linear array detector, 17 second linear array detector. DETAILED DESCRIPTION

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

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with 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 of the present invention.

[0055] The following combination Figure 1-Figure 3 The specific working mode of the confocal measurement system and the measurement method thereof according to the embodiment of the present invention is described in detail:

[0056] Figure 1 FIG. 4 shows a schematic structural diagram of a confocal measurement system according to an embodiment of the present invention.

[0057] The confocal measurement system in the embodiment of the present invention includes a laser light source 1, a first beam splitter 2, a second beam splitter 5, a focusing lens 3, a position measurement unit, and an angle measurement unit. The position measurement unit is a differential confocal measurement component. The angle measurement unit includes a third beam splitter 13, a first cylindrical mirror 14, a first linear array detector 16, a second cylindrical mirror 15, and a second linear array detector 17.

[0058] In this embodiment of the present invention, a laser light source 1 emits a collimated white light beam with a wavelength of λ, which is split by a first beam splitter 2 and transmitted to a focusing lens 3 for focusing. The focused light beam is incident on the surface of an object to be measured 4. After reflection from the surface of the object to be measured 4, it passes through the focusing lens 3 and emerges as a parallel light beam. The parallel light beam is incident on the first beam splitter 2, reflected by the first beam splitter 2, and then split by the second beam splitter 5. Part of the light beam is transmitted as an angle measurement beam and incident on the angle measurement unit for angle measurement, while the other part is reflected as a position measurement beam and incident on the position measurement unit for position measurement. In this embodiment of the present invention, the first beam splitter 2 is a non-polarizing beam splitter with a splitting ratio of 50:50.

[0059] The angle measurement beam is incident on the third beam splitter 13 for splitting. The transmitted beam, serving as the first angle measurement beam, is sequentially incident on the first cylindrical mirror 14 and the first linear array detector 16. The reflected beam, serving as the second angle measurement beam, is sequentially incident on the second cylindrical mirror 15 and the second linear array detector 17. Data from the first and second linear array detectors 16, 17 are collected and analyzed to obtain tilt angle information of the object under test 4. The differential confocal measurement assembly obtains position information of the object under test 4 using the differential confocal measurement method. Combining this position information with tilt angle information, it simultaneously obtains surface shape information and surface inclination information of the object under test 4.

[0060] The present invention provides a preferred embodiment in which the first cylindrical mirror 14 and the second cylindrical mirror 15 are both plano-convex cylindrical lenses, with their convex surfaces facing the first linear array detector 16 and the second linear array detector 17, respectively. Furthermore, the first cylindrical mirror 14 and the second cylindrical mirror 15 are arranged perpendicular to each other. The circular light spots incident on the first cylindrical mirror 14 and the second cylindrical mirror 15 are shaped into linear light sources in both the transverse and radial directions, respectively. This reduces the dimensionality of the two-dimensional inclination angle information of the object under test 4 in both the transverse and radial directions. The first linear array detector 16 and the second linear array detector 17 then collect the light intensity signal distribution data, thereby completing the two-dimensional angle measurement.

[0061] The present invention provides a preferred embodiment, a differential confocal measurement component

[0062] It includes a transmission assembly, a fourth beam splitter 6, a front-focus focusing lens 8, a front-focus pinhole 10, a front-focus photoelectric detector 12, a front-focus focusing lens 7, a back-focus pinhole 9, and a back-focus photoelectric detector 11; wherein,

[0063] The transmission assembly is fixedly connected to the focusing lens 3. The transmission assembly controls the focusing lens 3 to move back and forth along the direction of the laser beam to control the imaging position of the surface to be measured. The interferometer is used to measure the displacement value of the focusing lens 3. The object plane of the pre-focus focusing lens 8 is located before the focus, and a pre-focus photodetector 12 is set on its image plane; the object plane of the pre-focus focusing lens 7 is located after the focus, and a post-focus photodetector 11 is set on its image plane.

[0064] The position measurement beam is incident on the fourth beam splitter 6 for splitting. A part of the beam is reflected as the pre-focus measurement beam, which passes through the pre-focus focusing lens 8 and the pre-focus pinhole 10 in sequence and then enters the pre-focus photoelectric detector 12; the other part of the beam is transmitted as the post-focus measurement beam, which passes through the pre-focus focusing lens 7 and the post-focus pinhole 9 in sequence and then enters the post-focus photoelectric detector 11.

[0065] Figure 2 FIG. 4 is a flow chart showing a confocal measurement method in an embodiment of the present invention.

[0066] The embodiment of the present invention also provides a measurement method of a confocal measurement system, which implements measurement based on the confocal measurement system. Figure 2 As shown, the following steps are included:

[0067] S1. Build a confocal measurement system, including a laser light source 1, a first beam splitter 2, a focusing lens 3, a second beam splitter 5, a third beam splitter 13, a first cylindrical mirror 14, a first linear array detector 16, a second cylindrical mirror 15, a second linear array detector 17, and a differential confocal measurement assembly, arranged sequentially along the optical path. The pixels of the first linear array detector 16 and the second linear array detector 17 correspond one-to-one to the intensity values of the received beams.

[0068] The light beam emitted by the laser light source 1 is transmitted to the surface of the object to be measured 4 through the first beam splitter 2, the focusing lens 3, and the aperture in sequence. The light beam reflected by the surface of the object to be measured 4 returns to the first beam splitter 2 along the original optical path. The light beam is reflected by the first beam splitter 2 and is then split by the second beam splitter 5. The reflected light beam and the transmitted light beam after splitting are respectively used as the angle measurement beam and the position measurement beam for measurement;

[0069] The angle measurement beam is incident on the third beam splitter 13 for splitting. The transmitted beam is incident on the first cylindrical mirror 14 and the first linear array detector 16 as the first angle measurement beam with reduced dimension. The reflected beam is incident on the second cylindrical mirror 15 and the second linear array detector 17 as the second angle measurement beam with reduced dimension. The data processing component collects the signals of the first linear array detector 16 and the second linear array detector 17 for analysis to obtain the tilt angle information of the surface of the object 4 under test.

[0070] The position measurement beam is incident on the confocal microscopy measurement component or the differential confocal measurement component, and the data processing component collects the signal of the confocal microscopy measurement component or the differential confocal measurement component for analysis to obtain the position information of the object to be measured 4;

[0071] Then, the surface shape information and surface inclination information of the object to be measured 4 are obtained simultaneously.

[0072] S2,

[0073] The method for obtaining the position information of the object to be measured 4 is: differential confocal measurement method.

[0074] The method for obtaining the inclination angle information of the surface of the object to be measured 4 is as follows: a one-dimensional curve is formed on the target surface of the first linear array detector 16 and the second linear array detector 17 respectively, and the one-dimensional curves respectively represent the pixel distribution curve of the intensity of the received first angle measurement beam and the pixel distribution curve of the intensity of the second angle measurement beam. The centroid method is used to extract the centroid pixel of the one-dimensional curves formed by the first linear array detector 16 and the second linear array detector 17, thereby completing the two-dimensional inclination angle measurement.

[0075] In the embodiment of the present invention, calibration is taken as an example for detailed description, and the same principle applies if calibration is not required.

[0076] S200a, replace the object 4 with a plane reflector with a zero tilt angle, first focus the object 4 using the differential confocal measurement assembly, then collect two sets of voltage signal data of the first angle measurement beam and the second angle measurement beam incident on the first linear array detector 16 and the second linear array detector 17, and use the centroid method to obtain the corresponding horizontal and vertical coordinates of the first linear array detector 16 and the second linear array detector 17, respectively. Complete calibration.

[0077] Among them, the formula (1) of the centroid method is as follows:

[0078]

[0079] The pixel numbers on the first linear array detector 16 and the second linear array detector 17 are 1 to n, and the signal data collected on each corresponding pixel is recorded as I rij , where i = x, y, j = 1, 2…n, x and y represent two sets of signal data in the horizontal and radial directions respectively.

[0080] According to the pixel sizes of the first linear array detector 16 and the second linear array detector 17, the formula (2) is used to calculate The numerical value of .

[0081]

[0082] S201a, such as Figure 3 As shown, the plane reflector used for calibration is replaced by the object to be measured 4, the pixels on the first linear array detector 16 and the second linear array detector 17 are numbered 1 to n, and the signal data collected on each corresponding pixel is recorded as I ij , where i = x, y, j = 1, 2…n, x and y represent two sets of signal data in the horizontal and radial directions respectively.

[0083] S202a. Collect two sets of voltage signal data from the first angle measurement beam and the second angle measurement beam incident on the first linear array detector 16 and the second linear array detector 17. Process the data using the centroid method according to formula (3) to obtain the pixel number coordinates corresponding to the centroids of the first angle measurement beam and the second angle measurement beam in the horizontal and radial directions. That is, extract the pixel number coordinates corresponding to the centroid of the reflected beam in the horizontal and radial directions, and the specific position can be obtained based on the actual pixel size. Formula (3) is as follows:

[0084]

[0085] S203a, when the surface of the object to be measured 4 is tilted, the tilt amplitude of the reflected light beam is twice the tilt angle of the surface. According to the pixel sizes of the first linear array detector 16 and the second linear array detector 17, as shown in FIG. Figure 3 As shown, according to formula (4), the specific position distance of the surface of the object to be measured 4 can be obtained;

[0086]

[0087] The tilt angle of the surface of the object 4 is obtained according to the specific position distance of the surface of the object 4, which can be specifically expressed as formula (5) and formula (6):

[0088]

[0089]

[0090] Wherein, d is the pixel size, f is the focal length of the focusing lens 3, Δr1 and Δr2 are the longitudinal and lateral offsets of the angle measurement beam when the surface of the object 4 is tilted, and θ1 and θ2 are the tilt angles of the surface of the object 4 in two dimensions, respectively.

[0091] The present invention uses calibration to avoid errors inherent in confocal measurement systems. It also leverages the properties of a cylindrical mirror to shape a collimated light beam into a linear light source for tilt angle measurement, while a linear array detector collects light intensity distribution data. While ensuring high precision and resolution, it also achieves a higher signal-to-noise ratio, faster dynamic response, and the ability to measure tilt angles in two dimensions simultaneously.

[0092] The differential confocal measurement method in step S2 in the embodiment of the present invention is specifically as follows:

[0093] S201b, driving the focusing lens 3 to move by the transmission assembly, respectively collecting the light signal intensity I of the pre-focus photoelectric detector 12 and the post-focus photoelectric detector 11 vf , I vbIn the embodiment of the present invention, the transmission component selects the piezoelectric ceramic in the prior art to drive the focusing lens 3 to move, and the axial offset of the focusing lens 3 is changed. Finally, two response curves with similar shapes but axial deviations can be obtained, which are located on both sides of the focus. The front focus axial light signal intensity response curve is recorded as I vf , the back focus axial light signal intensity response signal is recorded as I vb .

[0094] S202b, when the light intensity of the pre-focus photodetector 12 is equal to the light signal intensity of the post-focus photodetector 11, vf and I vb The two signals are subtracted and then divided by the sum of the two signals to perform a normalization process to obtain the differential confocal response curve I diff , the curve is shown in formula (7):

[0095]

[0096] S203b, the zero crossing point of the differential confocal response curve corresponds to the optimal focusing position on the surface of the object 4 to be measured, and the displacement value of the focusing lens 3 corresponding to the zero crossing point position of the differential confocal signal curve is measured by the interferometer to obtain the position information of the measured point on the surface of the object 4 to be measured.

[0097] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the 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, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0098] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0099] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A confocal measurement system, characterized in that: It includes a laser light source, a first beam splitter, a second beam splitter, a focusing lens, a position measurement unit and an angle measurement unit; wherein, The position measurement unit is a differential confocal measurement component; The angle measurement unit includes a third beam splitter, a first cylindrical mirror, a first linear array detector, a second cylindrical mirror and a second linear array detector; The light beam emitted by the laser light source is split by the first beam splitter and transmitted to the focusing lens for focusing. The focused light beam is incident on the surface of the object to be measured, is reflected by the surface of the object to be measured, passes through the focusing lens, and is incident on the first beam splitter. After being reflected by the first beam splitter, it is incident on the second beam splitter for splitting. A portion of the light beam is transmitted as an angle measurement beam and is incident on the angle measurement unit for angle measurement, and the other portion is reflected as a position measurement beam and is incident on the position measurement unit for position measurement. The angle measurement beam is incident on the third beam splitter for splitting, the transmitted beam is incident on the first cylindrical mirror and the first linear array detector in sequence as the first angle measurement beam, and the reflected beam is incident on the second cylindrical mirror and the second linear array detector in sequence as the second angle measurement beam, data from the first linear array detector and the second linear array detector are collected, and the tilt angle information of the object to be measured is obtained by analyzing the data; The differential confocal measurement component obtains position information of the object to be measured according to the differential confocal measurement method; The surface information and the inclination angle information of the object to be measured are simultaneously acquired by combining the position information and the inclination angle information.

2. The confocal measurement system according to claim 1, characterized in that: The first cylindrical mirror and the second cylindrical mirror are both plano-convex cylindrical lenses, and the convex surfaces thereof are respectively oriented toward the first linear array detector and the second linear array detector.

3. The confocal measurement system according to claim 1, characterized in that: The first cylindrical mirror and the second cylindrical mirror are arranged perpendicular to each other.

4. The confocal measurement system according to claim 1, characterized in that: The differential confocal measurement assembly includes a transmission assembly, a fourth beam splitter, a front-focus focusing lens, a front-focus pinhole, a front-focus photodetector, a back-focus focusing lens, a back-focus pinhole, and a back-focus photodetector; wherein, The transmission assembly is fixedly connected to the focusing lens, and the transmission assembly controls the focusing lens to move back and forth along the direction of the laser beam to control the imaging position of the surface to be measured. The interferometer is used to measure the displacement value of the focusing lens; the object plane of the pre-focus focusing lens is located before the focus, and the pre-focus photodetector is set on its image plane; the object plane of the post-focus focusing lens is located after the focus, and the post-focus photodetector is set on its image plane; The position measurement beam is incident on the fourth beam splitter for splitting, and a portion of the beam is reflected as a pre-focus measurement beam, which passes through the pre-focus focusing lens and the pre-focus pinhole in sequence and is incident on the pre-focus photodetector; the other portion of the beam is transmitted as a post-focus measurement beam, which passes through the post-focus focusing lens and the post-focus pinhole in sequence and is incident on the post-focus photodetector.

5. A measurement method of a confocal measurement system, characterized in that: The measurement is performed based on the confocal measurement system, including the following steps: S1. Build a confocal measurement system, including a laser light source, a first beam splitter, a focusing lens, 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, and a differential confocal measurement component, which are arranged in sequence along the optical path; The pixels of the first linear array detector and the second linear array detector correspond one-to-one to the intensity values of the received light beams; The light beam emitted by the laser light source is sequentially transmitted through the first beam splitter, the focusing lens, and the aperture to the surface of the object to be measured. The light beam reflected by the surface of the object to be measured returns to the first beam splitter along the original optical path. The light beam is reflected by the first beam splitter to the second beam splitter for splitting. The reflected light beam and the transmitted light beam after splitting are respectively used as the angle measurement beam and the position measurement beam for measurement; The angle measurement beam is incident on the third beam splitter for splitting, the transmitted beam is incident on the first cylindrical mirror and the first linear array detector as a first angle measurement beam with reduced dimension, and the reflected beam is incident on the second cylindrical mirror and the second linear array detector as a second angle measurement beam with reduced dimension, and the data processing component collects signals from 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 microscopy measurement component or the differential confocal measurement component, and the data processing component collects and analyzes the signal of the confocal microscopy measurement component or the differential confocal measurement component to obtain the position information of the object to be measured; Then simultaneously obtain the surface information and inclination information of the object to be measured; S2、 The method for obtaining the position information of the object to be measured is: differential confocal measurement method; The method for obtaining the inclination angle information of the surface of the object to be measured is: a one-dimensional curve is formed on the target surface of the first linear array detector and the second linear array detector respectively, and the one-dimensional curve represents the pixel distribution curve of the intensity of the received first angle measurement beam and the pixel distribution curve of the intensity of the second angle measurement beam respectively. The centroid method is used to extract the pixels of the centroids of the one-dimensional curves formed by the first linear array detector and the second linear array detector respectively, thereby completing the two-dimensional inclination angle measurement.

6. The measuring method according to claim 5, characterized in that The method for obtaining the tilt angle information in step S2 is specifically as follows: S201a, number the pixels on the first linear array detector and the second linear array detector as 1 to n, and record the light intensity signal data collected on each corresponding pixel as I ij , where i = x, y, j = 1, 2…n, x, y represent two sets of signal data in the horizontal and radial directions respectively; S202a, collecting two sets of voltage signal data of the first angle measurement beam and the second angle measurement beam incident on the first linear array detector and the second linear array detector, processing the data using the centroid method according to formula (1), and obtaining the pixel number coordinates corresponding to the centroids of the first angle measurement beam and the second angle measurement beam in the horizontal direction and the vertical direction; formula (1) is as follows: S203a, obtaining the tilt angle of the surface of the object to be measured using formula (2) according to the pixel sizes of the first linear array detector and the second linear array detector; Wherein, d is the pixel size, f is the focal length of the focusing lens, and θ1 and θ2 are the tilt angles of the surface of the object to be measured in two dimensions, respectively.

7. The measuring method according to claim 6, characterized in that Before step S201a, a pre-calibration step is also included: S200a. Replace the object to be measured with a plane reflector with a zero tilt angle. First, focus the object using a differential confocal measurement assembly. Then, collect two sets of voltage signal data of the first angle measurement beam and the second angle measurement beam incident on the first linear array detector and the second linear array detector. Use the centroid method to obtain the corresponding horizontal and vertical coordinates of the first linear array detector and the second linear array detector to complete the calibration.

8. The measuring method according to claim 5, characterized in that The differential confocal measurement method in step S2 is specifically as follows: S201b, driving the focusing lens to move by the transmission component, respectively collecting the light signal intensity I of the pre-focus photoelectric detector and the post-focus photoelectric detector vf , I vb ; S202b, when the light intensity of the pre-focus photodetector is equal to the light signal intensity of the post-focus photodetector, obtaining a differential confocal signal curve I diff , the curve is shown in formula (3): S203b, measuring the focusing lens displacement value corresponding to the zero-crossing position of the differential confocal signal curve by an interferometer, and thereby obtaining the position information of the point to be measured on the surface of the object to be measured.

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