A confocal measurement system based on lateral encoding and its measurement method

Abstract

The present invention provides a confocal measurement system and a measurement method based on lateral coding, which belong to the field of optical detection technology. The measurement system realizes lateral coding of the spectrum by adding a spectroscopic dispersion component to the existing confocal measurement system. The measurement method solves the problem that the existing confocal measurement technology can only adopt a point-by-point scanning measurement method by combining the geometric optics of lateral coding with a mathematical algorithm. By means of lateral coding, the measurement dimension in one direction is reduced, and the confocal measurement technology is converted from a point measurement mode to a line scanning measurement mode. While improving the measurement accuracy of the existing measurement system, the measurement time is shortened. The measurement system and method provided by the present invention not only measure the comprehensive three-dimensional information of the object to be measured, but also measure the tilt angle of the object to be measured in real time, thereby effectively overcoming the limitation that the existing confocal measurement technology cannot simultaneously measure the three-dimensional spatial information and the angle tilt information of the object to be measured.

Description

Technical Field

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

[0002] Confocal microscopy measurement technology is an optical imaging technology that performs outstandingly in the field of surface topography measurement. Compared with traditional measurement technology, confocal microscopy measurement technology has higher transverse axial resolution and longitudinal axial resolution, and can provide more accurate surface profile data. With these advantages, confocal microscopy measurement technology has been widely used in fields such as automatic optical inspection of microstructures, semiconductor manufacturing, materials science, and biomedicine. Its unique imaging method can effectively suppress scattered light and out-of-focus light in traditional microscopes, thereby achieving independent imaging of different layers of the sample while maintaining high resolution. This layered imaging capability makes confocal microscopy measurement technology play a key role in precision measurement and complex sample analysis.

[0003] However, the existing confocal microscope measurement technology faces some challenges in practical applications. The point-by-point scanning measurement method is easily affected when the measurement time is long. When the measurement surface is tilted, the measurement accuracy of the system tends to drop significantly. This is because the reflection path of the light beam on the tilted surface changes, causing the light signal to shift, thus causing measurement errors. In addition, the long measurement time also increases the interference of environmental factors on the measurement results, further affecting the stability and reliability of the measurement.

[0004] The Chinese patent application "Linear differential confocal displacement sensor system based on lateral encoding" (patent application number CN202411349752.9) discloses a linear differential confocal displacement sensor system based on lateral encoding. While ensuring the measurement accuracy of the differential confocal microscope, it converts it from point measurement to line scanning mode measurement, and uses a blazed grating to achieve spectral lateral encoding, so that light of different wavelengths can be decomposed, and the measured components are measured through an achromatic lens in the desired order. By analyzing the light intensity signals of different wavelengths, all information on the lateral height of the sample can be obtained at the same time. Although this method solves the problem of long measurement time using point-by-point scanning measurement method. However, while measuring height information, it is still impossible to simultaneously measure the tilt angle. Summary of the invention

[0005] The present invention overcomes the deficiencies of the prior art and provides a confocal measurement system based on lateral encoding and a measurement method thereof.

[0006] A confocal measurement system based on lateral encoding comprises a first measurement unit and a second measurement unit; wherein:

[0007] The first measuring unit includes a light source component, a first beam splitter, a second beam splitter, a first achromatic focusing lens, a first signal receiving component, and a second signal receiving component arranged along the optical path;

[0008] The second measuring unit includes a spectroscopic dispersion component and an object moving component for moving the object to be measured;

[0009] The light beam emitted by the light source component is split by the first beam splitter, and the transmitted light beam after the splitting is sequentially reflected by the light splitting and dispersion component and transmitted by the second beam splitter to the surface of the object to be measured, and the light beam forms a light beam with transverse coding and carrying information of the object to be measured, and the light beam reflected by the surface of the object to be measured is transmitted by the first achromatic focusing lens and then split by the second beam splitter;

[0010] The reflected light beam split by the second beam splitter is incident on the first signal receiving component, and the tilt angle analysis of the object to be measured is performed according to the signal received by the first signal receiving component; the transmitted light beam split by the second beam splitter is sequentially dispersed and reflected by the light-splitting and dispersion component and reflected by the first beam splitter, and is incident on the second signal receiving component, and the height analysis of the object to be measured is performed according to the signal received by the second signal receiving component.

[0011] Further, the light-splitting and dispersing component includes a blazed grating and a telecentric aperture arranged along the optical path;

[0012] The blazed grating is used to disperse and separate light beams of different wavelengths, so that the light beams can be transversely encoded;

[0013] The telecentric aperture is used to eliminate the magnification change of the light beam and make the light beam parallel to the optical axis of the measurement system.

[0014] Further, the first signal receiving component includes a second achromatic focusing lens and a planar array spectrometer array;

[0015] The second achromatic focusing lens is used to focus light beams of different wavelengths and eliminate chromatic aberration;

[0016] The planar spectrometer array is used to receive light beam signals of different wavelengths for imaging.

[0017] Further, the second signal receiving component includes a focusing lens, a pinhole and an imaging spectrometer;

[0018] The focusing lens is used to focus the parallel light beam;

[0019] The pinhole is used to suppress the defocused light beam and reduce the interference of the scattered light beam;

[0020] The imaging spectrometer is used to receive light beam signals for imaging.

[0021] Further, the light source assembly includes a light source and a collimating lens;

[0022] The light source is used to emit a continuous white light beam;

[0023] The collimating lens is used to collimate the light beam emitted by the light source into a parallel light beam.

[0024] The present invention also provides a measurement method of a confocal measurement system based on lateral encoding, comprising the following steps:

[0025] S1, placing a plane reflector with a zero tilt angle on the object moving assembly, starting a measurement system, and obtaining first position information of light beams of different wavelengths imaged on the array of the planar array spectrometer after being respectively reflected by different positions of the plane reflector;

[0026] S2, placing the object to be tested on the object moving assembly, the light beam emitted by the light source assembly is transmitted through the first beam splitter, reflected by the light splitting and dispersion assembly, transmitted through the second beam splitter, and transmitted through the first achromatic focusing lens to the surface of the object to be tested, so as to form a light beam with transverse coding and carrying information of the object to be tested, the light beam is optically split by the system, and the split light beams respectively form a light beam with transverse coding tilt angle information and a light beam with transverse coding height information, and are respectively received by the planar array spectrometer and the imaging spectrometer;

[0027] S3,

[0028] The method for measuring the tilt angle of the object to be measured is:

[0029] By analyzing the information of the light beam received by the planar array spectrometer array, the position information of light beams of different wavelengths being imaged on the planar array spectrometer array after being respectively reflected by different positions of the plane reflector and different positions of the object to be measured is obtained, and then the corresponding inclination angle information of the transverse axis of the surface of the object to be measured is obtained, and the inclination angle measurement of the object to be measured is completed;

[0030] The height measurement method of the object to be measured is:

[0031] By analyzing the spectrum information of the light beam received by the imaging spectrometer, the light intensity information reflected by light beams of different wavelengths at different positions of the object to be measured is obtained, and then the corresponding height information of the surface of the object to be measured in the transverse axis direction is obtained to complete the height measurement of the object to be measured;

[0032] S4, controlling the object moving assembly to move the object to be measured, and repeating steps S2 and S3 until the measurement of the object to be measured is completed.

[0033] Furthermore, the method for measuring the tilt angle of the object to be measured in step S3 is specifically as follows:

[0034] Acquire second position information of light beams of different wavelengths imaged on the array of the planar array spectrometer after being respectively reflected by different positions of the object to be measured;

[0035] Obtaining a light beam with the same wavelength at the first position information and the second position information, respectively, and calculating the measured displacements of the two position information;

[0036] Obtaining theoretical displacements of two pieces of position information corresponding to light beams of the same wavelength in the first position information and the second position information;

[0037] By calculating the measured displacement and the theoretical displacement, the tilt angle information of the measuring point of the object to be measured under the light beams of different wavelengths is obtained, and the tilt angle measurement of the object to be measured is completed.

[0038] Furthermore, the calculation formula of the measured displacement is as follows:

[0039]

[0040] Wherein, S represents the measured displacement of light beams of different wavelengths; S0 represents the number of offsets of the planar array spectrometer and the distance between two adjacent spectrometers in the planar array spectrometer array; , Respectively represent the position of the abscissa and ordinate of the array of the planar array spectrometer in the first position information; , Respectively represent the position of the abscissa and ordinate of the array of the planar array spectrometer in the second position information; Indicates wavelength.

[0041] Furthermore, the calculation formula of the theoretical displacement is as follows:

[0042]

[0043] in, represents the theoretical displacement of light beams of different wavelengths; d represents the grating spacing of the blazed grating; represents the angle of the central axis of the incident light beam relative to the normal of the blazed grating; m represents the diffraction order of the blazed grating; Indicates the inclination angle of the surface of the object to be measured relative to the optical axis; represents the focal length of the first achromatic focusing lens and the second achromatic focusing lens.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a confocal measurement system based on transverse encoding and a measurement method thereof, which realizes transverse encoding of the spectrum by adding dispersive optical components to the existing confocal optical measurement system. The existing confocal optical measurement system can only adopt a point-by-point scanning measurement method. Through the transverse encoding method, the measurement dimension in one direction is reduced, and the confocal optical measurement system is converted from a point measurement mode to a line scanning measurement mode. While improving the measurement accuracy of the existing confocal optical measurement system, the measurement time is shortened.

[0046] The measurement method of the confocal measurement system based on lateral encoding provided by the present invention collects optical information in the measurement system, and through an analysis method combining optics and algorithms, can not only measure the comprehensive three-dimensional information of the object to be measured and obtain the spatial imaging information of the object to be measured, but also can perform real-time measurement of the inclination angle of the measuring point on the surface of the object to be measured, thereby effectively overcoming the limitation of the existing confocal display measurement technology that cannot simultaneously measure the three-dimensional spatial information and the inclination angle information of the object to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic structural diagram of a confocal measurement system based on lateral encoding in an embodiment of the present invention;

[0048] Figure 2 is a schematic flow chart of a confocal measurement method based on lateral encoding in an embodiment of the present invention;

[0049] Figure 3 It is a schematic diagram of the spectral information offset of the surface to be measured with an inclined angle on the array of the planar array spectrometer in an embodiment of the present invention.

[0050] The reference numerals are as follows:

[0051] 1-light source, 2-collimating lens, 3-first beam splitter, 4-blazed grating, 5-telecentric aperture, 6-second achromatic focusing lens, 7-array spectrometer array, 8-second beam splitter, 9-first achromatic focusing lens, 10-object to be measured, 11-object moving assembly, 12-focusing lens, 13-pinhole, 14-imaging spectrometer. DETAILED DESCRIPTION

[0052] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Embodiment 1

[0054] The invention provides a confocal measurement system based on lateral encoding.

[0055] Figure 1 A schematic structural diagram of a confocal measurement system based on lateral encoding according to an embodiment of the present invention is shown.

[0056] like Figure 1 As shown, an embodiment of the present invention provides a confocal measurement system based on transverse encoding, including a first measurement unit and a second measurement unit. The first measurement unit includes a light source 1, a collimating lens 2, a first beam splitter 3, a second beam splitter 8, a first achromatic focusing lens 9, a second achromatic focusing lens 6, a planar array spectrometer array 7, a focusing lens 12, a pinhole 13 and an imaging spectrometer 14 arranged in sequence along the optical path. The second measurement unit includes a spectroscopic dispersion component including a blazed grating 4, a telecentric aperture 5 and a carrier moving component 11 arranged along the optical path. In the embodiment of the present invention, the carrier moving component 11 for moving the object to be measured 10 adopts a piezoelectric ceramic driver in the prior art to move the object to be measured 10.

[0057] The light source 1 emits a continuous white measuring light beam which is collimated into a parallel light beam by the collimating lens 2. The parallel light beam is split by the first beam splitter 3. The transmitted light beam after the splitting is diffracted by the blazed grating 4 and dispersed into light beams of different wavelengths, which can make the light beams of different wavelengths realize transverse encoding. The light beams of different wavelengths are incident on the second beam splitter 8 through the telecentric aperture 5 for beam splitting. The transmitted light beam after the splitting is incident on the surface of the object to be measured 10 through the first achromatic focusing lens 9 to scan the surface of the object to be measured 10. The telecentric aperture 5 can eliminate the magnification change of the light beam, make the light beam parallel to the optical axis of the measurement system, and improve the overall measurement accuracy of the measurement system. The light beam forms a light beam with transverse encoding and carrying the information of the object to be measured 10. It is transmitted to the surface of the object to be measured 10 through the second beam splitter 8 to scan the surface information of the object to be measured 10 and then reflected. At this time, the reflected light beam forms a light beam with transverse encoding and carrying the information of the object to be measured 10. After being transmitted through the first achromatic focusing lens 9, it is split again by the second beam splitter 8.

[0058] The reflected light beam split by the second beam splitter 8 is incident on the second achromatic focusing lens 6 and then received by the area array spectrometer array 7. The tilt angle analysis of the object to be measured 10 is performed according to the signal of the area array spectrometer array 7. The transmitted light beam split by the second beam splitter 8 is sequentially transmitted through the telecentric aperture 5, reflected by the blazed grating 4, reflected by the first beam splitter 3, focused by the focusing lens 12, and incident on the imaging spectrometer 14 through the pinhole 13. The height analysis of the object to be measured 10 is performed according to the signal received by the imaging spectrometer 14. The pinhole 13 can suppress the defocused light beam of the measuring light beam, reduce the interference of the scattered light beam, and improve the measurement accuracy of the measuring system.

[0059] The confocal measurement system based on transverse encoding provided by the embodiment of the present invention uses the light beam diffracted by the blazed grating 4 and the telecentric aperture 5 to scan and measure the object to be measured 10, which not only eliminates the magnification change introduced by the transverse encoding measurement beam, but also is equivalent to using the transverse axial linear scanning measurement, and one measurement can achieve the scanning of a plane. After completing the scanning of a plane, the object to be measured 10 is moved longitudinally by the piezoelectric ceramic driver for scanning. Compared with the cofocal optical measurement technology in the prior art, it is necessary to scan three dimensions during scanning to obtain all the information of the object to be measured 10 in order to perform three-dimensional reconstruction, reduce the dimensional measurement in one direction, and greatly save the measurement time. The measurement system provided by the embodiment of the present invention only needs to scan two dimensions through transverse encoding, while ensuring the measurement accuracy, it improves the measurement efficiency and reduces the measurement workload. By changing the grating pitch and blazed angle of the blazed grating 4, the emission angle of the specific wavelength light beam can be controlled, so that the specific wavelength light beam passes through the focal plane of the first achromatic focusing lens 9 in the expected order or arrangement, that is, the measurement beam is stably arranged with the designed or calibrated expected value to achieve transverse axial linear encoding. The measurement system provided by the embodiment of the present invention adds tilt angle measurement to the optical system only through common optical devices. It can not only scan the three-dimensional information of the object 10 to be measured, but also realize the real-time measurement of the tilt angle of the measuring point of the object 10 to be measured, so that the confocal measurement system based on lateral encoding has a wide application range and better application prospects.

[0060] Embodiment 2

[0061] The invention provides a measurement method of a confocal measurement system based on lateral encoding.

[0062] Figure 2 A schematic flow chart of a measurement method of a confocal measurement system based on lateral encoding according to an embodiment of the present invention is shown.

[0063] like Figure 2 As shown, an embodiment of the present invention provides a measurement method of a confocal measurement system based on lateral encoding, comprising the following steps:

[0064] S1. Place a plane reflector with a zero tilt angle on the piezoelectric ceramic driver, which is the position of the object to be measured 10 during measurement. Start the confocal measurement system. The light source 1 is dispersed and transversely encoded by the blazed grating 4 to become measurement beams of different wavelengths. The measurement beams of different wavelengths are respectively reflected by different positions of the plane reflector and imaged at different positions of the array spectrometer 7. The coordinates of the above positions are recorded. , }, the coordinate set of these positions is called the first position information. , Respectively represent the horizontal coordinate and vertical coordinate in the first position information.

[0065] The measurement method step S1 provided in the embodiment of the present invention is a data collection work in a calibration step, and the calibration is to reduce the error of the measurement system and the measurement method in practical applications and improve the measurement accuracy. In practical applications, other methods can be used for calibration, and the present invention does not limit this.

[0066] S2. Place the object to be measured 10 on the object moving assembly 11. The light beam emitted by the light source 1 assembly is transmitted through the first beam splitter 3, reflected by the spectroscopic dispersion assembly, transmitted through the second beam splitter 8, and transmitted through the first achromatic focusing lens 9 to the surface of the object to be measured 10, forming a transversely coded measuring beam carrying information of the object to be measured 10. The measuring beam is optically split by the system, and the split measuring beams respectively form a beam with transversely coded tilt angle information and a beam with transversely coded height information, which are received by the planar array spectrometer array 7 and the imaging spectrometer 14 respectively.

[0067] The measurement method provided in the embodiment of the present invention collects optical information of the planar array spectrometer array 7 and the imaging spectrometer 14 in the measurement system. Through the analysis method combining optics and algorithms, it can not only measure the comprehensive three-dimensional information of the object to be measured 10 and obtain the spatial imaging information of the object to be measured 10, but also can perform real-time measurement of the tilt angle of the measuring point on the surface of the object to be measured 10, thereby effectively overcoming the limitation of the existing confocal optical measurement technology that cannot measure spatial and angular tilt at the same time.

[0068] S3,

[0069] The method for measuring the tilt angle of the object to be measured in the embodiment of the present invention is specifically as follows:

[0070] When the light source 1 emits a continuous white measuring light beam and passes through the blazed grating 4, it is dispersed and separated into single-wavelength diffraction light beams of different wavelengths. By analyzing the information of the light beam received by the planar array spectrometer array 7, the position information of the light beams of different wavelengths imaged on the planar array spectrometer array 7 after being reflected by different positions of the plane reflector and different positions of the object to be measured 10 is obtained, and then the corresponding inclination angle information of the surface of the object to be measured 10 in the horizontal axis direction is obtained, thereby completing the inclination angle measurement of the object to be measured 10.

[0071] In the embodiment of the present invention, a planar array spectrometer array 7 is used as a receiving end for measuring and analyzing the tilt angle, which can simultaneously receive and resolve spectral information of multiple wavelengths, and the spectrum acquisition frequency of the planar array spectrometer array 7 is generally several orders of magnitude higher than the transverse axial scanning frequency. Therefore, during a transverse axial scanning process, the tilt angles of the free-form surfaces of all transverse axial measurement points of the object to be tested 10 can be measured simultaneously, and then the piezoelectric ceramic driver is controlled to move the object to be tested 10 for the next transverse axial scanning and deep scanning, which can not only ensure the measurement accuracy but also ensure the measurement speed.

[0072] In the actual measurement process, since the surface to be measured of the object to be measured 10 is usually a free-form surface with an inclination angle, the actual imaging position and the theoretical imaging position of light beams of different wavelengths on the area array spectrometer array 7 are often offset, and these offsets will cause errors in the actual measurement results. The measurement method of the present invention calculates the measured displacement when there is an inclination angle and the theoretical displacement when there is no inclination angle, which reduces the error and improves the measurement accuracy of the measurement results of the present invention. At the same time, the inclination angle of the object to be measured 10 can also be measured, which improves the measurement accuracy and further expands the application scope of the confocal measurement system based on lateral encoding and its measurement method.

[0073] Figure 3 The schematic diagram of the spectrum information offset of the surface to be measured with a tilt angle on the array of the planar array spectrometer is shown. Taking the offset of a single wavelength beam as an example, the offset of beams of different wavelengths can be understood in the same way. Figure 3 As shown, for ease of understanding, the planar array spectrometer array 7 is arranged along the x-axis and y-axis directions, wherein: is the imaging position of a single wavelength light beam in the first position information on the planar array spectrometer array 7 when there is no tilt angle. A is the imaging position of a single wavelength light beam in the second position information on the planar array spectrometer array 7 when there is a tilt angle. The distance between the two points is the amount of offset caused by the tilt angle.

[0074] The positions where the light beams of different wavelengths are imaged on the array spectrometer array 7 after being reflected at different positions of the object to be measured 10, and the coordinates of the above positions are recorded { , }, the coordinate set of these positions is called the second position information. , Respectively represent the horizontal coordinate and vertical coordinate in the second position information.

[0075] Obtain a light beam of the same wavelength. In the embodiment of the present invention, a light beam of 400 nm wavelength is selected in the first position information , the light beam with a wavelength of 400nm is at the second position information A, and the measured displacement of the two position information is calculated.

[0076] The calculation formula for the measured displacement is:

[0077] (1)

[0078] Wherein, S represents the measured displacement of light beams of different wavelengths; S0 represents the number of offsets of the planar array spectrometer array 7 and the distance between two adjacent spectrometers in the planar array spectrometer array 7; , Respectively represent the positions of the abscissa and ordinate of the planar array spectrometer array 7 in the first position information; , Respectively represent the positions of the abscissa and ordinate of the area array spectrometer array 7 in the second position information; Indicates wavelength.

[0079] Obtain the theoretical displacement of the two position information corresponding to the light beam of the same wavelength in the first position information and the second position information. That is, when the information with a wavelength of 400nm is selected in the first position information, the information with a wavelength of 400nm should also be selected in the corresponding second position information. The calculation formula for calculating the theoretical displacement of the same wavelength is:

[0080] (2)

[0081] in, represents the theoretical displacement of light beams of different wavelengths; d represents the grating spacing of the blazed grating 4; represents the angle of the central axis of the incident light beam relative to the normal of the blazed grating 4; m represents the diffraction order of the blazed grating 4; Indicates the tilt angle of the surface of the object to be measured 10 relative to the optical axis; represents the focal lengths of the first achromatic focusing lens 9 and the second achromatic focusing lens 6.

[0082] The specific value of the measured displacement can be calculated by formula (1). If the value of the measured displacement is equal to the value of the theoretical displacement, the inclination angle of the measuring point of the object 10 under the light beam of different wavelengths can be calculated by formula (2): The value of is used to complete the measurement of the tilt angle of the object to be measured 10.

[0083] It can be seen from formula (2) that the measurement method provided in the embodiment of the present invention can control the emission angle of the light beam of a specific wavelength by changing the grating pitch and blaze angle of the blazed grating 4, so that the light beam of a specific wavelength passes through the focal plane of the first achromatic focusing lens 9 in the expected order or arrangement, that is, the measurement light beam is stably arranged at the designed or calibrated expected value to achieve transverse and axial linear encoding.

[0084] The following is a formula for the theoretical displacement of light beams of different wavelengths in the method for measuring the tilt angle of the object to be measured 10. In the measurement method provided in the embodiment of the present invention, the measuring light beam is reflected by the surface of the object to be measured 10 to form a light beam with a transverse code carrying information of the object to be measured 10, that is, in the transverse code x-axis direction, if the point to be measured encounters a tilt angle relative to the optical axis The free-form surface, the inclination angle of the reflected beam relative to the optical axis will be Since the measuring beam passes through the focus of the first achromatic focusing lens 9, the first achromatic focusing lens 9 converts the tilt angle into an offset distance of the reflected beam, that is, the tilt angle is converted into the displacement distance of the offset.

[0085] When the continuous white measuring beam emitted by the light source 1 passes through the blazed grating 4, it is separated into a single-wavelength diffracted beam, which satisfies the following relationship:

[0086] (3)

[0087] in, represents the angle between the m-th order diffraction beam of blazed grating 4 and the normal of blazed grating 4; represents the angle between the incident light beam and the normal of the blazed grating 4.

[0088] From the optical theory, we know that Each wavelength of the light beam will be separated according to the following formula (4), and the diffraction angle of each wavelength of the light beam incident on the first achromatic focusing lens 9 is for:

[0089] (4)

[0090] The position where each wavelength beam is incident on the first achromatic focusing lens 9 is:

[0091] (5)

[0092] in, represents the position of the light beam with the center of the first achromatic focusing lens 9 as the origin on the first achromatic focusing lens 9; L represents the distance from the center of the blazed grating 4 to the first achromatic focusing lens 9.

[0093] Measuring the beam at an angle of inclination After incident on the first achromatic focusing lens 9, a focus will be formed on the focal plane. The position of the focus is related to the incident angle and the incident position When encoding horizontally, the horizontal axis coordinates of different wavelengths are It can be calculated by geometric relationship:

[0094] (6)

[0095] When the measuring surface of the object to be measured 10 has an inclination angle relative to the optical axis When, after reflection, we can obtain: the tilt displacement point of the reflected light beam after it exits the first achromatic focusing lens 9 for:

[0096] (7)

[0097] in, It represents the deviation caused by the inclination of the surface to be measured of the object to be measured 10.

[0098] The inclination angle of the reflected light beam exiting the first achromatic focusing lens 9 is The parameters of the first achromatic focusing lens 9 and the second achromatic focusing lens 6 are the same. After being reflected by the first achromatic focusing lens 9 and the second beam splitter 8, the incident point and incident angle of the light beam entering the second achromatic focusing lens 6 are the same as the exit point and exit angle of the second achromatic focusing lens 6. After focusing, the light beam is focused and imaged on the array 7 of the planar array spectrometer. The horizontal axis coordinate of the wavelength is Calculated by optical geometric relationship:

[0099] (8)

[0100] make , we can get the single wavelength horizontal axis coordinate when there is no tilt angle :

[0101] (9)

[0102] Finally, the theoretical displacement of beams of different wavelengths at tilt angles can be obtained. :

[0103] (10)

[0104] The method for measuring the height of the object to be measured in the embodiment of the present invention is to use the spectral information received by the imaging spectrometer in the prior art to measure the height of the object to be measured, specifically:

[0105] When the light source 1 emits a continuous white measuring light beam, it is dispersed and separated into a single-wavelength diffraction light beam after passing through the blazed grating 4. By analyzing the spectral information of the specific wavelength light beam received by the imaging spectrometer 14, the light intensity information reflected by light beams of different wavelengths at different positions of the object to be measured 10 is obtained. By analyzing the light intensity signals of different wavelengths, all the information on the horizontal axis of the height of the object to be measured 10 can be obtained at the same time, thereby completing the height measurement of the object to be measured 10.

[0106] S4, move and control the piezoelectric ceramic driver to control the longitudinal axial movement of the object to be tested 10, and repeat steps S2 and S3 until the measurement of the object to be tested 10 is completed. The method provided by the present invention uses a transverse axial linear scan, and a plane scan can be achieved in one measurement. After the scan of a plane is completed, the object to be tested is moved in the longitudinal axial direction by the piezoelectric ceramic driver for scanning until the measurement of the entire object to be tested 10 is completed.

[0107] The present invention embodiment verifies the effectiveness of the measurement method of the technical solution of the present invention through experiments. The parameters of the filter wheel confocal measurement system based on transverse encoding are as follows: the beam width of the light source 1 is 4.2 mm, the focal lengths of the first achromatic focusing lens 9 and the second achromatic focusing lens 6 are both 3.3 mm, the pinhole size is 15 μm, and the calculated axial resolution is 2.02 μm. A standard plane mirror is used as the object to be measured in the verification experiment, and the surface accuracy standard PV value is 3.56 μm and the RMS value is 0.89 μm.

[0108] Through experimental comparison, the measurement method provided by the embodiment of the present invention is compared with the traditional measurement method. The comparison results are as follows:

[0109] Comparison Table

[0110] name PV (μm) RMS (μm) Standard flat mirror type 3.56 0.89 Traditional method measurement 3.92 0.98 The present invention measures 3.32 0.83

[0111] By comparison, the measurement accuracy of the technical solution of the present invention and the traditional method is improved by 15%. It can be seen that the measurement method provided by the present invention can measure the tilt angle while measuring the height of the object to be measured, and effectively eliminate the error caused by the tilted surface while measuring the tilt angle, thus significantly improving the measurement accuracy.

[0112] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0113] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0114] The above specific implementations of the present invention do not constitute a limitation on the protection scope 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 protection scope of the claims of the present invention.

Claims

1. A confocal measurement system based on lateral encoding, characterized in that: It includes a first measuring unit and a second measuring unit; wherein, The first measuring unit comprises a light source component arranged along the optical path, a first beam splitter (3), a second beam splitter (8), a first achromatic focusing lens (9), a first signal receiving component, and a second signal receiving component; The second measuring unit comprises a spectroscopic dispersion component and an object moving component (11) for moving the object to be measured (10); The light beam emitted by the light source component is split by the first beam splitter (3), and the transmitted light beam after the splitting is reflected by the light splitting and dispersion component in turn and transmitted by the second beam splitter (8) to the surface of the object to be tested (10), and the light beam forms a light beam with transverse coding and carrying information of the object to be tested (10), and the light beam reflected by the surface of the object to be tested (10) is transmitted by the first achromatic focusing lens (9) and then split again by the second beam splitter (8); The reflected light beam split by the second beam splitter (8) is incident on the first signal receiving component, and the tilt angle analysis of the object to be measured (10) is performed according to the signal received by the first signal receiving component; the transmitted light beam split by the second beam splitter (8) is sequentially dispersed and reflected by the light splitting and dispersing component and reflected by the first beam splitter (3) and is incident on the second signal receiving component, and the height analysis of the object to be measured (10) is performed according to the signal received by the second signal receiving component; The light-splitting and dispersion component comprises a blazed grating (4) and a telecentric aperture (5) arranged along the light path; The blazed grating (4) is used to disperse and separate light beams of different wavelengths, so that the light beams can be transversely encoded; The telecentric aperture (5) is used to eliminate the magnification change of the light beam and make the light beam parallel to the optical axis of the measurement system; The first signal receiving component comprises a second achromatic focusing lens (6) and a planar array spectrometer array (7); The second achromatic focusing lens (6) is used to focus light beams of different wavelengths and eliminate chromatic aberration; The planar spectrometer array (7) is used to receive light beam signals of different wavelengths for imaging.

2. The confocal measurement system based on lateral encoding according to claim 1, characterized in that: The second signal receiving component comprises a focusing lens (12), a pinhole (13) and an imaging spectrometer (14); The focusing lens (12) is used to focus the parallel light beam; The pinhole (13) is used to suppress the defocused light beam and reduce the interference of the scattered light beam; The imaging spectrometer (14) is used to receive light beam signals for imaging.

3. The confocal measurement system based on lateral encoding according to claim 1, characterized in that: The light source assembly comprises a light source (1) and a collimating lens (2); The light source (1) is used to emit a continuous white light beam; The collimating lens (2) is used to collimate the light beam emitted by the light source (1) into a parallel light beam.

4. A measurement method using the confocal measurement system based on lateral encoding according to any one of claims 1 to 3, characterized in that: The steps include: S1, placing a plane reflector with a zero tilt angle on the object moving assembly (11), starting the measurement system, and obtaining first position information of light beams of different wavelengths being imaged on the planar array spectrometer array (7) after being reflected by light beams of different wavelengths at different positions of the plane reflector; S2, placing the object to be measured (10) on the object moving component (11), the light beam emitted by the light source component is transmitted through the first beam splitter (3), reflected by the light splitting and dispersion component, transmitted through the second beam splitter (8), and transmitted through the first achromatic focusing lens (9) to the surface of the object to be measured (10), thereby forming a light beam with transverse coding and carrying information of the object to be measured (10), the light beam is optically split by the measuring system, and the split light beams respectively form a light beam with transverse coding tilt angle information and a light beam with transverse coding height information, and are respectively received by the planar array spectrometer array (7) and the imaging spectrometer (14); S3、 The method for measuring the tilt angle of the object to be measured (10) is: By analyzing the information of the light beam received by the planar array spectrometer array (7), the position information of light beams of different wavelengths being imaged on the planar array spectrometer array (7) after being respectively reflected by different positions of the plane reflector and different positions of the object to be measured (10) is obtained, and then the corresponding inclination angle information of the transverse axis of the surface of the object to be measured (10) is obtained, thereby completing the measurement of the inclination angle of the object to be measured (10); The height measurement method of the object to be measured (10) is: By analyzing the spectrum information of the light beam received by the imaging spectrometer (14), light intensity information of light beams of different wavelengths reflected at different positions of the object to be measured (10) is obtained, and then the corresponding height information of the surface of the object to be measured (10) in the transverse axis direction is obtained, thereby completing the height measurement of the object to be measured (10); S4, controlling the object moving assembly (11) to move the object to be measured (10), and repeating steps S2 and S3 until the measurement of the object to be measured (10) is completed.

5. The measurement method of the confocal measurement system based on lateral encoding according to claim 4, characterized in that: The method for measuring the tilt angle of the object to be measured (10) in step S3 is specifically as follows: Acquiring second position information of light beams of different wavelengths imaged on the planar array spectrometer array (7) after being respectively reflected by different positions of the object to be measured (10); Obtaining a light beam with the same wavelength at the first position information and the second position information, respectively, and calculating the measured displacements of the two position information; Obtaining theoretical displacements of two pieces of position information corresponding to light beams of the same wavelength in the first position information and the second position information; By calculating the measured displacement and the theoretical displacement, the tilt angle information of the measuring point of the object to be measured (10) under light beams of different wavelengths is obtained, and the tilt angle measurement of the object to be measured (10) is completed.

6. The measurement method of the confocal measurement system based on lateral encoding according to claim 5, characterized in that: The calculation formula of the measured displacement is as follows: Wherein, S represents the measured displacement of light beams of different wavelengths; S0 represents the number of offsets of the planar array spectrometer array (7) and the distance between two adjacent spectrometers in the planar array spectrometer array (7); Respectively represent the positions of the abscissa and ordinate in the planar array spectrometer array (7) in the first position information; They respectively represent the positions of the abscissa and ordinate of the planar array spectrometer array (7) in the second position information; λ represents the wavelength.

7. The measurement method of the confocal measurement system based on lateral encoding according to claim 6, characterized in that: The calculation formula of the theoretical displacement is as follows: Wherein, S(λ, α) represents the theoretical displacement of light beams of different wavelengths; d represents the grating spacing of the blazed grating (4); β represents the angle of the central axis of the incident light beam relative to the normal of the blazed grating (4); m represents the diffraction order of the blazed grating (4); α represents the inclination angle of the surface of the object to be measured (10) relative to the optical axis; and f represents the focal length of the first achromatic focusing lens (9) and the second achromatic focusing lens (6).

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