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

Abstract

The present invention provides a spectral confocal measurement system based on transverse coding and a measurement method thereof, belonging to the field of optical detection technology. The spectral confocal measurement system based on transverse coding provided by the present invention includes a spectral position measurement unit and a spectral angle measurement unit, by adding a dispersion adjustment component, a spatial filtering component and a spectral receiving device to the existing confocal measurement system, through the transverse coding technology of the spectrum, the spatial filtering technology and the spectral positioning technology, using a one-dimensional spectrum wavelength to accurately complete the position measurement and angle measurement of the point to be measured, solves the technical problem that in the existing confocal measurement technology, when the light spot shape of the received light spot changes, the brightness is uneven, the light spot energy is weak or the interference factor is too large, the accurate measurement cannot be performed.

Description

Technical Field

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

[0002] Confocal microscopy measurement technology is a powerful three-dimensional structure visualization tool that is widely used in fields such as semiconductor wafer inspection. It is highly valued for its ability to accurately measure surface profiles. However, traditional confocal microscopy measurement technology requires point-by-point scanning, resulting in slow image acquisition. In order to increase the imaging speed, one of the commonly used techniques is the tandem scanning method, which uses a Nipkow disk to achieve simultaneous illumination of multiple points on the sample. However, multi-point illumination is prone to crosstalk and scattering noise, thereby reducing the signal-to-noise ratio and overall sensitivity of the system. In order to obtain a better signal-to-noise ratio, the confocal pinhole can only occupy a small area on the disk surface, resulting in low illumination efficiency.

[0003] To improve the problems in the existing technology, the confocal displacement sensor technology was born. This sensor technology does not require vertical scanning movement. This sensor technology is equipped with a white light source and a spectrometer. When white light passes through the objective lens, due to the chromatic aberration effect, light of different wavelengths is focused at different focal lengths behind the objective lens. The defocused light reflected from the sample surface will be filtered out by the confocal pinhole in front of the spectrometer. Based on the known relationship between wavelength and focal length, the height information of each point on the sample surface can be decoded by analyzing the reflected light through the spectrometer. In order to obtain the three-dimensional profile of the area, the sample needs to be scanned point by point horizontally through the X and Y translation stages.

[0004] However, the existing confocal displacement sensor technology faces some challenges in practical applications. Since the spectral confocal displacement sensor technology measures the spatial position of the measured surface while measuring the surface tilt angle, the surface tilt angle is mainly determined by measuring the movement of the return light beam after passing through the dispersion lens, adding the splitter prism and the two-dimensional position sensor detector or the light spot on the CCD camera. Therefore, the biggest problem faced by the spectral confocal displacement sensor technology is that compared with monochromatic light, the white light source has the problem of weak beam energy caused by factors such as energy dispersion, light source efficiency and coherence. Therefore, the spot positioning accuracy of the two-dimensional position sensor detector and the CCD camera is low, which in turn affects the angle measurement accuracy. 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] The spectral confocal measurement system based on transverse encoding includes a spectral position measurement unit and a spectral angle measurement unit; wherein,

[0007] The spectral position measuring unit comprises a light source, a collimating lens, a first beam splitter, a first dispersive lens, a second beam splitter, a second dispersive lens, a confocal pinhole and a first spectral receiving device which are arranged in sequence along the optical path;

[0008] The spectral angle measurement unit comprises a dispersion adjustment component, a spatial filtering component and a second spectral receiving device which are sequentially arranged along the optical path;

[0009] The light beam emitted by the light source is collimated by the collimating lens and then split by the first beam splitter. The reflected light beam after the splitting is scattered by the first dispersive lens and then incident on the surface of the object to be measured and then reflected. The reflected light beam forms an information light beam carrying information of the object to be measured. The information light beam is transmitted by the first dispersive lens and then incident on the second beam splitter. The transmitted light beam after the splitting by the second beam splitter is transmitted to the second dispersive lens and the confocal pinhole, and then incident on the first spectrum receiving device after passing through the confocal pinhole. The spectral information received by the first spectrum receiving device is analyzed to obtain the position information of the point to be measured on the surface of the object to be measured.

[0010] The reflected light beam split by the second beam splitter is sequentially incident on the dispersion adjustment component for dispersion and beam correction, then incident on the spatial filter component for beam signal filtering and convergence, and then incident on the second spectrum receiving device, and the spectrum information received by the second spectrum receiving device is analyzed to obtain the angle information of the surface of the object to be measured.

[0011] Furthermore, the dispersion adjustment component includes a first prism and a second prism. The reflected light beam split by the second beam splitter is incident on the first prism. The first prism disperses the light beam into light beams of different wavelengths and angles, and then is incident on the second prism. After refraction and correction by the second prism, it becomes a parallel light beam of different wavelengths and is incident on the spatial filtering component.

[0012] Furthermore, the first prism and the second prism are in a triangular or trapezoidal shape.

[0013] Furthermore, the first prism and the second prism are made of the same material.

[0014] Further, the spatial filtering assembly includes a microlens array and an optical fiber arranged along the optical path;

[0015] The microlens array filters out the messy beam signals in the parallel beams of different wavelengths emitted by the second prism, and simultaneously converges the effective spectrum information;

[0016] The effective spectrum information is incident on the optical fiber for filtering and is simultaneously transmitted to the second spectrum receiving device.

[0017] The present invention also provides a measurement method of a spectral confocal measurement system based on lateral encoding, comprising the following steps:

[0018] S1, placing a plane reflector at the object to be measured, starting a spectral confocal measurement system based on transverse encoding, and obtaining a reference central wavelength according to the spectral information received by the second spectral receiving device at this time;

[0019] S2, placing the object to be measured in the spectral confocal measurement system based on transverse encoding, and respectively acquiring spectral information received by the first spectral receiving device and the second spectral receiving device;

[0020] S3, obtaining the position information of the corresponding point to be measured on the surface of the object to be measured by analyzing the spectrum information received by the first spectrum receiving device;

[0021] By analyzing the spectrum information received by the second spectrum receiving device and the reference central wavelength, the corresponding angle information of the point to be measured on the surface of the object to be measured is obtained.

[0022] Furthermore, the specific method of obtaining the angle information of the corresponding point to be measured on the surface of the object to be measured is:

[0023] According to the spectrum information received by the second spectrum receiving device, the central wavelength of the point to be measured on the surface of the object to be measured is obtained;

[0024] According to the central wavelength of the point to be measured on the surface of the object to be measured, the reference central wavelength and the parameters of the spectral confocal measurement system based on lateral encoding, the angle information of the point to be measured on the surface of the object to be measured is calculated. The calculation formula (1) is specifically as follows:

[0025] (1)

[0026] in, represents the angle information of the point to be measured on the surface of the object to be measured; L represents the distance between the centroids of the first prism and the second prism; Indicates the emission angle corresponding to the wavelength received by the second spectrum receiving device when measuring the measured point on the surface of the object to be measured; represents the reference central wavelength; represents the focal length of the microlens array; It represents the emission angle corresponding to the wavelength received by the second spectrum receiving device when acquiring the reference central wavelength.

[0027] Furthermore, according to the spectrum information received by the second spectrum receiving device, a specific method for acquiring the central wavelength of the point to be measured on the surface of the object to be measured at this time is: centroid method or Gaussian fitting method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention is a spectral confocal measurement system and a measurement method based on transverse coding. By adding a dispersion adjustment component, a spatial filtering component and a spectral receiving device to the existing confocal measurement system, the position and angle measurement of the point to be measured are accurately completed using a one-dimensional spectral wavelength through the transverse coding technology of the spectrum, the spatial filtering technology and the spectral positioning technology, and the existing confocal measurement technology is changed to measure by a light spot. When the shape of the received light spot changes, the brightness is uneven, the light spot energy is weak or the interference factor is too large, accurate measurement cannot be performed. In addition, the system and method of the present invention can not only measure the three-dimensional position information of the object to be measured and obtain the spatial imaging information of the object to be measured, but also measure the inclination angle of the measurement point on the surface of the object to be measured, thereby effectively overcoming the limitations of the existing confocal measurement technology in measuring position and inclination angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of a spectral confocal measurement system based on transverse encoding in an embodiment of the present invention;

[0031] Figure 2 It is a flow chart of a spectral confocal measurement method based on lateral encoding in an embodiment of the present invention.

[0032] The reference numerals are as follows:

[0033] 1-light source, 2-collimating lens, 3-first beam splitter, 4-first dispersive lens, 5-object to be measured, 6-second beam splitter, 7-second dispersive lens, 8-confocal pinhole, 9-first spectrum receiving device, 10-first prism, 11-second prism, 12-microlens array, 13-optical fiber, 14-second spectrum receiving device. DETAILED DESCRIPTION

[0034] 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.

[0035] Embodiment 1

[0036] The invention provides a spectral confocal measurement system based on transverse encoding.

[0037] Figure 1 A schematic structural diagram of a spectral confocal measurement system based on transverse encoding according to an embodiment of the present invention is shown.

[0038] like Figure 1 As shown, a spectral confocal measurement system based on transverse encoding includes a spectral position measurement unit and a spectral angle measurement unit. In an embodiment of the present invention, the spectral position measurement unit includes a light source 1, a collimating lens 2, a first beam splitter 3, a first dispersion lens 4, a second beam splitter 6, a second dispersion lens 7, a confocal pinhole 8 and a first spectrum receiving device 9 arranged in sequence along the optical path. The spectral angle measurement unit includes a dispersion adjustment component, a spatial filtering component and a second spectrum receiving device 14 arranged in sequence along the optical path. In the embodiment provided by the present invention, both the first spectrum receiving device 9 and the second spectrum receiving device 14 are spectrometers, which can be used as instruments that can measure wavelength and positioning information in combination with wavelength length in actual use.

[0039] In the embodiment provided by the present invention, the light source 1 emits a divergent complex continuous white light beam with a wavelength of 400-700nm, which is collimated into a parallel light beam by the collimating lens 2 and then split by the first beam splitter 3. The reflected light beam after splitting is scattered by the first dispersive lens 4. Due to the action of the first dispersive lens 4, the white light beams of different wavelengths are linearly expanded axially along the optical axis direction, incident on the surface of the object to be measured 5 and then reflected. The light beam after reflection forms an information light beam carrying information of the object to be measured 5. The information light beam is reflected to the first dispersive lens 4, transmitted through the first dispersive lens 4, and then incident on the second beam splitter 6 in the form of a parallel light beam. The transmitted light beam after splitting by the second beam splitter 6 is a position measurement light beam. The position measurement light beam is transmitted to the confocal pinhole 8, and then incident on the first spectrum receiving device 9 after passing through the confocal pinhole 8. The spectrum information of the position measurement light beam received by the first spectrum receiving device 9 is analyzed to obtain the position information of the surface of the object to be measured 5.

[0040] The spectral position measurement unit part in the embodiment provided by the present invention belongs to the classic confocal displacement measurement technology in the prior art. The role of the confocal pinhole 8 is crucial. The position of the confocal pinhole 8 and the spatial position of the test point of the object 5 to be tested are conjugate to each other. The confocal displacement measurement technology continues the development of the classic confocal microscope. Therefore, the axial response function can be derived according to the response function of the confocal microscope, and the relationship between the light energy detected at the confocal position and the axial defocus amount. In the embodiment of the present invention, the spectral position measurement unit part uses a divergent complex continuous white light source 1. The spectral position measurement unit can be regarded as an integration of countless confocal microscopes, and the wavelength and displacement correspond one to one to form a mapping relationship. The spectral information of the position measurement light beam received by the first spectral receiving device 9 is analyzed. For any wavelength in the focus state, its light intensity is significantly higher than other wavelengths. Its wavelength information is extracted through the peak value, and then the displacement information of the test point on the surface of the object 5 to be tested is found through the mapping relationship to achieve the position measurement of the object 5 to be tested.

[0041] The reflected light beam after being split by the second beam splitter 6 is an angle measurement beam. The angle measurement light beam is sequentially incident on the dispersion adjustment component for dispersion and beam correction, and then incident on the spatial filter component for beam signal filtering and convergence, and then incident on the second spectrum receiving device 14. The spectrum information received by the second spectrum receiving device 14 is analyzed to obtain the angle information of the surface of the object 5 to be measured.

[0042] The dispersion adjustment component in the embodiment provided by the present invention includes a first prism 10 and a second prism 11. The reflected light beam split by the second beam splitter 6 is incident on the first prism 10, and the first prism 10 disperses the light beam into light beams of different wavelengths and different angles, and then the light beams are incident on the second prism 11. After being refracted and corrected by the second prism 11, the light beams are converted into parallel light beams of different wavelengths and incident on the spatial filtering component.

[0043] The embodiment of the present invention provides a preferred method, in which the shape of the first prism 10 and the second prism 11 is a triangle or a trapezoid. The present invention uses a triangular prism or a trapezoidal prism to facilitate the calculation of the incident angle and the exit angle of the angle measurement light beam, that is, to facilitate the subsequent calculation of the angle information of the point to be measured. In the embodiment provided by the present invention, the same material is used for the first prism 10 and the second prism 11 to unify the refractive index of the prism material, that is, to facilitate the subsequent calculation of the angle information of the point to be measured. The material of the first prism 10 and the second prism 11 can be selected from optical glass, such as BK7 or Fused Silica, which have good optical properties in the visible light range. The specific calculation process will be described in the subsequent embodiments. In practical applications, the optical device used in the dispersion adjustment component only needs to be able to split and disperse the angle measurement light beam into parallel light beams of different wavelengths. The shape and material can be selected according to the specific application, and the embodiment of the present invention is not limited by comparison.

[0044] The first prism 10 disperses the incident parallel white light into light beams of different wavelengths and angles. Since light beams of different wavelengths have different refractive indices and refraction angles in the prism, this will cause the light beams to undergo different degrees of deflection angle changes in the first prism 10. The second prism 11 is used to correct the deflection angle changes introduced by the first prism 10, so that light beams of different wavelengths remain parallel after dispersion. In the design of the dispersion adjustment component, the two prisms can be arranged at appropriate angles to correct the light beam dispersion effect produced by the first prism 10, so that the outgoing light beams are parallel again.

[0045] In the embodiment provided by the present invention, the spatial filtering component includes a microlens array 12 and an optical fiber 13 arranged along the optical path. The microlens array 12 filters out the messy light beam signals in the parallel light beams of different wavelengths emitted by the second prism 11, and simultaneously focuses the parallel light beams, that is, converges the effective spectral information, and the effective spectral information is incident into the optical fiber 13 and transmitted to the second spectrum receiving device 14. In the embodiment provided by the present invention, the optical fiber 13 not only plays the role of transmitting the effective spectral information, but also plays the role of filtering equivalent to a pinhole, filtering the stray light introduced by the focusing of the microlens array 12. In practical applications, an optical mask plate can also be used instead of the microlens array 12, but the focusing and filtering effects of the optical mask plate are inferior to those of the microlens array 12, and the optical mask plate has only one focusing lens, which will cause all the light beams of the entire measurement system to be gathered, and the pressure for the subsequent acquisition of the central wavelength extraction of the surface of the object to be measured 5 is too large, which affects the measurement accuracy. Therefore, it can be selected according to the specific situation, and the present invention does not limit this.

[0046] In the embodiment provided by the present invention, the spatial filtering component uses a microlens array 12 and an optical fiber 13, and the optical fiber 13 can receive the light beam of any lens of the microlens array 12 for subsequent analysis, so that only part of the light beam in the entire system is extracted and filtered twice. First, the microlens array 12 is used to filter most of the stray light of the entire optical system to prevent the stray light from affecting the subsequent determination of the central wavelength of the point to be tested; then, the optical fiber 13 is used to filter the stray light introduced by the microlens array 12 for a second time, and effective spectral information is further extracted, so as to facilitate the subsequent use of peak detection technology to extract the central wavelength of the point to be tested on the surface of the object 5 to be tested.

[0047] The confocal measurement system in the prior art mainly determines the tilt angle of the point to be measured on the surface of the object to be measured 5 by measuring the centroid movement of the light spot added to the beam splitter prism and the two-dimensional position sensor detector after the return light beam passes through the dispersion lens, or the centroid movement of the light spot added to the beam splitter prism and the CCD camera. Compared with monochromatic light, white light sources have the problem of weak beam energy caused by factors such as energy dispersion, light source efficiency and coherence. Therefore, due to the low accuracy of the light spot positioning of the two-dimensional position sensor detector or CCD camera, the angle measurement accuracy is affected. The recognition and processing of the light spot depends on image processing technology. The accuracy of the image processing technology algorithm directly affects the calculation of the centroid movement of the light spot, and factors such as equipment resolution, light spot morphology and imaging noise will also affect the accuracy of the measured angle. The spectral confocal measurement system based on transverse coding provided by the present invention, when measuring the surface angle information of the object to be measured 5, is different from the prior art in that the centroid displacement of the light spot is used for calculation. Instead, the centroid movement of the light spot is replaced by measuring the shift of the wavelength, and the resolution of the wavelength recognition technology is higher than the spatial resolution of the image processing technology, and each wavelength has a clear position in the spectrum, so the displacement or change of the spectral line can be accurately measured. The spectral confocal measurement system based on transverse coding provided by the present invention uses a spectral measurement technology based on transverse coding, which utilizes the intrinsic characteristics of light and is not affected by factors such as image blur and deformation, so that higher measurement accuracy and stability can be obtained. The change in wavelength can be accurate to several decimal places, thereby improving the accuracy of the angle measurement of the point to be measured.

[0048] Embodiment 2

[0049] The invention provides a spectral confocal measurement system based on transverse encoding.

[0050] Figure 2 A schematic flow chart of a measurement method of a spectral confocal measurement system based on lateral encoding according to an embodiment of the present invention is shown.

[0051] like Figure 2 As shown, a measurement method of a spectral confocal measurement system based on lateral encoding includes the following steps:

[0052] S1. Place a plane reflector at the object to be measured 5, start the spectral confocal measurement system based on transverse encoding, obtain the spectral information received by the second spectral receiving device 14 at this time, and obtain the reference central wavelength according to the spectral information received by the second spectral receiving device 14 at this time. In the embodiment provided by the present invention, both the first spectral receiving device 9 and the second spectral receiving device 14 are spectrometers.

[0053] The embodiment of the present invention provides a preferred method, and the calculation method of the reference center wavelength can be calculated by using the centroid method or Gaussian fitting method in the prior art. The present invention is described by taking the centroid method as an example, and the calculation formula (1) is as follows:

[0054] (1)

[0055] in, Indicates the reference center wavelength; represents the wavelength of the ith measurement point, Represents the light intensity energy value corresponding to the i-th wavelength.

[0056] S2. Place the object to be measured 5 in a spectral confocal measurement system based on transverse encoding, and obtain spectral information received by the first spectral receiving device 9 and the second spectral receiving device 14 respectively.

[0057] S3, analyzing the spectrum information of the position measurement light beam received by the first spectrum receiving device 9. For any wavelength in the focus state, its light intensity is significantly higher than other wavelengths, and its wavelength information is extracted through the peak value, and then the displacement information of the surface of the object to be measured 5 is found through the mapping relationship, so as to realize the position measurement of the surface of the object to be measured 5.

[0058] By analyzing the spectrum information and the reference center wavelength received by the second spectrum receiving device 14 , the angle information of the corresponding surface point to be measured of the object to be measured 5 is obtained.

[0059] The principle of the angle measurement method provided by the embodiment of the present invention is as follows:

[0060] In the measurement method provided in the embodiment of the present invention, in order to facilitate the calculation of the angle information of the measured point on the surface of the object 5 to be measured and to ensure the symmetry of the incident light beam, the shape of the first prism 10 and the second prism 11 in the embodiment of the present invention is an isosceles right triangle; the material of the first prism 10 and the second prism 11 is also the same. The calculation principle of prisms of other shapes and materials is the same, and the embodiment of the present invention is described in detail only by taking this as an example.

[0061] The reflected light beam split by the second beam splitter 6 is incident on the first prism 10 and the second prism 11 in sequence, and the light beam is refracted in both the first prism 10 and the second prism 11. For the convenience of explanation, the optical principle is explained by taking one prism as an example, and the same is true for two prisms. According to Snell's law, the refraction of the light beam can be expressed by the following formula (2):

[0062] (2)

[0063] Wherein, n1 represents the refractive index of the incident medium, which is air in the embodiment provided by the present invention; n2 represents the refractive index of the material of the first prism 10 and the second prism 11; θi represents the angle of incidence; θ r Represents the angle of refraction. Take a prism as an example to explain the optical principle. The same is true for two prisms. When the light beam passes through the first surface of the prism, Snell's law applies and the refraction angle θ is calculated. r The beam then travels inside the prism and eventually reaches the second face of the prism.

[0064] The refractive index of the prism material is not a constant, but is related to the wavelength of the light beam. This phenomenon is called dispersion. The refractive index n(λ) of the prism material can be expressed by the following formula (3):

[0065] (3)

[0066] Where A, B and C represent the dispersion constants of the prism materials respectively; represents the refractive index of the prism when the wavelength is λ; λ represents the wavelength. In practical applications, the prism material is selected from optical glass, such as BK7 or Fused Silica, which has good optical properties in the visible light range. In the embodiment provided by the present invention, BK7 glass is used as the material of the prism, and the refractive index of the prism can be expressed by the following formula (4):

[0067] (4)

[0068] In the embodiment provided by the present invention, the light beam is incident at an angle θ i Angle of incidence, refracted at angle θ inside the prism r The geometric angle here depends on the shape of the prism. In the embodiment provided by the present invention, the first prism 10 and the second prism 11 of isosceles right angle shape are selected, and the incident angle of the light beam reaching the second surface of the prism can be calculated by using geometric relationship.

[0069] In the embodiment provided by the present invention, the first prism 10 and the second prism 11 are isosceles right angle shaped, that is, the vertex angle of the prism is θ p =45°, then the light beam will form an angle with the second exit surface when propagating inside the first prism 10 This angle is the incident angle of the light beam on the second surface of the second prism 11, which can be expressed by the geometric angle relationship formula (5) of the prism:

[0070] (5)

[0071] Among them, θ p represents the vertex angle of the first prism 10 and the second prism 11, Represents the incident angle of the light beam on the second surface of the second prism 11.

[0072] The light beam is refracted back into the air from the second face of the second prism 11, and Snell's law is applied again to calculate the angle of incidence , the specific calculation formula (6) is as follows:

[0073] (6)

[0074] in, Represents the exit angle of the light beam on the second surface of the second prism 11.

[0075] In the embodiment provided by the present invention, the distance between the centroids of the first prism 10 and the second prism 11 is L, and the position of each wavelength light beam on the exit plane is calculated using the lateral displacement formula. In the embodiment provided by the present invention, the light source 1 emits a divergent continuous white light beam with a wavelength of 400-700nm, and its position on the second surface of the second prism 11 can be calculated respectively, and according to the dispersion characteristics of the light, the offset relationship of the lateral distribution position of the light beams of different wavelengths can be obtained. The specific calculation formula (7) is as follows:

[0076] (7)

[0077] in, Indicates the offset of the lateral distribution position of light beams of different wavelengths; and They represent light beams of different wavelengths.

[0078] In the embodiment provided by the present invention, the first prism 10 and the second prism 10 have the same shape and material, and therefore are described by the same formula.

[0079] When the measuring beam is focused on the test point on the surface of the object 5, if the test point on the surface of the object 5 is tilted by σ degrees, the displacement of the measuring beam reflected by the test point on the surface of the object 5 on the exit pupil plane can be calculated by the principle of geometric optics. The specific calculation formula (8) is as follows:

[0080] (8)

[0081] in, Indicates the displacement of the measuring light beam reflected by the measuring point on the surface of the object 5 to be measured on the exit pupil plane; Represents the angle information of the point to be measured on the surface of the object to be measured 5; represents the focal length of the microlens array 12 .

[0082] The displacement of the measuring beam reflected by the test point on the surface of the object 5 on the exit pupil plane is proportional to the focal length and the tilt angle of the test point on the surface of the object 5. When the object 5 is tilted, the displacement of each wavelength separated by the spectral angle measurement unit is also nearly linear. When the object to be tested 5 is tilted, the system measures the wavelength received by the second spectrum receiving device 14 at the point to be tested on the surface of the object to be tested 5, and obtains the corresponding emission angle .

[0083] Therefore, the angle information of the measured point on the surface of the object 5 to be measured is calculated, and the specific calculation formula (9) is as follows:

[0084] (9)

[0085] In summary, the measuring method of the spectral confocal measurement system based on transverse coding provided by the present invention establishes a connection between the angle of the point to be measured on the surface of the object 5 to be measured and the spectral displacement by measuring the displacement change of the spectrum, and obtains the lateral displacement of the measuring light beam to form a functional relationship between the wavelength and the displacement. By measuring the wavelength by spectrum, the inclination angle of the point to be measured on the surface of the object 5 to be measured is accurately measured. The measuring method of the spectral confocal measurement system based on transverse coding provided by the present invention utilizes the intrinsic characteristics of light, is not disturbed by factors such as image blur and deformation, and can obtain higher measurement accuracy and stability. The scheme of spectral angle measurement in the measuring method of the spectral confocal measurement system based on transverse coding provided by the present invention is more resistant to interference, especially in complex experimental or industrial environments. The wavelength measured by the spectrometer depends on the physical properties of light and is not directly disturbed by external factors such as changes in ambient light, dust, and temperature fluctuations. The measurement method in the prior art captures the position movement of the centroid of the light spot by a CMOS or CCD camera, which is easily affected by external factors. And the imaging system of the prior art will produce errors under environments such as different light intensities, different temperatures or mechanical vibrations. The stability of the image depends on the exposure, focus state and lens imaging quality of the camera. The spot distortion and non-ideal Gaussian distribution of the spot in the centroid calculation process will introduce errors. Therefore, the measurement method of the spectral confocal measurement system based on lateral coding provided by the present invention has better environmental adaptability and anti-interference ability, and is particularly suitable for high-precision measurement tasks that are sensitive to external environmental interference.

[0086] 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.

[0087] 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.

[0088] 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 spectral confocal measurement system based on lateral encoding, comprising a spectral position measurement unit, characterized in that: Also includes a spectral angle measurement unit; wherein, The spectral position measurement unit comprises a light source (1), a collimating lens (2), a first beam splitter (3), a first dispersion lens (4), a second beam splitter (6), a second dispersion lens (7), a confocal pinhole (8) and a first spectrum receiving device (9) which are arranged in sequence along the optical path; The spectral angle measurement unit comprises a dispersion adjustment component, a spatial filtering component and a second spectral receiving device (14) arranged in sequence along the optical path; The light beam emitted by the light source (1) is collimated by the collimating lens (2) and then split by the first beam splitter (3). The reflected light beam after the splitting is scattered by the first dispersive lens (4) and then incident on the surface of the object to be measured (5) and then reflected. The reflected light beam forms an information light beam carrying information of the object to be measured (5). The information light beam is transmitted by the first dispersive lens (4) and then incident on the second beam splitter (6). The transmitted light beam after the splitting by the second beam splitter (6) is transmitted to the second dispersive lens (7) and the confocal pinhole (8). After passing through the confocal pinhole (8), it is incident on the first spectrum receiving device (9). The spectrum information received by the first spectrum receiving device (9) is analyzed to obtain the position information of the surface of the object to be measured (5). The reflected light beam split by the second beam splitter (6) is incident on the dispersion adjustment component in sequence for dispersion and beam correction, then incident on the spatial filter component for signal filtering and convergence of the light beam, and then incident on the second spectrum receiving device (14), and the spectrum information received by the second spectrum receiving device (14) is analyzed to obtain the angle information of the surface of the object to be measured (5).

2. The spectral confocal measurement system based on lateral encoding according to claim 1, characterized in that: The dispersion adjustment component comprises a first prism (10) and a second prism (11); The reflected light beam split by the second beam splitter (6) is incident on the first prism (10), and the first prism (10) disperses the light beam into light beams of different wavelengths and angles, which are then incident on the second prism (11), and after being refracted and corrected by the second prism (11), become parallel light beams of different wavelengths which are incident on the spatial filtering component.

3. The spectral confocal measurement system based on lateral encoding according to claim 2, characterized in that: The first prism (10) and the second prism (11) are in the shape of a triangle or a trapezoid.

4. The spectral confocal measurement system based on lateral encoding according to claim 3, characterized in that: The first prism (10) and the second prism (11) are made of the same material.

5. The spectral confocal measurement system based on lateral encoding according to claim 4, characterized in that: The spatial filtering component comprises a microlens array (12) and an optical fiber (13) arranged along the optical path; The microlens array (12) filters out the disordered light beam signals in the parallel light beams of different wavelengths emitted by the second prism (11), and simultaneously converges the effective spectral information; The effective spectrum information is incident on the optical fiber (13) for filtering and is simultaneously transmitted to the second spectrum receiving device (14).

6. A measurement method using the spectral confocal measurement system based on lateral encoding according to any one of claims 1 to 5, characterized in that: The steps include: S1, placing a plane reflector at the object to be measured (5), starting a spectral confocal measurement system based on transverse encoding, and obtaining a reference central wavelength according to spectral information received by the second spectral receiving device (14) at this time; S2, placing the object to be measured (5) in the spectral confocal measurement system based on transverse encoding, and respectively acquiring spectral information received by the first spectral receiving device (9) and the second spectral receiving device (14); S3, obtaining the position information of the corresponding surface point to be measured of the object to be measured (5) by analyzing the spectrum information received by the first spectrum receiving device (9); By analyzing the spectrum information received by the second spectrum receiving device (14) and the reference central wavelength, the angle information of the corresponding point to be measured on the surface of the object to be measured (5) is obtained.

7. The measurement method of the spectral confocal measurement system based on transverse encoding according to claim 6, characterized in that: The specific method of obtaining the angle information of the corresponding surface point to be measured of the object to be measured (5) is: According to the spectrum information received by the second spectrum receiving device (14), the central wavelength of the surface of the object to be measured (5) received at this time is obtained; According to the central wavelength of the point to be measured on the surface of the object to be measured (5), the reference central wavelength and the parameters of the spectral confocal measurement system based on transverse encoding, the angle information of the point to be measured on the surface of the object to be measured (5) is calculated, and the calculation formula is as follows: in, represents the angle information of the point to be measured on the surface of the object to be measured (5); L represents the distance between the centroids of the first prism (10) and the second prism (11); Indicates the emission angle corresponding to the central wavelength received by the second spectrum receiving device (14) when measuring the point to be measured; represents the reference central wavelength; represents the focal length of the microlens array (12); Indicates the emission angle corresponding to the central wavelength received by the second spectrum receiving device (14) when acquiring the reference central wavelength.

8. The measurement method of the spectral confocal measurement system based on transverse encoding according to claim 7, characterized in that: The specific method of obtaining the central wavelength of the test point on the surface of the object to be tested (5) received at this time according to the spectrum information received by the second spectrum receiving device (14) is: centroid method or Gaussian fitting method.

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