Biaxial linear spectral confocal system for measuring three-dimensional information of object surface

Abstract

The invention provides a biaxial spectral confocal system for measuring three-dimensional information of an object surface, and relates to the technical field of precision optical measurement, the system comprises a light source module, a biaxial spectral confocal module and an optical radiation processing module; the light source module comprises a white light source and a first light filter which are sequentially connected; the double-axis spectrum confocal module comprises a first dispersion assembly, a second dispersion assembly and a second light filter which are sequentially connected; wherein the first dispersion assembly processes optical radiation from the light source module and then transmits the optical radiation to the surface of an object to be measured; the second dispersion assembly receives optical radiation reflected by the surface of the object to be measured and transmits the optical radiation to the second optical filter; the optical radiation processing module comprises a third dispersion assembly and a detector which are sequentially connected, and the third dispersion assembly receives the optical radiation from the second optical filter and focuses the optical radiation on the detector. According to the invention, high-precision and high-efficiency object surface three-dimensional information measurement is realized.

Description

Technical Field

[0001] The invention relates to the technical field of precision optical measurement, and in particular to a dual-axis spectral confocal system for measuring three-dimensional information of an object surface. Background Art

[0002] In recent years, the remarkable growth of precision manufacturing has promoted the simultaneous leap of precision machining and testing technology. In the fields of manufacturing and scientific research, the demand for measurement accuracy, range and speed has become increasingly stringent, which has promoted the widespread application of optical 3D surface measurement technology. With its high precision, high efficiency and non-contact advantages, this technology has shown great potential in high-speed detection, product development and quality control.

[0003] Traditional optical detection technology is often limited by the axial scanning process, resulting in low measurement efficiency and accuracy limited by mechanical precision. As an emerging optical measurement method, spectral confocal technology cleverly combines laser confocal and spectral dispersion technology to achieve high signal-to-noise ratio and axial tomography without axial scanning, significantly improving the measurement speed and becoming a key technology for large-area submicron measurement.

[0004] Spectral confocal measurement technology has quickly become a research focus due to its high precision, fast response and strong environmental adaptability. Based on the direct correspondence between wavelength and axial distance, the technology uses the dispersion characteristics of complex wide-spectrum light sources to focus light of different wavelengths at different heights, and achieves high-precision measurement of three-dimensional surfaces by detecting the confocal wavelength.

[0005] Although point spectral confocal displacement sensors are now popular in the market, a single measurement can only provide single-point height information, and needs to be combined with two-dimensional scanning to construct three-dimensional data. This process is not only inefficient, but also easily affected by the accuracy of the scanning equipment. In addition, existing spectral confocal sensors often face the challenges of complex structure and bulky volume of dispersion mirrors and spectral demodulation systems, which limits their application in complex environments.

[0006] In view of this, it is particularly important to develop an innovative linear spectral confocal 3D measurement system to overcome the limitations of existing technologies, improve measurement efficiency and flexibility, and meet a wider range of measurement needs. Summary of the invention

[0007] To this end, an embodiment of the present invention provides a dual-axis spectral confocal system for measuring three-dimensional information of an object surface, which is used to solve the problems of low measurement efficiency, complex system structure, large size, etc. of spectral confocal displacement sensors in the prior art.

[0008] In order to solve the above problems, an embodiment of the present invention provides a dual-axis spectral confocal system for measuring three-dimensional information of an object surface, the system comprising a light source module, a dual-axis spectral confocal module and a light radiation processing module;

[0009] The light source module comprises a white light source and a first filter which are sequentially arranged;

[0010] The dual-axis spectral confocal module includes a first dispersion component, a second dispersion component and a second filter which are sequentially arranged; wherein the first dispersion component processes the light radiation from the light source module and then transmits the light radiation to the surface of the object to be measured; and the second dispersion component receives the light radiation reflected from the surface of the object to be measured and transmits it to the second filter;

[0011] The optical radiation processing module comprises a third dispersion component and a detector which are arranged in sequence, wherein the third dispersion component receives the optical radiation from the second filter and focuses it onto the detector.

[0012] Preferably, the first optical filter and the second optical filter are both slit filters, the two slit filters have the same length, and the first optical filter and the second optical filter are symmetrically arranged with respect to the focal plane of the first dispersion component.

[0013] Preferably, the second filter is arranged in a focal plane of the second dispersive component.

[0014] Preferably, the first dispersive component and the second dispersive component are arranged symmetrically with respect to a focal plane of the first dispersive component.

[0015] Preferably, the first dispersion component, the second dispersion component and the third dispersion component have the same structure, all adopt an Offner structure, and all include a concave spherical reflector and a convex spherical reflective grating.

[0016] Preferably, the number of line pairs of the convex spherical reflection grating is n / mm, and the optical axis forms a non-90° angle with the surface normal of the object to be measured, where n represents the number of line pairs per millimeter of the convex spherical reflection grating, which is selected and determined according to actual application scenarios and measurement requirements.

[0017] Preferably, the first dispersive component further comprises a first plane mirror.

[0018] Preferably, the second dispersive component further comprises a second plane mirror.

[0019] Preferably, the detector is a planar array detector, which is arranged on the focal plane of the third dispersive component.

[0020] The embodiment of the present invention further provides a method for measuring the height of an object surface. The method uses the above-mentioned dual-axis spectral confocal system for measuring three-dimensional information of an object surface to measure the height of the object surface, and specifically includes:

[0021] Using a white light source to provide light radiation, and using a first filter to convert the received light radiation into linear broad spectrum light radiation;

[0022] Using a first dispersion component to disperse the generated linear wide-spectrum optical radiation, separating the optical radiation according to different wavelengths, and then transmitting the optical radiation to the surface of the object to be measured, so that the optical radiation of different wavelengths is focused at different heights perpendicular to the normal line of the surface of the object to be measured, forming an inclined focal plane at a certain angle to the optical axis;

[0023] receiving optical radiation reflected from the surface of the object to be measured using a second dispersive component and transmitting the optical radiation to a second filter in a specular reflection direction;

[0024] Using a second filter to filter the optical radiation reflected from the surface of the object to be measured, filtering out the optical radiation within a specific wavelength range;

[0025] using a third dispersion component to receive the optical radiation in a specific wavelength range filtered out by the second optical filter and focusing the optical radiation onto a detector;

[0026] The detector is used to obtain the imaging position information of the light radiation, and the height information of the surface of the object to be measured is obtained according to the imaging position information.

[0027] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0028] (1) The present invention uses linear wide-spectrum light radiation for spectral confocal measurement, so that the system can obtain two-dimensional spatial information at one time: on the one hand, the spatial distribution in the direction of the slit line field of view, and on the other hand, the surface height information of the object corresponding to different wavelengths on the focal plane. This method overcomes the problem of low sampling efficiency in traditional point light source spectral confocal measurement. The three-dimensional spatial distribution of the object to be measured can be quickly constructed through one-dimensional push scanning, achieving high-precision and high-efficiency non-contact measurement. The height information of the surface of the object to be measured directly corresponds to the wavelength information of the light radiation. This feature ensures the accuracy and reliability of the measurement results.

[0029] (2) The present invention adopts a dual-axis structure, and forms a spectral confocal measurement system with a linear field of view by cascading three independent linear dispersion imaging optical paths. This process includes linear field of view spectroscopic imaging, linear spectral light recombination, and linear field of view re-spectroscopic imaging. Compared with the single-axis structure, this design significantly improves the axial resolution. At the same time, the dispersion system of the linear light source and the receiving system of the reflected light from the surface of the object to be measured are independent of each other and have symmetrical structures. This design not only reduces the energy loss of light radiation in the system, but also effectively improves the energy utilization rate and suppresses the interference of stray light, thereby further improving the measurement accuracy and stability.

[0030] (3) The present invention adopts the Offner structure, which is a total reflection system that can effectively reduce the volume of the sensor while ensuring the same measurement performance, making the sensor structure more compact. At the same time, by using a convex spherical reflection grating for spectral separation, the use of prisms and other spectroscopic elements is avoided, which not only simplifies the structure of the system, but also achieves spectral separation to a greater extent, thereby being able to measure a larger depth range and maintain good linearity and structural simplicity. These characteristics enable the sensor to meet the actual use requirements of small size, large range, and small distortion, providing strong technical support for fields such as precision manufacturing and scientific research. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the implementation cases of the present invention or the technical solutions in the prior art, the following is a brief description of the drawings required for use in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0032] Figure 1 It is a schematic structural diagram of a dual-axis spectral confocal system for measuring three-dimensional information of an object surface provided in an embodiment;

[0033] Figure 2 Schematic diagram of the structure of the dual-axis spectral confocal module in the embodiment;

[0034] Figure 3 The figure is a flow chart of a method for measuring the height of an object surface provided in an embodiment.

[0035] The description of the figures in the specification is as follows: 11, white light source; 12, first optical filter; 21, first plane reflector; 22, first concave spherical reflector; 23, first convex spherical reflection grating; 24, second concave spherical reflector; 25, second convex spherical reflection grating; 26, second plane reflector; 27, second optical filter; 31, focal plane; 41, third concave spherical reflector; 42, third convex spherical reflection grating; 43, detector. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0037] Embodiment 1

[0038] In order to solve the problems of low measurement efficiency, complex system structure, large size, etc. in the existing spectral confocal displacement sensor. Figure 1 As shown, an embodiment of the present invention provides a dual-axis spectral confocal system for measuring three-dimensional information of an object surface, the system comprising a light source module, a dual-axis spectral confocal module and a light radiation processing module;

[0039] The light source module comprises a white light source 11 and a first optical filter 12 which are arranged in sequence, and is used to generate linear wide-spectrum light radiation;

[0040] The dual-axis spectral confocal module includes a first dispersion component, a second dispersion component and a second filter which are sequentially arranged; wherein the first dispersion component processes the linear wide-spectrum light radiation generated by the light source module and then transmits the light radiation to the surface of the object to be measured; the second dispersion component receives the light radiation reflected by the surface of the object to be measured and transmits it to the second filter 27;

[0041] The optical radiation processing module comprises a third dispersion component and a detector 43 which are arranged in sequence, wherein the third dispersion component receives the optical radiation from the second filter 27 and focuses it onto the detector 43 .

[0042] It can be seen from the above technical solution that the present invention proposes a dual-axis spectral confocal system for measuring three-dimensional information on the surface of an object. The dual-axis spectral confocal system proposed in the present invention realizes efficient non-contact measurement of three-dimensional information on the surface of an object through the ingenious combination of linear wide-spectrum light radiation and dual-axis dispersion components. The system not only improves the sampling efficiency and axial resolution, but also effectively reduces the sensor volume, increases the measurement depth range, and maintains excellent linearity and low distortion characteristics through the compact Offner total reflection design and convex spherical reflection grating. These advantages together give the system the significant advantages of high precision, high efficiency, small size, and large range, meeting the actual needs of measuring three-dimensional information on the surface of objects in complex environments.

[0043] In the light source module of the present invention, the white light source 11 and the first optical filter 12 are arranged in sequence, that is, the light emitted by the white light source 11 is first irradiated onto the first optical filter 12. Specifically, the white light source 11 is used to provide light radiation, and the first optical filter 12 converts the received light radiation into continuous, uniform linear wide-spectrum light radiation.

[0044] As an optional specific implementation, the white light source 11 has a high light radiation flux in the 480nm-720nm band, providing illumination in the visible light range.

[0045] like Figure 2As shown, in the dual-axis spectral confocal module of the present invention, the first dispersion component, the second dispersion component and the second filter are sequentially arranged. Specifically, the dual-axis spectral confocal module can be divided into two parts, a transmitting end and a receiving end, wherein the first dispersion component serves as a transmitting end, and is used to disperse the linear wide-spectrum light radiation generated by the light source module, and separate the light radiation according to different wavelengths; and then transmit the light radiation to the surface of the object to be measured, so that the light radiation of different wavelengths is focused at different heights perpendicular to the normal line of the surface of the object to be measured, forming an inclined focal plane (the focal plane of the first dispersion component) 31 at a certain angle to the optical axis. The second dispersion component and the second filter 27 serve as a receiving end, wherein the second dispersion component is used to receive the light radiation reflected from the surface of the object to be measured, and transmit the light radiation to the second filter 27 in the direction of mirror reflection. The second filter 27 is used to filter the light radiation reflected from the surface of the object to be measured, and filter out the light radiation in a specific wavelength range.

[0046] As an optional specific implementation, the first filter 12 and the second filter 27 are both slit filters, the two slit filters have the same length, the first filter and the second filter are symmetrically arranged about the focal plane 31 of the first dispersion component, and the first filter 12 and the second filter 27 have the same length, both of which are 18 mm.

[0047] As an optional specific implementation, the second filter is arranged on the focal plane of the second dispersion component, and is used to filter the non-focused wavelength light radiation reflected from the surface of the object to be measured, so that the light radiation focused on the surface of the object to be measured and with a wavelength falling within a specific range can pass through, and the light radiation that cannot be focused on the normal line of the surface of the object to be measured cannot enter the second filter 27 symmetrically with the optical path before focusing, thereby increasing the system signal-to-noise ratio.

[0048] As an optional specific implementation, the first dispersion component and the second dispersion component are respectively distributed on both sides of the object to be measured, and are symmetrically arranged about the focal plane 31 of the first dispersion component. The first dispersion component and the second dispersion component respectively form two optical axes with a certain angle on both sides of the object to be measured, thereby forming a dual-axis structure, and the angle between the two axes affects the axial resolution of the final measurement.

[0049] As an optional specific implementation, the first dispersion component, the second dispersion component and the third dispersion component have the same structure, all adopt the Offner structure, and all include a concave spherical reflector and a convex spherical reflective grating. In this embodiment, the curvature radius of the concave spherical reflector is 195 mm, and the curvature radius of the convex spherical reflective grating is 95 mm.

[0050] Furthermore, the number of line pairs of the above-mentioned convex spherical reflection grating is n / mm, and the optical axis is at a non-90° angle (for example, a 45° angle) with the surface normal of the object to be measured, wherein n represents the number of line pairs per millimeter of the convex spherical reflection grating, which is selected and determined according to the actual application scenario and measurement requirements. Light radiation in a certain wavelength range is transmitted to the convex spherical reflection grating at a certain incident angle, and the first-order diffraction light is reflected to the concave spherical reflector, without the need for prisms and other light-splitting elements, thereby reducing the energy loss of light radiation in the system and achieving spectral separation to a greater extent.

[0051] Specifically, the first dispersion component includes a first concave spherical reflector 22 and a first convex spherical reflective grating 23 ; the second dispersion component includes a second concave spherical reflector 24 and a second convex spherical reflective grating 25 ; and the third dispersion component includes a third concave spherical reflector 41 and a third convex spherical reflective grating 42 .

[0052] As an optional specific implementation manner, the first dispersion component further includes a first plane reflector 21 , and the first plane reflector 21 is used for deflecting the linear wide-spectrum light radiation to the first concave spherical reflector 22 .

[0053] As an optional specific implementation, the second dispersion component further includes a second plane reflector 26 , and the second plane reflector 26 is used to deflect the optical radiation reflected by the surface of the object to be measured to the second filter 27 .

[0054] As can be seen from the above, the present invention realizes a total reflection system by adopting the Offner structure. This design significantly reduces the volume of the sensor while maintaining the measurement performance unchanged, making the structure more compact. At the same time, a convex spherical reflection grating is used in the system for spectral separation. This process does not require traditional prisms and other spectroscopic elements, thereby being able to achieve effective separation of the spectrum to a greater extent, supporting measurements in a larger depth range, and the system has better linearity and a simpler structure. Such a design enables the present invention to meet the practical application requirements of small volume, large range, and low distortion.

[0055] In addition, the present invention adopts a unique dual-axis structure, which constitutes a spectral confocal measurement system with a linear field of view through three independent but cascaded linear dispersion imaging optical paths. The working principle of this system can be summarized as follows: first, linear field of view spectroscopic imaging is performed, then linear spectral light is compounded, and finally, linear field of view re-spectroscopic imaging is performed. Compared with the traditional single-axis structure, the dual-axis structure of the present invention can significantly improve the axial resolution. More importantly, the dispersion system of the linear light source and the receiving system of the reflected light on the surface of the object to be measured are independent of each other but symmetrical in structure. This design significantly reduces the energy loss of light radiation during transmission, improves energy utilization, and effectively suppresses the interference of stray light, thereby improving the overall measurement performance.

[0056] In the optical radiation processing module of the present invention, the third dispersion component and the detector 43 are sequentially arranged. Specifically, the third dispersion component is used to receive the optical radiation of a specific wavelength range filtered by the second optical filter, and focus the optical radiation onto the detector 43. The detector 43 is used to obtain the imaging position information of the optical radiation, and obtain the height information of the surface of the object to be measured according to the imaging position information.

[0057] As an optional specific implementation, the detector 43 is a planar array detector, which is arranged on the focal plane of the third dispersion component.

[0058] Embodiment 2

[0059] like Figure 3 As shown, the present invention provides a method for measuring the height of an object surface. The method uses the dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to the first embodiment to measure the height of the object surface, and specifically includes:

[0060] Using a white light source 11 to provide light radiation, and using a first filter 12 to convert the received light radiation into linear broad spectrum light radiation;

[0061] Using a first dispersion component to disperse the generated linear wide-spectrum optical radiation, separating the optical radiation according to different wavelengths, and then transmitting the optical radiation to the surface of the object to be measured, so that the optical radiation of different wavelengths is focused at different heights perpendicular to the normal line of the surface of the object to be measured, forming an inclined focal plane 31 at a certain angle to the optical axis;

[0062] Using a second dispersion component to receive optical radiation reflected from the surface of the object to be measured, and transmitting the optical radiation to the second filter 27 in the direction of specular reflection;

[0063] Using the second filter 27 to filter the optical radiation reflected from the surface of the object to be measured, filtering out the optical radiation within a specific wavelength range;

[0064] Using a third dispersion component to receive the optical radiation of a specific wavelength range filtered out by the second optical filter 27, and focusing the optical radiation onto a detector 43;

[0065] The detector 43 is used to obtain the imaging position information of the light radiation, and the height information of the surface of the object to be measured is obtained according to the imaging position information.

[0066] Specifically, the light emitted by the white light source 11 as a point light source is irradiated on the first filter 12. The first filter 12 converts the light emitted by the white light source 11 into a line light source (linear wide-spectrum light radiation). After the line light source is reflected by the first dispersion component, the light of different wavelengths is focused on different heights of the surface normal of the object to be measured, and an inclined focal plane 31 with a certain angle to the optical axis is formed in the direction perpendicular to the surface of the object to be measured. Only the light focused on the surface normal of the object to be measured can be perfectly focused. After being reflected by the surface of the object to be measured, it is reflected by the second dispersion component in the direction of mirror reflection and reaches the second filter 27. The second filter 27 and the first filter 12 meet a conjugate relationship, and finally the reflected light enters the subsequent light radiation processing module with a large transmittance. The light that fails to be focused on the surface of the object to be measured cannot reach the position conjugated with the first filter 12, is filtered by the second filter 27, and cannot enter the subsequent light radiation processing module.

[0067] A method for measuring the height of an object surface in the present embodiment is implemented based on the aforementioned dual-axis spectral confocal system for measuring three-dimensional information of the object surface. Therefore, the specific implementation method of the method for measuring the height of an object surface can be seen in the embodiment section of the dual-axis spectral confocal system for measuring three-dimensional information of the object surface. Therefore, its specific implementation method can refer to the description of the corresponding embodiments of each part, which will not be elaborated here.

[0068] In addition, since the method for measuring the surface height of an object in this embodiment is implemented based on the aforementioned dual-axis spectral confocal system for measuring three-dimensional information of the object surface, its function corresponds to that of the above system, and in order to avoid redundancy, it will not be repeated here.

[0069] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A dual-axis spectral confocal system for measuring three-dimensional information of an object surface, characterized in that: It includes a light source module, a dual-axis spectral confocal module and a light radiation processing module; The light source module comprises a white light source and a first filter which are sequentially arranged to generate linear wide-spectrum light radiation; The dual-axis spectral confocal module includes a first dispersion component, a second dispersion component and a second filter which are sequentially arranged; wherein the first dispersion component processes the linear wide-spectrum light radiation generated by the light source module and then transmits the light radiation to the surface of the object to be measured; the second dispersion component receives the light radiation reflected by the surface of the object to be measured and transmits it to the second filter; The optical radiation processing module comprises a third dispersion component and a detector which are arranged in sequence, wherein the third dispersion component receives the optical radiation from the second filter and focuses it onto the detector.

2. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 1, characterized in that: The first optical filter and the second optical filter are both slit filters, the two slit filters have the same length, and the first optical filter and the second optical filter are symmetrically arranged with respect to the focal plane of the first dispersion component.

3. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 1, characterized in that: The second filter is arranged in a focal plane of the second dispersive component.

4. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 1, characterized in that: The first dispersive component and the second dispersive component are arranged symmetrically with respect to the focal plane of the first dispersive component.

5. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 1, characterized in that: The first dispersion component, the second dispersion component and the third dispersion component have the same structure, all adopt an Offner structure, and all include a concave spherical reflector and a convex spherical reflective grating.

6. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 5, characterized in that: The number of line pairs of the convex spherical reflection grating is n / mm, and the optical axis is at a non-90° angle with the surface normal of the object to be measured, where n represents the number of line pairs per millimeter of the convex spherical reflection grating, which is selected and determined according to the actual application scenario and measurement requirements.

7. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 5, characterized in that: The first dispersive component also includes a first plane mirror.

8. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 5, characterized in that: The second dispersive component also includes a second plane mirror.

9. The dual-axis spectral confocal system for measuring three-dimensional information of an object surface according to claim 1, characterized in that: The detector is a planar array detector, which is arranged on the focal plane of the third dispersion component.

10. A method for measuring the height of an object surface, characterized in that: The method uses the dual-axis spectral confocal system for measuring three-dimensional information of the surface of an object according to any one of claims 1 to 9 to measure the height of the surface of the object, and specifically includes: Using a white light source to provide light radiation, and using a first filter to convert the received light radiation into linear broad spectrum light radiation; Using a first dispersion component to disperse the generated linear wide-spectrum optical radiation, separating the optical radiation according to different wavelengths, and then transmitting the optical radiation to the surface of the object to be measured, so that the optical radiation of different wavelengths is focused at different heights perpendicular to the normal line of the surface of the object to be measured, forming an inclined focal plane at a certain angle to the optical axis; receiving optical radiation reflected from the surface of the object to be measured using a second dispersive component and transmitting the optical radiation to a second filter in a specular reflection direction; Using a second filter to filter the optical radiation reflected from the surface of the object to be measured, filtering out the optical radiation within a specific wavelength range; using a third dispersion component to receive the optical radiation in a specific wavelength range filtered out by the second optical filter and focusing the optical radiation onto a detector; The detector is used to obtain the imaging position information of the light radiation, and the height information of the surface of the object to be measured is obtained according to the imaging position information.

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