A galvanometer-based spectral confocal three-dimensional measurement system
By using a galvanometer-based spectral confocal three-dimensional measurement system, efficient scanning of the sample surface is achieved through galvanometer deflection and dispersion components. This solves the accuracy and speed problems caused by vibration introduced by mechanical scanning, and realizes high-precision and fast three-dimensional measurement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHAN JINGCE ELECTRONICS GRP CO LTD
- Filing Date
- 2025-06-13
- Publication Date
- 2026-07-07
AI Technical Summary
In existing spectral confocal three-dimensional measurement systems, mechanical scanning introduces vibrations, leading to reduced measurement accuracy and slower measurement speed.
A galvanometer-based confocal 3D measurement system is adopted, which scans the sample surface by galvanometer deflection and combines it with a telecentric dispersive objective or microlens array for dispersive spectroscopy to achieve high-precision and rapid 3D measurement.
It improves measurement accuracy and speed, especially when measuring surface irregularities, enabling more precise measurements along the normal direction, thus enhancing scanning speed and resolution.
Smart Images
Figure CN224471014U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of microstructure three-dimensional measurement technology, and in particular to a spectral confocal three-dimensional measurement system based on a galvanometer. Background Technology
[0002] 3D inspection technology based on spectral confocalization is a commonly used technique in the field of optical inspection of 3D microstructures such as wafers, LED panels, and PCBs. It has the advantages of high inspection accuracy and fast inspection speed.
[0003] A schematic diagram of a 3D microstructure detection system based on spectral confocalization is shown below. Figure 1 As shown, the basic principle of its detection is as follows: The polychromatic light beam emitted by the polychromatic light source, after passing through lens group 01 and lens group 02, will undergo dispersion along the z-axis. That is, beams of different wavelengths will be focused at different positions along the z-axis, as shown in the figure, the focal planes along the z-axis from top to bottom are λ1, λ2, and λ3. Assuming that the surface of a certain region of the sample to be tested is located on the focal plane of the beam with wavelength λ2, the beam with wavelength λ2 will converge into a focal spot on the surface of that region of the sample, while the beams with wavelengths λ1 and λ3 will be diffused in that region. Lens group 03 is the same as lens group 01, and the slit position is conjugate with the position of the polychromatic light source. Therefore, after the beam reflected back from the sample passes through lens group 02, the beam splitter, and lens group 03, the portion of the beam with wavelength λ2 will still converge into a focal spot on the slit plane, while the portions of the beam with wavelengths λ1 and λ3 will also form diffused spots on the slit plane. After spatial filtering by the slit, the imaging spectrometer will obtain the spectral line with wavelength λ2. When the stage moves to focus the light beam onto another region of the sample, if the surface height of that region changes, the spectrometer will acquire spectral lines of the corresponding wavelength. In this way, three-dimensional detection of the sample can be performed through scanning.
[0004] Existing point scanning and line scanning systems require mechanical scanning to achieve three-dimensional measurement of the entire DUT. Mechanical scanning inevitably introduces vibration, reducing measurement accuracy. Furthermore, mechanical scanning takes longer.
[0005] Therefore, those skilled in the art urgently need to develop and acquire a spectral confocal three-dimensional measurement system based on a galvanometer. Utility Model Content
[0006] In order to address one or more of the above-mentioned defects or improvement needs of the existing technology and to overcome the problems caused by the measurement speed and measurement accuracy in the existing technology, this utility model proposes a three-dimensional detection technology based on spectral confocalization. According to the system implemented by this utility model, the above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.
[0007] This utility model discloses a spectral confocal three-dimensional measurement system based on a galvanometer, the system comprising,
[0008] A light source for generating a polychromatic light beam; a collimation assembly for collimating the polychromatic light beam.
[0009] A dispersive optical component for spatially adjusting the position of the polychromatic beam and then dispersing it;
[0010] The dispersive optical component has a galvanometer that receives the polychromatic beam and is used to adjust the different reflection positions of the polychromatic beam in space.
[0011] The dispersive optical component has a dispersive element, which is used to receive light at the corresponding reflection position after being processed by the galvanometer, and to split the wavelength to different depths in the first spatial direction.
[0012] The light at different depths is reflected by the sample to be measured and then coupled into the imaging spectrometer;
[0013] The first spatial direction is the optical axis direction of the dispersive element, and the different reflection positions are different positions corresponding to the surface of the sample to be measured.
[0014] Furthermore, the galvanometer has a first deflection angle, the smallest unit of which is matched with the resolution of the optical system of the spectral confocal three-dimensional measurement system.
[0015] Furthermore, the dispersive element is a telecentric dispersive objective lens, and the light from the different reflection positions generates dispersive beams that are substantially consistent with the normal direction in the first spatial direction. The normal direction is the normal direction at the current position on the surface of the sample to be measured.
[0016] Furthermore, the beam-splitting element is a microlens array, and the light from different reflection positions generates dispersive beams in a first spatial direction that are substantially consistent with the normal direction, where the normal direction is the normal direction at the current position on the surface of the sample to be measured. Thus, the microlens array is configured to have a certain dispersive function, and the light corresponding to the respective array region is dispersed.
[0017] Furthermore, the light at different depths is reflected by the sample to be measured, passes through the dispersive optical component, and is then coupled into the imaging spectrometer via imaging from the back surface of the slit.
[0018] Furthermore, the dispersive optical component has a beam splitter. After the light at different depths is reflected by the sample to be measured, it passes through the dispersive element, the beam splitter, and the slit before being coupled into the imaging spectrometer.
[0019] Furthermore, there is one galvanometer, the polychromatic beam is a linear beam, and the deflection of the galvanometer enables one-dimensional scanning of the surface of the sample to be measured.
[0020] Furthermore, there are two galvanometers, orthogonally deflected, and the polychromatic beam is a linear beam. The deflection of the galvanometers enables two-dimensional scanning of the surface of the sample to be measured.
[0021] Furthermore, the galvanometer has an adjustment structure.
[0022] Furthermore, the dispersive optical component has a beam splitter, and a lens group is also provided between the beam splitter and the slit in the reflected light path.
[0023] In summary, the beneficial effects of the above-described technical solutions conceived by this utility model compared with the prior art include:
[0024] A galvanometer-based spectral confocal three-dimensional measurement system is proposed. Compared with the mechanical scanning methods in existing point scanning and line scanning systems, it achieves one-dimensional scanning of the sample by deflecting one galvanometer, or two-dimensional scanning of the sample by deflecting two galvanometers orthogonally. The vibration introduced by the galvanometer deflection is small, which can effectively improve the measurement accuracy. In addition, the galvanometer has a small deflection amplitude and a fast deflection speed during scanning, which can effectively improve the scanning measurement speed.
[0025] Furthermore, by employing a telecentric dispersive objective lens in the dispersive component of the galvanometer-based confocal 3D measurement system, and coordinating it with the overall scanning optical path, the wavelength dispersion can remain essentially parallel to the normal direction even when the galvanometer is adjusted to change multiple positions of the reflected light. This enables precise measurement of the Δh direction in surface measurements, especially in the case of measuring uneven surface structures. It allows for more accurate measurement of the Δh direction, which is aligned with the normal direction of the surface being measured, thereby further improving measurement accuracy while increasing the scanning measurement speed. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the composition of a three-dimensional microstructure detection system based on spectral confocalization in the existing technology;
[0027] Figure 2 This is a schematic diagram of the calculation of the sample surface based on the detection wavelength of a sample with an uneven surface, according to the existing three-dimensional microstructure detection system based on spectral confocalization.
[0028] Figure 3 This is a schematic diagram of the composition structure of a spectral confocal three-dimensional measurement system based on a galvanometer, implemented according to this utility model. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.
[0030] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of the invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0031] Existing spectral confocal detection systems can be divided into two types based on the light source: point light source and line light source.
[0032] In such Figure 1 In the point-scanning confocal spectral detection system shown, the polychromatic beam emitted by the point polychromatic light source converges into a single point on the corresponding focal plane, representing the height of the sample area illuminated by that point in a single exposure. Therefore, the stage needs to move and scan in both the x and y directions to perform three-dimensional measurements of the sample.
[0033] In such Figure 1 In the line-scan confocal spectral detection system shown, the linear polychromatic light source is placed along the x-axis. The polychromatic beams emitted from this source converge at their respective focal planes to form a line along the x-axis. Therefore, a single camera exposure can acquire all spectral information corresponding to different heights within the entire linear region of the sample illuminated by this line. Thus, three-dimensional measurement of the sample can be performed simply by moving the stage along the y-axis.
[0034] In an online scanning spectral confocal detection system, Figure 2 (a) is the cross-section of the sample. Figure 2 (b) is a spectral schematic image of the sample surface structure obtained by the system in a single exposure; calculation Figure 2 The width Δp of the raised spectral line in (b) and its wavelength difference Δλ with the base spectral line can be obtained respectively. Figure 2 The width Δd and height Δh of the rectangular protruding surface of the sample shown in (a) are given. See [reference needed]. Figure 2 In (c), both the raised spectral line and the base spectral line have corresponding intensity distributions along the direction of the spectral wavelength. The algorithm first determines the wavelength λ2 corresponding to the peak intensity of the raised spectral line and the wavelength λ1 corresponding to the peak intensity of the base spectral line, and then subtracts them to obtain the wavelength difference Δλ, that is, Δλ = λ2 - λ1.
[0035] Existing point scanning and line scanning systems require mechanical scanning to achieve three-dimensional measurement of the entire DUT. Mechanical scanning inevitably introduces vibration, reducing measurement accuracy. Furthermore, mechanical scanning takes longer.
[0036] This invention proposes a spectral confocal three-dimensional measurement system based on a galvanometer. Compared with the mechanical structure that drives the sample to scan in point scanning and line scanning systems, this system achieves the scanning measurement of the entire DUT by controlling the galvanometer's deflection angle and building the galvanometer's scanning structure, resulting in faster measurement speed.
[0037] This utility model first discloses a spectral confocal three-dimensional measurement system based on a galvanometer. The system includes a light source 01 for generating a polychromatic light beam, a dispersive optical component for dispersing the polychromatic light beam after adjusting the incident angle in space; the polychromatic light beam is adjusted in space, where space refers to the propagation space of the polychromatic light beam. The purpose of adjusting the position in space is to enable the light beam generated by the light source to be incident on the surface of the sample 06 to be measured at a certain adjustment frequency after the spatial adjustment, so as to complete the measurement of the entire surface without moving the sample 06 by scanning the incident light with the incident position adjusted.
[0038] Adjusting the incident angle in space allows the incident angle of light incident from light source 01 to be changed without altering the emission angle of light source 01. Furthermore, by controlling the change in the spatial adjustment position, the resolution of the angle adjustment can be mapped to the resolution of the scanning measurement.
[0039] The dispersive optical component has a galvanometer 04, which receives a polychromatic beam and is used to adjust the different reflection positions of the polychromatic beam in space. The different adjustment positions of the polychromatic beam are mainly due to the different deflection angles of the polychromatic beam received directly or indirectly on the galvanometer 04, which result in different spatial reflection positions of the beam.
[0040] The dispersive optical assembly has a dispersive element that receives light from the corresponding reflection position after being processed by the galvanometer 04 and disperses the light to focal planes at different depths in a first spatial direction. Ultimately, it generates different depths in the first spatial direction. In one specific embodiment, a lens with a focal plane design is used in the dispersive process to achieve the effect of light dispersion. Thus, the light dispersed at different depths is distributed on the focal plane of the dispersive lens, such as... Figure 2 As shown, light of different wavelengths produces wavelength dispersion in the direction of the substrate surface; the first spatial direction points to the optical axis of the dispersive element, which may or may not be consistent with the normal direction of the surface of the sample 06 to be measured; different reflection positions correspond to different positions in the direction of the surface of the sample 06 to be measured; wherein, the normal direction of the surface of the sample 06 to be measured is the average normal direction of the surface, corresponding to the surface of the sample 06 to be measured with unknown surface characteristics, which may exhibit, such as Figure 2 The uneven surface structure shown has a normal direction that can be represented as the normal direction of the substrate surface. Light from focal planes at different depths is reflected by the sample 06 and then coupled into the imaging spectrometer 09.
[0041] The galvanometer 04 has a first deflection angle in the propagation space of the optical path. The smallest unit of this first deflection angle matches the resolution of the optical system of the spectral confocal three-dimensional measurement system. This ensures that the beam scanning the surface of the sample 06 to be measured can be processed by the overall optical system and then resolved after being coupled into the detector. The optical resolution is determined by the characteristics of the light source and the parameters of the optical system, taking into account factors such as aberrations, alignment errors, and detector performance. The deflection angle of the galvanometer 04 can be adjusted accordingly under the control of its control system to complete the continuous scanning of the surface of the sample 06 to be measured. The first deflection angle of the galvanometer 04 matches the resolution of the optical system.
[0042] The dispersive optical assembly includes a dispersive element 05, which in one embodiment of this invention is a telecentric dispersive objective lens. Light from different reflection positions produces a depth of focus in the first spatial direction. The telecentric dispersive objective lens causes the wavelengths to be arranged in the first spatial direction in a direction that is nearly perpendicular to the normal, for example. This arrangement, firstly, enables higher precision identification and measurement of the surface Δh of an object, and secondly, enables precise measurement of the corresponding structure for some concave or convex depth structures that are basically parallel or consistent with the normal direction.
[0043] In another embodiment, the dispersive element 05 is a microlens array, where light from different reflection positions produces a depth of focus parallel to the normal direction in the first spatial direction. The microlens array is an array arrangement of multiple dispersive element units; after receiving light at the adjusted position in the array portion at the corresponding position, dispersal occurs. Preferably, the array portion is provided with a collimating lens to improve the dispersive effect at the corresponding position.
[0044] Light from focal planes at different depths is reflected by the sample 06 to be measured, passes through the dispersive optical components, and is coupled into the imaging spectrometer 09 via the surface of the slit 08.
[0045] In one embodiment, the polychromatic beam is a linear beam, and there is one galvanometer 04. The galvanometer 04 is deflected at an angle in one scanning dimension to achieve one-dimensional scanning of the surface of the sample 06 to be measured.
[0046] In another embodiment, there are two galvanometers 04, which are orthogonally deflected and the polychromatic beam is a linear beam. The deflection of the galvanometers 04 enables two-dimensional scanning of the surface of the sample 06 to be measured.
[0047] The beam-splitting optical assembly also includes a lens group 02 and a beam splitter 03 sequentially arranged in the incident light path in the direction of light source propagation, and a lens group 07 between the beam splitter 03 and the slit 08 in the reflected light path.
[0048] In one specific embodiment of this utility model, such as Figure 3 As shown, a linear polychromatic light source 01 (along the X-axis) emits a polychromatic beam. After passing through lens group 02, beam splitter 03, galvanometer 04, and lens group 05, beams of different wavelength components form focal planes of different depths in the sample space. The beam reflected back from the surface of the sample 06 to be measured passes through lens group 05, galvanometer 04, beam splitter 03, and lens group 07, and is imaged on the surface of slit 08. Slit 08 performs spatial filtering on the beam, coupling the beam of the corresponding wavelength components into the imaging spectrometer 09. In another embodiment, the dispersive optical component has a beam splitter 03 in the optical path structure. Light from focal planes of different depths is reflected by the sample 06 to be measured, passes through dispersive element 05, beam splitter 03, and slit 08, and is then coupled into the imaging spectrometer 09. In this arrangement of beam splitter 03, slit 08 moves according to the scanning settings of the optical path to achieve coupled imaging.
[0049] like Figure 3 As shown, when the deflection angle of galvanometer 04 is controlled to be at deflection position I, the polychromatic beam reflected by it, after passing through lens group 05, forms focal planes of different depths along the Z-axis at position I' of the sample 06 to be measured, with different wavelength components. Assuming that position I' of the sample is at the focal plane of the λ3 component beam, the reflected beam, after passing through lens group 05, galvanometer 04, beam splitter 03, and lens group 07, is imaged on the surface of slit 08. Slit 08 performs spatial filtering on the imaging spot, filtering out the λ1 and λ2 component beams, while the λ3 component beam passes through the slit and couples into the imaging spectrometer 11. Similarly, the deflection angle of galvanometer 04 can be controlled to be at deflection positions II and III, respectively, so that the λ2 and λ1 component beams respectively pass through slit 08 and couple into the imaging spectrometer 11, while other component beams are filtered out.
[0050] Based on the above principles, by simply controlling the deflection angle of the galvanometer 04, the surface of the sample 06 to be measured can be scanned, thus achieving three-dimensional measurement.
[0051] Figure 3 The system shown achieves one-dimensional scanning measurement of the sample along the Y direction using galvanometer 04. When the sample size is large, two-dimensional scanning of the sample along the X and Y directions can be achieved by orthogonally deflecting the two galvanometers.
[0052] The description in this specification is merely an illustrative example of the present invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the content of this specification or exceed the scope defined in the claims, they shall all fall within the protection scope of this invention.
Claims
1. A spectral confocal three-dimensional measurement system based on a galvanometer, characterized in that, The system includes, Light source (01) for generating polychromatic light beam; collimation assembly (02) for collimating the polychromatic light beam. Dispersive optical components (04, 05) are used to adjust the position of the polychromatic beam in space and then disperse it; The dispersive optical components (04, 05) have a galvanometer (04) that receives the polychromatic beam and is used to adjust the different reflection positions of the polychromatic beam. The dispersive optical components (04, 05) have a dispersive element (05) which is used to receive light after it has been reflected by the galvanometer (04) and split the wavelength to different depths in the first spatial direction. The light at different depths is reflected by the sample to be measured (06) and then coupled into the imaging spectrometer (09); the first spatial direction is the optical axis direction of the dispersive element (05), and the different reflection positions are different positions corresponding to the surface of the sample to be measured (06).
2. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1, characterized in that, The galvanometer (04) has a first deflection angle, the smallest unit of which is matched with the resolution of the optical system of the spectral confocal three-dimensional measurement system.
3. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1 or 2, characterized in that, The dispersive element (05) is a telecentric dispersive objective lens. The light from the different reflection positions generates dispersive beams that are basically consistent with the normal direction in the first spatial direction. The normal direction is the normal direction at the current position on the surface of the sample to be measured (06).
4. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1 or 2, characterized in that, The dispersive element (05) is a microlens array. The light from the different reflection positions generates dispersive beams that are basically consistent with the normal direction in the first spatial direction. The normal direction is the normal direction at the current position on the surface of the sample to be measured (06).
5. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1, characterized in that, The light at different depths is reflected by the sample to be measured (06), and after passing through the dispersive optical components (04, 05) and the slit (08), it is coupled into the imaging spectrometer (09).
6. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1 or 2, characterized in that, The dispersive optical components (04, 05) have a beam splitter (03). The light at different depths is reflected by the sample to be measured (06) and then coupled into the imaging spectrometer (09) after passing through the dispersive element (05), the beam splitter (03), and the slit (08).
7. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1 or 2, characterized in that, There is one galvanometer (04), the polychromatic beam is a linear beam, and the deflection of the galvanometer (04) realizes one-dimensional scanning of the surface of the sample (06) to be measured.
8. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 1 or 2, characterized in that, There are two galvanometers (04) set orthogonally, the polychromatic beam is a linear beam, and the deflection of the galvanometers (04) realizes two-dimensional scanning of the surface of the sample (06) to be measured.
9. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 8, characterized in that, The galvanometer (04) has an adjustment structure.
10. The spectral confocal three-dimensional measurement system based on a galvanometer as described in claim 9, characterized in that, The dispersive optical components (04, 05) have a beam splitter (03), and a lens group (07) is also provided between the beam splitter (03) and the slit (08) in the reflected light path.