Diaphragm and spectrum confocal measuring device
By introducing a stop in the spectral confocal measurement device, the light intensity of non-target wavelengths is weakened, and the existing three-dimensional measurement system has been solved, and the higher signal-to-noise ratio and imaging accuracy are achieved, which simplifies the design process.
Patent Information
- Application Number
- CN202421980597.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-14
- Publication Date
- 2025-05-09
- Estimated Expiration
- 2034-08-14
AI Technical Summary
The existing three-dimensional measurement systems have low signal-to-noise ratio, limited imaging accuracy, and high design complexity and difficulty, which cannot meet the needs of high-precision measurement.
A diaphragm is designed, including a light shielding member and a body member, which is arranged coaxially with the light pass channel, which can weaken the light intensity of non-target wavelengths and improve the signal-to-noise ratio of the spectral confocal measuring device.
Effectively suppress diffuse reflected light introduced by irregular structures on the surface of the object to be measured, improve signal-to-noise ratio, improve imaging accuracy, and simplify design complexity.
Smart Images
Figure CN222850762U_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of optical elements and three-dimensional measurement, and more specifically, to an aperture and spectral confocal measurement device. Background Art
[0002] With the rapid development of my country's advanced manufacturing industry, the demand for precision measurement is increasing. Among them, spectral confocal displacement measurement technology has received widespread attention due to its high precision, strong adaptability, and high efficiency. Spectral confocal technology is based on confocal technology and combines the optical dispersion phenomenon to focus light of different wavelengths at different axial positions. By analyzing the focused wavelength of the reflected light from the surface to be measured, the position of the surface to be measured is solved based on the mapping relationship between the calibrated wavelength and the position of the object to be measured. This technology is widely used in semiconductor chips, industrial manufacturing, aerospace, medical equipment and other fields.
[0003] The existing three-dimensional measurement system uses a pinhole array and other methods to improve the single-point spectral confocal system to achieve multi-point rapid measurement, higher measurement efficiency, and improved image quality. At the same time, by improving the design of the filter component and the spectroscopic imaging component, such as increasing the number of pinholes and optimizing the design of the image plane coordinates, the detection speed and imaging accuracy of the system can also be improved. In addition, by adjusting the parameters of the lighting component and optimizing the design of the dispersion objective lens component, such as setting the two coaxially, the problem of blind spots in the field of view can be avoided; or by changing the curvature and material of the lens in the dispersion objective lens component, the imaging quality of the system can also be improved.
[0004] Although the existing three-dimensional measurement system has improved the measurement accuracy to a certain extent, there are still some problems and limitations. First, the lateral resolution of the existing three-dimensional measurement system is limited by the spacing between the pinholes, and it is easy to be mixed with the diffuse reflected light introduced by the irregular structure of the surface to be measured, the signal-to-noise ratio is poor, and the measurement area is small, resulting in limited imaging accuracy of the system and unable to meet the needs of high-precision measurement. Secondly, although the dispersive objective lens has the advantage of linear response, the multi-order diffraction spots greatly reduce the utilization rate of light energy, resulting in low light return efficiency and low signal-to-noise ratio; finally, since the various components in the system affect each other, any design changes in any part may have an impact on other parts, increasing the complexity and difficulty of system design.
[0005] In summary, it can be seen that the existing three-dimensional measurement system has problems such as high noise, low signal-to-noise ratio and limited imaging accuracy. How to improve the signal-to-noise ratio of the three-dimensional measurement system and improve imaging accuracy without affecting the performance of other parts of the system, simplifying the design complexity and reducing the design difficulty has become an urgent problem to be solved. Utility Model Content
[0006] In view of the defects of the prior art, the purpose of the present application is to provide an aperture and spectral confocal measurement device, aiming to solve the problems of low signal-to-noise ratio and limited imaging accuracy of the existing three-dimensional measurement system.
[0007] To achieve the above-mentioned purpose, in a first aspect, the present application provides an aperture, which is applied to a spectral confocal measurement device, in which light beams of different wavelengths are focused at different heights, and the aperture comprises: a light shielding member and a main body member;
[0008] The main body is provided with a light passage inside;
[0009] The shading member is arranged inside the main body and coaxially with the light passage, so that at least part of the light beam passing through the aperture cannot pass through the light passage due to the shading of the shading member.
[0010] It can be understood that the aperture, shading member and light passage provided in the present application are coaxial, which can prevent at least part of the light beams of different wavelengths from passing through the light passage due to the shading of the shading member, weaken the light intensity of non-target wavelengths incident on the target height, and improve the signal-to-noise ratio of the target wavelength reflected from the target height received by the spectral confocal measurement device. It can be seen that the above aperture is applied to the spectral confocal measurement device, which can effectively suppress the diffuse reflection light introduced by the irregular structure on the surface of the object to be measured, improve the signal-to-noise ratio, and thus improve the imaging quality of the system.
[0011] In some embodiments, the light passage is a circular light passage.
[0012] In some embodiments, the shading element is a circular light-proof thin sheet structure.
[0013] In a second aspect, the present application provides a spectral confocal measurement device, comprising: at least one aperture described in the first aspect or any of the embodiments of the first aspect, and an illumination component, a beam splitter, a dispersive objective lens component, and an imaging component;
[0014] The illumination assembly, the beam splitter and the dispersion objective lens assembly are coaxially arranged in sequence;
[0015] The beam splitter is capable of transmitting the incident light beam output by the illumination assembly to the dispersion objective lens assembly;
[0016] The dispersion objective lens assembly is used to disperse the light of different wavelengths in the transmitted incident light beam so that the light of different wavelengths is focused at different heights of the object to be measured; and to receive the reflected light beam reflected by the surface of the object to be measured, and emit the reflected light beam to the beam splitter;
[0017] The beam splitter reflects the received reflected light beam to the imaging component;
[0018] The imaging component is arranged on the reflected light path of the beam splitter to form an image of the received reflected light beam;
[0019] The at least one aperture is arranged in the reflection light path between the object to be measured and the imaging component.
[0020] It is understandable that providing at least one aperture in the above-mentioned spectral confocal measurement device can effectively reduce noise, improve signal-to-noise ratio, reduce imaging broadening, and improve imaging accuracy, which can effectively solve the problems of low signal-to-noise ratio and limited imaging accuracy of traditional spectral confocal measurement devices.
[0021] In some embodiments, the apparatus further comprises: a pinhole mask array plate;
[0022] The pinhole mask array plate is provided with a plurality of rows and columns of pinholes arranged at intervals, which are arranged one-to-one corresponding to the different heights. The outgoing light of each wavelength reflected by the height is focused to the corresponding pinhole of the pinhole mask array plate and emitted from the corresponding pinhole.
[0023] In some embodiments, the pinhole mask array plate is disposed between the beam splitter and the dispersive objective lens assembly; or the pinhole mask array plate includes two, the first pinhole mask array plate is disposed between the illumination assembly and the beam splitter, and the second pinhole mask array plate is disposed between the beam splitter and the imaging assembly.
[0024] In some embodiments, the at least one aperture is disposed at at least one of the following positions: between the object to be measured and the dispersive objective lens assembly, between the dispersive objective lens assembly and a beam splitter, or between the beam splitter and an imaging assembly.
[0025] For example, the above positions are optional, and the aperture can also be placed at other positions of the spectral confocal measurement device. Those skilled in the art can select a specific position to reduce noise in the spectral confocal measurement device according to actual needs, so as to achieve the best noise reduction effect.
[0026] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:
[0027] The present application provides an aperture and a spectral confocal measurement device. After adding an aperture to the spectral confocal measurement device, the signal-to-noise ratio of the reflected spectral signal is improved, which can effectively solve the problems of low signal-to-noise ratio and limited imaging accuracy of the traditional spectral confocal measurement device. Furthermore, the present application improves the signal-to-noise ratio and imaging accuracy by using an aperture in the imaging system, which can avoid the increased design complexity and difficulty caused by the mutual influence of various components in the system. Compared with the prior art, the design of the present application is simpler and easier to implement. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a structural schematic diagram of an aperture provided in an embodiment of the present application;
[0029] Figure 2 is another structural schematic diagram of an aperture provided in an embodiment of the present application;
[0030] Figure 3 It is a structural schematic diagram of a spectral confocal measurement device provided in an embodiment of the present application;
[0031] Figure 4 is another structural schematic diagram of a spectral confocal measurement device provided in an embodiment of the present application;
[0032] Figure 5 is a schematic diagram of focusing light paths at different target heights corresponding to the aperture provided in an embodiment of the present application;
[0033] Figure 6 is a schematic diagram of the optical path when there is no aperture in the spectral confocal measurement device provided in an embodiment of the present application;
[0034] Figure 7 is a schematic diagram of the optical path when an aperture is present in the spectral confocal measurement device provided in an embodiment of the present application;
[0035] In all the drawings, the same figure marks are used to represent the same elements or structures, among which: 10 represents a main body, 20 represents a shading member; 11 represents an illumination assembly; 12 represents a dispersion objective lens assembly; 13 represents a filtering assembly, 131 represents a spectroscope, 132 represents a pinhole mask array plate; and 14 represents an imaging assembly. DETAILED DESCRIPTION
[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described below with reference to the accompanying drawings and in combination with the embodiments.
[0037] In order to enable ordinary technicians in the field to better understand the technical solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments, and all should belong to the protection scope of the present application.
[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are applicable to distinguishing similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition. The terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or that are state-owned for these processes, methods, products or devices.
[0039] It should also be noted that the division of multiple embodiments in the present application is only for the convenience of description and should not constitute a special limitation. The features in various embodiments can be combined and referenced to each other without contradiction.
[0040] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.
[0041] Figure 1 is a schematic diagram of a structure of an aperture provided in an embodiment of the present application; the aperture is applied to a spectral confocal measurement device, in which light beams of different wavelengths are focused at different heights, such as Figure 1 As shown, the aperture includes: a main body 10 and a light shielding member 20;
[0042] The main body 10 has a light passage inside;
[0043] The shading member 20 is disposed inside the main body 10 and coaxially with the light passage, so that at least a portion of the light beam passing through the aperture cannot pass through the light passage due to the shading of the shading member 20 .
[0044] It should be noted that, in the aperture provided in the present application, the shading element is coaxial with the light passage. If the shading element is not present, different wavelengths are focused at different heights, and the focusing point is located in the axial direction of the light passage. When the shading element is present, the above-mentioned aperture can weaken the light intensity of non-target wavelengths incident on the target height, thereby improving the signal-to-noise ratio of the target wavelength received by the spectral confocal measurement device.
[0045] In some embodiments, the light passage is a circular light passage.
[0046] In some embodiments, the shading member 20 is a circular light-proof thin sheet structure.
[0047] It should be noted that the outer boundary of the main body 10 can be as follows: Figure 1 The circle shown can also be other shapes, such as Figure 2 Furthermore, the exterior of the main body 10 may be other regular or irregular shapes; the space between the boundary of the light passage in the main body 10 and the exterior boundary of the main body 10 is a solid body, which may be a light shielding member.
[0048] It is understandable that those skilled in the art can design the diameter and position of the shading member 20 as required so as to improve the signal-to-noise ratio of the target wavelength.
[0049] Furthermore, the aperture shape can be in various forms, such as a grid shape, a solid shape, a circular shape, a square shape, a triangle shape, etc.
[0050] Figure 3 Schematic diagram of a spectral confocal measurement device provided in an embodiment of the present application; Figure 3 As shown, the device includes: an illumination component 11, a dispersion objective lens component 12, a filtering component 13, a beam splitter 131, a pinhole mask array plate 132 and an imaging component 14.
[0051] Among them, the lighting component 11 may include: a line light source or a surface light source for outputting high-brightness incident light. Furthermore, the incident light can reach the filtering component 13 after passing through a lens combination. The lens combination includes one or more lenses for modulating the optical path of the incident light to improve the collimation and brightness of the light.
[0052] The filtering assembly 13 is arranged between the illumination assembly 11 and the dispersive objective lens assembly 12, and may include a beam splitter 131 and a pinhole mask array 132; wherein the beam splitter 131 is arranged at an angle relative to the incident light. In one embodiment, the pinhole mask array 132 is arranged between the beam splitter 131 and the dispersive objective lens assembly 12, and a plurality of light-transmitting pinholes arranged at intervals are arranged on the pinhole mask array 132. The incident light sequentially passes through the beam splitter 131 and the pinhole mask array 132 and then reaches the dispersive objective lens assembly 12.
[0053] The dispersive objective lens assembly 12 is used to disperse the incident light, and the light of the target wavelength among the light of different wavelengths after dispersion is focused on the corresponding measuring point of the measured object, and the outgoing light of the target wavelength formed by reflection from the measuring point is received. For example, the dispersive objective lens assembly 12 includes a plurality of lens assemblies, and by controlling parameters such as the thickness of each lens and the distance between the lenses, it can expand the incident light of different wavelengths in the axial direction to obtain light of different target wavelengths, λ1, λ2 and λ3, and focus on the target heights of the small ball of the measured object h1, h2 and h3, respectively, and form outgoing light of the target wavelength after reflection from the small ball of the measured object and return to the dispersive objective lens assembly 12.
[0054] As mentioned above, the position information of the object to be measured carried by the outgoing light with target wavelengths of λ1, λ2 and λ3 is recorded as (x1, h1), (x2, h2) and (x3, h3) respectively, and the outgoing light is focused to the plane where the pinhole mask array plate 132 is located after passing through the dispersion objective lens assembly 12. In particular, the outgoing light of different wavelengths can only be converged to a sufficiently small size in the corresponding pinholes on the pinhole mask array plate 132. For example, the outgoing light of wavelength λ1 is focused on the pinhole x1ˋ, and the outgoing light of wavelengths λ2 and λ3 is focused on the pinholes x2ˋ and x3ˋ respectively. For different pinholes, the light of non-target wavelength will diverge more and more as the wavelength deviates from the target wavelength, and therefore will be blocked and filtered out by the pinhole mask array plate 132.
[0055] The outgoing light passing through the pinhole mask array plate 132 is reflected to the imaging component 14 via the beam splitter 131 . Furthermore, the dispersive objective lens component 12 is coaxially arranged with the illumination component 11 , and the incident light is parallel to the optical path of the outgoing light before being reflected by the beam splitter 131 .
[0056] In another embodiment, Figure 4 As shown, two pinhole mask array plates 132 can be respectively arranged between the lighting component 11 and the beam splitter 131 and between the beam splitter 131 and the imaging component 14. The incident light passes through the first pinhole mask array plate 132 and the beam splitter 131 in sequence and then reaches the dispersion objective lens component 12. The outgoing light passes through the dispersion objective lens component 12 and is reflected by the beam splitter 131 to the second pinhole mask array plate 132. The pinholes on the two pinhole mask array plates 132 correspond to each other one by one. The outgoing light of different wavelengths passes through the second pinhole mask array plate 132 and reaches the imaging component 14.
[0057] The imaging component 14 is used to receive the outgoing light reflected by the spectroscope 131, and focus the outgoing light of different wavelengths on the image plane coordinates corresponding to the pinhole and the measuring point on the imaging plane. The imaging plane mentioned is, for example, the imaging plane of the camera photosensitive element. For example, the position information of the object to be measured carried by the outgoing light with a wavelength of λ1 is (x1, h1), and the image plane coordinate point focused on the imaging plane after passing through the pinhole x1ˋ on the pinhole mask array plate 131 is (x1ˋˋ, y1). The position information of the object to be measured carried by the outgoing light with a wavelength of λ2 is (x2, h2), and the image plane coordinate point focused on the imaging plane after passing through the pinhole x2ˋ on the pinhole mask array plate 131 is (x2ˋˋ, y2). Similarly, for example, if n points are sampled on a scanning line of the object to be measured, the position information of the object to be measured carried by the outgoing light with a wavelength of λn is (xn, hn), and the image plane coordinate point focused on the imaging plane after passing through the pinhole xnˋ on the pinhole mask array plate 131 is (xnˋˋ, yn).
[0058] Furthermore, we can Figure 1 and / or Figure 2 The apertures provided are set at Figure 3 or Figure 4 At least one of the positions 1, 2 and 3 shown. In addition, more apertures can be provided in the spectral confocal measurement device of the present application, and the apertures can also be placed in other suitable positions to best improve the imaging quality of the device.
[0059] Figure 5 Schematic diagram of focusing light paths at different target heights corresponding to the aperture provided in the embodiment of the present application; Figure 5 As shown in the figure, different target wavelengths λ1 / λ2 / λ3 are focused at different heights, that is, the target wavelengths corresponding to different heights h1 / h2 / h3 are λ1 / λ2 / λ3 respectively. The wavelengths that are not focused at a certain target height (height) are non-target wavelengths and belong to the noise at this target height.
[0060] Figure 6 Schematic diagram of the optical path when there is no aperture in the spectral confocal measurement device provided in the embodiment of the present application; Figure 6 As shown in the figure: when there is no aperture, the first target wavelength λ1 is focused at the target height h1, and the second target wavelength λ2 is focused at the target height h2; when the first target wavelength λ1 is incident on the target height h2, it will become the non-target wavelength λ1 at the target height h2; if the diffuse reflection beam of the non-target wavelength λ1 at the target height h2 is Figure 6 When the arrow is in the triangular area and its direction passes through the focus point at the target height h1, it will become the non-target wavelength noise at the target height h2, which will cause the signal-to-noise ratio of the target wavelength λ2 at the target height h2 to decrease, affecting the imaging quality. The same is true for other target heights.
[0061] Figure 7 Schematic diagram of the optical path when an aperture is present in the spectral confocal measurement device provided in an embodiment of the present application; Figure 7 As shown: when the aperture is present, although the light intensity of the target wavelengths λ1 and λ2 focused at the target heights h1 and h2, respectively, is slightly reduced, the light shielding element in the aperture can correspondingly suppress the diffusely reflected light beams of non-target wavelengths at the target height; for example Figure 7 In the embodiment, a large number of diffusely reflected light beams of non-target wavelength λ1 in the triangular area at the target height h2 cannot continue to be incident on the spectral confocal measurement device, which greatly increases the signal-to-noise ratio of the target wavelength λ2 at the target height h2.
[0062] In a specific experiment, a person skilled in the art found through experiments that when no aperture is added, Figure 5The mixed intensity ratio of the target wavelength intensity at different target heights h1, h2 and h3 shown in the figure is 0.5:1:0.4; after adding the aperture, the target wavelength intensity at h1, h2 and h3 is h1ˋ / h2ˋ / h3ˋ; in summary, by comparison: the target wavelength intensity ratio before and after adding the aperture: h1:h2:h3:h1ˋ:h2ˋ:h3ˋ=0.5:1:0.4:0.13:0.5:0.1. From the above comparison results, it can be seen that although the energy intensity at h2 is reduced, the components of h1 and h3 will be greatly reduced. Therefore, after adding the aperture, the spectral confocal measurement device can effectively reduce the noise at the target height h2, improve the signal-to-noise ratio, and enhance the imaging quality.
[0063] The aperture provided in the present application solves the problems of high noise, low signal-to-noise ratio and limited imaging accuracy in spectral confocal measurement devices; it can effectively suppress diffuse reflected light introduced by irregular structures on the surface to be measured, improve the signal-to-noise ratio, and thus improve the imaging quality of the system; the above-mentioned aperture structure is simple and adjustable, and can improve the imaging quality of the three-dimensional measurement system without affecting the performance of other parts of the system, simplify the design complexity, reduce the design difficulty and other technical problems.
[0064] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.
[0065] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.
[0066] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. An aperture, applied to a spectral confocal measurement device, in which light beams of different wavelengths are focused at different heights, characterized in that: The aperture comprises: a light shielding member and a main body member; The main body is provided with a light passage inside; The shading member is arranged inside the main body and coaxially with the light passage, so that at least part of the light beam passing through the aperture cannot pass through the light passage due to the shading of the shading member.
2. The diaphragm according to claim 1, characterized in that The light passage is a circular light passage.
3. The aperture according to claim 1, characterized in that The shading element is a circular light-proof thin sheet structure.
4. A spectral confocal measurement device, characterized in that: include: At least one aperture as claimed in any one of claims 1 to 3, and an illumination assembly, a beam splitter, a dispersive objective assembly, and an imaging assembly; The illumination assembly, the beam splitter and the dispersion objective lens assembly are coaxially arranged in sequence; The beam splitter is capable of transmitting the incident light beam output by the illumination assembly to the dispersion objective lens assembly; The dispersion objective lens assembly is used to disperse the light of different wavelengths in the transmitted incident light beam so that the light of different wavelengths is focused at different heights of the object to be measured; and receiving a reflected light beam reflected by the surface of the object to be measured, and emitting the reflected light beam to the beam splitter; The beam splitter reflects the received reflected light beam to the imaging component; The imaging component is arranged on the reflection light path of the beam splitter to form an image of the received reflection light beam; The at least one aperture is arranged in the reflection light path between the object to be measured and the imaging component.
5. The spectral confocal measurement device according to claim 4, characterized in that: Also includes: A pinhole mask array plate; The pinhole mask array plate is provided with a plurality of rows and columns of pinholes arranged at intervals, which are arranged one-to-one corresponding to the different heights. The outgoing light of each wavelength reflected by the height is focused to the corresponding pinhole of the pinhole mask array plate and emitted from the corresponding pinhole.
6. The spectral confocal measurement device according to claim 5, characterized in that: The pinhole mask array plate is arranged between the beam splitter and the dispersive objective lens assembly; or the pinhole mask array plate includes two, the first pinhole mask array plate is arranged between the illumination assembly and the beam splitter, and the second pinhole mask array plate is arranged between the beam splitter and the imaging assembly.
7. The spectral confocal measurement device according to any one of claims 4 to 6, characterized in that: The at least one aperture is arranged at at least one of the following positions: between the object to be measured and the dispersive objective lens assembly, between the dispersive objective lens assembly and the beam splitter, or between the beam splitter and the imaging assembly.