Composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements

Abstract

This invention relates to a composite vibration-assisted flexible conformal polishing device for complex curved optical elements, comprising a gantry with a worktable positioned below it; a vertical vibration mechanism is positioned on the gantry facing the working bearing area to provide vertical vibration force; a flexible conformal polishing disk conformally and uniformly fits the optical element to its lower end; the optical element is located on a horizontal sliding vibration mechanism in the working bearing area, achieving short-distance reciprocating sliding vibration in the lateral direction; the short-distance reciprocating sliding vibration in the lateral direction and the vertical vibration combine to form a composite vibration. The vibration of the flexible conformal polishing disk in both the vertical and horizontal directions improves the material removal efficiency of the optical element and enhances the fit characteristics of the flexible conformal polishing disk to the complex curved optical element, thereby improving the smoothness of small-scale ripples. It can be used for rapid removal of defects remaining from previous processing during rough polishing, and can also be used to remove small-scale ripples after sub-aperture polishing.

Description

Technical Field

[0001] This invention relates to the field of optical processing technology, and more specifically to a composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements. Background Technology

[0002] Polishing techniques for optical components include two categories: full-aperture polishing and sub-aperture polishing. Full-aperture polishing, a traditional technique with a long history, uses a large polishing disc. During polishing, the entire surface of the component is in contact with the disc simultaneously. Therefore, full-aperture polishing has significant advantages in suppressing mid-frequency waviness errors, improving processing efficiency, and reducing processing costs. However, because large polishing discs make it difficult to selectively remove high and low areas from the component surface, full-aperture polishing faces significant challenges in achieving high-precision, deterministic control of low-frequency surface shape errors. Therefore, sub-aperture polishing is usually required for subsequent low-frequency surface shape convergence processing. Sub-aperture polishing, a deterministic polishing technique developed with the advent of computer technology in the 1970s, uses small-sized removal tools to selectively remove local areas of the component surface to correct shape errors. Therefore, it has significant advantages in deterministic control of low-frequency surface shape errors. However, when small-sized removal tools scan the component surface to correct low-frequency surface shape errors, small-scale waviness is introduced into the component surface due to convolution effects, polishing spot instability, and residence time deviations, thus affecting mid-frequency errors. In recent years, the impact of mid-frequency waviness error on the performance of optical systems has received increasing attention from the industry and has become a key technical indicator that urgently needs to be improved during the processing of optical components.

[0003] Complex curved surface optical elements are optical elements with varying radii of curvature on their surfaces. They mainly include aspherical elements and freeform surface elements, and have wide applications in high-power laser devices, conformal optical systems (conformal windows and fairings, etc.), photolithography systems, and astronomical telescope systems. Compared to planar and spherical optical elements, using complex curved surface optical elements in optical systems offers unique advantages in reducing the number of optical elements, simplifying the optical system structure, increasing design freedom, and achieving special optical performance. Therefore, it has gradually become one of the main development trends in the field of optical applications.

[0004] Traditional full-aperture polishing uses large-size polishing tools, primarily flexible asphalt polishing discs, artificial polyurethane pads, and damping cloths. Their working surfaces are typically planes and spheres with uniform radii of curvature. These tools are suitable for processing planar and spherical optical components with the same uniform radius of curvature. When the polishing tool moves a long distance across the component surface, it smooths out local ridges and grooves with varying radii of curvature. However, for aspherical, freeform, and conformal optical windows, due to the non-uniform radius of curvature on their surfaces, the polishing tool can easily damage localized areas with significant deviations in radius of curvature when moving long distances across the component surface.

[0005] Given the characteristic that the surface curvature radius of optical components changes slowly rather than abruptly, polishing can be achieved while maintaining the local curvature radius of the component surface by moving the polishing disc a very short distance. For components with non-uniform curvature radii, if the polishing tool can cover and conform well to the entire surface of the component—that is, if the polishing tool and the component have the same curvature radius in various local areas—then controlling the reciprocating movement of the polishing tool within a short range on the component surface can remove the surface material. Furthermore, because the curvature radius of the component surface changes slowly, the polishing tool can maintain the curvature radius of the component in various areas without being damaged during short-distance movement.

[0006] Therefore, given the difficulty of processing complex curved optical components using traditional full-aperture polishing and the tendency of sub-aperture polishing to generate small-scale ripples on the component surface, how to provide a composite vibration-assisted flexible conformal polishing device suitable for processing complex curved optical components is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] Therefore, the purpose of this invention is to propose a composite vibration-assisted flexible conformal polishing device for complex curved optical elements, which solves the problems that traditional full-aperture polishing is difficult to process complex curved optical elements and that sub-aperture polishing is prone to generating small-scale ripples on the element surface.

[0008] The present invention provides a composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements, comprising:

[0009] A gantry frame, with a workbench located below it, the top of the workbench and the area below the gantry frame forming a working load-bearing area;

[0010] A vertical vibration mechanism is provided on the gantry frame facing the working bearing area to provide vertical vibration force.

[0011] A flexible conformal polishing disk, wherein the lower end of the vertical vibration mechanism is fixed with a flexible conformal polishing disk that conforms to and uniformly fits the optical element;

[0012] And a horizontal sliding vibration mechanism, wherein the optical element is located on the horizontal sliding vibration mechanism in the working bearing area, and the horizontal sliding vibration mechanism realizes the transverse short-distance reciprocating sliding vibration; the transverse short-distance reciprocating sliding vibration and the vertical vibration are combined to form a composite vibration.

[0013] Furthermore, the gantry frame is fixed to the foundation or workbench.

[0014] Furthermore, the working bearing area provides a bearing space for polishing the optical element in both the vertical and horizontal directions simultaneously.

[0015] Furthermore, the vertical vibration mechanism is an ultrasonic transducer, which is connected to an ultrasonic generator.

[0016] Furthermore, the horizontal sliding vibration mechanism includes:

[0017] A mechanical vibration unit, which is fixed to the top of the worktable;

[0018] A sliding part is provided on the worktable, arranged parallel to the mechanical vibration part, and the sliding part is connected to the output end of the mechanical vibration part;

[0019] The top end of the sliding part is connected to the support part that supports the optical element.

[0020] Furthermore, the mechanical vibration unit is an exciter or a voice coil motor, and is connected to a vibration controller.

[0021] Furthermore, the sliding part adopts a short-distance reciprocating linear sliding of a sliding table module.

[0022] Furthermore, the slide module includes:

[0023] A base, which is fixed to the worktable;

[0024] The base has two sets of linear rails at its top.

[0025] A slider is slidably mounted on the linear guide and is connected to the output end of the mechanical vibration unit.

[0026] Furthermore, the supporting part is a tray, which is connected to the sliding part. It is provided with an upward enclosure and forms a polishing liquid storage area, which is provided with a liquid outlet channel.

[0027] Furthermore, the flexible conformal polishing disk is composed of a rigid substrate, a flexible layer, and a polishing layer, and the rigid substrate is fixed to the lower end of the vertical vibration mechanism.

[0028] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a composite vibration-assisted flexible conformal polishing device for complex curved optical elements. By driving the flexible conformal polishing disk to vibrate in the vertical and horizontal directions, the material removal efficiency of the optical element is improved, and the fitting characteristics of the flexible conformal polishing disk to the complex curved optical element are improved, thereby enhancing the smoothing effect of small-scale ripples. Composite vibration-assisted full-aperture conformal polishing can be used for rough polishing to quickly remove surface / subsurface defects remaining from previous processing, and can also be used to remove small-scale ripples after sub-aperture polishing.

[0029] The flexible conformal polishing disk structure enables uniform contact with complex curved optical elements, improving the material removal effect for complex curved optical elements. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 The attached figure is a schematic diagram of the structure of the composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements provided by the present invention;

[0032] Figure 2 The attached figure is a top view of the composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements provided by the present invention.

[0033] Figure 3 The attached figure is a schematic diagram of the tray and sliding module of the composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements provided by the present invention.

[0034] Figure 4 The attached figure illustrates a structural schematic diagram of a specific embodiment of the flexible conformal polishing disk of the present invention;

[0035] Figure 5 The attached figure illustrates the surface shape error distribution before and after polishing the optical element using the device of the present invention. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] Complex curved surface optical elements are optical elements with varying radii of curvature, mainly including aspherical elements and freeform surface elements. In existing technologies, traditional full-aperture polishing typically uses planes and spheres with uniform radii of curvature. These polishing tools are suitable for processing plane and spherical optical elements with the same uniform radius of curvature. However, when the polishing tool moves a long distance across the element surface, it smooths out local ridges and grooves with different radii of curvature. For complex curved surface optical elements, traditional full-aperture polishing tools easily damage local areas with large deviations in radius of curvature when moving long distances across the element surface. Sub-aperture polishing corrects shape errors by selectively removing local areas of the element surface using small-sized removal tools. Therefore, it has a significant advantage in the deterministic control of low-frequency surface shape errors. However, when small-sized removal tools scan the element surface to correct low-frequency surface shape errors, small-scale ripples are introduced into the element surface due to convolution effects, polishing spot instability, and residence time deviations, thus affecting mid-frequency errors.

[0040] In view of this, for the fabrication of complex curved optical elements, embodiments of the present invention disclose a composite vibration-assisted flexible conformal polishing device for complex curved optical elements, see appendix. Figure 1-3 The system includes: a gantry frame 1, with a worktable 2 positioned below the gantry frame 1, the top of the worktable 2 forming a working bearing area with the bottom of the gantry frame 1; a vertical vibration mechanism 3, with the gantry frame 1 facing the working bearing area, for providing vertical vibration force; a flexible conformal polishing disk 4, with the lower end of the vertical vibration mechanism 3 fixed with a flexible conformal polishing disk 4 that conforms to and uniformly fits the optical element 8; and a horizontal sliding vibration mechanism, with the optical element 8 located on the horizontal sliding vibration mechanism in the working bearing area, achieving lateral short-distance reciprocating sliding vibration through the horizontal sliding vibration mechanism; the lateral short-distance reciprocating sliding vibration combined with the vertical vibration forms a composite vibration.

[0041] The above-described embodiments improve the material removal efficiency of optical elements by driving the flexible conformal polishing disk to vibrate in both the vertical and horizontal directions, and also improve the fitting characteristics of the flexible conformal polishing disk for complex curved optical elements, thereby enhancing the smoothing effect of small-scale ripples. Composite vibration-assisted full-aperture conformal polishing can be used for rough polishing to quickly remove surface / subsurface defects remaining from previous processing, and can also be used to remove small-scale ripples after sub-aperture polishing, overcoming the shortcomings of existing full-aperture and sub-aperture polishing techniques for complex curved optical elements.

[0042] It is worth noting that the short distance referred to in this invention is relative to the long distance of a full-diameter polishing device.

[0043] In the above embodiments, the gantry frame 1 can be directly fixed to the foundation or fixed to both sides of the workbench 2.

[0044] The aforementioned working bearing area refers to the bearing space that can provide for the simultaneous polishing of the optical element 8 in both the vertical and horizontal directions. In other words, there are no requirements for the specific structural shape formed by the gantry 1 and the worktable 2, as long as it can meet the vibration processing requirements in both the vertical and horizontal directions of the optical element.

[0045] In a specific embodiment of the present invention, see the appendix. Figure 1 The vertical vibration mechanism 3 is an ultrasonic transducer, which is connected to an ultrasonic generator 30, which can be located outside the worktable 2. The ultrasonic transducer drives the flexible conformal polishing disk 4 to perform ultrasonic vibration at a designed frequency and amplitude. A frequency of 20kHz and an amplitude of 50μm can be designed to drive the flexible conformal polishing disk 4 to perform ultrasonic vibration.

[0046] More advantageously, in a specific embodiment of the present invention, the horizontal sliding vibration mechanism includes: a mechanical vibration part 5, which is fixed to the top of the worktable 2; a sliding part, which is arranged parallel to the mechanical vibration part 5 on the worktable 2 and connected to the output end of the mechanical vibration part 5; and a support part, whose top end is connected to a support part for supporting the optical element 8. Thus, the support part moves laterally following the sliding part, and the mechanical vibration part 5 provides power to the sliding part.

[0047] In a preferred embodiment, the mechanical vibration unit 5 is an exciter or a voice coil motor, and is connected to a vibration controller 50, which can be located outside the workbench 2.

[0048] In an embodiment of the present invention, the sliding part employs a slide module 6 for short-distance reciprocating linear sliding. Specifically, the slide module 6 includes: a base 63, which is fixed to the worktable 2; linear rails 62, with two sets of linear rails 62 formed on the top of the base 63; and a slider 61, which slides on the linear rails 62 and is connected to the output end of the mechanical vibration part 5.

[0049] See Appendix Figure 2 The output end of the mechanical vibration unit 5 is connected to an output rod 51 and a connecting rod 52. The output rod 51 is a straight rod structure, and its end is connected to one end of the connecting rod 52. The connecting rod is a bent rod, and the other end of the connecting rod 52 is connected to the slider 61, thus transmitting the power of the mechanical vibration unit 5 to the slider 61.

[0050] See appendix Figure 3 The supporting part is a tray 7, which is connected to the sliding part. It has an upward-facing enclosure and forms a polishing liquid storage area, which has an outlet channel. The enclosure can be made of plastic, and the polishing liquid can be discharged from the outlet channel.

[0051] See appendix Figure 4 The flexible conformal polishing disk 4 is sequentially and fixedly connected from top to bottom to a rigid substrate 41, a flexible layer 42, and a polishing layer 43 that conform to the optical element 8. The rigid substrate 41 is fixed to the lower end of the vertical vibration mechanism 3. The rigid substrate 41, flexible layer 42, and polishing layer 43 can be bonded together with high-strength adhesive to form a whole, or fixed together with fasteners, which must not extend beyond the working surface of the polishing layer 43; alternatively, they can be fixed together as a whole by external fixing on the basis of bonding. The size of the flexible conformal polishing disk is slightly larger than that of the optical element to be processed. The diameter of the flexible conformal polishing disk 4 is 200mm, and the diameter of the optical element to be processed 8 is 180mm. The curvatures of the flexible conformal polishing disk are adapted to the curvatures of the optical element. The structural design of the flexible conformal polishing disk achieves uniform contact with complex curved optical elements, improving the material removal effect for complex curved optical elements.

[0052] When processing using the above-described device, the optical element to be processed is fixed in a tray. Polishing slurry (cerium oxide polishing slurry, particle size ~1μm) is evenly sprayed onto the surface of the optical element, and the slurry is supplied into the tray to immerse the optical element. The flexible conformal polishing disk is fixedly connected to an ultrasonic transducer, ensuring that the flexible conformal polishing disk uniformly conforms to the optical element. The ultrasonic transducer drives the flexible conformal polishing disk to perform ultrasonic vibration in the vertical direction; the vibration output rod of the mechanical vibration mechanism drives the slider of the slide module, the tray fixed on the slider, and the optical element to be processed through the connecting rod, to perform mechanical vibration along the linear track. Vertical ultrasonic mechanical vibration and horizontal mechanical vibration are formed between the flexible conformal polishing disk and the optical element, and the flexible conformal polishing disk removes material from the surface of the optical element.

[0053] See appendix Figure 5 The left view is a schematic diagram of the surface shape error of an optical element without polishing by the device of the present invention, and the right view is a schematic diagram of the surface shape error of an optical element polished by the device of the present invention. In comparison, the optical element without polishing by the device of the present invention has obvious small-scale wavy texture on its surface after being shaped and polished by sub-aperture magnetorheological polishing technology. After being polished by the device of the present invention, the small-scale wavy texture is significantly smoothed.

[0054] This invention proposes a combined ultrasonic and mechanical vibration polishing method. By driving a flexible conformal polishing disk to perform ultrasonic vibration in the vertical direction, combined with mechanical vibration of the optical element in the horizontal direction, the material removal efficiency of the optical element is improved. Furthermore, the fit of the flexible conformal polishing disk to complex curved optical elements is enhanced, thereby improving the smoothness of small-scale ripples. Ultrasonic and mechanical vibration-assisted full-aperture conformal polishing can be used for rough polishing to quickly remove surface / subsurface defects remaining from previous processing, and can also be used after sub-aperture polishing to remove small-scale ripples.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0056] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements, characterized in that, include: A gantry frame (1) is provided below the gantry frame (1), and the top of the workbench (2) and the bottom of the gantry frame (1) form a working load-bearing area; A vertical vibration mechanism (3) is provided on the gantry (1) facing the working bearing area, for providing vertical vibration force; Flexible conformal polishing disk (4), the lower end of the vertical vibration mechanism (3) is fixed with a flexible conformal polishing disk (4) that conforms to and is uniformly attached to the optical element (8); And a horizontal sliding vibration mechanism, wherein the optical element (8) is located on the horizontal sliding vibration mechanism in the working bearing area, and the horizontal sliding vibration mechanism realizes lateral short-distance reciprocating sliding vibration; The combination of lateral short-distance reciprocating sliding vibration and vertical vibration forms a composite vibration; The horizontal sliding vibration mechanism includes: a mechanical vibration part (5) fixed to the top of the worktable (2); a sliding part arranged on the worktable (2) alongside the mechanical vibration part (5) and connected to the output end of the mechanical vibration part (5); and a support part connected to the top of the sliding part to support the optical element (8). The mechanical vibration unit (5) is an exciter or a voice coil motor and is connected to the vibration controller (50); The sliding part adopts a short-distance reciprocating linear sliding of a sliding table module (6).

2. The composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements according to claim 1, characterized in that, The gantry (1) is fixed on the foundation or workbench (2).

3. The composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements according to claim 1, characterized in that, The working bearing area provides a bearing space for the optical element (8) to be polished in both the vertical and horizontal directions.

4. The composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements according to claim 1, characterized in that, The vertical vibration mechanism (3) is an ultrasonic transducer, which is connected to the ultrasonic generator (30).

5. The composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements according to claim 1, characterized in that, The slide module (6) includes: A base (63) is fixed to the workbench (2); The base (63) has two sets of linear rails (62) on its top. A slider (61) slides on the linear guide (62) and is connected to the output end of the mechanical vibration unit (5).

6. The composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements according to claim 1, characterized in that, The supporting part is a tray (7), which is connected to the sliding part. It is surrounded by a barrier and forms a polishing liquid storage area. The polishing liquid storage area is provided with a liquid outlet channel.

7. The composite vibration-assisted flexible conformal polishing device for complex curved surface optical elements according to any one of claims 1-6, characterized in that, The flexible conformal polishing disk (4) is composed of a rigid substrate (41), a flexible layer (42) and a polishing layer (43), and the rigid substrate (41) is fixed to the lower end of the vertical vibration mechanism (3).

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