Additive fabrication of optical components

Abstract

To provide improved manufacture of glass optical elements such as mirror substrates.SOLUTION: A method of forming an optical component includes depositing slurry that includes glass powder material onto a facesheet, and fusing the glass powder material to the facesheet to form a first core material layer on the facesheet. The method also includes successively fusing the glass powder material in a plurality of additional core material layers to build a core material structure on the facesheet. The method can include selectively depositing slurry including the glass powder material over only a portion of at least one of the facesheet, the first core material layer and / or one of the additional core material layers. Depositing the slurry can also include extruding the slurry from an extruder.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to optical elements and additive manufacturing, and more particularly, to, for example, additive manufacturing of optical elements from low-expansion glass.

Background Art

[0002] Conventional lightweight glass mirror substrates are produced by subtractive manufacturing, milling, grinding, polishing, or etching material away from large glass boules. These processes can create a rigid lightweight glass structure with an accurately shaped optical surface that is stable under thermal and mechanical loads. However, because glass is brittle, it is difficult to produce many small, complex features using these conventional processes, and such complex features can be important for the manufacture of lightweight optical elements.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The prior art has been considered adequate for its original purpose. However, there remains a need to improve the manufacture of glass optical elements such as mirror substrates. The present disclosure provides a solution to this problem.

Means for Solving the Problems

[0004] A method of forming an optical component includes depositing a slurry comprising a glass powder material onto a surface plate and fusing the glass powder material to the surface plate to form a first core material layer on the surface plate. The method also includes continuously fusing the glass powder material into a plurality of additional core material layers to create a core material structure on the surface plate.

[0005] The method includes disposing the surface plate on a mandrel before fusing the glass powder material to the surface plate The fusion of glass powder material to a surface plate may also include the step of fusing the glass powder material to a polishable surface of the surface plate. At least one of the steps of depositing a slurry containing glass powder material and fusing glass powder material sequentially to form a plurality of additional core material layers may include the step of selectively placing the slurry containing glass powder material on only a portion of at least one of the surface plate, the first core material layer, and / or one of the additional core material layers. The step of depositing the slurry may include the step of extruding the slurry from an extruder. The fusion of glass powder material may include, for example, the step of fusing low-expansion glass powder to form low-expansion glass using a laser. The fusion of glass powder material may include the step of fusing low-expansion titania silica glass powder to form low-expansion titania silica glass. The fusion of glass powder material to a surface plate may include the step of fusing glass powder material to a surface plate with a contour that matches the optical properties.

[0006] The step of continuously fusing glass powder materials may include the step of forming a mirror substrate. The formation of the mirror substrate may include the step of forming an optimal three-dimensional mirror topology that minimizes the mass of the mirror substrate while providing a level of rigidity and stability that exceeds predetermined minimum requirements. The step of continuously fusing glass powder materials may include the step of varying various material properties in the form of a continuous layer, and / or the step of varying material properties based on the position within the continuous layer.

[0007] The optical components include a glass surface plate. A first layer of low-expansion glass is fused to the glass surface plate. Multiple successively fused layers form a core material structure on the assembly including the surface plate and the first layer.

[0008] The surface plate is two-dimensional or three-dimensional, and may be contoured to match optical properties. The surface plate may include a polishable surface. The first layer is fused to the polishable surface of the surface plate. The first layer and the multiple consecutively fused layers may include a fused low-expansion glass powder material, such as low-expansion titania silica glass powder. The surface plate, the first layer, and the consecutively fused layers can form a mirror substrate. The mirror substrate may include an optimal three-dimensional mirror topology that minimizes the mass of the mirror substrate while providing a level of rigidity and stability exceeding predetermined minimum requirements. The multiple consecutively fused layers may include a glass material, which has material properties that vary in the form of the consecutive layers and / or based on its position within the core material structure.

[0009] These and other features of the system and method of the subject matter of the disclosure will be readily apparent to those skilled in the art by reading the following detailed description of preferred embodiments together with the drawings.

[0010] Preferred embodiments of the apparatus and method are described below in detail with reference to the drawings, so that a person skilled in the art to which the subject matter of the disclosure belongs may easily understand the method of manufacture and use of the apparatus and method of the subject matter of the disclosure without excessive experimentation. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic side elevation view of an exemplary embodiment of a mirror substrate constructed according to the present disclosure, showing a mandrel, a surface plate, and a core material structure of a continuous layer that has been additively fabricated and deposited on the surface plate. [Figure 2] Figure 1 is a schematic perspective view of a mirror substrate, showing how an extruder selectively deposits a slurry of glass powder material. [Figure 3] This is a schematic plan view of the mirror substrate shown in Figure 1, illustrating how a laser beam fuses powder materials. [Modes for carrying out the invention]

[0012] Refer to the drawings. In the drawings, similar reference numerals indicate similar structural features or aspects of the subject matter of the disclosure. Optical components of this disclosure are described and illustrated, not limiting, for illustrative purposes. A partial diagram of an exemplary embodiment is shown in Figure 1, generally designated by reference numeral 100. Other embodiments or aspects thereof of the optical components according to this disclosure are shown in Figures 2 and 3 and described below. Using the systems and methods described herein, optical components such as mirror substrates can be additively fabricated from low thermal expansion glass.

[0013] Figure 1 shows an optical component 100, such as a mirror substrate, on a mandrel 102. A method for forming the optical component 100 includes placing a preformed glass surface plate 104 on the mandrel 102. The surface plate 104 may be made of titania silica glass, may be relatively thin, and may be contoured to suit optical properties, for example, to provide a desired or predetermined mirror contour in two or three dimensions. A glass powder material is fused to a polishable surface 114 of the surface plate 104 to form a first core material layer 106 on the surface plate 104. The glass powder material is then fused sequentially in the form of a plurality of additional core material layers 108 to create a core material structure 110 on the surface plate 104. The final layer 112 is fused to the surface of the core material structure 110 opposite to the surface plate 104, as seen from the first layer 106. The surface plate 104 becomes part of the final optical component 100.

[0014] Referring to Figure 2, the method involves depositing a liquid slurry containing glass powder material onto the polishable surface 114 of the surface plate 104 by depositing the slurry using a connected extruder 124. The extruder 124 is connected to a conveyor system 126 to selectively deposit the slurry onto only a portion of at least one of the surface plate 104, the first core material layer 106, and / or one of the additional core material layers 108. In other words, the extruder 124 extrudes the slurry onto the top surface of an assembly 115 including the surface plate 104, the first core material layer 106, and / or one or more of the additional core material layers 108, as arranged in Figures 1 and 2. The slurry may contain glass powder material, which is suspended in a liquid gel, water, or a fluid suitable for extrusion through a nozzle 128 for precise and selective deposition or printing onto the assembly 115. The slurry, after being deposited, can be dried to obtain a dry powder of glass material that can be fused into the assembly 115. The glass powder material can be configured to form a low-expansion glass material when fused; for example, low-expansion titania silica glass powder can be fused to form low-expansion titania silica glass.

[0015] Referring to Figure 3, each of these powder layers is fused into the assembly 115 to form a cross-section of the desired shape, becoming the core material structure 110. Fusion can be performed using a laser beam 116. Figure 3 schematically shows that the laser beam 116 fuses a portion 118 of the deposited powder covering the assembly 115 to form a glass layer fused only in the triangle shown in the figure. The direction of movement of the laser beam 116 around the triangular pattern is indicated by the large arrow in Figure 3. The portion 120 of the powder fused by the laser beam 116 is schematically shown in Figure 3. After fusing a given layer, before depositing a slurry for the next layer, mechanical polishing and grinding can optionally be used in creating the assembly 115, for example, to ensure that the fused layer has a uniform thickness.

[0016] This technology enables mirror substrates or other optical components having an optimal three-dimensional topology that minimizes the mass of the mirror substrate while providing a level of rigidity and stability exceeding predetermined minimum requirements. The continuously fused layers described herein may involve fusing glass powder materials such that the material properties change in the form of a continuous layer and / or based on the position within a given layer. For example, the triangular portion 118 in Figure 2 can be formed from glass having a first set of material properties, and the remaining portion 122 on the surface of the assembly 115 can be formed from glass having a second set of material properties, so that a given layer 108 has different sets of material properties within the layer itself as a function of the position within the layer 108.

[0017] Unlike conventional additive manufacturing, where a portion is printed onto a build plate and then removed from the build plate, the surface plate 104 functions as both a build plate and part of the final product. As a finishing step, the final layer 112 and / or the opposite surface 130 of the surface plate 104 shown in Figure 1 can be polished and coated.

[0018] The methods and systems of the present disclosure, as described above and as shown in the drawings, provide an optical component having an optimal three-dimensional geometric topology, including an amorphous topology having superior properties that may include very complex features and smaller complex features that cannot be reliably produced using conventional techniques, to achieve the required rigidity and stability for a given application and load, for example, minimizing the mass of a mirror substrate. Compared to the prior art, it is also possible to manufacture low-expansion glass more quickly using the techniques disclosed herein, and it is possible to create larger glass mirror substrates than in the prior art. With respect to enabling the creation of a glass mirror substrate larger than the size possible using conventional techniques with a build plate, this results from the fact that, under the prior art, high-temperature additive manufacturing can cause thermal stresses that distort parts during manufacture and that there is a risk that those parts may peel away from the build plate. This peeling process limits how large a component can be manufactured under conventional additive manufacturing techniques, but not under the techniques disclosed herein. The thermal expansion behavior and viscoelastic behavior of titania silica glass at high temperatures are important for the realization of larger additive manufacturing structures. The fusing of the additive manufacturing layers to the build plate is also important for the realization of larger additive manufacturing structures.

[0019] The apparatus and method of the disclosed subject matter have been shown and described with reference to preferred embodiments, and it will be readily understood by those skilled in the art that changes and / or modifications may be made to the apparatus and method of the disclosed subject matter without departing from the scope of the disclosed subject matter.

Description of the Reference Numerals

[0020] 100 Optical component 102 Mandrel 104 Surface plate 106 Core material layer 108 Core material layer 110 Core material structure 112 Final layer 114 Surface 115 Assembly 116 Laser beam Part of the deposited powder Portion of the powder to be fused Remaining portion Connecting extruder Conveyor system Nozzle Opposite surface

Claims

1. The steps include: arranging a substrate for an optical component, which has a preformed glass surface plate mounted on a mandrel; A step of forming a layered core material structure on the substrate, comprising depositing different slurries containing glass powder material on at least one of the surface plate and an already formed portion of the layered core material structure, and forming the layered core material structure on the substrate by fusing the deposited glass powder material using laser irradiation, Includes, A method for forming an optical component in which at least one layer of the layered core material structure has a uniform thickness and, after being fused by laser irradiation, has different optical properties depending on its position within the layer.

2. The method according to claim 1, further comprising the step of mechanically polishing the at least one layer of the layered core material structure so that the at least one layer has a uniform thickness.

3. The method according to claim 1, wherein, after the formation of the layered core material structure, the layered core material structure has a three-dimensional geometric topology.

4. The method according to claim 1, wherein the at least one layer of the layered core material structure contains different glass materials within a uniform thickness of the at least one layer.

5. The at least one layer of the layered core material structure is A step of selectively depositing a first slurry containing a first glass powder material onto only a first portion of at least one of the already deposited layers of the surface plate and the layered core material structure, A step of selectively depositing a second slurry containing a second glass powder material different from the first glass powder material onto only a second portion of at least one of the already deposited layers of the surface plate and the layered core material structure, The method according to claim 1, formed by...

6. The method according to claim 1, wherein the step of depositing the different slurries includes the step of extruding each of the different slurries from an extruder.

7. The method according to claim 1, wherein the step of fusing the deposited glass powder material includes moving a laser beam along the deposited glass powder material.

8. The method according to claim 1, wherein each of the different slurries comprises a glass powder material suspended in a liquid gel.

9. The method according to claim 1, further comprising drying the deposited slurry containing the glass powder material before fusing the deposited glass powder material.

10. The method according to claim 1, wherein each glass powder material comprises low-expansion titania silica glass powder.

11. The method according to claim 1, further comprising polishing the outer surface of the layered core material structure on the side opposite to the substrate.

12. The method according to claim 1, further comprising applying a coating to the outer surface of the layered core material structure opposite to the substrate.

13. The method according to claim 12, wherein the coating is a mirror coating.

14. The method according to claim 3, wherein the three-dimensional geometric topology is amorphous topology.

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