Powder bed additive manufacturing of low expansion glass

Abstract

To provide improved manufacturing of glass optics.SOLUTION: A method of forming an optical component includes fusing glass powder material to a 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 positioning the facesheet on a mandrel prior to fusing the glass powder material to the facesheet. Fusing the glass powder material to the facesheet can include fusing the glass powder material to a polishable surface of the facesheet.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventional lightweight glass reflector substrates are created by subtracting, milling, grinding, polishing, or etching material from larger glass boules. These methods can produce rigid, lightweight glass structures with precisely engineered optical surfaces that remain stable under thermal and mechanical loads. However, because glass is fragile, it is difficult to fabricate many small, intricate features using these conventional methods, which can be critical to the production of lightweight optical elements. Summary of the Invention [Problem to be solved by the invention]

[0003] The prior art has been deemed satisfactory for these intended purposes. However, there is a continuing need for improved production of glass optical elements, such as reflector substrates. The present disclosure provides a solution for this problem. [Means for solving the problem]

[0004] A method of forming an optical element includes fusing a glass powder material to a face sheet to form a first core material layer on the face sheet. The method also includes sequentially fusing the glass powder material into a plurality of additional core material layers to build a core material structure on the face sheet.

[0005] The method can include placing the facesheet on a mandrel prior to fusing the glass powder material to the facesheet. Fusing the glass powder material to the facesheet can include fusing the glass powder material to a side of the facesheet opposite the polishable surface of the facesheet.

[0006] At least one of fusing the glass powder to form a first core material layer and sequentially fusing the glass powder material into a plurality of additional core material layers comprises: depositing a powder onto at least one of the face sheet, the first core material layer, and / or one of the additional core material layers; and selectively fusing only a portion of the powder; may include.

[0007] Depositing the powder may include depositing the powder on the entire assembly of the facesheet and any subsequent layers of glass subsequently fused thereto. Fusing the glass powder material may include fusing a low expansion glass powder into the low expansion glass. Fusing the glass powder material may include fusing a low expansion titania-silica glass powder into the low expansion titania-silica glass. Fusing the glass powder material to the facesheet may include fusing the glass powder material to the facesheet in close conformation with optical properties.

[0008] The sequential fusing of the glass powder materials can include forming a reflector substrate. The forming of the reflector substrate can include forming an optimal three-dimensional reflector morphology that minimizes reflector substrate mass while providing a level of stiffness and stability beyond a certain minimum necessary requirement. The sequential fusing of the glass powder materials can include varying material properties in subsequent layers and / or varying material properties based on position in subsequent layers.

[0009] The optical element includes a glass facesheet. A first layer of low expansion glass is fused to the glass facesheet. A plurality of sequentially fused layers form a core material structure over the assembly including the facesheet and the first layer.

[0010] The facesheet may be contoured for optical properties. The front surface of the facesheet may include a polishable surface. The first layer may be fused to a surface of the facesheet opposite the polishable surface of the facesheet. The first layer and the plurality of sequentially fused layers may include a fused low expansion glass powder material, such as a low expansion titania-silica glass powder. The facesheet, the first layer, and the sequentially fused layers may form a reflector substrate. The reflector substrate may include an optimized three-dimensional reflector morphology that minimizes reflector substrate mass while providing a level of stiffness and stability beyond a predetermined minimum requirement. The plurality of sequentially fused layers may include glass materials having different material properties among the sequential layers and / or based on location within the core material structure.

[0011] These and other features of the subject disclosed systems and methods will be more readily understood by those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.

[0012] Preferred embodiments thereof are described in detail herein below with reference to certain drawing figures so that those skilled in the art to which the subject disclosure pertains can readily understand, without undue experimentation, how to make and use the subject disclosure devices and methods. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic side view of an exemplary embodiment of a reflector substrate constructed in accordance with the present disclosure, showing a mandrel and a facesheet having successive layers of additively manufactured core material structures deposited on the facesheet. [Diagram 2] 2 is a schematic top view of the reflector substrate of FIG. 1 illustrating the laser beam selectively fusing portions of the powder material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Reference is now made to the drawings, in which like reference numbers indicate similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not by way of limitation, a partial view of an exemplary embodiment of an optical element according to the present disclosure is shown in FIG. 1, which is generally designated by the reference numeral 100. Another embodiment of an optical element according to the present disclosure or aspects thereof is shown in FIG. 2, as will be described later. The systems and methods described herein can be used for additive manufacturing of light-weidth reflector substrates from low thermal expansion glasses.

[0015] FIG. 1 shows an optical element 100, such as a reflector substrate, on a mandrel 102. The method of forming the optical element 100 includes placing a preformed glass face sheet 104 on the mandrel 102. The face sheet 104 may be made of titania-silica glass, may be relatively thin, and is contoured for optical properties, for example, to obtain a desired or predetermined reflector profile. A glass powder material is fused to a polishable surface 114 of the face sheet 104 to form a first core material layer 106 on the face sheet 104. The glass powder material is then sequentially fused into a number of additional core material layers 108 to build a core material structure 110 on the face sheet 104. A final layer 112 is fused to a surface of the core material structure 110 opposite the face sheet 104 from the first layer 106. The face sheet 104 becomes part of the finished optical element 100.

[0016] 2, during additive manufacturing, the powder for each successive layer 108 may be deposited over the entire top surface as oriented in FIG. 1, i.e., the surface where laser fusing of the assemblage 115 including the face sheet 104, the first core material layer 106, and / or the one or more additional core material layers 108 occurs. The powder may be deposited in a thin film by any other suitable technique and need not be selectively deposited. The glass powder material may be configured to form a low expansion glass material when the powder is fused, for example, low expansion titania-silica glass powder may be fused into a low expansion titania-silica glass powder.

[0017] Each such layer of powder may be fused in its entirety or may be fused only selectively, resulting in only a portion of the powder actually being fused to the mass 115 to form a cross-section of the desired shape in the core material structure 110. Fusing may be accomplished by using a laser beam, such as a CO2 laser, although any suitable type of laser may be used. In FIG. 2, a laser beam 116 is shown diagrammatically fusing a portion 118 of the deposited powder coating the mass 115 to form a layer of glass fused only in the triangular shape shown. The direction of movement of the laser beam 116 around the triangular pattern is indicated by the large arrow in FIG. 2. A portion 120 of the powder that is about to be fused by the laser beam 116 is shown diagrammatically in FIG. 2. This technique allows the formation of a reflector substrate or other optical element with an optimal three-dimensional morphology that minimizes the mass of the reflector substrate while providing a level of stiffness and stability beyond certain minimum requirements. Sequential fusing of layers as described herein may include fusing glass powder materials to vary material properties in subsequent layers and / or to vary material properties based on location in a given layer. For example, triangular portion 118 in FIG. 2 may be formed of glass having a first set of material properties, and the remaining portion 122 of the surface of the assemblage 115 may be formed of glass having a second set of material properties, such that a given layer 108 has a different set of material properties within it depending on location within the layer 108.

[0018] Unlike traditional additive manufacturing, where a part is printed on a build plate and then removed from it, facesheet 104 both functions as the build plate and becomes part of the finished product. As a finishing step, the front side of facesheet 104 shown in FIG. 1, i.e., the surface of facesheet 104 opposite layer 108, can be polished and coated.

[0019] The disclosed method and system described above and shown in the drawings provide optical elements with superior properties that may include highly complex features, optimal three-dimensional morphology (such as amorphous morphology with smaller complex features than conventional techniques to minimize mass, such as the reflector substrate, while providing the stiffness and stability required for a given application and load). The techniques disclosed herein can also provide faster production of low expansion glass compared to conventional techniques, and can make larger glass reflector substrates than conventional techniques. With regard to being able to make larger glass reflector substrates than conventional techniques using build plates, this is due to the fact that in conventional techniques, the high temperature of additive manufacturing can cause thermal stresses that distort the part during production and can cause it to peel off from the build plate. This peeling process limits how large an element can be made in conventional techniques, but is not a constraint of the techniques disclosed herein.

[0020] While the apparatus and method of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and / or modifications may be made thereto without departing from the scope of the subject disclosure. [Explanation of symbols]

[0021] 100 Optical Elements 102 Mandrel 104 Face Sheet 106 First core material layer 108 Core material layer 110 Core Material Structure 112 Final Layer 114 Polishable Surfaces 115 Aggregate 116 Laser Beam

Claims

1. fusing a glass powder material to a facesheet to form a first core material layer on the facesheet; and building a core material structure on said facesheet by sequentially fusing glass powder material into a plurality of additional core material layers; A method for forming an optical element comprising:

2. At least one of fusing glass powder to form the first core material layer and sequentially fusing glass powder material into a plurality of additional core material layers comprises: depositing a powder onto at least one of the facesheet, the first core material layer, and / or one of the additional core material layers; and selectively fusing only a portion of said powder; The method of claim 1 , comprising:

3. 10. The method of claim 1, wherein depositing the powder comprises depositing the powder over the entire assembly of the facesheet and any subsequent layers of glass that are subsequently fused thereto.

4. The method of claim 1 , wherein fusing the glass powder material comprises fusing a low expansion glass powder into a low expansion glass.

5. The method of claim 4, wherein fusing the glass powder material comprises fusing a low expansion titania-silica glass powder into the low expansion titania-silica glass.

6. The method of claim 1 , wherein fusing the glass powder material to the facesheet comprises fusing the glass powder material to a facesheet contoured for optical properties.

7. The method of claim 1 , further comprising placing the facesheet over a mandrel prior to fusing the glass powder material to the facesheet.

8. The method of claim 1 , wherein fusing the glass powder material to the facesheet comprises fusing the glass powder material to a side of the facesheet opposite the polishable surface of the facesheet.

9. The method of claim 1 , comprising sequentially fusing glass powder materials to form a reflector substrate.

10. 10. The method of claim 9, wherein forming the reflector substrate comprises forming an optimal three-dimensional reflector morphology that minimizes reflector substrate mass while providing a level of stiffness and stability that exceeds certain minimum requirements.

11. The method of claim 1 , wherein successive fusing of glass powder material includes varying the properties of the material in subsequent layers.

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