Patent Application
20180127297
The present disclosure relates to optics and additive manufacturing, and more particularly to additively manufacturing optics e.g., from low expansion glass.
Conventional lightweight glass mirror substrates are generated with subtractive manufacturing, milling, grinding, polishing, or etching away material from a large glass boule. These processes can create a stiff, lightweight glass structure with a precisely shaped optical surface, which remains stable under thermal and mechanical loads. But because glass is fragile, it is challenging to manufacture many small, intricate features with these conventional processes, and such intricate features can be important to manufacturing lightweight optics.
The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved manufacturing of glass optics such as mirror substrates. This disclosure provides a solution for this problem.
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 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 glass powder material to the facesheet. Fusing glass powder material to the facesheet can include fusing the glass powder material to a side of the facesheet opposing a polishable surface of the facesheet.
At least one of fusing glass powder to form the first core material layer and successively fusing glass powder material in a plurality of additional core material layers can include:
depositing powder over at least one of the facesheet, the first core material layer, and/or the one of the additional core material layers; and
selectively fusing only a portion of the powder.
Depositing powder can include depositing powder over an entire assembly of the facesheet and any subsequently layers of glass subsequently fused thereto. Fusing glass powder material can include fusing low expansion glass powder into low expansion glass. Fusing glass powder material can include fusing low expansion titania-silica glass powder into low expansion titania-silica glass. Fusing glass powder material to a facesheet can include fusing glass powder material to a facesheet that is contoured for optical properties.
Successively fusing glass powder material can include forming a mirror substrate. Forming a mirror substrate can include forming an optimal three-dimensional mirror topology that minimizes the mass of mirror substrate while providing a level of stiffness and stability above a predetermined minimum requirement. Successively fusing glass powder material can include varying material properties in successive layers and/or varying material properties based on position in the successive layers.
An optical component includes a glass facesheet. A first layer of low expansion glass is fused to the glass facesheet. A plurality of successively fused layers form a core material structure on an assembly that includes the facesheet and the first layer.
The facesheet can be contoured for optical properties. A front side of the facesheet can include a polishable surface. The first layer can be fused to a side of the facesheet opposite the polishable surface of the facesheet. The first layer and the plurality of successively fused layers can include fused low expansion glass powder material, e.g., low expansion titania-silica glass powder. The facesheet, first layer, and successively fused layers can form a mirror substrate. The mirror substrate can include an optimal three-dimensional mirror topology that minimizes the mass of mirror substrate while providing a level of stiffness and stability above a predetermined minimum requirement. The plurality of successively fused layers can include glass material with material properties that vary in successive layers and or that vary based on position within the core material structure.
These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of an optical component in accordance with the disclosure is shown in
Referring now to
Each such layer of powder is fused either in its entirety or can be only selectively fused so that only a portion of the powder is actually fused to the assembly 115 to form the cross-section of the desired geometry into the core material structure 110. The fusion can be achieved by using a laser beam, e.g., of a CO2 laser, however any suitable type of laser can be used. In
Unlike conventional additive manufacturing, where a part is printed on a build plate and later removed therefrom, the facesheet 104 serves as a build plate and also becomes part of the finished product. As a finishing process, the front surface of facesheet 104 shown in
The methods and systems of the present disclosure, as described above and shown in the drawings, provide for optical components with superior properties potentially including very intricate features, optimal three-dimensional geometric topologies, including amorphous topologies with smaller more intricate features than in conventional techniques, to minimize mass, e.g., of mirror substrates, while achieving required stiffness and stability for given applications and loads. It is also possible to provide quicker fabrication of low expansion glass using techniques disclosed herein, compared to conventional techniques, and it is possible to make larger glass mirror substrates than in convention techniques. With respect to allowing making larger glass mirror substrates than in conventional techniques using build plates, this stems from the fact that under conventional techniques, the high temperatures of additive manufacturing can case thermal stresses during manufacture that warp a part and can cause it to peel off from the build-plate. This peeling process limits how large a component can be manufactured under conventional techniques, but it is not a limitation for techniques disclosed herein.
While the apparatus and methods 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.
