A light weight optical assembly comprising an optical surface, such as a mirror or an optically transparent surface, which surface is in the form of a plate and is supported by and fused to a fused silica perforated support structure, which support structure comprises walls extending longitudinally transverse to the major surfaces of the optical plate wherein the optical plate is fused to the walls at the interface of the ends of the walls and the rear surface of the optical plate, especially a device having a supporting structure whose perforations are of a diameter between 40 and 80 mm, which perforations are substantially uniformly distributed throughout its area, all extending generally axially parallel to each other, especially a support structure comprising large and small perforations with said small perforations having a smaller diameter, at least at the outer edge of the supporting structure.
This application is a continuation in part of applications, Ser. Nos. 491,525 and 630,147, filed Sept. 30, 1965 and Sept. 23, 1966 respectively, both now abandoned, the contents of which applications are incorporated herein by reference. This application is a continuation of Ser. No. 825,087, filed Mar. 20, 1969, now abandoned.
In a powder beam etching machine, slopes are formed in upper and lower edge surfaces of a rib formed along an outer margin of a platen and through-holes are formed around four corners. With such an arrangement, the powders adhered work may readily be removed by injection of air during a cleaning operation.
A light-weight mirror for astronomical purposes is disclosed. The mirror consists of a mirror plate, a back plate and a supporting framework disposed between them and consisting of a plurality of rows of tubes. The rows of tubes are staggered one from the other. Each tube in a row has a line or strip of contact with two adjacently disposed tubes of the next row. The tubes are welded together along the contact line or strip. The thickness of the tube wall is reduced in the area of the contact line or strip.
An inexpensive, lightweight reflective assembly member having good optical quality is provided. The reflective assembly is particularly adaptable to accommodating temperature variations without providing destructive thermal stresses and reflective slope errors. The reflective assembly may consist of a thin lamina reflective surface member and a lightweight substrate member of cellular structure. The respective materials may be chosen so that the coefficient of thermal expansion will be approximately the same. The substrate can comprise a cellular glass block while the reflective lamina member can be a thin sheet of glass with appropriate reflective coating. The lamina and cellular substrate member can be bonded together to form the reflective assembly. The method of fabrication includes abrading the cellular substrate with an abrasive master die to form an appropriate concave surface. An adhesive can be applied to the abraded surface and a lamina reflective surface can be placed under a uniform pressure to conform the reflective surface onto the desired abraded surface of the substrate.
The lightweight constructional element of a sandwich structure having two cover plates comprises a honeycomb structure arranged between the cover plates which holds the cover plates spaced from each other. The honeycomb structure is formed by empty cans, especially used beverage cans, placed side by side whose axes are at right angles to the cover plates and which are arranged in a close packed or a rectangular array. The cans may be attached by adhesive to form a low cost lightweight and strong array.
