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.
A micromachined reflector antenna system is integrated onto a substrate by firstly etching a reflector aperture surface defining a dish cavity in an oxide layer and secondly rotating a hinge over the reflector aperture surface with the hinge being used as the reflector central feed. The micromachined reflector antenna system can be made with an array of reflector antennas and integrated onto a single substrate with front end receiver circuits operating as a high frequency receiver on a chip with reduced size and cost and operating at hundreds of GHz.
A reflector for solar collectors including a mirror-coated glass plate of which the plate thickness lies below the thickness required for a self-supporting glass plate, and in which the glass plate has the mirror-coated side thereof bonded to a support member, thus providing a high-quality, lightweight structure.
A mirror for the collection of solar energy is formed by creating a depression in the ground, mounting thereover a support structure having working heads for applying a fortifying layer, a transition layer and then a foam layer, shaping the foam layer and then cementing a finished mirror layer to the finished foam layer.
A mirror substrate, in particular for use in astronomical optics, comprises two symmetrical preformed plates of glass (10, 12) glued by their respective inside faces (26, 28) on either side of an intermediate structure (14), the outside face (38) of one of the plates (10) being suitable for subsequently receiving a reflecting coating. The intermediate structure (14) is a composite structure made of glass foam which is substantially uniform in nature, and in the preferred embodiments it comprises a central core (16) of glass foam together with two sets (18 and 20) of blocks of glass foam.
The method is characterized by moulding at least one slab of a thermoplastic, normally solid material under heat treatment against a matrix having a form substantially matching that of the final mirror to form a shell (6) introducing into the shell a material selected from the group consisting of; (1) glass bubbles of a thermoplastic, normally solid material; (2) a composition of a powder of a thermoplastic, normally solid material together with an expanding agent, and; (3) mixtures thereof, and bringing the glass bubbles and the powder particles of the composition resp., the latter after expansion, to adhere, on one hand to each other, and on the other to the shell to form a porous supporting structure. The mirror blank according to the invention comprises a shell (6) of a thermoplastic, normally solid material and a supporting structure of the material in said group filling the shell, the glass bubbles and the powder particles resp. being attached to each other and to the shell. If sheet glass is used for the shell and as a powder in the composition, the composition will further include 0-2% by weight of viscosity reducing Li.sub.2 CO.sub.3 and 4% by weight of CaCO.sub.3 as an expansion agent (all counted on the glass powder).
