Described is an improvement in a thin membranous reflector having a continuous array of inwardly bending support cable means around its perimeter for stretched-flat tension-spring support at discrete outwardly extending apex locations of such array. The improvement resides in imparting a creep characteristic to such cable means which matches that of the reflector membrane while subjected to the flatness-inducing tensioning thereof, in behalf of assuring preservation of a stretched-flat state of ...

This glassless mirror comprises a frame having grooves at its outer sides receiving a reflective sheet held in stretched condition by a flexible strip pressing the sheet into the grooves. The frame may be made of one extrusion having milled out or mitered corner angles to allow bending the extrusion into polygonal shape. A spring clip retains the meeting ends of the frame in alignment. The flexible strip is so shaped that it can easily be pressed into the groove and allowed to expand to hold the...

A planar mirror having a reflective surface including a metallized thin film reflective sheet material in a stretched condition over a raised ridge on one side of the supporting frame, with means for securing the film in the stretched condition over the frame. A resilient wedge-like member is positioned and gripped between an upper flange member of each frame member and a supporting substrate member such that compressive reaction forces of the resilient members are in balanced equilibrium with c...

A reflector for electromagnetic radiation with an easily replaceable reflective membrane that is especially useful in solar collectors. The reflector comprises an annular housing, an elastic reflective membrane, a ring supporting the membrane, an evacuation assembly for evacuating the housing and drawing the elastic membrane into the housing, and a fastening assembly which releasably snap-fits the ring and membrane assembly to the housing in a gas-tight manner.

A plastic film mirror is formed by attaching a highly reflective, metallized polyester film to a frame having a rigid base section and a resilient upper section capable of bending inwardly towards the interior of the mirror, and subjecting said film to an elevated temperature for a specific period of time to cause the film to shrink in at least one direction. The shrinking of the film urges the resilient upper section of the frame inwardly thereby causing said film to be maintained in a state of...

The present invention provides an improved, adjustable focal length mirror that includes a tubular member having one end closed by a first transparent wall. A second, deformable wall that has a reflecting surface in opposition to the transparent wall is mounted in the tubular member in order to define therewith, and in combination with the transparent wall, a first hollow space. A frame is also provided for supporting the deformable wall in spaced opposition to the transparent wall. The supporti...

A thin membrane is mounted on an optically flat circular outer ring and stretched over a smaller optically flat circular inner ring. Differential pressure is applied to the annulus formed between the inner and outer rings to prestrain the membrane and separately applied to the inner ring where the mirror figure will be produced. The inner ring has a doubly curved top surface and is optically fiat so that the membrane can freely move across the inner ring as incremental stress is applied via the ...

A curved reflector of electro-magnetic radiation formed of an elastic, reflective membrane which utilizes a partial vacuum to provide the curvature to the membrane and an adjustable valve to vary such curvature, and therefore the focal length of the reflector. The valve comprises a central aperture in the membrane and a body adjustably mounted above the aperture with a flow restricting surface thereon which overlies the aperture.

A focusing reflective mirror which is fabricated of a hoop structure having a reflective metalized membrane stretched over one face thereof and a metalized backing membrane over the opposite side forming a closed reflective structure. The contour of the flexible reflective surface is controlled by a differential pressure between the enclosed area behind the reflective surface and the ambient pressure. The particular configuration or contour of the reflective surface is controlled by a electropne...

An optical layer device having a substrate with a surface having one or more layers of either dielectric or metallic materials provided thereon characterized by the substrate being mounted on a holder and being of an elastically deformable material and means for deforming the substrate so that the substrate may be deformed in a predetermined spherical or aspherical fashion. Depending on the construction of the layers, the device may be utilized as either a variable reflector or a variable interf...