| abstract |
A solar reflecting mirror includes a shaped glass substrate having a focal area, a reflective coating over its convex surface and a sodium ion barrier layer over its concave surface. The shaped substrate has a strain pattern having a radial tension strain at the bottom area, and circumferential compression strain at the periphery of the substrate. As the distance from the periphery of the shaped substrate increases, the circumferential compression strain decreases to a "transition line" where circumferential tension strain begins. As the distance from the transition line in a direction toward the bottom area of the glass substrate increases, the circumferential tension increases. To compensate for the strain pattern in the shaped glass substrate to avoid buckling of, and surface cracks of, the barrier layer, the barrier layer including an oxide of silicon and aluminum thickness, among other things is varied on. A method of making the solar mirror from shaped sections is also discussed. |