Thermally switched reflective optical shutter

Abstract

The thermally switched reflective optical shutter is a self-regulating “switchable mirror” device that reflects up to 100% of incident radiant energy above a threshold temperature, and reflects up to 50% of incident radiant energy below a threshold temperature. Control over the flow of radiant energy occurs independently of the thermal conductivity or insulating value of the device, and may or may not preserve the image and color properties of incoming visible light. The device can be used as a construction material to efficiently regulate the internal temperature and illumination of buildings, vehicles, and other structures without the need for an external power supply or operator signals. The device has unique aesthetic optical properties that are not found in traditional windows, skylights, stained glass, light fixtures, glass blocks, bricks, or walls. The device can be tailored to transmit sufficient visible light to see through in both the transparent and reflective states, while still providing significant control over the total energy transmission across the device.

What is claimed is: 
     
         1 . A glass spandrel section for regulating the reflection of radiant energy comprising
 a first reflective polarizer;   a second polarizer; and   a thermotropic depolarizer positioned between the first reflective polarizer and the second polarizer that adjusts polarization of incident light when below a threshold temperature, wherein   above the threshold temperature up to 100% of incident light is reflected by the device, and   below the threshold temperature up to 50% of incident light is reflected by the device.