Optofluidic smart glass with refractive-compensating structure allowing transparency with refractive index mismatch

A smart glass is a glass or window in which the light transmission properties can be altered through external stimuli. The most popular types of commercially available smart windows use applied voltage to change the device’s properties. As a result, the glass can shift with an applied signal from transparent to opaque, filtering some or all wavelengths of visible light. Although commercial versions of this technology exist, they are still costly. Previous experiments in our group used corner cube retro-reflecting panels with a fluidic reservoir, where the fluid is the stimulus that shifts the device state. When dry, the window retroreflects and is thus opaque, and introducing perfect index-matching fluid results in transparency—however, any slight refractive index mismatch between fluid and the building material results in tri-refractions. The tri-refractions result from the corner cube’s nature as a prism with a triangular base. This new structure was created to correct the path of the light rays and consequentially eliminate the dependence of the perfect refractive index matching between fluid and the building component—in this case, an acrylic-like material. The proposed structure was tested and modeled using ray tracing software, confirming the refractive compensating principle. Experimental structures have been produced with injection molding, 3D printing and CNC Machining. AutoCAD 3D, LightTools, and Matlab were the software used for testing and design.