Corner cube and spherical retroreflectors are ubiquitous in conspicuity and range-finding applications since they reflect light back to the illumination source with unmatched efficiency. A majority of these retroreflector applications are naked-eye applications meaning they are used in the visible spectrum for applications such as road markers, signage, safety markers, friend-foe identification, ranging. Other applications include free-space communications. More recently, switchable retroreflection has been realized through electro-mechanics or multiple quantum wells for free-space communications. However, lack of scalability, complex fabrication and limited spectrum present challenges if these devices are to be used in naked-eye applications.
Electrowetting has demonstrated robust beam steering, lenses, displays, and lab on chip devices with simple and scalable fabrication techniques. Electrowetting is voltage manipulation of wetting of polar liquids on a dielectric surface. It is envisioned that the same effect can be used to modulate retroreflection from corner cubes by means of an optical lenslet. In this dissertation we present a novel switchable retroreflector platform based on electrowetting that can potentially be a suitable candidate for naked-eye applications.
Presented in this dissertation is the world’s first simple, scalable, inexpensive, high contrast, low power and wide view angle electrowetting retroreflector for visible spectrum applications. Preliminary understanding of the electrowetting retroreflector is presented by means of simple theoretical models. Experimental investigation of contrast ratio, view angle, switching speeds and power consumption is undertaken in view of addressing the needs of naked eye applications. The achieved results clearly promote it as a good choice for the switchable retroreflector platform in visible and infra-red spectrum applications.