Mechanically Driven Tunable Microlenses

Many mechanically tunable microlenses are designed as circular chambers covered by thin flexible membranes. The membrane deforms when pressure is applied to the lens liquid through external actuation. In addihon, some microlenses are formed through air-liquid or liquid-liquid interfaces (immiscible, with different refractive indices). These interfaces may also be varied by applying pressure that adjusts the radii of curvatures of the spherical membranes in air-liquid devices and the focal lengths of the microlenses formed via liquid-liquid interfaces. 

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Chapter 6, Mechanically Driven Tunable Microlenses, continues with examples of microlenses tuned by a variety of mechanical methods. These mechanically tunable microlenses can be categorized as thin-membrane lenses with varying apertures, pressures, and surface shapes swellable hydrogel lenses liquid-liquid interface lenses actuafed by environmentally stimuli-respon-sive hydrogels and oscillating lens arrays driven by sound waves. 

Miniaturizing optical systems has been an active field of endeavor in recent years. The most important components in all optical systems are their lenses. In many cases, changing the focal distance of a system involves adjusting the whole system. However, such on-the-fly adjustments are often hard to realize for miniaturized systems. Developing miniature structures for tunable focus microlenses with variable focal lengths has attracted great interest. Many methods such as electrical fields and mechanical forces have been investigated. In this chapter, we will discuss electrically driven tunable microlenses. 

Unlike traditional glass lenses, focal lengfhs of microlenses can be tuned by various electrical and mechanical techniques. Chapter 5, Electrically Driven Tunable Microlenses, describes several examples of electrically tuned microlenses including liquid-crystal-based lenses and liquid lenses driven by electrostatic forces, dielecfrophorefic forces, electrowetting, and electrochemical reactions. 

Unlike traditional glass lenses, focal lengths of microlenses can be tuned electrically or mechanically by various mechanisms. In this chapter we will describe a series of electrically tuned microlenses (1) liquid lenses covered with a thin polymer film and driven by electrostatic forces (2) lens arrays utilizing dielectrophoretic effect (3) electrochemically activated liquid lenses (4) tunable liquid lenses actuated by electrowetting and (5) liquid crystal (LC) lenses. 

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