The new electrowetting zoom optical element from visible light into the mid-infrared band

Researchers at the University of Colorado have developed a lens type (and a steering prism) capable of electrofocusing without moving parts with a spectral passband from 400 to 5000 nanometers and have experimentally demonstrated at wavelengths of 588, 1550 and 3000 nm . The lens is based on the electrowetting technique, where changing the voltage changes the wettability of the liquid lens to change its contact angle, which in turn changes its shape. The concept of electrowetting is not new in itself, it is the wide spectral range. Applications include imaging, spectroscopy, microscopy, lidar and adaptive optics for continuous monitoring.

This lens contains two liquids with different refractive indices. The two fluids are a Room Temperature Ionic Liquid (RTIL) and dodecane known as n-propyl-n-methylpyrrolidinebis (fluorosulfonyl) imide (Pyr133a).

Electro-wetting lenses fabricated on Indium Tin Oxide (ITO) substrates are suitable for wavelengths from visible to 2000 nm while lenses fabricated on silicon substrates are suitable for medium wave infrared (MWIR). The lenses have diopters of 7, 19 and 23 at 588, 1550, and 3000 nm, respectively.

An electrowetting deflection prism based on a fluid permeable from visible to mid-wave infrared

An electrowetting steering prism operating at 1550 nm was also fabricated to deflect the beam beyond an angle of 1.12 ° (which could then be easily amplified with other conventional optical elements or with different nonpolar liquids instead of dodecane) .