Thermally actuated liquid tunable microlens with embedded thermoelectric driver and sub-second response time

This paper reports a thermally actuated microlens. The microlens has an embedded thermoelectric heat pump that drives a water based heat engine. In the liquid heat engine, the water temperature is changed to tune the lens through the thermal expansion of water. The shape of a pinned water meniscus at an aperture is deformed in response to the net volume change in the water, creating a tunable lens with sub-second thermal response time (0.8 second). By a temperature change from 20°C to 30°C, focal length of the microlens varies continuously from -22.6 mm to ±∞ and then to +22.6 mm.