Fluidic optical switch by pneumatic actuation

We proposed a fluidic optical switch based on pneumatic actuation. A small amount of liquid is suspended in a cylinder in vertical position and separates the hollow cylinder into two chambers. A clear pillar with a ball head is fixed in the top chamber. An air channel is used to connect the bottom chamber and a syringe. By controlling the air pressure of the bottom chamber, the liquid can be moved up and down easily. When the liquid is lifted up, the pillar head can enter the liquid and a channel is opened. When the liquid moves down, the liquid can get rid of the pillar and the channel is closed. Our results show that the device can obtain a high optical attenuation (∼1178:1) within a reasonable response time (∼ 97 ms). The aperture of the channel is highly circular. The diameter of the channel can be tuned from ∼ 0 to ∼ 4.5 mm. Such an optical switch has potential applications in light shutters, variable optical attenuators, and adaptive irises.