A 4 bit digital liquid lens for variable focal length

Abstract

We present a 4 bit digital liquid lens for variable focal length using a 4 bit actuator (b(1), b(2), b(3) and b(4) bit actuators). The 4 bit actuator, where 1, 2, 4 and 8 unit pneumatic actuators are serially connected with binary-combination, pushes a discrete fluidic volume into the lens in 2(4) different levels. Thus, the 4 bit digital actuation mode (b(4)b(3)b(2)b(1)) from (0000) to (1111) makes 2(4) different levels of lens curvature and focal length. Experimentally, we verify that the 4 bit actuator pushes the volume of 0.074 nl +/- 0.02 nl to the lens per one bit and changes the focal length from 3.63 mm to 38.6 mm in 16 levels. The present 4 bit digital liquid lens performs the focal length variation without requiring high-cost controllers or sensors for precise control of the pressure or fluidic volume, thus it is suitable for use in integrated optical systems.