Electronically controlled liquid-crystal microlens array with plane swing focus and tunable focal length

In this study, a kind of electronically controlled liquid-crystal microlens array (LCMLA) with plane swing focus and tunable focal length instead of a commonly microlens array with a fixed focal length and then focus distribution for high-resolution image acquisition, wavefront measurement, and distortion wavefront correction, is proposed. The LCMLA mainly consists of two glass substrates coated with a film of indium-tin-oxide (ITO) transparent material on one side. Each sub-unit top layer is composed of four sub-square electrodes, and the bottom layer is a circular electrode. The key technological steps in electrode fabrication contain an ultraviolet lithography, a dry etching (ICP etching), and final electron beam evaporation and overlay. The current LCMLA can be realized in three operating modes under external driving circuitry, including intensity image acquiring, wavefront measurement and distortion wavefront correction. The LCMLA is only in the image acquisition mode under the condition of no driving electrical signal. As the same driving electrical signals are applied onto the top four sub-electrodes of each sub-unit, the LCMLA is in the wavefront measurement mode. The LCMLA is in the key wavefront correction mode when different driving electrical signals are simultaneously applied onto the top four sub-electrodes of each sub-unit. Experiments show that the focal point of the LCMLA can be moved along the optical axis and over the focal plane by applying appropriate driving voltage signals.