Correcting the wavelength-induced phase deviation of Pancharatnam-Berry lenses.

Liquid-crystal-based Pancharatnam-Berry optical elements are widely used in virtual reality and augmented reality. However, the mismatch between exposure wavelength and operating wavelength leads to an undesirable phase deviation to the lenses, which in turn causes severe aberration especially when the f-number is small. To overcome the mismatched wavelength problem and to obtain a nearly ideal lens phase profile, a new exposure method using two template lenses with different focal lengths is proposed and experimentally validated. Our results indicate that such a lens indeed exhibits a better imaging performance than that fabricated by traditional interference method.