We report on the properties of a fast F/1.5 geometric-phase lens with a focal length of 37 mm at 633 nm and a 24.5 mm diameter. This lens employs photo-aligned liquid crystal layers to implement the spatially varying Pancharatnam-Berry phase, leading to the expected polarization- and wavelength-dependent focusing. An achromatic spectrum is achieved using (chiral nematic) multi-twist retarder coatings, with high first-order (≥98%) and low zero-order (≤1%) transmittance across 450-700 nm. We measure traditional optical metrics of the GP lens including focused spot profile and modulation transfer function through knife edge testing and NBS 1963a resolution charts. This work includes a comparison to similar F/# conventional thick and thin lenses.
Kathryn J. Hornburg, Jihwan Kim, and Michael J. Escuti, "Experimental characterization of a F/1.5 geometric-phase lens with high-achromatic efficiency and low aberration," Proc. SPIE 10125, Emerging Liquid Crystal Technologies XII, 101250Y (Presented at SPIE OPTO: February 01, 2017; Published: 15 February 2017); https://doi.org/10.1117/12.2258545.
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