ABSTRACT Liquid crystal (LC) Pancharatnam–Berry phase optical elements (PBOEs) are promising components for XR displays owing to their unique advantages, including lightweight, ultrathin form factor and polarization‐dependent diffraction behavior. A key challenge for PBOEs is achieving high diffraction efficiency over a broad wavelength range because the efficiency depends not only on the LC layer design but also on the local pattern period. This complexity makes accurate evaluation difficult, particularly for space‐variant devices such as PB lenses, where conventional millimeter‐scale probe beams inevitably introduce crosstalk between regions. Here, we present microscopic diffraction spectrometry, in which the propagating direction and polarization are filtered in a microscope to enable characterization of diffraction by the PB phase in localized areas of diameter 100 μm and below. We demonstrate the capability of the proposed technique by quantifying the impact of alignment defects localized within ~10‐μm‐diameter regions on diffraction efficiency, and by generating a spatial efficiency map of a PB lens that reveals performance variations within a single element. We anticipate that this method will be valuable not only for the research and development of high‐performance PBOEs but also for quality control in mass production.
Yoshida et al. (Sat,) studied this question.