Laboratory demonstration of the birefrigent point-diffraction interferometer wavefront sensor

The direct imaging of extrasolar planets requires extreme adaptive optics (ExAO) in the near-infrared wavelengths. The ExAO needs a high-efficient wavefront sensor (WFS) to measure the phase aberration accurately with a small number of photons. In addition, the WFS in the ExAO is required to run at high sampling rates of 1- 7 kHz. To meet these requirements, we developed the birefringent point-diffraction interferometer (b-PDI) presented in our earlier paper. We tested the b-PDI in the laboratory with a polychromatic light source with wavelengths of 800 +/- 100 nm. The b-PDI showed a relatively high efficiency, comparable to that of a fixed pyramid WFS. The b-PDI has a low calculation cost and a small readout region, which are suitable for high-speed sampling at 6.5 kHz.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement