Laboratory Demonstration of Spatial Linear Dark-Field Control for
Imaging Extrasolar Planets in Reflected Light
Abstract
We present the first laboratory tests of Spatial Linear Dark Field
Control (LDFC) approaching raw contrasts (5e-7) and separations
(1.5–5.2 lambda/D) needed to image jovian planets around Sun-like stars
with space-borne coronagraphs like Roman-CGI and image exo-Earths around
low-mass stars with future ground-based 30m class telescopes. In four
separate experiments and for a range of different perturbations, LDFC
largely restores (to within a factor of 1.2–1.7) and maintains a dark
hole whose contrast is degraded by phase errors by an order of
magnitude. Our implementation of classical speckle nulling requires a
factor of 2–5 more iterations and 20–50 DM commands to reach contrasts
obtained by spatial LDFC. Our results provide a promising path forward
to maintaining dark holes without relying on DM probing and in the
low-flux regime, which may improve the duty cycle of high-contrast
imaging instruments, increase the temporal correlation of speckles, and
thus enhance our ability to image true solar system analogues in the
next two decades.