High contrast testbed results with black silicon shaped pupils

NASA plans to image terrestrial exoplanets with the Habitable Worlds Observatory (HWO). HWO's large primary mirror will most likely be segmented, which introduces extra diffraction in the image. Apodization, either with deformable mirrors or a dedicated mask, is needed to suppress this diffraction. Reflective apodizers for the Roman Coronagraph were flight qualified and demonstrated 4e-9 contrast in vacuum testbeds. In our current work, we aim to show that black silicon apodizers can provide the 1e-10 contrast needed by HWO. Last year for our first milestone, we showed that the incoherent light contribution from scattering off black silicon is negligible for the HWO contrast budget. Our next milestone is to achieve <5e-10 raw contrast on the Decadal Survey Testbed 2 bench in vacuum with a shaped pupil coronagraph. Here we present our most recent testbed results.