High-contrast imager for complex aperture telescopes (HiCAT): 6. Two deformable mirror wavefront control (Conference Presentation)

The goal of the High-contrast imager for Complex Aperture Telescopes(HiCAT) testbedis to demonstrate coronagraphic starlightsuppression solutions for future segmented aperturespace telescopessuch as the Large UV, Optical, IR telescope(LUVOIR) mission concept being studied by NASA. The testbeddesign has the flexibility to enable studies with increasing complexity for telescope aperturegeometries starting with off-axis telescopes, then on-axis telescopeswith central obstruction and support structures. The testbedimplements the ApodizedPupil Lyot Coronagraph(APLC) optimized for the HiCAT aperture, which is similar to one of the possible geometries considered for LUVOIR. Wavefrontcan be controlled using continuous deformable mirrors, and wavefrontsensing is performed using the imaging camera, or a dedicated phase retrievalcamera, and also in a low-order wavefrontsensing arm. We present a progress update of the testbedin particular results using two deformable mirrorcontrol to produce high-contrast dark zone, and preliminary results using the testbed’s low order Zernike wavefront sensor.