The low-order wavefront sensor for the PICTURE-C mission

• Main Authors: Mendillo, Christopher B. (Author), Brown, Joshua (Author), Martel, Jason (Author), Howe, Glenn A. (Author), Hewawasam, Kuravi (Author), Finn, Susanna C. (Author), Cook, Timothy A. (Author), Chakrabarti, Supriya (Author), Douglas, Ewan S. (Author), Mawet, Dimitri (Author), Guyon, Olivier (Author), Singh, Garima (Author), Lozi, Julien (Author), Cahoy, Kerri (Contributor), Marinan, Anne D. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Aeronautics and Astronautics (Contributor)
• Format: Article
• Language: English
• Published: SPIE, 2018-05-07T19:11:55Z.
• Subjects: Article
• Online Access: Get fulltext

 The PICTURE-C mission will fly a 60 cm off-axis unobscured telescope and two high-contrast coronagraphs in successive high-altitude balloon flights with the goal of directly imaging and spectrally characterizing visible scattered light from exozodiacal dust in the interior 1-10 AU of nearby exoplanetary systems. The first flight in 2017 will use a 10[superscript -4] visible nulling coronagraph (previously flown on the PICTURE sounding rocket) and the second flight in 2019 will use a 10[superscript -7] vector vortex coronagraph. A low-order wavefront corrector (LOWC) will be used in both flights to remove time-varying aberrations from the coronagraph wavefront. The LOWC actuator is a 76-channel high-stroke deformable mirror packaged on top of a tip-tilt stage. This paper will detail the selection of a complementary high-speed, low-order wavefront sensor (LOWFS) for the mission. The relative performance and feasibility of several LOWFS designs will be compared including the Shack-Hartmann, Lyot LOWFS, and the curvature sensor. To test the different sensors, a model of the time-varying wavefront is constructed using measured pointing data and inertial dynamics models to simulate optical alignment perturbations and surface deformation in the balloon environment.