Novel instrument concepts for characterizing directly imaged exoplanets


Current high-contrast exoplanet imagers are optimized to find new exoplanets; they minimize diffracted starlight in a large area around a star. I present four novel instrumental approaches that are optimized to characterize these discoveries by minimizing starlight in a small area around the known location of an exoplanet: 1) coronagraphs that remove virtually all starlight over an octave in wavelength while transmitting more than 90% of the exoplanet signal; 2) holographic wavefront sensors that measure aberrations in the science focal plane; 3) ultra-fast adaptive optics systems that minimize these aberrations; and 4) direct minimization of the remaining starlight. By integrating these technologies with a high spectral- resolution, integral- field spectrograph that can resolve the Doppler shift and the polarization difference between the starlight and the reflected light from the exoplanet, it will be possible to determine the atmospheric composition, temperature and velocity structures of exoplanets and their spin rotation rate and orbital velocity. This will ultimately allow the upcoming extremely large telescopes to characterize rocky exoplanets in the habitable zone to look for signatures of life.