Differential Imaging with a Multicolor Detector Assembly: A New Exoplanet Finder Concept

Simultaneous spectral differential imaging is a high contrast technique bywhich subtraction of simultaneous images reduces noise from atmosphericspeckles and optical aberrations. Small non-common wave front errors betweenchannels can seriously degrade its performance. We present a new concept, amulticolor detector assembly (MCDA), which can eliminate this problem. Thedevice consists of an infrared detector and a microlens array onto the flatside of which a checkerboard pattern of narrow-band micro-filters is deposited,each micro-filter coinciding with a microlens. Practical considerations forsuccessful implementation of the technique are mentioned. Numerical simulationspredict a noise attenuation of 10^-3 at 0.5" for a 10^5 seconds integration ona mH=5 star of Strehl ratio 0.9 taken with an 8-m telescope. This reaches acontrast of 10^-7 at an angular distance of 0.5" from the center of the starimage.Comment: 13 pages, 5 figures, accepted APJ