High-Contrast Imaging Performance of a Tunable Filter for Space-based Applications I: Laboratory Performance

作者：Ingraham P^*; Doyon R; Beaulieu M; Rowlands N; Scott A

来源：Publications of the Astronomical Society of the Pacific, 2011, 123(910): 1412-1422.

The scanning capability of a tunable filter represents an attractive option for performing high-contrast imaging through spectral differential imaging (SDI), a speckle-suppression technique widely used by current ground-based high-contrast imaging instruments. The performance of such a tunable filter is illustrated through the Tunable Filter Imager (TFI), which used to be part of the science instrument complement of the James Webb Space Telescope (JWST). The TFI features a low-order Fabry-Perot etalon that enables imaging spectroscopy at an average resolving power of 100. Also included is a high-contrast imaging mode featuring a Lyot coronagraph aided by spectral differential imaging (SDI). Using a TFI prototype etalon, we demonstrate the calibration technique to be used in the parallelization of the etalons reflective plates and then evaluate the etalon's ability to perform speckle suppression through SDI. The improvement in contrast ranges from a factor of similar to 10 at working angles greater than 11 lambda/D, increasing up to a factor of similar to 60 at 5 lambda/D. These results are consistent with a Fresnel optical propagation model, which we use to show that the contrast improvement is limited by the test bed, and not the etalon. Our results demonstrate that a tunable filter such as the JWST TFI is an attractive solution for performing speckle suppression in space through multiwavelength imaging.

• 出版日期2011-12