PISCES: An integral field spectrograph to advance high contrast imaging technologies

摘要

We present a novel optical integral field spectrograph (IFS) called the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES), which will be a facility class instrument within the NASA Exoplanet Exploration Program's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory. Integral field spectroscopy is ideal for imaging faint exoplanets: it enables spectral characterization of exoplanet atmospheres and can improve contrast by providing chromatic measurements of the target star's point-spread function (PSF). PISCES at the HCIT will be the first IFS to demonstrate imaging spectroscopy in the 10~(-9) contrast regime required for characterizing exoplanets imaged in scattered light. It is directly relevant as a prototype for IFS science instruments that could fly with the AFTA Coronagraph, the Exoplanet Probe missions currently under study, and/or the ATLAST mission concept. We present the instrument requirements, a baseline design for PISCES, a simulation of its performance, a solution to mitigate spectral crosstalk, experimental verification of our simulator, and the final vacuum compatible opto-mechanical design. PISCES will be assembled and tested at the Goddard Space Flight Center (GSFC), and subsequently delivered and integrated into the HCIT facility. Testing at HCIT will verify the performance of PISCES and its ability to meet the requirements of a space mission, will enable investigations into broadband wavefront control using the IFS as an image plane sensor, and will allow tests of contrast enhancement via multi-wavelength differential imaging post-processing. Together with wavefront control and starlight suppression, PISCES is thus a key element for maturing the overall integrated system for a future coronagraphic space mission. PISCES is scheduled to receive first light in the HCIT in 2015.