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Feasibility of the Four‐Quadrant Phase Mask in the Mid‐Infrared on the James Webb Space Telescope

The James Webb Space Telescope (formerly the Next Generation Space Telescope) will be capable of unprecedented science, owing to its large diameter, its low background, and its dedicated IR instruments. One of these instruments is a mid‐IR facility called MIRI (Mid‐IR Instrument), which is being studied through a collaboration of US and European teams. Our group at Observatoire de Meudon has developed a coronagraphic device for the MIRI camera. Taking advantage of the reduced star‐planet contrast in this spectral range, the prime goal of this coronagraph is the direct detection of extrasolar planets. Differential imaging in several well‐chosen spectral windows is foreseen. In this paper, we evaluate the manufacturing process of the coronagraphic masks and compare the intrinsic performance, as measured in the laboratory, with the scientific requirements.