High Contrast Imaging with the JWST NIRCAM Coronagraph

Itelativc to ground-haxd telescopes, the James Wcbb Space Telescope (JWST) will havc a substantial sensitivity advantage in thc 2.2-5pm wavelength range where brown dwarfs and hot Jupiters are thought to havc significant brightness cnhance~nents. To facilitate high contrast imaging within this band, the Near-Infrared Camera (NIRCAM) will cmploy a Lyot cor.onagraph with an array of band-limited image-plane occulting spots. In this paper, wc provide the science motivation for high contrast imaging with NIRCAM, comparing its expected pertbnnanec to that of the Keck, Gemini and 30 rn (TM'T) telescopes equipped with Adaptive Optics systems of different capabilities. We]:hen describe our design for the NIRCAM coronagraph that enables imaging over the entire sensitivity range of the instrumen ( while providing significant operational flexibility. We describe the various design tradeoffs that were made in consideration of alignment and aberration scnsitivities and present contrast performance in thc prcsencc of JW!ST1s cxpcctcd optical aberrations. Finally wc show an example of a two-color image subtraction that can provide 10" companion sensitivity a t sub-arcsecond separations