We propose a coronagraphic system for segmented telescopes, which is sufficiently
insensitive to the telescope pointing errors and finite angular diameter of the host
star to enable high-contrast imaging of potentially habitable planets. The inner working
angle of the coronagraphic system is 1 lambda/D (theoritical limit), and there is no outer
limit in priciple. The proposed coronagraphic system is made up of a new focal plane
mask and an optimized Lyot stop. By placing two of the new coronagraph systems in
succession to be orthogonal to each other, we can construct a coronagraphic system with
fourth-order null. The proposed system is limited to narrow-band usage. We achieve the
performance simulations of this coronagraphic system based on analytical expressions
derived in this study, considering a monochromatic light of 0.75 ¦Ìm and an off-axis
primary mirror with a diameter of 8.5 m; LUVOIR-b telescope model is assumed. Thanks to
the wide working area of the mask, the result shows that terrestrial planets orbiting K
and G dwarfs can be detected under the condition that the telescope pointing jitter is
less than 0.01 lambda/D = 240 as.