  High performance coronagraphic imaging at small inner working angle requires
efficient control of low order aberrations. The absence of accurate pointing
control at small separation not only degrades coronagraph starlight rejection
but also increases the risk of confusing planet's photons with starlight
leaking next to the coronagraph focal plane mask center. Addressing this issue
is essential for preventing coronagraphic leaks, and we have thus developed a
new concept, the Lyot-based pointing control system (LPCS), to control pointing
errors and other low order aberrations within a coronagraph. The LPCS uses
residual starlight reflected by the Lyot stop at the pupil plane. Our
simulation has demonstrated pointing errors measurement accuracy between 2-12
nm for tip-tilt at 1.6 micron with a four quadrant phase mask coronagraph.
