Limiting contrast (deepest contrast with a S /N > 5 planet reconstruction) as a function of photon count for various numbers of grating. The planet is at a distance of 4λ/D from the star. The reference intensity I_ref is the maximum intensity found in a single pixel in the data cube for a single grating before the addition of photon noise. Each plotted point is the result of ten instances of photon noise being averaged.