Simultaneous multi-piston measurement method in segmented telescopes

We propose a method to simultaneously detect the multi-piston between segments. The relation between the piston of any two segments and amplitude of the modulation transfer function (MTF) sidelobes (MTF_nph) is derived. The piston can be retrieved by this relation after measuring the MTF_nph. This method's capture range is the operating light’s coherence length, the accuracy is 0.026λ (λ = 633 nm) RMS. The MTF model of a mask with sparse multi-subaperture configuration is established. The arrangement rules, to avoid the sidelobes overlapping, are obtained. The mask with a sparse 18 sub-aperture configuration is designed, which makes the MTF sidelobes distribution non-redundant.