Fig. 2.

Simulations of the proposed inverse matrix based phase estimation algorithm versus the auto-correlation and cross-correlation algorithms. The period of the illumination pattern was 195 nm and the minimum detectable period in this simulation was 214 nm. As the radial pattern consisted of certain frequencies, the auto-correlation algorithm failed to retrieve the correct phase under low modulation depth conditions even though the number of photons was large. The value of m in the lower left of each subfigure demotes the modulation depth. In this simulation, Poisson noise was introduced, the minimum detectable number of photons was 10, and 24 phases were simulated when calculating the mean phase error.