Rational phase mask to extend the depth of field in optical-digital hybrid imaging systems

We propose a novel phase mask called the rational phase mask (RPM) to extend the depth of field in optical-digital hybrid imaging systems. Using the invariance to defocus of the modulation transfer function as the merit function, we adopt the simulated annealing algorithm to optimize the RPM together with the other three existing phase masks. Numerical comparisons prove the RPM's superiority.