Phase mask coded with the superposition of four Zernike polynomials for extending the depth of field in an imaging system

A phase mask represented as the superposition of the four Zernike polynomials associated with primary coma and the trefoil aberrations is presented. The restoration process of the intermediate image is performed by means of the use of the quasi-point source concept. Numerical results of the extended depth of field are presented and compared with other methods of wave front coding applied on a microscope.