"mission is 100% and T=0 indicates light transmission is 0%; and wherein S is calculated by the equation: S(x,y)=sin [πP/2λ(x2 +y2)+kA(tan (y/x))+β] wherein P is the power difference between two extreme foci, ?? is the wavelength of interest, k is a spiral shape control parameter, x and y are the Cartesian coordinates of the lens with the origin located at the center of the lens and" . . . . .