Curved kinoform lenses for stigmatic imaging of axial objects

We present a generalized approach for determination of the location of full-period zones and the surface-relief profile of a spherically curved kinoform lens that provides stigmatic imaging between any two prespecified points on axis. A common framework is provided for the treatment of both converging and diverging kinoform lenses. Some illustrative numerical results demonstrate the convenient amenability of our method in practical applications.