Effects of fabrication errors in the diffractive optical element on the modulation transfer function of a hybrid lens.

Diffractive optical elements (DOEs) are often used to improve the performance of optical systems. However, when a blazed DOE is machined, shape errors can be generated in the discontinuity region of the DOE due to the finite radius of the processing tool. We simulated the effects of this shape error on the optical path and modulation transfer function (MTF) in a hybrid lens for a compact camera module. The decrease rate of the MTF was larger in the low-spatial-frequency domain and when the light entered at a low incident angle.