3D printed stacked diffractive microlenses

Planar lenses such as metalenses and diffractive lenses exhibit severe field-dependent aberrations when imaging extended objects with high numerical aperture. This problem can be overcome by stacking at least two of such devices on top of each other. In this work, we present such stacked imaging systems, namely doublets and triplets of diffractive optical elements. They are fabricated by femtosecond direct laser writing in one single step without the need for alignment in sizes of below 200 mu m in diameter and 100 mu m in height. The lenses allow for efficient sub mu m resolution imaging at visible wavelengths combined with a full field-of-view of up to 60 degrees. As additional benefit, our approach dramatically reduces the writing times of 3D printed lens systems to below 15 minutes. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement