High-resolution confocal microscopy with low-NA objectives based on diffractive lens arrays

High resolution and large fields of view are difficult to achieve simultaneously by microscope objectives. In this work, we develop a reflection confocal microscope based on diffractive lens arrays to solve the problem. We demonstrate a prototype that generates a spot array with a numerical aperture of 0.78. Laterally, experiments show a spatial cutoff frequency of 1024 lp/mm by a 0.15 NA objective, and 912 lp/mm by a 0.07 NA objective with a 785 nm diode laser. Axially, an average height of 961 nm with a standard deviation of 49 nm is measured with a 925.5 nm calibrated step height target.