Application of DOE in confocal microscopy for surface measurement

In traditional confocal microscopy, there is a trade-off between spatial resolution and field of view due to the limitations of objectives. To solve this problem, diffractive optical elements (DOEs) with overlapping apertures are used to generate high-NA illumination spots in a large area. However, currently such DOEs can only be used as illuminators which are not suitable for 3D surface measurements. In this work, the idea of superposition is utilized to expand the scope of application of the DOEs. These DOEs are designed by simulation and tested in the experiments. The results show that the proposed DOEs can be used in 3D surface measurements and have the potential to solve the problem of high-NA objectives.