High-NA Confocal Measurement by Diffractive Optical Elements

Diffractive optical elements (DOEs) can produce high-numerical-aperture (NA)spots over a large field. They can be combined with a low-NA objective to measure a large area with high resolution. This work shows experiments of using DOEs in reflection confocal microscope to resolve small structures beyond the capability of the objective. Both qualitative and quantitative results have shown enhancement in lateral and axial resolution by the application of the DOEs, which also agrees to the imaging theory of confocal microscopes.