Effects of primary aberrations on a dark-field microscopy imaging system with the sharper focusing lens

Abstract

The effects of primary aberrations of the sharper focusing lens on the image quality is analyzed for a dark-field microscopy imaging system, which is illuminated by a left-circularly (LC) polarized Laguerre–Gaussian (LG) vortex beam. To confirm the aberration tolerance range of the sharper focusing lens for precise measurement, the analytical expression of the field distribution on the image plane is deduced. Then the dark-field image results corresponding to a defect with a scale of 6µm×6µm are simulated. The influence of the spherical error, coma, and astigmatism on the imaging quality is compared in detail. Then the verification test has been carried out to show the effects of different primary aberrations. Finally, both the simulation and experiment results help us to identify that the tolerance range of spherical aberration, astigmatism, and coma should be less than 1.5λ, 1λ, and 1.25λ, respectively.