Aberration on excitation focal spot caused by oblique interface with refractive indices discontinuous and its correction with pure‐phase compensation for laser scanning microscopy

Abstract

The interface of mediums with refractive indices discontinuous, for example airglass and glass-water, are inevitable in microscopic imaging. In this work, the aberration of oblique interface with refractive index discontinuous on the laser scanning microscope was investigated theoretically with numerical simulations. It was found that the position, shape and FWHM of focal spots, were all significantly affected by the aberration due to oblique interface. The aberration can cause serious shifting of focal spots in the axial direction of beam during -scanning and lead to an inaccurate reconstruction of three-dimensional (3D)targets. The aberration can also lead to a decreasing spatial resolution. To correct the influence of the aberration, a pure-phase modulation method has been proposed. By applying a phase compensation map into a spatial light modulator (SLM), the oblique interface aberration had been corrected experimentally in a laser scanning microscope. We hope this research can attract the attention of researchers when using scanning microscope, especially for reconstructing 3D biological and material structures.

Supplementary document for Non-iterative multifold strip segmentation phase method for six-dimensional optical field modulation - 5607590.pdf

“…The Mowiol® 4-88 liquid has a refractive index of 1.518 which is consistent with that of the cover slip and immersion oil. Thus, the difference of refractive indices between solution and coverslip can be significantly reduced, accompanied by the smaller influence of aberration caused by refractive index mismatch [3]. During measurement, several drops of the mixed solution were placed on a coverslip and evaporated.…”