Evaluation of different illumination designs for tunable 3D structured illumination microscopy through model-based restoration

Abstract

In a tunable 3D structured illumination microscopy (3D-SIM) based on an illumination system comprised by a multi-slit array and a Fresnel biprism, the 3D structured illumination (SI) pattern depends on the design of the slit array. Previous work studied the impact of the illumination pattern design on the achieved extension of the compact support of the tunable 3D-SIM optical transfer function. In this contribution, we use simulations with different illumination designs that utilize a different number of slits, to evaluate system performance by investigating the lateral and axial resolution achieved in the restored images computed with a regularized iterative 3D model-based algorithm, which minimizes the mean square error between the model and data. Three illumination designs are investigated in which the number of slits is N = 3, 9 and 11 while the corresponding distance between the slits is <i>x</i>₀ = 488 μm, 122 &mu;m and 100 &mu;m, respectively. A 3D star-like object, commonly used in resolution analysis of imaging systems, is used in the simulations. Results are quantified using the mean square error and the structured similarity index as well as intensity profiles that show the achieved resolution and robustness to noise in each case. The lateral and axial 3D-SIM theoretical resolution limits are achieved in the presence of 20-dB Poisson noise while small differences are evident in the results from 15-dB simulated data obtained using the 3 investigated designs.