Artifact Halo Reduction in Phase Contrast Microscopy Using Apodization

Abstract

A new phase contrast microscopy technique for halo reduction is proposed. This technique is based on an apodization method combined with the Zernike phase contrast method. Although it has been a diflicult theoretical problem, the proposed technique achieves halo reduction by considering angles of diffraction and phase differences. The technique utilizes an apodized phase plate consisting of a quarter wave phase shift ring with a 250/0 transmittance, and a pair of adjacent rings, which have 500/0 transmittance. This element is placed at the back focal plane of the objective. The result is startling, halo reduced images of phase objects providing enhanced inner details. Key word~: phase contrast microscopy, apodization, halo, apodized phase plate, angle of diffraction, phase difference