Development of a circularly polarizing microscope with a polarizing undulator

Abstract

A circularly polarizing microscope by which we intend to obtain images with CD (circular dichroism) or CIDS (circular intensity differential scattering) in order to observe the structure and distribution of biomolecules has been constructed by using a polarizing undulator as the polarizing light source. The polarizing undulator with crossed and retarded magnetic field having fifteen periods was installed in the electron storage ring NIJI‐II in the Electrotechnical Laboratory. A Schwarzschild‐type mirror system combined with a convex mirror was developed in order to focus the undulator radiation to a microbeam keeping the quality of polarization of the radiation from the undulator. The beam size was from 0.66 μm (at wavelength 200 nm) to 0.96 μm (at 400 nm). Using a scanning sample stage and a photomultiplier which was positioned in the back of the sample, some images with transmitted and scattered light from fibrous DNA have been obtained. Attempts have also been made at obtaining images with CD and CIDS from the alternation between right‐ and left‐handed circularly polarized radiation from the undulator.