Abstract: The invention relates to a phase annulus consisting of a phase shifting thin-film system, which, in the case of a cemented system, has the following structure: (first) substrate-Ag-nH-cement-(second) substrate, or a structure: (first) substrate-n1-Ag-n2-cement-(second) substrate. In the case of an uncemented structure, the thin-film system has the following structure: substrate-Ag-nH-air, wherein nH, n1 or n2 represent the respective refractive index of a dielectric film. Phase shifting of the positive phase contrast can be regulated in a targeted manner.

Abstract: An interference filter having 17 coatings of alternating high and low index materials is located on the illumination path of an optical device and provides correction for green color distortion on the observation path and correction for blue color distortion on the photo path in order that both the observed image and photographed image are color neutral.