The C-BD Diascopic Brightfield/Darkfield stand introduced with the Nikon SMZ1500 uses a seven-sided toroidal mirror to substantially reduce stray light. Use this interactive Java tutorial to explore how mirror shape affects the amount of light entering the objective in darkfield stereoscopic microscopy.
To operate the tutorial, use the slider bar to morph the mirror assembly between a standard cylindrical reflection mirror and the new Nikon toroidal mirror. Stray light reflected from the cylindrical mirror ordinarily causes a decrease in contrast when using short-working distance objectives under darkfield diascopic illumination, because a considerable amount of light enters the objective front lens. When using a toroidal mirror, direct light is shielded from entering the objective.
Matthew J. Parry-Hill and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.