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c. 1895-1939

Maker: Carl Zeiss, Jena, Germany

zeiss vi
zeiss vi

This is a vertical illuminator which uses a prism to direct light from a horizontal source down through the obective. The prism traverses one side of the inside of the illuminator. An oval-shaped opening allows light to be directed towards most of the prism. The prism can be adjusted via a tiny knob to direct light down through the objective which acts as a condenser. Light returns through the rest of the aperture of the objective. With this kind of illuminator, the entire field of view cannot be evenly illuminated, but the intensity of the illumination is brighter than with a coverslip type of illuminator. The top screws into the nosepiece and the objective then screws into the bottom of the illuminator. The top knurled fitting can rotate independently of the rest of the illuminator, so that the opening of the illuminator can be fixed in a particular direction. This model has no provision for dark ground illumination. It was sold by Zeiss for over 40 years. Another version of this illuminator is known which has a thin slit cut in it, which allows the introduction of one of two dark-field stops to allow dark ground illumination as well as standard bright field illumination. For more examples of vertical illuminators and their history, please see the vertical illuminator page.