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TIGHLMANN-TYPE VERTICAL ILLUMINATOR WITH VARIABLE APERTURES

c. 1885-

Maker: Meyrowitz (A)

 Microscope Vertical Illuminator
Microscope Vertical Illuminator  Microscope Vertical Illuminator  Microscope Vertical Illuminator
Microscope Vertical Illuminator  Microscope Vertical Illuminator  Microscope Vertical Illuminator

Vertical illuminators are used for illumination of solid or opaque objects with higher power objectives. Although with low power, top-illumination from the side can suffice, as the magnification increases and the focal length shortens, light cannot easily be directed onto the top of an opaque specimen. Vertical illuminators allow the light directed through the hole in the side to be reflected off the overslip to come down onto the specimen from above through the objective. The light reflected off the subject allows the reflected light to pass back up in the opposite direction through the objective and then through the coverslip, reaching the eyepiece.

In 1881, Tighlmann reported in the JRMS, a vertical illuminator with variable apertures. In this model, a cylinder with various different size apertures rotated around the hole in the body of the illuminator to regulate the diameter of the light beam entering the device. Complaints were raised about this device in that making the adjustment was not as delicate as required for high power work so it was not popular. A similar design was produced by Meyrowitz for their Bulloch-Meyrowitz microscopes of the late 19th century, and that is the model shown here.