This is a Carl Zeiss Compound Monocular Microscope. The Carl Zeiss Company was founded by a German scientist, Carl Zeiss in 1846 and initially specialised in single-lens microscopes. In 1857, Zeiss sold their first compound microscope. The microscope we have here was built circa 1890 by the Carl Zeiss Company and is an example of Zeiss’ later models of compound microscopes. Compound microscopes, unlike single lens microscopes we will explore later on this tour, uses a system of two or more lenses dubbed collectively as the objective lens, and the eyepiece. The objective lens, closest to the specimen being observed (‘the object’), creates a real image that is then magnified for the user to observe as a virtual image (by the ‘eye piece’). This particular Zeiss microscope came with six objective lenses and three eyepiece lenses. Each different objective lens is situated in a turret that may be rotated so as to achieve different magnifications.
Although compound microscopes can provide much greater magnification than simple microscopes, as well as better focusing and resolving power, there is still a fundamental limit for any given microscope. This limit was first discovered and described by Zeiss’ business partner Professor Ernst Abbe. In 1866 Abbe became one of the company's research directors and was responsible for many breakthroughs in the area of microscopes and lenses. Some of these breakthroughs include the Abbe condenser lens, the oil immersion technique, the concept of numerical aperture and the aforementioned resolution limit of a light microscope. The resolution limit is set by the wave nature of light at approximately 1000 times magnification.
The microscope in the cabinet uses an Abbe condenser lens. The condenser lens is one of the main components in every compound microscope. A condenser lens sits underneath the specimen and above the illumination source and concentrates the light through the specimen and into the objective lens. The Abbe condenser lens has two controls, one that moves the condenser towards or away from the stage and a second that controls the diameter of the light beam. This means that the observer can optimize the brightness and evenness of the light as well as the contrast. Abbe condensers are best suited to magnifications of 400 times or smaller.
Abbe also founded the Carl Zeiss Foundation in 1889. The foundation is the sole shareholder of both the Carl Zeiss company and Schott company and is dedicated to the betterment of its employees as well as the advancement of natural and mathematical science through research and teaching.
This item is part of the UQ Physics Museum Microscopes Tour
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