Solar Microscope
This is an article about the development of the solar microscope or sometimes known as projection microscope. The inventor of this great equipment in microscopy is a German physician and naturalist Johann Lieberkühn. He used this microscope in studying small animals and in his study of zoology, illuminating them with sunlight using an instrument that bore his name. The microscope model that became widespread though was the one designed and built by the London optician John Cuff and was also the one who first used the solar microscope with a heliostat.
The solar microscope is a device in microscopy that projects real, greatly enlarged images of objects onto a screen, in instances when the specimens details are too small to be observed by the naked eye. The name solar is due to the fact that to have a sharp image, the object would be intensely illuminated with sunlight using a heliostat but the denomination remained unvaried even when other light sources, such as the arc lamp, were used.
To have the object in sharp focus and sufficiently enlarged on the screen so that its details can be observed, the position of the objective is adjusted by turning the appropriate rack screw so that the object falls beyond the focus at a distance from it of not more than the focal length. The object is usually attained by inclining the mirror to a greater or less extent by means of an endless screw, and at the same time turning the mirror itself round the lens. Since the direction of the light of the sun is continuously changing, the position of the mirror outside the shutter must also be adjusted, so that the reflection is always in the direction of the axis of the microscope.
Important parts of the solar microscope include the brass tube which consists of two pieces, one a truncated cone and the other a cylinder with slides, that have an extension inside the narrower part of the former. Another important part of the microscope is the shelf for objects on which the support for the slides moves. At the center it has a circular aperture and lies with four pins with spring spacers on another burnished brass plate attached to the narrower end of the tube. Then theres objective, composed of a system of converging lenses of short focal length held by a staff which, by means of a rack screw, allows it to move towards or away from the slide. At the wider end, the microscope tube is threaded so that it can be screwed onto the heliostat. It has a converging lens which, by completely covering the aperture, captures the sunlight reflected by the heliostat mirror, making it converge onto one lens placed at the end of the tube and, in turn, makes it converge on the object. The distance between the two lenses and the convergence of the sunlight can be adjusted by manually moving the cylindrical part of the tube up and down inside the other part and then making fine adjustments by means of a rack screw.
http://physics.kenyon.edu/EarlyApparatus/Optics/Solar_Microscope/Solar_Microscope.html