How Leeuwenhoek's Microscope Worksby Contributor
Anton van Leeuwenhoek
Anton van Leeuwenhoek (1632 to 1723) was a Dutch cloth merchant who made literally hundreds of microscopes. Although compound lenses were invented at that time, they were not yet perfected, and so Leeuwenhoek's microscopes all worked based on a more simple magnification system. Leeuwenhoek's skill as a lens grinder was essential to the success of his microscopes and enabled him to make what were essentially glorified magnifying glasses that could magnify an object up to more than 100 times.
The Basic Leeuwenhoek Microscope
The standard Leeuwenhoek Microscope is composed of four parts: a small lens to magnify the object, a spike to hold the object in front of the lens (and rotate it if need be), a screw to adjust the position of the object and a large base plate to hold it all together. The object is impaled upon the spike, and the screws are used to rotate the object and move it closer to or farther from the lens.
How It Works
The object is held firmly in place behind the lens, which creates a virtual image of the object that is larger than the actual object. By placing the object closer to the convex lens than the actual focal length of the lens, the object becomes closer than the intended focus, and thus appears larger in the image created in the lens.
The skewered object, in the case of the Leeuwenhoek Microscope, is held firmly in place behind the lens closer than the focal point of that convex lens. However, since each individual has a different focal length, an adjustment screw is provided to vary the distance between object and lens to make sure that optimum magnification can be achieved.
For information on making your own Leeuwenhoek Microscope, see Resources below.