Leeuwenhoek's microscope. Man looking through the tiny lens of an early microscope made by the Dutch scientist Anton van Leeuwenhoek (1632-1723). Leeuwenhoek's microscopes have a single lens mounted in a flat sheet of metal, which allows magnifications of up to x200. In the 1670s, Leeuwenhoek used a microscope similar to this in order to observe and describe single-celled animals (protozoa and bacteria), which he named 'animalcules', for the first time in history.