Anton van Leeuwenhoek invented the simple microscope in 1674, according to About.com. The simple microscope had one lens, which van Leeuwenhoek used to examine insects and other small objects.
Anton van Leeuwenhoek's simple microscope did not look much like modern microscopes. Each microscope had two metal plates, which were riveted together. The microscope lens was located between these plates.
The magnifying capability of each microscope depended on the quality of the lens inside the instrument. According to researchers from the Museum of Microscopy, some scientists suspect van Leeuwenhoek experimented with lenses made from blown glass. Microscopes made with these lenses had superior magnification capabilities when compared with other microscopes from the same period.