The microscope has revolutionized medical science perhaps more than any other single piece of technology. Simply put, modern understanding of health and illness-and of life itself-would be impossible without microscopes. Medical historians D.H. Kruger, P. Schneck, and H.R. Gelderblom write, "A major step in our present understanding of life was the ability to analyse structures and minute organisms too small to be scrutinised by the naked eye."1

Microscopes have been crucial to medical discoveries for centuries. In the 1600s, the first microscopes revealed the existence of microbes and bacteria. In the late 1800s, vastly improved instruments helped prove that germs carry disease. They were also crucial to discoveries about the structure and behavior of cells, which contain some of the building blocks of life.

More recently, specialized microscopes have been key to other breakthroughs. For instance, they have made it...