In the 17th century, it was discovered that combining two convex lenses increased significantly the magnification, and this device was the microscope's predecessor. The first true microscope, a combination of a piece of convex lens and a piece of concave lens overlapped, also known as a compound microscope, was made by Dutch opticians Jensen and his sons, and later improved by Italian astronomer Galileo Galilei, which made the microscope brings a better effect.　　The first microscopes were simple, only magnifying 50-200 times, but later they were improved and developed gradually. The optical microscope could magnify objects up to about 1500...