The optical microscope mainly consists of an eyepiece, an objective lens, a stage, and a reflector. Eyeglasses and objective lenses are convex lenses with different focal lengths. The focal length of the convex lens of the objective lens is smaller than the focal length of the convex lens of the eyepiece. The objective lens is equivalent to the lens of a projector, through which an object is formed into an inverted and enlarged real image. The eyepiece is equivalent to an ordinary magnifying glass, and the real image is formed into an upright and enlarged virtual image through the eyepiece. Objects that pass through the microscope to the human eye are inverted and enlarged virtual images. Reflectors are used to reflect and illuminate objects being observed. Reflective mirrors generally have two reflective surfaces: one is a planar mirror, which is used when the light is strong; One is a concave mirror, which is used when the light is weak and can concentrate the light.

The microscope has opened up a new world in human vision, and for the first time, people have seen hundreds of "new" micro animals and plants, as well as the internal structures of everything from the human body to plant fibers. Microscopes also help scientists discover new species and help doctors treat diseases.