For a separate eyepiece, when you place the object where it can image, it will form a positive image or a reverse image. We have learned that the convex lens can be used as a magnifying glass. When we place the object at a point within the focal point of the convex lens, the virtual image formed by it will be in the clear vision interval and then enlarged through the viewing angle so that we can see the object clearly. When placed between one and two focal lengths, we can also obtain a magnified inverted real image. Therefore, the optical principle of the microscope is to use the magnification properties of the above two convex lenses at the same time. Ordinary compound optical microscopes have two convex lenses on the stage. After passing through the convex lens, the inverted and enlarged real image is obtained, and the real image is at the focal length of the second lens (ie the eyepiece), so that the viewing angle can be enlarged to the magnified virtual image. Therefore, the magnification of the microscope is equal to the objective lens and the eyepiece. the result of the multiplication