. Optical microscopes

Optical lenses made of curved glass or other transparent materials can magnify objects for imaging. Optical microscopes use this principle to magnify tiny objects to a size sufficient for human eyes to observe. Modern optical microscopes usually use two levels of magnification, which are completed by the objective lens and the eyepiece respectively. The object to be observed is located in front of the objective lens, and is magnified by the objective lens in the first stage to form an inverted real image, and then the real image is magnified by the eyepiece in the second stage to form a virtual image, and what the human eye sees is the virtual image. The total magnification of a microscope is the product of the magnification of the objective lens and the magnification of the eyepiece. Magnification refers to the magnification ratio of linear dimensions, not the area ratio.