The smallest microbody that the microscope lens can achieve is 0.2 microns.

　　The naked eye cannot see the fine parts smaller than 0.1 mm on the object. The microscope is essentially an instrument that obtains magnified images of the fine parts so that they can be seen clearly. The volatility of light imposes a fundamental limit on how fine a microscope can "resolve". This limit has nothing to do with the magnification of the microscope, which can be increased indefinitely by increasing the number of lenses or using stronger lenses.

　　 The smallest microbody that a microscope can distinguish is called its resolving power. For various reasons, the smallest detail reproduced in a given image may be larger than the resolution power of the instrument, in order to distinguish it from the resolution power. It is called image resolution. Therefore, the distinguishing power, as its name suggests, represents the theoretical or practical resolution of the instrument. The resolution refers to the actual effect.

　　 The basic component of a microscope is a lens. The properties of the optical system of the lens are well-known to everyone. The basic optical system of a microscope consists of a series of lenses, which produce a series of progressively enlarged images. The brightness of the final image is determined by the intensity of radiation entering the objective lens from the object to be tested and the total magnification.

　　 is proportional to the decrease in brightness. Therefore, it is necessary to gather as much illumination radiation as possible. In order to produce a visible bright image. To achieve this, the aperture angle of the objective lens—the angle of the radiation cone received by the objective lens—must be large. This angle can be defined by the half-angle of the light cone that is emitted from each point of the test object and enters the objective lens. As everyone knows, the lens aberration becomes more serious when the angle increases, so in order to condense more light, a more perfect lens is needed.