The imaging principle of the microscope
A microscope and a magnifying glass have the same function, that is, to turn a small object in the vicinity into a magnified image for the human eye to observe. It's just that a microscope can have a higher magnification than a magnifying glass.
Figure 2 is a schematic diagram of an object being imaged by a microscope. In the figure, for convenience, both the objective lens L1 and the eyepiece L2 are represented by a single lens. Object AB is located in front of the objective lens at a distance greater than the focal length of the objective lens, but less than twice the focal length of the objective lens. Therefore, after it passes through the objective lens, it will inevitably form an inverted magnified real image A'B'. A'B' is located at the object focal point F2 of the eyepiece, or very close to F2. Then magnify it into a virtual image A''B'' through the eyepiece for eye observation. The position of the virtual image A''B'' depends on the distance between F2 and A'B', which can be at infinity (when A'B' is on F2) or at the observer's photopic distance ( When A'B' is to the right of focus F2 in the figure). The eyepiece acts like a magnifying glass. The difference is that what the eye sees through the eyepiece is not the object itself, but the image of the object that has been enlarged once by the objective lens.
