Object lens is the most important optical component of a microscope. It uses light to make the first image of the object being examined. Therefore, it directly affects the quality of the image and various optical technical parameters. It is the first standard to measure the quality of a microscope.
The structure of objective lens is complex and its manufacture is precise. Usually, it is composed of lens groups. The lenses are separated from each other at a certain distance to reduce the phase difference. Each group of lenses is made up of one or more lenses with different materials and parameters. There are many specific requirements for objective lens, such as axis alignment and focus alignment.
Modern microscopic objective has reached a high level of perfection, its numerical aperture has approached the limit, and the resolution of the field of view center has little difference from the theoretical value. However, the possibility of increasing the field of view and improving the image quality of the edge of the field of view still exists, and the research work is still in progress.
The magnification factor of an objective is the ability of an objective to magnify the magnification of an object in its online length. There are two ways to express it. One is to scale directly on the objective lens, such as 8 x, 10 x, 45 x, etc. The other is to scale the focal length f of the objective lens on the objective lens. The shorter the focal length, the higher the magnification. The former magnification formula is M = L / F object, L is the length of the optical cylinder, L value is very accurate in design, but in practical application, the length of the mechanical cylinder is commonly used because of poor measurement. The length of the barrel of the mechanical mirror refers to the straight line distance from the interface of the eyepiece of the microscope. The length of the barrel of the mechanical mirror is indicated numerically on each objective.