What is working distance WD
The working distance is also called the object distance, which refers to the distance from the surface of the front lens of the objective lens to the object to be inspected. During microscope inspection, the object to be inspected should be between one and two times the focal length of the objective lens. Therefore, it and the focal length are two concepts. What is usually called focusing is actually adjusting the working distance.
In the case of a certain numerical aperture of the objective lens, the working distance is short and the aperture angle is large.
A high-power objective lens with a large numerical aperture has a small working distance.
