A 3-lens is a combination of optical components consisting of three lenses. These lenses can focus, disperse, or change the direction and shape of light. They are usually made of transparent materials, such as glass or plastic, and have different curvature radii and shapes to control the propagation path of light. 3 lenses can be widely used in various optical systems, such as cameras, telescopes, microscopes, etc.

The advantage of a 3-lens is its diversity and flexibility. Due to its composition of three different lenses, it can be used for different optical application needs. In addition, the 3-lens can control the propagation path of light by changing the curvature radius and relative position, thus adapting to different optical application requirements.