The principles and applications of fixed focus and telecentric lenses

Fixed focus lens refers to a lens with a fixed focal length. The characteristic of this type of lens is that it has  only one focal length, or only one field of view, without the concept of focal length, or only one field of view.  Fixed focus lenses do not have zoom function. Fixed focus lenses are widely used in industrial automation or  machine vision systems due to their stable image quality and convenient use. Therefore, they are often  referred to as industrial lenses, industrial fixed focus lenses, industrial camera lenses, and machine vision  lenses. 

The telecentric lens is translated from Telecentric Lens. Tele "is far, which means" far "in Chinese; 'Central',  translated as' central '. The direct translation of 'Telecentric Lens' is' telecentric lens'. The telecentric lens is an optical product generated by applications, and there is no very rigorous definition in  academia. It is mainly designed to correct the parallax of traditional industrial lenses. It can maintain the  magnification of the obtained image within a certain object distance range, which is very important for  applications where the measured object is not on the same surface. 

In the optics of prism, a telecentric lens is an imaging lens with a principal axis parallel to the optical axis; A  telecentric lens can also be defined as an imaging lens with an entrance position at a distance (or infinity); A  simpler understanding is that a telephoto lens is an imaging lens that maintains a constant magnification  within a certain working distance range. Due to its design principles, the telecentric lens has two major  features: a large depth of field and low distortion. In measurement applications, the characteristics of the  telecentric lens are particularly well demonstrated.