In optical systems, telecentric lenses are lenses with a special optical path design that effectively eliminates aberrations and distortions to provide more accurate images. The optical path types of telecentric lenses are mainly divided into object-side telecentric, image-side telecentric and double telecentric types, each of which has its own unique features and advantages.

I. Object-side telecentric lens

The design of an object-side telecentric lens is characterized by an aperture diaphragm placed in the focal plane of the optical system on the image side, while the object-side main light rays are parallel to the optical axis with the center of convergence of the main light rays located at infinity on the object side. The main advantage of this type of optical path design is that it eliminates object-side reading errors due to inaccurate focusing.

The object-square telecentric lens is more adaptable to the distance of the object, no matter whether the object is far from the lens or close to the lens, you can get a clear image. At the same time, because the main ray of the object square is parallel to the main ray of the optical axis, so it can effectively avoid the image distortion brought about by the tilt of the ray.

II. Like-square telecentric lens

The design of an image-square telecentric lens is characterized by an aperture diaphragm placed in the focal plane of the optical system on the object side, while the image-square main rays are parallel to the optical axis and the convergence center of the main rays is located at the image-square infinity. The main advantage of this type of optical path design is the elimination of measurement errors introduced by inaccurate focusing of the image side.

The optical path of the image-square telecentric lens is designed so that light rays from the image-square pass through the lens and converge into a clear image on the object-square. This imaging method makes the lens more sensitive to changes in the position of the image, allowing for more accurate measurement of the position and size of the object.

III. Double telecentric lens

The double telecentric lens combines the dual role of object/image side, where the main light rays are not only parallel when entering the lens, but also parallel when exiting. In addition, the double telecentric lens does not deform the projected image in the direction of the optical axis, which ensures higher accuracy when measuring.

When choosing to use telecentric lenses, you need to choose according to the specific application scenarios and needs. At the same time, it is also necessary to consider the focal length of the lens, aperture, interface type and other factors to ensure that the selected lens can meet the actual needs.