There are three telecentric lenses:
1. The object-side telecentric lens – the object telecentric lens is the aperture diaphragm placed in the optical system of the image side focal plane, when the aperture diaphragm placed on the image plane focal plane, even if the object distance changes, like The distance also changed, but the height did not change, ie the measured object’s size did not change. Telecentric lens for industrial precision measurement, distortion is minimal. High-performance can reach no distortion.
2. Like a telecentric lens – like a telecentric lens, by placing an aperture stop on the focal plane of the object so that the principal square of the image is parallel to the optical axis so that although there is a change in the mounting position of the CCD chip, The projected image size remains the same.
An advantage of a telecentric lens is that the camera’s chip gets uniform light, as only light parallel to the optical axis can be incident on the micro-lens in front of the CCD / CMOS chip. So that the image will not appear shaded.
3. Telecentric lens on both sides – This lens combines the advantages of both lenses above.
In industrial image processing / machine vision, generally only use the object telecentric lens! Occasionally there are telecentric lenses on both sides (of course, the price is higher). In the field of industrial image processing / machine vision, telecentric lenses do not generally work, so the industry does not have to use it.
Post time: Dec-04-2018