The Advantages of Telecentricity

The ability to quickly perform repeatable, high-accuracy measurements is critical to maximizing the performance of many machine vision systems. For such systems, a telecentric lens allows the highest possible accuracy to be obtained. This section discusses the unique performance characteristics of telecentric lenses and how telecentricity can impact system performance.

Conventional lenses have angular fields of view (AFOV) such that as the distance between the lens and object increases, the magnification decreases. This is how human vision behaves and contributes to our depth perception. This AFOV results in parallax, also known as perspective error, which decreases accuracy, as the observed measurement of the vision system will change if the object is moved (even when remaining within the depth of field [DOF]) due to the magnification change. Telecentric lenses eliminate the parallax error characteristic of conventional lenses by having a constant, non-angular FOV; at any distance from the lens, a telecentric lens will always have the same FOV.  

Pictures of Telecentric Lens

Specificaitons of Customized CCTV Visual Lens

Video of High Resolution Telecentric Lens 

People also ask

• What is the difference between telecentric and normal lenses?
  In a non-telecentric lens, when an object is moved in and out of focus, the part blurs asymmetrically due to parallax and the magnification change that is associated with its AFOV. Telecentric lenses, however, blur symmetrically since there is no angular component to the FOV.
• What is the effect of a telecentric lens?
  Another particularity of telecentric lenses is the effect that, even in axial direction (Z-direction, towards or away from the camera), measured distances have the same image scale within a defined range.

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