Do you need repeatable, high-accuracy measurements? Then maybe you need to fit a telecentric lens to your machine vision system.
When viewed with a telecentric lens, an object will remain exactly the same size, no matter how much it moves around. This is in contrast to more conventional lenses, for which close objects appear much bigger than those farther away. But how does this work, and what all are telecentric lenses good for? Let’s examine those two questions here.
How Telecentric Lenses Work
A telecentric lens is actually a multi-part optical lens assembly designed to eliminate parallax, or perspective error. The figure below illustrates the difference between the field of view of a conventional lens and a telecentric lens: while a conventional lens has an angular field of view, the field of view of the telecentric lens is constant. This means that a telecentric lens has the same field of view at any distance from the lens.