Introduction

Measurements done a Profile Projector with telecentric lenses are more accurate and have better repeatability when compared to those done on Profile Projectors with non-telecentric  lens system.

This statement holds true but one needs to carefully evaluate the added benefit of accuracy and repeatability for one’s particular application against the added cost of telecentric lens system. Depending on the dimensions and the kind of part that needs to be measured a telecentric lens might or might not be an ideal solution for you.

Surface Features on the Part

The primary advantage of telecentric lens is that its magnification does not change in respect to depth. Thus, the size of the image does not change even if it is slightly out of focus.  Now imagine you have a part that has multiple surface features on different planes. Now on a standard non-telecentric lens system, parts of the image which are in focus and parts that are out-of focus will not have actual dimensions, resulting in errors in measurements. However in a telecentric system, features lying on different planes, though slightly out-of-focus will still have the actual dimensions in the image resulting in accurate measurements. So that if your part has surface dimensions on different planes that need to be measured, a telecentric profile projector is what you need.

Wide-spaced dimensions

The other advantage of the telecentric lens system is that the images are produced by parallel light rays resulting in lower distortions compared to non-telecentric systems. So that if you need to measure dimensions that are as long as the image itself, distortions will creep in resulting in lower values. These variations are extremely small and it needs to be seen if you actually need such level of accuracy.

We hope by this information you will be able to evaluate if investing in a telecentric lens system for a Profile Projector makes sense for your particular application.