By: G. Hölzer

Telecentric lenses - Fundamentals, applications, challenges

Originally only used in microscopy, telecentric lenses have come to be used more and more in industrial image processing over the past 20 years. In fact, these lenses are indispensable for high accuracy measurements and for demanding inspection tasks. They are used, for example, to compensate for varying working distances and to avoid perspective distortion when 3-D objects are being inspected. Telecentric lenses are a key element in quality management systems. They enable highly accurate shape measurements and reliable inspection of objects.

Dr. Claudia Brückner, head optical developer at Vision Control, explores this topic in an article in the 2013 "Jahrbuch Optik und Feinmechanik".

Her article gives users an overview of the most fundamental aspects of this special lens construction. A tool that makes it possible to identify opposing and dependent parameters when designing telecentric lenses is introduced in the section "Telecentric lenses - degrees of freedom". An important criterion used to estimate the necessary exposure time and the fundamental brightness characteristics of images produced by telecentric lenses are detailed in the section "Luminosity of telecentric lenses". In the section "Lighting", the possibilities offered by various different lighting options in connection with telecentric lenses are described and a particularly directed form of lighting using telecentric lights is explored in more detail.

The annual publication "Jahrbuch Optik und Feinmechanik" (ISBN 987-3-00-041353-7) is edited by Dr.-Ing. Wolf-Dieter Prenzel and published by OPTIK-Verlag.