Telecentric Illumination's Advantages and Applications

Imaging and detection projects require precise optical components and calibration to achieve excellent performance. These machine vision inspection applications use imaging lenses, light sources, cameras, and mechanical devices as key components. The selection of imaging lenses and cameras is an important part of the success of the application; however, lighting is equally important. Telecentric illumination is one of the more precise types of lighting geometries.

Working Principle of Telecentric Illumination

Using high-quality optical glass lenses allows the light from fiber optic light guides or LED spotlights to remain parallel. Diverging light from the light source enters the multi-lens assembly, thus becoming parallel and highly focused. Almost all the light that enters the telecentric illuminator (ignoring back reflection and light absorption from individual optical lenses) will illuminate the object being inspected. Additionally, many telecentric illuminators come with an iris to control the intensity of the provided illumination.

When combined with LED pattern projectors and crosshairs, a standard telecentric imaging lens can be used as a telecentric illuminator. Like typical telecentric illuminators, light passing through the telecentric imaging lens is collimated, eliminating diffuse reflection when forming object contours. However, unlike telecentric illuminators, using a telecentric imaging lens may reveal defects in the LED projector.

Advantages of Telecentric Illumination

Telecentric illumination is ideal for precision measurement applications where accuracy, repeatability, and light flux are critical to successful measurements. Telecentric illumination has powerful micro-defect detection capabilities, higher measurement accuracy, and repeatability compared to standard backlight illumination. It can eliminate blurred edges caused by diffuse reflection in different applications, increase parallel light intensity, and bring high contrast images while eliminating blurred edges. Furthermore, by increasing light intensity, telecentric illumination can shorten camera exposure times, resulting in faster system speeds and greater light flux compared to standard backlight illumination. Telecentric illumination also ensures a greater distance between the object and the light source.

Applications of Telecentric Illumination in Various Fields

Telecentric illumination is widely used in industrial vision technology. First, in guidance applications, it is used to locate or report the position and orientation of parts in 2D or 3D space to machine controllers, or to perform alignment and geometric pattern matching. Second, in inspection applications, telecentric illumination helps detect defects, contaminants, functional flaws, and other irregularities in manufacturing products. Third, in measurement applications, telecentric illumination calculates distances between two or more points on an object to determine whether it meets the requirements of the vision system, otherwise, the system will signal to eject the defective object from the production line. Finally, in identification applications, telecentric illumination is mainly used in OCR and OCV systems to read or verify the presence of codes and characters and to identify parts by setting specific requirements.