How to Choose a Bi-Telecentric Lens for Vision Applications

In the field of machine vision, the performance of a lens plays a critical role in determining the accuracy and reliability of inspection results. A standard FA lens has an inherent characteristic of perspective distortion, where objects appear larger when they are closer and smaller when they are further away. This perspective distortion, much like a concealed double-edged sword, significantly compromises the accuracy of precision inspection tasks. It acts as a veil of uncertainty over inspection data, posing considerable challenges for precise measurement and analysis.

Enhancing Data Accuracy and Efficiency with a Bi-Telecentric Lens

A bi-telecentric lens serves as a solution to this challenge, acting as a precise visual "correction master." Through its unique optical design, the lens ensures that light rays remain parallel to the optical axis as they enter and exit the optical system. This design is akin to a carefully constructed optical bridge, maintaining a constant image magnification. By eliminating perspective distortion, a bi-telecentric lens removes the veil of uncertainty, providing accurate inspection results. Additionally, it effectively suppresses stray light, enhancing the sharpness of object edges and facilitating efficient data processing.

Factors to Consider When Choosing a Bi-Telecentric Lens

When selecting a bi-telecentric lens for applications in precision measurement or defect inspection, it is essential to consider the following factors:

Object Thickness and Multiplane Inspection

For objects with significant thickness or those requiring inspection across multiple planes, such as food containers or beverage bottles, a bi-telecentric lens ensures accurate measurements across all planes. Unlike standard lenses, it maintains a constant magnification, providing reliable data for multiplane measurements.

Object Position and Angle Variability

In scenarios where objects are placed at uncertain angles relative to the lens, standard lenses often produce severe image distortion. However, a bi-telecentric lens remains unaffected by angle variations, ensuring consistent and accurate imaging. This characteristic makes it an ideal choice for applications requiring dependable data in unpredictable orientations.

Object Movement and Distance Variation

During inspections on production lines, objects may vibrate or shift, causing frequent changes in working distance. While standard lenses experience significant image quality degradation under these conditions, a bi-telecentric lens effectively eliminates measurement errors caused by distance variations. It ensures stable, precise results, contributing to the efficient operation of production systems.

Complex Object Structures

For objects with intricate geometries, apertures, or three-dimensional shapes, a bi-telecentric lens captures accurate and distortion-free images. It provides a true representation of the object’s features, making it an excellent tool for inspecting components with challenging structural characteristics.

Low Distortion and Uniform Brightness

When inspection tasks demand minimal distortion and uniform brightness across the entire image, a bi-telecentric lens excels. Unlike standard lenses that may introduce noticeable distortion and brightness inconsistencies, a bi-telecentric lens ensures virtually distortion-free imaging with consistent brightness, providing a solid foundation for high-precision analysis.

Directional Lighting for Defect Detection

In applications where specific directional lighting is required to detect defects, a bi-telecentric lens works seamlessly with parallel illumination systems. This combination ensures accurate defect detection, minimizing false positives and negatives by eliminating inconsistencies caused by improper lighting and lens characteristics.

Ultra-High Precision Requirements

For tasks requiring exceptional accuracy, with tolerances as low as 1 micron, a bi-telecentric lens is the preferred choice. Standard lenses often struggle to meet such stringent requirements, but a bi-telecentric lens serves as a high-precision measurement tool, supporting applications in high-end manufacturing and scientific research.

In measurement systems, changes in object distance are a major source of measurement errors. Standard lenses cause size variations in the captured image when the object distance changes, resulting in inaccurate measurements. Even if the distance remains stable, slight misalignments of the CCD sensor's sensitive surface can introduce measurement errors. A bi-telecentric lens effectively eliminates these errors. By maintaining a constant magnification, it ensures that the true size and features of the object are accurately represented. Serving as a reliable "error eliminator", the bi-telecentric lens forms the foundation for high-precision measurement systems. It ensures that each measurement reflects the genuine characteristics of the object, setting a new standard for accurate, reliable inspections in the field of machine vision.