Telecentric lenses come into play in machine vision inspection

Telecentric lenses (Telecentric) are designed to correct the parallax issues found in traditional industrial lenses. They maintain consistent magnification over a specific object distance range, which is crucial in applications where the objects being measured are not on the same plane. Because of their parallel light path design, telecentric lenses are highly favored in machine vision applications that require minimal lens distortion.

Industrial lenses are critical imaging components in machine vision systems. For a system to function optimally, the industrial lens must meet certain requirements. In the early 21st century, as machine vision systems were increasingly applied to precision inspection, regular industrial lenses struggled to meet these demands. To address the shortcomings of regular lenses and adapt to precision inspection needs, telecentric lenses were developed.

Telecentric lenses bring a qualitative leap to machine vision precision inspection due to their unique optical characteristics: high resolution, ultra-wide depth of field, ultra-low distortion, and unique parallel light design.

The purpose of telecentric lens design is to eliminate the variation in magnification caused by inconsistent distances between the object being measured (or CCD sensor) and the lens. Telecentric lenses can be categorized based on their design principles:

1. Object-Side Telecentric Design Principle and Function: In an object-side telecentric system, the aperture stop is placed at the image-side focal plane, with the object-side chief rays parallel to the optical axis, converging at infinity. This design helps eliminate reading errors due to inaccurate focusing on the object-side.

2. Image-Side Telecentric Design Principle and Function: In an image-side telecentric system, the aperture stop is placed at the object-side focal plane, with the image-side chief rays parallel to the optical axis, converging at infinity. This design eliminates measurement errors caused by imprecise focusing on the image-side.

3. Double-Sided Telecentric Design Principle and Function: This design combines the advantages of both object-side and image-side telecentricity. It's mainly used in visual measurement and inspection applications.

Telecentric lenses with double-sided telecentric design are primarily used in precision measurement and inspection due to their combined benefits, providing high accuracy and stability in machine vision systems.