Basic Categories of Telecentric Lenses

Basic Categories of Telecentric Lenses Telecentric lenses are a specialized type of lens used in optical systems, particularly in industrial and machine vision applications. They are designed to maintain consistent magnification regardless of changes in object distance, making them ideal for precise measurement and inspection tasks. The main categories of telecentric lenses are:

1. Object-Side Telecentric Lenses

   • In this type, the aperture stop is positioned at the image-side focal plane of the optical system. Even if the object distance changes, the image distance changes as well, but the image height remains constant, ensuring that the measured object size does not vary. These lenses are often used for industrial precision measurement applications, as they have minimal distortion. High-performance object-side telecentric lenses can achieve virtually no distortion.

2. Image-Side Telecentric Lenses

   • Here, the aperture stop is placed at the object-side focal plane, causing the image-side principal rays to be parallel to the optical axis. This design ensures that even if the installation position of the CCD sensor changes, the size of the projection on the CCD sensor remains consistent. This stability in image size makes image-side telecentric lenses useful in certain applications.

3. Double-Sided Telecentric Lenses

   • These lenses combine the advantages of both object-side and image-side telecentric lenses. In industrial image processing, the most commonly used type is the object-side telecentric lens, while double-sided telecentric lenses are occasionally used, albeit at a higher cost. In the field of industrial image processing and machine vision, image-side telecentric lenses generally don't play a significant role, and thus are rarely used.

Each type of telecentric lens has its specific use cases. Object-side telecentric lenses are prevalent in industrial and machine vision due to their ability to maintain consistent measurements despite variations in object distance. Double-sided telecentric lenses are used when additional precision and consistency are required, while image-side telecentric lenses have limited use in these industries.