The principle of telecentric parallel light source

In machine vision applications, strict requirements are placed on lens distortion, and telecentric lenses with their unique parallel optical path design are highly favored. These lenses can maintain a constant magnification across a range of object distances, which makes them invaluable in laser scanners, image measuring instruments, online inspections, medical equipment, automated devices, machine vision, and microscopy technology.

A point light source is an idealized source that emits light uniformly in all directions, often represented as a very small sphere that radiates light evenly. In contrast, a parallel light source emits light rays that are parallel and non-divergent, ensuring that the light pattern remains consistent regardless of the distance from the source to the illuminated surface.

Principles of Parallel Light Sources

Based on geometric optics, an object at infinity will form an image on the focal plane after passing through a lens; conversely, a light source from the focal plane will emerge as a parallel light beam after passing through a lens. If an object is placed on the lens's focal plane, it will form an image at infinity.

Compared to ordinary backlights, telecentric parallel light sources eliminate edge blurring caused by light diffusion, creating sharper and clearer images, thus enhancing measurement accuracy. Telecentric lenses are particularly suitable for capturing cylindrical and circular objects, while parallel light sources are ideal when precise measurement and consistent image quality are critical.

Applications of Telecentric Parallel Light Sources

Here are some common applications for telecentric parallel light sources:

1. Detecting Thick Objects: When objects have considerable thickness, a telecentric parallel light source can provide consistent illumination.
2. Measuring Circular Materials: When the outer diameter of cylindrical objects needs to be measured accurately, this type of light source is beneficial.
3. Detecting Non-Co-Planar Objects: Telecentric light sources help ensure consistent illumination across objects that aren't on the same plane.
4. Unknown Object-Lens Distances: When the exact distance between the object and the lens is unclear, telecentric parallel light sources offer a reliable solution.
5. Measuring Objects with Apertures or 3D Shapes: These light sources can provide the uniformity and precision needed to measure complex shapes or objects with holes.
6. Low Distortion and Uniform Brightness: When low distortion and consistent brightness are required, telecentric parallel light sources excel.
7. Defect Detection with Directional Lighting: When defects are only detectable under parallel lighting from a specific direction, this type of light source ensures optimal conditions.

Telecentric parallel light sources offer distinct advantages in high-precision inspection and are valuable companions to telecentric lenses in machine vision systems. The unique properties and long lifespan make them indispensable in various industrial applications.