Bi-Telecentric Lens: Making Visual Inspection More Accurate and Efficient!

Industrial lenses are important components in vision systems, and the selection of industrial lenses affects the imaging quality of the entire system. When performing visual inspections, issues such as the inability to detect spatial objects, control field changes, control image distortion, low contrast, high distortion, and reflections may arise. Ordinary industrial lenses cannot effectively solve these problems, which is where bi-telecentric lenses come in.

Bi-telecentric lenses can overcome the defect of ordinary industrial lenses' "near large, far small' issue. Their special optical design allows the camera to receive parallel light, addressing the accuracy problems caused by parallax, avoiding stray light, and ensuring a clear image contour.

Working Principle of Bi-Telecentric Lenses

Bi-telecentric lenses achieve this by adding a set of aspherical lens chips in the optical system. Their working principle is based on the reasonable design of a biconvex lens group and lens spacing. In this design, the central optical axes of the two convex lenses are raised relative to each other, and the spacing between the lenses is appropriate. This special construction allows bi-telecentric lenses to have both telecentric and pericentric focal points simultaneously.

When parallel light enters the bi-telecentric lens, it refracts on both convex lenses and converges at two different focal points. These focal points are known as the telecentric focal point and the pericentric focal point. The telecentric focal point refers to the point where the light converges farther from the lens group, while the pericentric focal point refers to the point where the light converges closer to the lens group.

Advantages of Bi-Telecentric Lenses

The uniqueness of bi-telecentric lenses lies in their ability to change the focal point position by adjusting the lens spacing. When the lens spacing is large, the telecentric focal point moves towards the camera, while the pericentric focal point moves towards the light source. Conversely, when the lens spacing is small, the telecentric focal point moves towards the light source, and the pericentric focal point moves towards the camera. This characteristic of changing focal point positions through lens spacing adjustment makes bi-telecentric lenses flexible and practical in photography.

Compared with ordinary lenses, bi-telecentric lenses have more lenses and layers, so their price is relatively higher. However, the advantages of bi-telecentric lenses are also very significant. They provide clearer and more natural shooting effects, and it is easier to show the depth of the subject.

Applications of Bi-Telecentric Lenses

Semiconductor Chip Inspection

In the field of semiconductor chip manufacturing, bi-telecentric lenses can be used for image measurement and inspection. During the manufacturing process of semiconductor chips, bi-telecentric lenses, through their high-precision and high-stability imaging system, ensure the product's quality and reliability.

Chip inspection generally requires a smaller field of view and higher precision, which ordinary FA lenses cannot achieve. This requires lenses with a large depth of field to simultaneously see clear images at different heights, improving measurement efficiency. Due to the bi-telecentric lens receiving parallel light, this characteristic makes the image contrast significantly better, more conducive to software inspection.

Transparent Glass Bottle Defect Inspection

The material of transparent glass bottles is easily interfered by external environmental light, prone to occlusion or whitening. Bi-telecentric lenses have a special optical design that can effectively solve light interference phenomena, clearly and accurately identifying small defects such as scratches and white spots.

Bi-telecentric lenses not only have high resolution but also extremely low telecentricity and distortion, resulting in clearer imaging. Therefore, the inspection accuracy is very high, which can greatly improve inspection efficiency and production quality.

Automotive Parts Inspection

In the manufacturing of automotive parts, many precise optical inspection and measurement applications are involved. Bi-telecentric lenses can achieve clear visual images at different working distances, thereby achieving high-precision optical measurement at different distances, improving assembly and quality inspection efficiency and accuracy.

Compared with telecentric lenses, bi-telecentric lenses have higher telecentricity. When selecting for precise measurement, if the accuracy requirement for the observed object is very high, bi-telecentric lenses are a good choice. They can successfully complete inspection tasks, significantly improving inspection accuracy, helping to reduce costs and increase efficiency.