The solution to the blurry surface defect image

In the field of industrial imaging, optical precision, clarity, and image consistency are critical for ensuring reliable inspection and measurement. This is particularly true when working with telecentric lenses, which have become essential for applications requiring precise dimensional measurement, high contrast edge detection, and consistent imaging across varying object positions within the depth of field. Among the many challenges encountered during industrial inspections, one recurring issue is the presence of blurry surface defects that compromise the accuracy of automated inspection systems. This problem is exacerbated when working within confined spaces, handling complex or reflective surfaces, or facing difficulties with achieving sufficient and uniform illumination. One particularly challenging scenario involves working with telecentric lenses under non-ideal lighting conditions, where even the most advanced illumination techniques may fail to produce clear and bright enough images of the object’s surface. This is where the innovative design of the Basson SUT065 series 2x telecentric lens offers a compelling solution.

Blurry surface defects are not merely the result of lens quality or sensor resolution; they often stem from complex interactions between optical design, lighting geometry, object surface properties, and working distance constraints. Conventional imaging setups may use ring lights, backlights, or diffuse dome lights to illuminate the object. However, these approaches often suffer from uneven illumination, shadowing effects, glare, or insufficient brightness, particularly when working within confined machine spaces where light positioning options are limited. In telecentric imaging systems, this challenge becomes even more pronounced because telecentric lenses demand consistent, uniform, and directional illumination to fully leverage their optical advantages.

Telecentric lenses are uniquely characterized by their ability to maintain constant magnification regardless of the object’s position along the optical axis within a defined depth of field. This property is essential for precision measurement and dimensional inspection applications where any perspective distortion would be unacceptable. However, the design requirements of telecentric lenses, particularly those intended for short working distances, can introduce conflicts between the lens’ physical dimensions, the available space for illumination systems, and the optical compatibility between the lens and the chosen light source. Standard coaxial illuminators, often used in conjunction with telecentric lenses, may suffer from working distance mismatches, inadequate light coverage, or interference with the imaging process itself, resulting in uneven illumination and reduced image clarity.

Recognizing the critical need for a compact yet high-performance telecentric lens that can mitigate these challenges, Basson developed the SUT065 series 2x telecentric lens. This lens is specifically engineered to balance several competing requirements: compact form factor, precision telecentricity, low distortion, and superior compatibility with integrated illumination systems. One of the defining features of the SUT065 series is its ability to maintain a telecentricity error and distortion rate of less than 0.05%, ensuring that objects are imaged with exceptional geometric accuracy.

This level of precision is particularly crucial in industries such as semiconductor inspection, medical device manufacturing, precision component assembly, and high-resolution surface defect detection. When inspecting small parts with fine features or subtle surface defects, even minute optical distortion or magnification variation can lead to inaccurate measurements or missed defects. The SUT065 series solves this problem by combining optomechanical precision with advanced optical coatings, ensuring that the entire field of view remains optically accurate and free of the nonlinear distortions common in conventional lenses.

The SUT065’s length of less than 100mm sets it apart from many competing telecentric lenses, which are often significantly larger. This compact design opens up new possibilities for integrating the lens into existing inspection systems, particularly in space-constrained environments such as production lines, automated assembly cells, and embedded inspection stations within larger machines. In many cases, limited mounting space has previously forced manufacturers to compromise on lens selection or adopt non-telecentric optics, sacrificing measurement precision in favor of physical compatibility. The SUT065 series eliminates this tradeoff, enabling precise telecentric imaging even in tight spaces.

The reduced size also contributes to improved system stability, as shorter lenses are inherently less susceptible to mechanical vibration or misalignment. This mechanical robustness is particularly advantageous for high-speed inspection applications, where even slight vibrations could degrade image quality and introduce measurement errors.

A key factor contributing to the superior imaging performance of the SUT065 series is its innovative coaxial illumination design. Traditional coaxial illuminators often struggle to deliver sufficient brightness or uniformity, particularly at short working distances where light must be precisely coupled into the imaging path. The SUT065 series addresses this limitation by incorporating a highly efficient coaxial lighting system that achieves more than 90% uniformity across the entire field of view.

This level of uniformity ensures that surface features and defects are rendered with consistent brightness, reducing the risk of missed defects due to localized shadowing or uneven exposure. Furthermore, the integrated design minimizes the potential for misalignment between the illumination source and the optical axis, ensuring that the full benefits of telecentric imaging are preserved.

The combination of compact size, optical precision, and superior illumination makes the SUT065 series ideal for a wide range of demanding inspection tasks. In electronics manufacturing, for example, the lens can be used to inspect solder joints, micro-components, and PCB surfaces, where clear imaging of small, reflective, or partially obscured features is essential. In the medical device industry, the lens is well-suited for inspecting syringes, catheters, or precision-molded components, where both dimensional accuracy and surface quality must be rigorously controlled.

Similarly, in automotive manufacturing, the SUT065 can play a crucial role in inspecting machined components, injection-molded parts, or precision assemblies, where both geometric and surface defect inspection are required. The ability to maintain clear, distortion-free imaging across varying object heights ensures that the lens can handle slight part positioning variations without compromising measurement accuracy.

Compared to conventional telecentric lenses, the SUT065 series stands out in several key areas. Traditional telecentric lenses designed for short working distances often suffer from bulkiness, making them difficult to integrate into automated systems. Many also rely on external, separately mounted illuminators, which introduces potential misalignment and requires additional calibration effort.

By contrast, the SUT065 series’ integrated coaxial illumination ensures optimal alignment out of the box, reducing setup time and eliminating one source of variability. Additionally, the high uniformity of the coaxial lighting eliminates the need for extensive post-processing to compensate for uneven illumination, further improving inspection reliability and reducing computational overhead.

When compared to non-telecentric lenses, the advantages become even more pronounced. Non-telecentric lenses inherently suffer from perspective distortion, meaning that objects closer to the lens appear larger than those farther away. This distortion complicates dimensional measurement and makes it difficult to reliably detect surface defects on non-flat or irregularly shaped objects. The SUT065’s true telecentric imaging eliminates this distortion, ensuring that object features are rendered at consistent magnification regardless of depth position.

The introduction of the SUT065 series reflects broader trends in the machine vision industry. As manufacturing processes become more automated, the demand for compact, precise, and easy-to-integrate imaging solutions continues to grow. At the same time, increasing product complexity and shrinking feature sizes place greater demands on imaging systems, requiring ever higher levels of optical performance.

The SUT065 series directly addresses these evolving requirements by offering a lens that combines high-end optical performance with practical design considerations tailored for modern manufacturing environments. Its compact form factor, built-in high-uniformity illumination, and exceptional telecentricity make it a compelling choice for manufacturers seeking to enhance inspection reliability while minimizing system complexity.

The Basson SUT065 series 2x telecentric lens represents a significant advancement in telecentric imaging technology, particularly for applications requiring short working distances, compact installation space, and high-precision surface inspection. By solving common problems associated with blurry surface defects, uneven illumination, and optical distortion, the SUT065 series empowers manufacturers to achieve more reliable and accurate inspections, even under challenging conditions. As industries continue to demand higher precision, faster inspection speeds, and smaller system footprints, innovations like the SUT065 series will play an increasingly vital role in enabling the next generation of industrial automation and quality assurance systems.

Basson focuses on machine vision products used for precision measurement and defect detection.

Basson not only provides high-precision bi-telecentric lens systems, telecentric lens systems, telecentric light sources, coaxial illuminations and optical lenses, but also offers customized services.

With products designed in Germany, business planned in the UK and products made in China, Basson is able to provide superior products to customers through its global team. Currently, Basson is in preparation of production and assembly of products in Japan.

Dr. Liu Lu, acting as CTO of Basson, is a PhD degree holder of Oxford University.

Production and testing instruments include optical vacuum coating machines manufactured by Satis in Switzerland and Leybold in Germany, a laser interferometer from Zygo in the US, a spectrophotometer from PerkinElmer in the US, a spherometer from Hofbauer Optik in Germany, a centering instrument from Kyoritsu Electric in Japan, a NC grinding device made by Kojima Engineering in Japan and an automatic centering machine made by Shonan in Japan.