How to Detect the Defects on the Transparent Hose Surface

The detection of transparent hose surface defects places an incredibly high demand on the lighting method and the uniformity of the lighting. Ring lights are a commonly used lighting source in many inspection scenarios. They are designed to provide even illumination around the object being inspected. However, when applied to the inspection of transparent hoses, they fall short in several aspects. When we attempted to use a ring light for the hose inspection, we encountered significant difficulties. The light distribution from the ring light was far from ideal. It failed to provide consistent illumination across the entire surface of the hose. Some areas received more light, while others were left in relative darkness. Specifically, the top of the hose presented a particularly challenging problem. Despite our efforts to adjust the position and intensity of the ring light, the top part of the hose remained completely dark. This made it impossible to observe any potential defects in that area. The reason for this is that the transparent nature of the hose causes light to pass through, reflect, and refract in complex ways.

Transparent hoses act like optical elements, causing light to reflect and refract as it interacts with the hose’s surface and interior. When the ring light hits the curved surface of the hose, it scatters in multiple directions. Some of the light is reflected back at angles that are not conducive to proper imaging, creating glare and hotspots. At the same time, the light that penetrates the hose may be refracted, changing its direction and intensity. This complex interplay of light reflection and refraction makes it difficult to obtain a clear and consistent image of the hose surface. Even minor variations in the hose’s thickness or curvature can lead to significant differences in the amount of light reaching the camera or the observer’s eye.

Achieving uniform lighting across the entire surface of the transparent hose is a formidable challenge. The hose’s cylindrical shape, combined with its transparency, means that different parts of the surface require different lighting angles. The areas near the edges of the hose may receive less light compared to the center, and the curvature of the hose can cause shadows to form on the opposite side. Additionally, any imperfections in the hose’s surface, such as slight bends or irregularities, can further disrupt the light distribution. Without uniform lighting, it becomes impossible to accurately detect and analyze surface defects. Defects may be hidden in the shadows or masked by the glare, leading to false negatives or inaccurate assessments of the hose’s quality.

The Basson coaxial telecentric lens emerges as a game-changer in the field of transparent hose surface defect detection. This lens is designed with advanced optical technology to address the specific challenges associated with inspecting transparent objects. One of the key features of the Basson coaxial telecentric lens is its exceptional resolution and uniformity. The lens is designed to provide a high level of clarity and detail in the images it captures. With a reliable resolution, it can distinguish even the tiniest of defects on the hose surface. Whether it’s a hairline crack, a minute bubble, or a barely visible scratch, the lens can accurately capture these details. The uniformity of the lens ensures that the image quality remains consistent across the entire field of view. There are no significant variations in sharpness or contrast from one part of the image to another. This is crucial for accurate defect detection as it allows for a comprehensive and reliable assessment of the hose surface. The distortion rate of the Basson coaxial telecentric lens is less than 0.05%. This extremely low distortion rate means that the images captured by the lens are highly accurate representations of the hose surface. There is minimal stretching, warping, or distortion of the objects in the image, which is essential for precise defect measurement and analysis.

The coaxial design of the Basson lens is another highlight that sets it apart from conventional lenses. In a coaxial telecentric lens, the optical axis of the lens is aligned with the axis of the light source. This unique design has several significant advantages when it comes to inspecting transparent hoses. The coaxial design addresses the lighting difficulties associated with transparent hose inspection. By aligning the light source and the lens axis, the light is directed straight onto the hose surface in a more controlled and efficient manner. This reduces the amount of light scattering and reflection that occurs, ensuring that more of the light reaches the hose surface and is reflected back towards the lens. As a result, the images captured are clearer and more consistent, with less glare and fewer shadows. The coaxial design also helps to overcome the problem of the hose’s transparency causing light to pass through without being properly detected. The light is focused on the surface, allowing for a better visualization of the surface features.

One of the most significant benefits of the coaxial design is its ability to eliminate the darkness that we experienced with the ring light, especially at the top of the hose. The coaxial light source provides illumination from the same direction as the lens is observing, ensuring that all parts of the hose surface are properly lit. This means that even the areas that were previously difficult to see, such as the top of the hose, are now clearly visible. The elimination of darkness allows for a complete and thorough inspection of the hose surface, leaving no area unexamined and reducing the risk of missing any potential defects. While the Basson coaxial telecentric lens addresses many of the lighting challenges associated with transparent hose inspection, the use of a ring light as a supplementary light source can further enhance the inspection process. The ring light can be used to provide additional light to the hose surface, supplementing the illumination from the coaxial light source. This additional light helps to increase the overall brightness of the hose surface, making it easier to detect even the faintest of defects. The ring light can be adjusted to control the intensity and angle of the light, allowing for customization based on the specific requirements of the inspection. For example, in some cases, a higher intensity of ring light may be needed to highlight certain types of defects, while in other cases, a lower intensity may be sufficient to avoid overexposure and maintain image clarity.

By eliminating shadows, the ring light helps to improve the visibility of the hose surface and increases the accuracy of defect detection. The combination of the Basson coaxial telecentric lens and the ring light can optimize the image quality for defect detection. The coaxial lens provides the high-resolution and uniform imaging, while the ring light enhances the overall illumination and fills in the gaps. The improved image quality makes it easier for inspectors to identify and analyze different types of defects. Before starting the hose surface detection process, proper setup and preparation are essential. The Basson coaxial telecentric lens needs to be carefully installed on the imaging device, such as a camera or a microscope. The lens should be aligned correctly to ensure that it is centered and focused on the hose surface. The installation process may vary depending on the type of imaging device, but it typically involves attaching the lens to the appropriate mount and adjusting the focus and aperture settings. The ring light should be positioned around the lens and the hose in a way that provides optimal illumination. The distance between the ring light and the hose should be adjusted to ensure that the light is evenly distributed across the hose surface. The angle of the ring light can also be adjusted to minimize glare and shadows. It may be necessary to experiment with different positions and angles to find the best setup for the specific hose being inspected. The transparent hose needs to be securely mounted in a stable position. The hose should be positioned in a way that allows for easy access to the entire surface for inspection. It is important to ensure that the hose is not distorted or bent during the mounting process, as this can affect the accuracy of the defect detection.

The detection of defects on the transparent hose surface is a complex and challenging task that requires careful consideration of lighting methods and the use of appropriate optical equipment. However, the Basson coaxial telecentric lens, with its reliable resolution, low distortion rate, and innovative coaxial design, provides a powerful solution to these challenges. When combined with a ring light for supplementary lighting, the inspection process becomes more efficient and accurate. This combination of the Basson coaxial telecentric lens and the ring light not only enables the detection of a wide range of surface defects but also ensures the quality and reliability of transparent hoses in various industries. By investing in this advanced inspection technology, manufacturers and quality control professionals can enhance their ability to produce high-quality products, reduce the risk of product failures, and ultimately improve customer satisfaction.

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.