Applications of Telecentric Lenses: When to Use Them in Machine Vision Inspection

Industrial lenses are one of the key components of machine vision systems. To ensure that the entire machine vision system functions at a high level, industrial lenses must also meet the required standards. In recent years, vision systems have rapidly developed in China's economy, and machine vision systems are widely used in fields that require precision inspection.

Special Industrial Lenses Have Emerged

However, general industrial lenses are unable to meet inspection requirements. To compensate for the shortcomings of general lenses and adapt to overhaul requirements, telecentric lenses have emerged. Therefore, telecentric lenses are mainly used for measuring the dimensions and inspecting the defects of precision equipment, and their technical advantages in precision inspection applications are gradually being recognized.

Telecentric lenses are designed to correct the parallax of traditional industrial lenses, allowing them to maintain a consistent image magnification over a certain distance range. This is crucial for applications where the measured object is not at the same location each time. Due to their unique parallel light path design, telecentric lenses have always been favored in visual system applications that have high standards for lens performance.

Industrial lenses are crucial imaging components in machine vision systems. To maximize the performance of the system, industrial lenses must meet specific requirements. In the early 21st century, with the widespread application of machine vision systems in the overhaul industry, general industrial lenses could not meet inspection requirements. To address the shortcomings of general lenses and adapt to overhaul needs, telecentric lenses emerged.

When to Use Telecentric Lenses in Vision System Inspection?

One of the main functions of telecentric lenses is their use as measuring lenses. Their primary feature is that under a telecentric perspective, there is no measurement error caused by the incident angle. Compared to standard lenses, the light in front of a telecentric lens is parallel to the optical axis. This keeps the image scale consistent throughout the depth of field, significantly reducing or eliminating measurement errors caused by changes in working distance, the extension of measurement objects along the optical axis, or inclined measurement surfaces. The following situations require the use of telecentric lenses:

• When the inspected objects are thick and require inspection of two or more planes, typical applications include food packaging boxes and mineral water bottles.

  
  

• When the placement of the measured object is uncertain and may form a certain angle with the lens.

  
  

• When the object being tested vibrates during the inspection process, such as oscillations in the production line causing changes in the working distance.

  
  

• When the measured object has an aperture or is a three-dimensional object.

  
  

• When there is a need for low distortion rates and almost completely consistent image brightness.

  
  

• When the defects to be detected can only be seen in parallel-illumination lighting conditions.

  
  

• When the inspection precision needs to exceed the standard, with an output precision of 1um.