Application of Telecentric Lens in Impurity and Liquid Level Detection of Filling Line

Industrial lens is an indispensable imaging element in machine vision system. If the system wants to fully perform its function, the lens must be able to meet the requirements of use. With the widespread application of machine vision systems in the field of precision inspection, ordinary industrial lenses are difficult to meet the inspection requirements. To make up for the lack of ordinary lens applications and meet the needs of precision inspection, telecentric lenses have emerged.

Telecentric lens has its own high-resolution, ultra-wide depth of field, ultra-low distortion, and its own parallel light design, and other optical characteristics. It brings a qualitative leap to precise inspection of machine vision. Satisfactory detection applications, we will use the example of BTOS bi-telecentric lens solution to make a comparative introduction for everyone.

Filling is a common process in industrial production. For the glass bottle filling shown in the figure below, we need to pay attention to its two characteristics, one is whether there are impurities and foreign matter in the filling liquid, and the other is the liquid level after filling. Whether the requirements are met.

Glass bottle filling inspection

These samples are characterized by light transmission, reflection, and susceptibility to interference from external ambient light. Light from various angles can cause obstruction or whitening, affecting the detection of impurities inside the liquid. Therefore, the main detection difficulty is the reflection of the glass bottle surface and the tube wall. Because the bottle itself is made of glass, the glass itself not only transmits light but also reflects light, so no matter how you shoot, a large part of the liquid image will be disturbed by the reflection of the glass bottle itself and cannot be detected. This problem will directly lead to the inability to use visual means Impurity detection of filling liquids. The effects of shooting with ordinary lenses are as follows:

Liquid detection in glass bottles (common lens)

  When encountering a problem that cannot be solved by the traditional optical system, we might as well change our mind and look at the effect of bi-telecentric lens shooting. The following figure shows the effect of shooting the same sample with a gigabit interface CCD camera and a BT series bi-telecentric lens:

Liquid detection in glass bottles (bi-telecentric lens)

As can be seen from the figure, the special optical structure of the bi-telecentric lens solves the problem of reflection that troubles us: the refraction of light after passing through the glass bottle and liquid does not block the imaging of the BT series telecentric system. All spaces filled with liquid in the body can be photographed without blind spots. If there are impurities, they will be more obvious, which makes the detection of impurities in the filling liquid possible. At the same time, with a certain light source, the position of the liquid level also becomes clearer and more stable. The following figure shows more examples of liquid level detection we have done:

Level detection case

  Through the above cases, I believe that readers have a certain understanding of the application of dual telecentric lenses in the filling line impurity and liquid level detection. If you are engaged in related work, you need to use dual telecentric products, welcome you Contact us anytime, BTOS Telecentric Optics will be happy to help you.