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Selection of optical lens for vision system
Author:Administrator   Published in:2019-11-20 14:14

Vision system optical lens is generally called camera lens or photographic lens, referred to as lens, its role is optical imaging. The lens is an important component in the machine vision system and plays a key role in image quality. It has an impact on several major indicators of image quality, including resolution, contrast, reduction, and viewing angle. Not only are there a wide variety of lenses, but the quality difference is also very large, but the average user often pays insufficient attention to the choice of the lens when designing the system, which leads to the failure to obtain the ideal image and even the system development failure. Therefore, the selection of the optical lens of the vision system It is also crucial.

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Visual system optical lens parameter selection:

1. High image resolution

The image resolution is typically measured in terms of the CTF (contrast transfer function) that quantifies the spatial frequency contrast of the image sensor in lp/mm (coil per mm). Most machine vision integrators often only collect a large number of inexpensive low-pixel, low-resolution lenses, and then only generate blurred images. With the AFT telecentric lens, high resolution images can be generated even with small pixel image sensors (eg 5.5 megapixels, 2/3").

2. Nearly zero distortion

The distortion coefficient is the percentage difference between the physical size and the imaging size of the image sensor. Ordinary machine lenses usually have distortions greater than 1-2%, which can seriously affect the accuracy of the measurement. In contrast, the telecentric lens is strictly controlled to less than 0.1% through strict manufacturing and quality inspection.

3. No visual error

When performing precision linear measurements in metrology applications, it is often necessary to observe from the standard front side of the object (not including the side at all). In addition, many mechanical parts cannot be placed accurately, and the measurement time interval is constantly changing. Software engineers need images that accurately reflect the real thing. The telecentric lens perfectly solves the above confusion: because the entrance pupil can be located at infinity, it only receives the main ray of the parallel optical axis when imaging.

4. Perspective

The perspective of the perspective is the angle of sight, that is, the visual system optical lens can see more "wide".

These parameters are related to each other. The relationship between the optical lens of the vision system is: (1) the smaller the focal length, the larger the angle of view; (2) the shorter the working distance, the larger the field of view. For ordinary lenses, the selection principle is: the closer the working distance is, the smaller the distortion of the lens is, the better the field of view is.

The above is the introduction of the selection of the optical lens of the vision system. Do you have a new understanding of the optical lens? If you want to know more about the optical lens, please pay attention to our TEO TECH.


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