Dimension detection from the initial extensive manual detection vernier caliper, micrometer measurement to machine vision high-precision detection, each stage reflects the unique advantages of machine vision technology. The emergence of telecentric lens has made machine vision detection a big step towards the degree of refinement.
The following three unique advantages of telecentric lens are discussed from the perspective of machine vision inspection:
Advantage 1: High resolution
The image resolution is generally measured by the CTF (Contrast Transfer Function) which quantifies the spatial frequency contrast of the image sensor. The unit of image resolution is lp/mm (Linear Coupling Per Millimeter). Most machine vision integrators only collect a large number of inexpensive low-pixel, low-resolution lenses, and finally only produce blurred images. Using telecentric lens, even with small pixel image sensor, high resolution image can be generated.
Advantage 2: Real telecentric design, ultra wide depth of field and low distortion
There used to be a view that telecentric lens mainly solves the problem of distortion. In fact, telecentric lens solves not only the problem of distortion, but also the additional property of telecentric lens. The unique optical characteristics of telecentric lens: when an object moves in the field of view, its magnification at different positions will not change, which determines that it can not be replaced by ordinary industrial lens in some fields. For example, its larger depth of field can be well adapted to the working environment of the scene. This is not a problem that can be solved only by algorithm.
High resolution telecentric lens.png
High resolution telecentric lens
Advantage 3: Unique parallel light path design.
Designing telecentric lenses for parallel-light imaging is not complicated in theory, but it is another matter to achieve certain resolution and imaging quality. The design and manufacture of telecentric lens is more difficult than that of lens in general sense. The reason is that the size of optical lens of telecentric lens is relatively large, which makes it more difficult to correct all kinds of aberrations of edge light. In order to obtain good image quality of edge field of view, higher product design and manufacturing accuracy are needed. In many cases, designers are required to have more abundant. Rich design experience can be achieved.
It is the telecentric lens that has the above three unique advantages: high resolution, ultra wide depth of field, and unique parallel light design. In recent years, it is the machine vision inspection technology that has been improved. At the same time, it also brings more advantages to the production enterprises, scientific research institutions, precision measurement and detection of instrument industry.
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