The importance of telecentric lenses in machine vision systems

               Far center optical lenses can reduce or even eliminate the magnification changes caused by object displacement; Picture distortion; Perspective error; Poor picture resolution; The uncertainty of object marginal orientation caused by the geometric shape of the light source constrains the accuracy and repeatability of measurement, making it a key component for developing high-precision measurement applications.

Characteristics of telecentric lens

1. Stability of magnification expansion

              Far center lenses not only enhance natural depth of field through aperture and magnification, but also have unparalleled optical effects compared to non far center lenses: when moving objects within a certain object distance range, the imaging remains unchanged, that is, the magnification remains unchanged. In the process of visual inspection, any project that requires accuracy will undergo a proportional conversion between object space and image space, and the actual size of the object will be restored through the size of the drawing.

  2. No perspective error constraint

                The telecentric lens establishes a two-dimensional correspondence when taking pictures of objects. It does not display the third dimension of the object being measured and does not affect the planar features with the depth dimension. Therefore, it becomes a perfect component for cross-sectional imaging and size measurement.

3. There is no uncertainty of marginal orientation

                When taking photos of objects with backlighting, it is often difficult to confirm the proper orientation of their edges. Because in a dark background, bright pixels at the edges of objects often stack with dark pixels. In addition, if the object has a highly three-dimensional shape, the gap effect will further constrain the measurement accuracy; The use of a telecentric lens can effectively constrain this effect: if the pupil aperture is small enough, the only reflected light that can enter the lens will be those rays that are close to parallel to the main optical axis. Because these rays are subject to very small deviations, the reflection from the surface of the object will not compromise the measurement accuracy.

                The widespread use of visual inspection systems is an inevitable result of the development of industrial automation, and the telecentric lens, as a key component for high-precision detection and measurement in machine vision systems, has irreplaceable advantages under specific conditions, which can enable the visual inspection system to achieve the expected measurement results.