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Vision-Doctor

Optics

Error-free depiction of the field of view

Optical errors

A variety of optical errors can occur in the lens system, almost all of which can affect the image processing process:

  • Geometric distortion, which causes uneven curvature or compression of the image, is particularly bad for the machine vision expert.
  • Classic aberrations include spherical and chromatic aberrations, coma and astigmatism. They result in blurred images on the sensor.
  • Other optical errors are caused by vignetting, high stray light due to missing coatings and insufficient MTF. They typically result in a reduction in contrast in all or certain areas of the image. This makes the image ‘flat’ and causes more unstable applications and less precise inspections.

As a general rule almost all optical errors...

  • interfere with image processing
  • can rarely be compensated for in the software with reasonable effort
  • can be avoided by using high quality lenses

Teilweise Korrektur optischer Fehler mit Hilfe von Abblenden

By cutting off the optical rays at the edges (artificial vignetting of the optics), certain imaging errors in spherical lenses, such as chromatic longitudinal errors, spherical aberration, coma and astigmatism, are reduced when the lens is stopped down.

This improves the quality of the optical image by eliminating focus variations and other blurriness.

Optimum imaging results are usually achieved with entocentric lenses with apertures of f/4 to f/8. Stopping down the lens further increases the effect of light diffraction at the mechanical slit of the aperture, which can lead to a visible loss of sharpness in the image.

Reduction of spherical aberration by stopping down the lens

Conclusion

Don't skimp on the optics and choose high quality lenses! The successful selection and interaction of ALL individual vision hardware components, together with the software, guarantees success.

The best possible optics are essential for high quality inspection!

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Optiken Industrielle Bildverarbeitung