Using newly developed and recently patented technology, Cognex has eliminated the speckle effect of laser lines, optimising triangulation-based 3D imaging. The In-Sight 3D-L4000 embedded vision system is the first product to bring the benefits of speckle-free laser lines to users.

The laser triangulation method has established itself as the definitive technology for 3D image processing in order to generate high-resolution and precise 3D image data. However, a weakness of the laser triangulation method has always been that the projected laser lines exhibit so-called speckles. Developers have been trying for years to reduce speckles using various methods, such as varying the wavelength and camera aperture, or taking multiple images and then calculating an average image. However, previous efforts did not lead to noticeably better results.

With its new, patented process, Cognex has found a solution to eliminate the occurrence and effects of speckles and produce extremely straight, clean and bright laser lines.

“The basis of the new technology is a blue laser with a wavelength of 450 nm,” explains Thomas Ruhnau, director of engineering at Cognex. “This laser beam is then deflected by a microelectromechanical mirror with ultrasonic vibrations in a plane to create a fanned beam. The beam is then directed on to a diffuser optic featuring a unique property: this optical element creates a perfect laser fan with a precisely defined width and an intensity distribution that is absolutely uniform along the line, eliminating the formation of speckle in the approach.”

Cognex has already integrated the new speckle-free blue laser optics into one of its products: In-Sight 3D-L4000 3D vision system, which enables users to achieve inspection speeds at least twice as fast as comparable competitive products, reports the company.

For further information
www.cognex.com