Over the last few weeks there’s been quite a bit of discussion on these pages about how to deal with speckle. (And thank you to all those who have taken the time to comment.)
“Speckle” is an issue with laser lines, since it complicates the business of finding the line center. If you’re doing laser triangulation-based 3D machine vision, you’ll know just what I mean.
Several commenters have reminded me that an alternative to the laser does exist. Smart Vision Lights have a family of LED Structured Light Pattern Projectors, as indeed do Opto-Engineering. I’ve not tried the projector from Smart Vision Lights, but I did have an opportunity recently to get “hands-on” with the Opto product. This did a fine job of projecting a uniform line, but I have to say that it lacked the intensity of a laser. In a 3D application that might mean making a trade-off between speed and precision, but it’s definitely something worth exploring.
These projectors have been around for a while, but Opto-Engineering has now taken them further with the addition of Schiempflug optics. These “straighten out” the distortion caused by projecting a pattern of lines from an angle, and if you’re interested in learning more, there’s a great video on Opto’s YouTube channel.
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3 comments:
Led lightning is indeed a good alternative for projects where speckle is an issue.
Another company providing excellent LED hardware is Effilux with whom we have recently collaborated:
http://www.aqsense.com/news/aqsense-news/138-led-lighting-enhances-3d-scanners-performance
I highly recommend Effilux product as well: very sharp transitions without the pesky scatter of lasers. Very nice company to work as well.
http://www.effilux.fr/1-35719-EFFI-Lase-Profilometer-LED-Lighting.php
The Opto Engineering 3D LED pattern projectors solve the defocusing issues that vision engineers face when projecting a series of lines on a sample and grabbing the image from the camera positioned at 90° to the surface. This permits to cover the bigger area of the component in comparison with a single laser line typically used. It's known that the LED light is less powerful than that of the laser however much depends on the application and strobbing the light is always an alternative.
On a separate note, I must admit that this blog seems to be the fastest currently existing machine vision news chanel!
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