The Helios system uses a narrowband light source combined with a bandpass filter placed in a Chronos camera. With this approach a significant amount of the light emitted in the scene is removed, yet the light emitted by the illumination source is retained. This strategy allows the Helios system to resolve phenomena that otherwise would not be observable.
Information regarding the Helios Welding Visualization System can be found in the following links
Also, please take a look at the following videos:
The welding process captured with the Helios welding visualization system.
Different types of welding