Optical techniques for real-time penetration monitoring for laser welding.
Optical techniques for real-time full-penetration monitoring for Nd:YAG laser welding have been investigated. Coaxial light emission from the keyhole is imaged onto three photodiodes and a camera. We describe the spectral and statistical analyses from photodiode signals, which indicate the presence of a full penetration. Two image processing techniques based on the keyhole shape recognition and the keyhole image intensity profile along the welding path are presented. An intensity ratio parameter is used to determine the extent of opening at the rear of a fully opened keyhole. We show that this parameter clearly interprets a hole in formation or a lack of penetration when welding is performed on workpieces with variable thicknesses at constant laser power.
Bardin
Fabrice
F
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. f.bardin@hw.ac.uk
Cobo
Adolfo
A
Lopez-Higuera
Jose M
JM
Collin
Olivier
O
Aubry
Pascal
P
Dubois
Thierry
T
Högström
Mats
M
Nylen
Per
P
Jonsson
Peter
P
Jones
Julian D C
JD
Hand
Duncan P
DP