In a method for determining a quality of welding at a weld between working material pieces, an emission intensity of a visible light emitted from the weld during a laser welding using a laser device emitting a laser having a wavelength falling in a range of the wavelengths of near infra-red rays is detected,...http://www.google.com.hk/patents/US6399915?utm_source=gb-gplus-share專利 US6399915 - Method and apparatus for determining quality of welding at weld between working material pieces
