Handheld LIBS for Metal Alloy Analysis
Laser induced breakdown spectroscopy (LIBS) has been known and used for almost two decades in a laboratory environment. However, the recent technological advancements has made the design of handheld LIBS analyzers possible. This development rapidly expanded the use of LIBS especially into field operations such as alloy sorting and analysis. Since LIBS is better suited for analysis of light elements such as lithium (Li), aluminum (Al), magnesium (Mg), and beryllium (Be) than, handheld x-ray fluorescence (XRF), it quickly gained industry acceptance as a method of choice for sorting alloys, and specifically aluminum scrap.
Detection and quantification of elemental composition – both heavy and light elements - is performed directly onboard the Rigaku KT-100S handheld LIBS metal analyzer. Together with the LIBS technique, the KT-100S performs spectral analysis of light emitted by plasma generated by a pulse of its 1064nm laser striking the samples surface. In the first stages of the process, a very short (on the order of nanoseconds) pulse of laser light, tightly focused on the surface of the sample generates a burst of high density energy that ablates a small mass of the sample and heats it to tens of thousands of degrees Kelvin, converting it to plasma. In the absence of other sources of energy, the plume of plasma begins to cool. During the next stages, the electrons freed from the atoms by the initial laser pulse start to recombine with ionized atoms to return to their original atomic states. In the process, electrons must shed the surplus energy which is released in the form of light, typically ranging between 200 to 700 nm (UV to red). The emitted light is collected and transmitted to the miniature spectrometer fitted with a high sensitivity CCD for spectral analysis. Finally, the resulting spectrum is processed using the analyzer’s proprietary identification algorithm, and determines the grade of the tested alloy in less than two seconds by matching its measured composition to the alloy grade library. The results also include the percentages of the individual elements found.