Optimization of experimental conditions by orthogonal test design in a laser-induced breakdown experiment to analyze aluminum alloys

The orthogonal test design is used to optimize the parameters of aluminum alloy laser-induced breakdown spectroscopy (LIBS). The signal to background ratio (SBR) of the line of Al I 396.15 nm dependence on the experimental parameters is analyzed. It is shown that the delay time of the ICCD, the gate width of the ICCD and the laser pulse energy have a great influence on the SBR, the parameters which affect the SBR of Al I 396.15 nm are, in order of the laser pulse energy, delay time of the ICCD, gate width. By optimizing the parameters of the experiment, the optimum conditions are determined and high spectral intensity and SBR are obtained under low laser energy. Besides, the sequential test is used to verify the result of the orthogonal test design, and it shows that they are in good agreement with each other. Therefore the orthogonal test design can be used as an optional scheme for the optimization of the LIBS. There are many advantages of the orthogonal test design, such as greatly reducing the workload, simple and rapid analysis, and with accurate results. It is useful to analyze the components of the aluminum alloy or other solid materials qualitatively and quantitatively under the optimum conditions.