Development Of Biomass Element Distribution Analysis System Based On DP-LIBS

Laser induced breakdown spectroscopy(LIBS)is an atomic emission spectroscopic detection technique that uses a high-energy pulsed laser focused on the surface of a sample to ablate the sample to produce plasma.The plasma emits the corresponding elemental spectrum during evolution.Using spectral lines,elements can be qualitatively and quantitatively analyzed.The LIBS has many advantages such as simultaneous analysis of multiple elements,low loss,fast detection speed,ability to detect various forms,etc.The LIBS technology has been widely used in environmental protection,steel smelting,ore,metal sorting,aerospace,etc.It has a broad vision of application.However,the LIBS technology has poor stability,especially for non-uniform samples that need to be scanned.The biological material samples have complex structures,and the sample surface is uneven.For analysis of biological material samples,this paper designed a system of elemental distribution analysis of biological materials based on DP-LIBS to improve signal stability and scanning detection of samples.The main results are listed below:1.Dual-pulse laser induced breakdown spectroscopy(DP-LIBS)was used to increase the elemental analysis detection limit.At the same time,an imaging system and a three-dimensional mobile platform were added to the double-pulse laser to perform real-time imaging of the samples,and the location of the ablation point was accurately determined.By combining the imaging system with the three-dimensional mobile platform,real-time automatic focusing of the samples to be ablated was realized,which ensured that the laser can focus on the same surface of the samples.2.The control software written based on LabVIEW effectively controlled the collinear DP-LIBS experimental system,CCD camera,and 3D mobile platform.The auto-focusing function of the samples can be achieved through the combination of image sharpness evaluation,auto-focusing algorithm,and a three-dimensional mobile platform.The sample can be real-timely and automatically focused to ensure that the position of each laser ablation sample is consistent and the signal stability is improved.As the imaging of the samples can be associated with the coordinate system,the samples can be analyzed by micro-zone scanning detection.3.The experimental verification showed that the relative standard deviation(RSD)of the spectral intensity was reduced from 16.7%to 6.7%using the autofocus system;the correlation coefficients of the quantitative analysis of Cr and Mn in the steel samples were increased from 0.851 and 0.639 to 0.947 and 0.923,respectively.The LIBS and the imaging system were combined to scan the rice kernels.The spectral signal intensity of Na and K ranged as:embryo>aleurone layer>endosperm.Therefore,the system can improve the stability and measurement accuracy of the signals,and also enable micro-zone scanning detection of biological samples.