Effects of Laser Beam Focusing Characteristics on Laser-Induced Breakdown Spectra

Abstract

The impact of altering laser focusing conditions on laser-induced breakdown spectroscopy experiments is investigated under ambient Earth laboratory and simulated Martian atmospheres. Experiments were performed in which the focal spot size was varied on a sample by altering the lens to sample distance with respect to targets of interest. Samples investigated include aluminum, copper, and steel. Specific neutral and ionic transitions of each sample were monitored. Atomic and ionic emissions show different intensity peak distributions along the varying lens to sample distance. Ionic species have peak emissions when laser plasma is initiated with a focused spot within the sample in ambient Earth laboratory air, while atomic emissions have peak intensities several millimeters deeper into a sample. In simulated Martian atmospheres, atomic emissions are observed to peak when the laser is focused within the sample, while ionic emissions have peak intensities when the laser is focused near the surface of a sample.

Multi-element signal enhancement mechanism investigation for laser ablation-assisted ultraviolet laser excited atomic fluorescence

“…Firstly, in the ablation process, whether it is plume or plasma still has not been studied, which is affected by many factors, such as laser parameters, focal conditions, and material properties. 26,27 When the uence of the ablation laser is below the ionization threshold, the ablated mass is only the vapor plume without free electrons. 24 If the energy of ablation laser is sufficient to overcome the threshold, plasma generated.…”

Resolution effects on spectral analysis of low alloy steel by laser-induced breakdown spectroscopy

“…Qingdong et al found that the quantitative analysis accuracy of a fiberoptic LIBS system was slightly higher than that of a traditional LIBS system and a portable LIBS system [11,12]. Experimental parameters such as laser energy, delay time and resolution are also factors that researchers have often considered [13,[14][15][16]. Khater et al searched for stable conditions suitable for spectrochemical analysis by changing the laser energy [17].…”

Effect of Plasma Temperature on Major Element Prediction Accuracy From Laser‐Induced Breakdown Spectroscopy

“…The Mars missions cited above calibrated their instruments using spectra collected at a uniform distance and a single plasma temperature (Anderson et al., 2022; Clegg et al., 2017). It is now apparent that plasma temperatures vary widely in Mars spectra collected under a range of target distances due to changes in the ablation spot size (Maurice et al., 2012, 2021; Melikechi et al., 2014; Mezzacappa et al., 2016; Surmick et al., 2021). Mismatches between lab data and spectra of unknowns measured on Mars may result in degradation of geochemical accuracy.…”