Fig. 1. Schematic diagram of the experimental setup

Fig. 2. Comparison of the time-integrated spectra under the conditions of non-flat and flat sample surfaces
The rock samples are (a) Coal stone, (b) Tourmaline, (c) Dolomite, (d) Fluorite, and (e) Limonite, respectively

Fig. 3. The influence of laser energy on spectral peak intensity (Fe Ⅰ 404.58 nm and Fe Ⅰ 438.35 nm) under the conditions of non-flat and flat sample surface
The variation of (a) the spectral intensity and (b) the reduction factor with laser energy

Fig. 4. Calculation of electron density and plasma temperature
Stark broadening profile of Fe Ⅰ 438.35 nm under the conditions of (a) non-flat and (b) flat sample surface; (c) The variation of electron density with laser energy under the conditions of non-flat and flat sample surface; (d) The variation of the plasma temperature with laser energy under the conditions of non-flat and flat sample surface

Table 1. Spectroscopic parameters of Fe(Ⅰ) lines in limonite sample