Laser-Induced Breakdown Spectroscopy at the DLR Laser Test Range

Abstract

A basic set-up for laser-induced breakdown spectroscopy (LIBS) at the DLR laser test range in Lampoldshausen and first LIBS spectra of selected samples are presented. The test range allows measurements in free atmosphere under daylight conditions at distances up to 130 m. With the help of a Cassegrain type telescope a pulsed Nd:YAG laser has been used to produce plasma on different samples at distances exceeding 50 m. The scattered light of the plasma was collected by a Newtonian telescope and analysed and detected by a gated spectrometer with an attached CCD camera. The plasma generating laser yields a maximum pulse energy of 800 mJ at a wavelength of 1064 nm and a pulse width of 8 ns. It also has the option to extract the second and third harmonics. LIBS spectra from 10 nm layers of gold on a silicon wafer, as well as from black powder and one of its main components, potassium nitrate, were recorded. The spectra are compared with respect to the laser wavelength, pulse energy, and energy density on the target.