Laser induced breakdown spectroscopy (libs) apparatus based on high repetition rate pulsed laser

Abstract

This invention discloses a laser induced breakdown spectroscopy (LIBS) apparatus based on a high repetition rate pulsed laser. The laser produces a train of laser pulses at a high repetition rate in the kHz or even higher range. When the laser beam hits the sample, it generates several thousands of micro-plasma emissions per second. Synchronized miniature CCD array optical spectrometer modules collect the LIBS signal from these micro-plasma emissions. By adjusting the integration time of the spectrometer to cover a plurality of periods of the laser pulse train, the spectrometer integrates the LIBS signal produced by this plurality of laser pulses. Hence the intensity of the obtained LIBS spectrum can be greatly improved to increase the signal-to-noise ratio (SNR) and lower the limit of detection (LOD). In addition, the influence of pulse to pulse variation of the laser is minimized since the obtained LIBS spectrum is the spectrum of a plurality of micro-plasma emissions produced by a plurality of laser pulses. The high repetition rate laser also makes it possible to measure the LIBS signal at a short and a long integration time and mathematically combining the two spectra to obtain a LIBS spectrum with enhanced dynamic range.