High repetition rate laser-induced breakdown spectroscopy using acousto-optically gated detection

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Laser-induced breakdown spectroscopy (LIBS) is a powerful technique for elemental analysis.
• Traditional LIBS setups can be limited by detection speed and sensitivity.
• High repetition rate lasers offer potential for faster analysis but require optimized detection methods.

Purpose of the Study:

• To develop and evaluate a novel LIBS setup for fast sample analysis.
• To improve the limit of detection (LOD) and sensitivity of LIBS measurements.
• To demonstrate the feasibility of using acousto-optical modulation for temporal gating in LIBS.

Main Methods:

• A high repetition rate laser (up to 50 kHz) was used as the excitation source.
• An acousto-optical modulator (AOM) was employed for fast temporal gating of emitted plasma radiation.
• Plasma radiation was diffracted by the AOM and detected using a compact Czerny-Turner spectrometer with a CCD line detector.

Main Results:

• The novel LIBS setup achieved rapid measurements with integration times as short as 10 ms.
• A limit of detection (LOD) of 0.13 wt.% for magnesium in aluminum alloys was obtained.
• The system demonstrated a high analysis rate of 100 analyses per second.
• Temporal gating with the AOM significantly improved LODs and overall sensitivity.

Conclusions:

• The combination of high repetition rate lasers and AOM-gated detection enables rapid and sensitive LIBS analysis.
• AOM technology is beneficial for temporally detecting plasmas induced by high repetition rate lasers.
• Compact, temporally gateable LIBS setups can be realized using AOMs, miniaturized spectrometers, and small lasers.