Proposal of Multi-pass Laser Spectroscopic Technique for Diagnosing Atmospheric Pressure Discharge Plasmas

Abstract

We propose a multi-pass laser spectroscopic technique which is useful for diagnosing atmospheric pressure discharges. The key to the technique is to recycle a single laser pulse with low energy many times through the measurement area, avoiding the perturbation that a high energy pulse would induce while maintaining large signal levels. The pulse from a Q-switched laser is injected into an optical cavity, and a Pockels cell is used to rotate the polarization of the beam 90°, trapping it in the cavity. We set up this laser system and successfully obtained a semi-infinite series of pulses.