He-Ne Laser for Intra-Cavity Enhanced Absorption Measurement

Abstract
It has been shown recently that when a relatively weak absorber is placed within a laser cavity an enhacement of absorption occurs1–3. This method has been succesfully used for trace analysis of Na1,4, I2 3,5, Sr and Ba+ 6, Eu(NO3)3 2,8, Pr(NO3)3, NdCl3 and HoCl3.8 In these experiments the absorbing species were placed inside the cavity of: flashlamp-pumped dye lasers1–4,6 continous wave dye lasers3,5 and dye lasers pumped by a ruby laser8.