Abstract

Multiphoton laser excitation of atoms followed by fluorescence or ionization detection has been used to observe a variety of atomic species in flames, reacting flows, and plasmas. Recently, amplified spontaneous emission (ASE) has been observed from two-photon excited C, O, Cl, and H atoms.³ ASE has several distinct advantages for atom diagnostic measurements. The ASE signal can be much larger than the laser-induced fluorescence signal, and it can be detected with small solid angle optical detection. The increased brightness can substantially increase the signal to background ratio in chemically reactive systems where measurement precision and detectivity is often limited by background optical emission. Because the ASE signal is collimated along the laser beam, the signal collection can share the same optical access port with the excitation laser. This arrangement simplifies optical alignment and significantly reduces the access requirements for measurements on large scale supersonic reacting flows and plasma devices.

© 1992 Optical Society of America