Developments of the amplified stimulated emission technique for spatially resolved species detection in flames

It is demonstrated that the amplified stimulated emission technique can be applied for spatially resolved detection of flame species requiring a two-photon excitation process. The approach utilizes two laser beams of different wavelengths produced by a dual wavelength package in the dye laser. By wavelength separation through the use of two different doubling crystals fulfilling the phase-matching condition for only one beam at a time, followed by crossing the beams in the flame, a substantial increase in spatial resolution is achieved. The technique is demonstrated on ammonia in a jet and on carbon atoms in a welding torch flame.