Intracavity technique for improved Raman/ Rayleigh imaging in flames.

A novel intracavity laser diagnostic has been developed to perform quantitative two-dimensional imaging of major species and temperature by using spontaneous Raman scattering and Rayleigh scattering in a turbulent flame. A flash-lamp-pumped dye laser cavity is modified to include sheet-forming optics and 100% reflecting end mirrors. In a comparison of this system with a laser configuration with the sheet-forming optics outside the cavity, the beam waist is comparable, while the intensity is increased by a factor of 5. This technique has applicability to many systems in which weak scattering must be monitored, such as Rayleigh scattering, Raman scattering, and laser-induced fluorescence of certain combustion radicals.