Flame diagnostic using optoacoustic laserbeam deflection and frequency modulation spectroscopy

Two laser-based techniques, Optoacoustic Laserbeam Deflection (OLD) and Frequency Modu­lation (FM) spectroscopy, were introduced for flame diagnostics. Flame temperature was measured by OLD with 1.5% precision and flame temperature profiles were taken. Ground state and excited state sodium within an aspirated flame were detected by FM-spectroscopy. Present limits of sensitivity are absorptions of 1.5·10–4and ground state sodium densi­ties of 3.3·106 cm–3. © 1983 SPIE.