Lidar thermometry using two-line atomic fluorescence.

Area of Science:

• Laser-based diagnostics
• Thermometry
• Combustion science

Background:

• Accurate temperature measurements are crucial for understanding and controlling combustion processes.
• Traditional methods often struggle with limited optical access in industrial applications.
• Remote sensing techniques offer a solution for in situ measurements in challenging environments.

Purpose of the Study:

• To develop and demonstrate a novel stand-off thermometry technique.
• To achieve spatially resolved temperature measurements in flames.
• To assess the feasibility of this technique for industrial applications.

Main Methods:

• Integration of Scheimpflug lidar with two-line atomic fluorescence (TLAF).
• Seeding of indium atoms into the flame for laser excitation.
• Use of tunable diode lasers at 410.17 nm and 451.12 nm for indium excitation.
• Collection of fluorescence signals using a line-scan detector and a 2D intensified CCD camera.

Main Results:

• Successful 1D and 2D spatially resolved temperature measurements in a flame.
• Measurements were performed at various heights above a porous-plug burner.
• Accuracy was primarily limited by spectral overlap and laser power uncertainties.

Conclusions:

• The combined Scheimpflug lidar and TLAF technique provides a viable method for remote, in situ thermometry.
• This approach is particularly valuable for industrial applications with limited optical access.
• Further refinement can improve accuracy and expand applicability.