Development of Doppler Global Velocimetery : Influence of Laser Stability for Measurement Accuracy
Details
DGV (Doppler Global Velocimetry) is a system to measure velocity of particles crossing a laser sheet, by analyzing the scattered doppler shifted frequency of a light sheet. The light frequency shift is very weak because of the very low speed of the particles compared to the speed of light. In order to overcome this problem, an absorption line of the molecular iodine is used: the absorption of iodine depends strongly on the light frequency going through the iodine vapor. By this mean, it is possible to measure the scattered light intensity going through the iodine and normalize it to the scattered light: this ratio gives us the percentage of light absorbed by the iodine and therefore the doppler shifted frequency can be traced back to particle velocity. In this paper, the measurement accuracy of DGV system was discussed from the point of view of the laser mono-mode stability.
