Development of Doppler Global Velocimetry using a DPSS laser

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DGV (Doppler Global Velocimetry) with a DPSS (Diode-Pump Solid State) laser is successfully developed in this research. DGV is a system to measure velocity of particles crossing a laser sheet, by analizing 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 was used. The frequency shift as a function of the absorption line of the iodine cell can be traced back to particle velocity. The optical setup with the DPSS laser and the iodine cell was developed in this research and measurement accuracy of the velocity field from the rotating disc was confirmed. It is found that the DPSS laser is suitable laser source for DGV system because of its high stability and narrow line width, as a result, high measurement accuracy is obtained by this system.