Development of Doppler Global Velocimetry using a DPSS laser

本研究成功地研制了一种基于二极管泵浦固体激光器的多普勒全局测速仪。DGV是一种通过分析光片的散射多普勒频移来测量穿过激光片的粒子速度的系统。光频移非常微弱，因为粒子的速度与光速相比非常低。为了克服这个问题，使用分子碘的吸收线。作为碘电池的吸收线的函数的频移可以追溯到粒子速度。本研究发展了一套以DPSS雷射与碘池为光源的光学系统，并验证了旋转圆盘速度场量测的准确性。实验结果表明，DPSS激光器具有稳定性高、线宽窄的特点，是适合于DGV系统的激光光源，因此，该系统具有较高的测量精度。

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.