Flow observation in a laser cut kerf

It is known that the quality of cutting plate using laser optics and the flow of assisting gas which is blowing in high speed from processing nozzle. It is estimated that particularly distribution of flow speed and of the gas in the cut kerf influences the characteristics of cutting, but there are various unknown things in them. Then, the target of this research is to find a best condition of cutting from visualization of the flow in the kerf with changing the pressure of assisting gas and the radius of the nozzle and width of the kerf by using optical device.