Measurement of temperature field with schlieren shearing interferometry of double frequency gratings

This paper dealt with the natural convection temperature field of unlimited heated plate with schlieren shearing interferometry of DFG (double frequency gratings). Both the experiment using shearing interferometry with DFG and that using schlieren shearing interferometry with DFG were performed, and the experimental principles and interferograms of heating plate obtained by the experiments were presented in detail. The effect of system astigmatism and coma on the interferometry diagram, which is caused by the out-axis radiation of light source, can be reduced to a certain degree by reduction of incident angle, increase of radius of reflective mirror and the adjustment of the position of DFG.