Comparison of Schlieren photography using different light sources

Schlieren technique is widely used to visualize the gradient of temperature fields and the gradient of density fields of fluid. The selection of light sources plays an important role. In this experiment, the aim was to compare Schlieren photography using white light, red light and laser by analyzing their ability to visualize the gradient of refractive index. By comparing the Schlieren images that was produced by visualizing static fluid and high speed fluid with a Z-type Schlieren system, we found that laser light had the largest sensitivity to be 1377.4 but the smallest dynamic range in detecting deflection angle to be 3.49 × 10-4 degrees. The red light had the second largest sensitivity to be 490.88 and the second smallest dynamic range to be 4.97 × 10-4 degrees. The white light had the smallest sensitivity to be 224.09 but the largest dynamic range which was 7.96×10-4 degrees.