Design and development of small scale index matching tunnel

Abstract

This report covers the design and development process of a refractive index matching for a small scale basis. This technique of refractive index matching is applied to optics measurement such as Particle Image Velocimetry (PIV) or Doppler Light Velocimetry (DLV), which is used to understand flow field around complicated objects. Firstly, equations related to refractive index mixture rules are reviewed and studied. The Lorentz-Loren equation, along with 3 other equations, based on the theoretical electromagnetic work or determined empirically, are applied to find out the amount of sodium iodide needed for refractive index matching when studying flow in objects made of acrylic. Next, an experiment is conducted to do the actual refractive index matching for sodium iodide in water mixture, by using a customized test rig. Suitable design and sodium thiosulfate is used, to overcome the issue of rapid oxidation of the sodium iodide solution when it is exposed to the atmosphere. Then, the results of the experiment are cross-checked with the theoretical equations, an analysis is being accounted for the difference in result. Finally, some components of the index matching tunnel are designed and fabricated for usage. The design of this index matching tunnel will be useful for future research in the study of fluids.