A new type of liquid refractometer

Abstract

A new liquid refractometer is proposed based on the phenomenon of total-internal reflection and the technique of heterodyne interferometry. A special designed glass probe is immersed in the tested liquid, and a light beam is guided within this probe due to the total internal reflections. After the light beam is totally reflected at the other end of the probe, it goes back in an anti-parallel direction of the original path. Because of multiple total-internal reflections, the phase difference, which is determined by the heterodyne interferometry between the p- and s-polarizations, is greatly enhanced to result in an accurate refractive index. The feasibility of this method was demonstrated by our experimental results, and a resolution of 5x10(-3) is obtained with our method. This method should, therefore, bear the merits of high accuracy, high stability, and easy operation.