Experimental Study Of The Optical Measurement Of Liquid’s Concentration

It has been a hot issue for scientists and researchers to do liquid’s concentration related study, in which optics related theoretical knowledge has played a more and more important role. Generally speaking, in order to obtain precise results of certain liquid’s concentration, the relation between the concentration of the liquid being tested and the related optical parameters is needed. In this paper, we analyzed three aspects of the optical properties of the tested solutions: the refractive index, the absorption spectroscopy and the optical rotation property of the tested liquid with certain concentration respectively. In our experiment, we did in-depth research on the Na Cl solution and sucrose solution, which all are the kind of liquid that has been played very important role in daily life as well as industrial production. Our research provides a reference as well as an example for studies on other kinds of liquid.To obtain refractive indexes of two different liquids with different concentration, we mainly adopted two measuring methods, which are the interference and diffraction of light. Specifically, we measured liquids’ concentration based on the relations between the refractive index and the grating diffraction angles before and after putting a grating into the liquid. During the date analysis, we specifically studied the influence on the measurement results due to the deviation of fringes’ spacing caused by the glass container’s thickness. We then compared our results to the public beta value of water’s refractive index; found that the revised refractive index is more close to that of the public beta value. We introduced and revised the high-order diffraction refractive index, too. Michelson interferometer optical path was set up for the measurement of refractive index, on which the principle of interference of light and four-step phase-shifting theory were based. The main principle of this method is to obtain the phase difference of the liquid under tested using four-step phase-shifting theory, then calculating the tested liquid’s refractive index as a function of the relation between phase difference and optical path difference. Additionally, we analyzed the liquid’s concentration related absorption spectroscopy and the optical rotation properties of sucrose solution. Moreover, we measured the rotation angle of sucrose solution, and came to the conclusion that the relation between liquid’s concentration and the rotation angle is basically linear.