Refractive index measurement using laser diffractometer

For refractive index measurement, this paper presents a new method based on a laser diffractometer, in which a reflective diffraction beam coincides with an incident beam. Calculation by using the angle of a reentry beam, grating pitch, and laser wavelength yields the refractive index. Based on a Littrow configuration, grating pitch measurement and immersion diffractometry are implemented to determine the refractive index of transparent liquids such as water, oil, and translucent liquids mixed with particles. Experimental results are presented to demonstrate variation in solution composition and the refractive index.