This instrument is designed for the measurement of refractive index(nD) and the average optical dispersion(NF-NC) of the transparent, the semitransparent and the solid matter (mostly transparent). It was connect with a circulating thermostatic bath, can measure the refractive index in 0℃~50℃. It also measures the Brix percentage of sugar solution[(0-95)℃ which is equal to th refractive index1.333-1.531]. It was widely used in oil industry, fat industry, pharmaceutical factories, paint, food processing, chemistry, sugar refineries, geologic etc., and relative factories, school and research center.