Research on a high-resolution and high-accuracy liquid refractive index measurement method based on optical...

High-accuracy refractive index measurement has long played an important role in fields such as biomedicine; however, current methods still face limitations. In this study, leveraging the self-collimating instrument's advantage of the highest accuracy in angle measurement, the variable refractive index of the liquid is introduced into the sensitive unit of the cavity coordinate system. A relationship is established between the self-collimating angular measurement dimension and the refractive index dimension. Theoretically, this method can achieve a refractive index resolution and accuracy on the order of 10^-6 RIU. Experimental results have achieved a resolution of 10^-5 RIU and an accuracy of 10^-4 RIU. Additionally, the system has the advantage of a wide measurement range, with the refractive index measurement spanning from 1.389 to 1.437 RIU.