A new method for describing the change of the laser beam axis trajectory in the Anderson differential cuvette to measure the refractive index of liquids

We substantiate the necessity of developing a small-sized refractometer with Anderson's differential cuvette for the highly accurate rapid check of the state of liquid media in real time. Problems that arise in determining optimal design parameters of the optical part of the refractometer to reduce the measurement error of the refractive index ranging from 1.2300 to 2.2300 are indicated. It is noted that for the problem of determining optimal parameters of Anderson's differential cuvette to be addressed, an analytical expression for the medium refractive index nm needs to be deduced as a function of all parameters of the optical part of the refractometer. For the first time, an equation is derived to study a change in the trajectory of the laser radiation axis inside and outside of the Anderson cuvette, depending on its various parameters, values of the refractive indices of the reference and examined liquids, ns and nm . The design of a small-sized differential-type refractometer for measurements is developed and results of studying various liquid media are presented. The measurement error of the refractive index of 0.0001 in the developed design of the refractometer is confirmed. Directions of research for the further error reduction are outlined, that would allow the developed refractometer design to be used in scientific research and as a verification scheme in metrology.