<title>New method for measuring refractive index of liquids</title>

Abstract

The paper discusses the peculiarities in measuring the refractive index of a liquid by means of detector using a planeparallel plate as a simple measuring element and collimated light beam from laser diode. It is shown that, thanks to the splitting of refracted beam into two components at the exit face ofthe measuring element, it is possible to achieve resolution of the detector about iO within the whole range of refractive index measurements.

Proposal for a New Differential High-Sensitivity Refractometer for the Simultaneous Measurement of Two Refractive Indices and Their Differences

“…Since our proposed method for measuring the refractive index is described only in conference proceedings [ 7 , 8 ], we consider the main details of the method below.…”

“…The proposed method for measuring the deflection angle [ 7 ] is illustrated in Figure 2 . The optical measuring element was a rectangular plane-parallel plate with polished edges, made of optical glass with RI n 2 .…”

“…The direction of the outgoing rays and their displacement associated with the changes in the RI of the liquid are recorded using a coordinate-sensitive photodetector. Previously [ 7 ], we proposed the design of a measuring cell and a new method for measuring the deflection angle, which allowed us to determine the RI with an accuracy of ~ . In [ 8 ], we applied this method to measure the concentration of polymer nanoparticles in aqueous suspensions and showed that the detection limit was ~1 mg/L.…”