Refractive index based optical Brix measurement technique with equilateral angle prism for sugar and Allied Industries

The refractometers are simple optical instruments for measuring dissolved solid contents by measuring the refractive index of a process solution by means of the total reflection created at the interface between an optical window and the sample solution. A beam ray from light source is directed to the interface between optical window and the sample solution. A part of the beam of ray is reflected from the solution entirely and partly refracted and absorbed in a solution. This causes an image, in which the location of borderline between light area depends on the critical angle of the total reflection and thus on the refractive index of the process solution. As concentration of sugar increases, the Brix and its refractive index increases, and therefore critical angle increases. The light reflection on detector decreases, which increases LDR resistance. As it is in upper arm of potential divider it decreases output voltage. Analog to digital converter, signal conditioning unit and microcontroller are developed for proper calibration and displaying the reading on LCD. The results are reported in this paper. (C) 2015 Published by Elsevier GmbH.