Influence of the apex angle of a hollow prism made from an ordinary commercial glass plate as a simple refractometer to the accuracy of the refractive index measurement of the edible oil

7th AIC‐ICMR on Sciences and Engineering 2017

自然科学;工业技术

Idris, N.^1 ; Maswati^1 ; Yusibani, E.^1

Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Jl. Syech Abdurrauf No. 3, Darussalam, Banda Aceh

23111, Indonesia^1

关键词: Abbe refractometers;    Angle of Incidence;    Apex angles;    Commercial glass;    Measurement accuracy;    Oil samples;    Refractive index measurement;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/352/1/012045/pdf
DOI  :  10.1088/1757-899X/352/1/012045

来源: IOP

【 摘 要 】

The influence of the apex angle of a hollow prism used as a simple refractometer to the accuracy of a refractive index measurement of the edible oil samples was studied. The hollow prism was made from an ordinary commercial glass plate with a thickness of 2 mm. The apex angle of the constructed hollow prism was varied. The edible oil sample used in this study was palm oil, namely the packaged, branded oil sample and the bulk oil sample. For measuring the refractive index, the oil sample was filled in the constructed hollow prism, and then a helium-neon laser beam was passed through the oil sample at a certain angle of incidence. The angle of minimum deviation of the transmitted laser He-Ne beam was measured and then was used for calculating the refractive index of the oil sample. The refractive index measurement was made using the hollow prism with different apex angles, ranging from 300 to 600. The measurement accuracy was estimated by comparing the refractive index measured using the hollow prisms to that of obtained using a standard Abbe refractometer. It was found that the refractive index of the edible oil can be measured accurately by using the hollow prism. It was also found that the accuracy of the refractive index measurement significantly changes with the apex angle of the hollow prism. The refractive index values measured using this simple refractometer deviate up to 3,49% from the refractive index value measured using the standard Abbe refractometer, especially when the apex angle of the prism is 30°. The measurement results with high accuracies obtained when using the hollow prisms with apex angles of 450 and 600. The optimum apex angle for the present constructed hollow prism is 450. The refractive index obtained using the hollow prism with the apex angle of 450 is 1,4623 and 1,4438 for the bulk oil and the packed, branded oil samples, respectively. This result suggests that the apex angle of the prism used affects largely the accuracy of the refractive index measurement.