A critical angle refractometer for heavy water analysis

An indigenous design and fabrication of a critical angle refractometer is presented for measuring the percentage purity of heavy water. The paper describes the optical design of a critical angle prism used in the instrument for obtaining achromatism. Based on the suitable optical design, a fused silica glass prism has been fabricated and used for constructing a critical angle refractometer suitable for heavy water analysis. The instrument has been calibrated for measuring the percentage purity of heavy water with light water as an impurity in the purity range of 0%-100%. The accuracy of measurement is found to be +/- 4%. The refractometer is useful for quick estimation of heavy water from samples collected in different containers due to possible leakage of heavy water in reactor pipelines.