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Measurement of the refractive index of glass with 10−4 level accuracy based on the lateral displacement method

I. M. Leite, A. Cabral, J. Coelho

The measurement of the refractive index of optical glass samples is a common and fundamental activity in numerous fields of expertise. Several measurement techniques exist with relative accuracies from 10  −  2 to, at least, 10  −  7 with complexities that are inversely related to the corresponding uncertainty. We describe an implementation of a technique based on the measurement of the lateral displacement variation of a collimated beam caused by the rotation of a parallel plate glass sample. The method was aimed to achieve an uncertainty in the range from 10  −  3 to 10  −  4 without increasing the complexity normally associated with techniques with this level of accuracy. The system was designed and optimized based on a detailed analysis of the uncertainty budget. We describe the implementation, the data processing, and the results obtained with calibrated samples, showing a relative uncertainty at the level of 10  −  4

optics; metrology; refractive index; glass

Optical Engineering
Volume 60, Number 6
2021 June

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia