Development of Low-Cost Abbe Refractometer

Refractive index and Abbe number are major physical properties of optical materials including glasses and transparent polymers. Refractive index is, in fact, not a constant number and is varied as a function of optical wavelength. The full refractive index spectrum can be obtained using a spectrometer. However, for optical component designers, three refractive indices at the wavelengths of 486.1 nm, 589.3 nm and 656.3 nm are usually sufficient for most of the design tasks, since the rest of the spectrum can be predicted by mathematical models and interpolation. In this paper, we propose a simple optical instrumental setup that determines the refractive indices at three wavelengths and the Abbe number of solid and liquid materials.