Ultrahigh-accuracy measurement of refractive index curves of optical materials using interferometry technology

A spectral-domain white-light interferometry and a two-slit laser interference system for measurement of the refractive index curves of optical materials over a wide wavelength range was reported. The interferometry was employed to measure the group refractive index of the materials. An integral algorithm was proposed to calculate the refractive index curve from the obtained group refractive index. The integration required the refractive index value for a specific wavelength which could be achieved by the two-slit laser interference system. A spectrum correction method was used for calculation of group optical path difference. The proposed method realized an ultrahigh accuracy measurement of refractive index curve better than 0.0002, making it attractive for the application in the determination of optical parameters of new materials.