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.　©　2018　Elsevier　Ltd