Precise description of dispersion of optical glass refractive exponent

Preliminary investigation is carried out and a problem is set concerning practical expediency and possibility to describe the optical glass refractive exponent dispersion with quasi-absolute accuracy (±10^-6). This accuracy is slightly worse than a limiting accessible optical homogeneity of a specific blank part (±5 • 10^-7) that can be reached with up-to-date precision annealing procedure. Practical results are obtained only for three types of optical glass "TK21", "CNR3", and "ОФ4".