OptiChar and OptiRe allows you to compare refractive indices and extinction coefficients on the same plot. This option is convenient when you wish to compare obtained optical constants with your previous results and values taken, for example, from Catalog or from various literature sources. 

In the right pane you can see comparison of refractive indices of TiO2 films deposited by three different deposition techniques.

Our experience in optical characterization and reverse engineering showed that this option in necessary and useful. See more in:

1. A. Tikhonravov, M. Trubetskov, T. Amotchkina, G. DeBell, V. Pervak, A. Sytchkova, M. Grilli, and D. Ristau, "Optical parameters of oxide films typically used in optical coating production," Appl. Opt. 50, C75-C85 (2011).
2. T. Amotchkina, M. Trubetskov, V. Pervak, B. Romanov, and A. Tikhonravov, "On the reliability of reverse engineering results," Appl. Opt. 51, 5543-5551 (2012).
3. A. Tikhonravov, T. Amotchkina, M. Trubetskov, R. Francis, V. Janicki, J. Sancho-Parramon, H. Zorc, and V. Pervak. "Optical characterization and reverse engineering based on multiangle spectroscopy." Appl. Opt. 51, 245-254 (2012).
4. S. Nevas, F. Manoocheri, E. Ikonen, A. V. Tikhonravov, M. A. Kokarev, M. K. Trubetskov, Optical metrology of thin films using high-accuracy spectrophotometric measurements with oblique angles of incidence, Proc. SPIE. 5250, Advances in Optical Thin Films 234 (2004).
5. A. V. Tikhonravov, M. K. Trubetskov, T. V. Amotchkina, A. A. Tikhonravov, D. Ristau, S. Günster, Reliable determination of wavelength dependence of thin film refractive index, Proc. SPIE. 5188, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies 331 (2003)