EN
Measurements of the refractive index profile have been made to provide data for obtaining local optical axis arrangement in the waveguide cross-section. Liquid crystalline planar waveguide tuned with the electric field has been used. A new approach is proposed to accomplish refractive index profile measurements in a direct way. The modal line method is presented as a tool that allows one to do it and to improve the attenuated total reflection disadvantages as well. The obtained results maintain applicability of the modal line method for a direct refractive index profile measurement. To verify the method, nematic 6CHBT (4-trans-4-n-hexyl-cyclohexyl- isothiocyanatobenzene) described earlier in the literature has been examined. A nematic mixture W602 contained 6CHBT as a main component has been examined too.