Dear Ravil,
when i tried to define KNbO3 under profile tab the material dialogue box look likes the image in my comment. You can see that ordinary refractive index is blurred because it is by default. To change extraordinary refractive index i just vanised the tik mark in the auto box … but for ordinary one there was no scope to do it. Let me know if there is another way…i choose z crystal cut and y propagation direction. If i choose x cut crystal then ordinary index can be changed but no extraordinary. I need a z cut crystal and i have to change both ordinary and extraordinary. Thanks
