Hi everyone, I have some questions about birefringence. I have searched in vain on the Internet and in a few books (it's tough to find books on birefringence). Usually determining how rays propagate after birefringence is simple because the light is incident normally and the ne of the e-ray is known. But in my situation, I need to analyze light that is incident at an angle. Moreover, the ne is also not known. As in only the maximum ne is known but ne as you know varies with the angle between the o-ray and the optic axis (if I am not wrong). So, ne should also change with the incident angle. Does anyone have an equation that takes in the incident angle, the max ne and the no and finds the walkoff angle + refraction angle? One more question: is birefringence expressed purely by differences in ne and no? So, suppose I know the ne for a given situation, I should be able to find the difference in angle between the o-ray and e-ray using only Snell's law? Or is there a separate equation for Poynting walkoff? I am rather confused about these topics. Basically, I understand birefringence conceptually but I have been unable to find appropriate equations to apply for specific optical systems involving birefringence. Hope some of you can help me with this. Even if you don't know the answers to the questions, it would be helpful if you can point me to some good sources either online or on paper. Thanks.