We report on the determination of liquid crystal pre-tilt inside cells fabricated using single crystal birefringent and dichroic windows of cerium doped strontium barium niobate. We show that the average pre-tilt is significantly affected by the crystalline windows, leading to much larger values than those obtained with glass windows using identical fabrication methods. The same technique can be used to determine pre-tilts as large as 40 degrees, which is significantly larger than normally measurable using the cell rotation method.