To lessen thermo-optic depolarization, a immediate way is to work with the thin crystal with compacta Raman spectra of DKDP crystals51 and b dependence from the variation in Raman shift in the entirely symmetric PO4 vibration in DKDP on the diploma of deuteration51. Visuals reprinted with the following authorization: (a)51, (b)fifty one from The Op