In this paper we study conoscopic patterns of single crystals of LiNbO3 congruent (Li/Nb = 0.946) and stoichiometric (Li/Nb = 1) compounds, as well as congruent crystals doped with cations: Mg2+ (0.86 wt.%), Zn2+ (0.03, 0.52, 0.62 wt.%), Cu2 + (0.015 wt.%), B3+ (0.12 wt.%), Gd3+ (0.51 wt.%), Y3+ (0.46 wt.%), Gd3+ (0.23 wt.%): Mg2+ (0.75 wt.%), Mg2+ (0.86 wt.%): Fe3+ (0.0036 wt.%), Ta5+ (1.13 wt.%): Mg2+ (0.011 wt.%), Y3+ (0.24 wt.%): Mg2+ (0.63 wt.%). Conoscopic patterns of lithium niobate crystals were recorded at excitation by He-Ne laser (λo = 632.8 nm) and the second harmonic of MLL-100 laser Y:Al garnet (λo = 532 nm, P = 1mW), which does not cause the effect of photorefractive and more powerful radiation of the second harmonic MLL-100 laser Y: Al garnet (λo = 532 nm, P = 90 mW). Irradiation of crystals radiation 632.8 nm and 532 nm (P = 1 mW) photorefractive effect is absent and there is no disclosure of the photoinduced light scattering indicatrix. In this case, conoscopic paintings reflect the state of structural defects in the crystal in the absence of photorefractive effect. When excited by MLL-100 laser radiation on Y:Al garnet (λo = 532 nm, P = 90 mW) in conoscopic patterns appear as its own crystal defects (defined composition and crystal growth conditions), and defects, induced by laser radiation. These crystals characterized by rather a low photorefractive effect. In crystals with a low effect of photorefractive optical distortions associated with the passage of laser light through the crystal is not "smeared" the strong destruction of the laser beam due to photorefractive effect, and confidently observable.