PURPOSE: To shut off thoroughly incident rays and to utilize a titled device as a shutter with little loss in the quantity of light by providing means for heating a homeotropically oriented liquid crystal sandwiched between a pair of substrates and a means for making light incident thereto at a specific angle or above.

CONSTITUTION: Transparent substrates 1, 2 having a refractive index ng formed with transparent resistors 4, 5 thereon sandwich a liquid crystal 3. The refractive index n0 of the ordinary rays of the liquid crystal and the refractive index nISO of the liquid phase have the relation n0<ng≤nISO, and all of the incident light 8 having Sin-1(n0/ng) incident angle or above are totally reflected light 10, when the liquid crystal 3 maintains a homeotropic state V with respect to the surface of the substrate 1. If the resistors 4, 5 are electrically heated, the liquid crystal 3 is transferred to the liquid phase I having isotropy, and all of the incident light having any incident angle θ are transmitted light 9. The incident light 8 is thus transmitted or totally reflected as desired and since no polarizing plates are used, the titled device is usable as a liquid crystal-optical shutter permitting high speed control with little loss in the quantity of light.