PURPOSE: To shut off thoroughly incident rays and to make a titled device usable as a shutter with little loss in the quantity of light by sandwiching a liquid crystal between a pair of substrates and making light incident at the angle larger than a specific angle to a liquid crystal cell having the refractive index of the liquid crystal selected smaller than the refractive index of the substrates.

CONSTITUTION: Transparent substrates 1, 2 having a refractive index ng formed of transparent resistors 4, 5 sandwich a liquid crystal 3. A linearly polarizing plate 8 is arranged to have the direction 10 of the transmission axis thereof in the direction at a right angle to the homogeneous arrangement H of the liquid crystal, and the refractive index n0 of the liquid crystal 3 with respect to linearly polarized incident light 9' is selected smaller than the refractive index ng. If the polarized light 9' is made incident to the cell at the incident angle θ larger than the angle determined by Sin-1(n0/ng), total reflected light 12 is obtd. Now when the resistors 4, 5 are electrically heated, the liquid crystal 3 are transferred to the liquid phase I having isotropy, and the light passes through the liquid phase I irrespectively of the incident angle θ, by which transmitted light 11 is obtd. The incident light is thus totally reflected or transmitted by the heating with the resistors, whereby the titled device is made usable as a liquid crystal-optical shutter with little loss in the quantity of light.