PURPOSE: To switch incident light by disposing an element which is composed of an irregular ferrodielectric crystal plate comprising forming opposing two faces respectively perpendicularly to the C-axis between a polarizer and an analyzer.

CONSTITUTION: An element 21 which comprises forming the front and back two faces of gadolinium molybdate respectively perpendicularly to the C-axis, arraying a plurality of transparent electrodes of strip form in parallel on one Z face and providing a transparent full surface electrode on the other is configured behind a polarizer 7 by way of a 1/4 wavelength plate 18 and a slit plate 17 and further an analyzer 8 is disposed behind the element 21 by way of an analyzer 19, a 1/4 wavelength plate 18' and a slit plate 17'. Hence, if the directions of polarization are aligned by applying a negative voltage to the lead wires of the element 21, rays are cut off. If a positive voltage is applied, that portion transmits light, by which light is radiated in strip form, thus the element which switches the incident light and generates accurate patterns may be provided