PURPOSE: To reduce influence by diffraction of a surface acoustic wave, to execute an optical deflection exactly, and to greatly improve the image resolution, by providing a surface wave waveguide for enclosing the surface wave energy in a surface acoustic wave propagation path.

CONSTITUTION: An inter-digital electrode 3 of a surface acoustic wave is formed on a piezoelectric substrate 1 having an optical waveguide 2 consisting of a titanium diffused layer, and a surface wave waveguide 9 consisting of an aluminum thin film, etc. is provided. According to this constitution, since the waveguide 9 is provided, energy of a surface wave to be propagated is inclosed in the waveguide 9, a diffraction phenomenon of the surface wave becomes extremely small, and in the waveguide 9, the surface wave is propagated, holding a straight line state. In this state, when a light beam 6 is inputted from the lateral direction, it is deflected exactly, and deflected optical beams 81, 82 are generated. In this way, the optical deflection is executed exactly, and the image resolution is improved remarkably.