Liquid-Crystal Reflective Beam Deflector with Microscale Alignment Pattern

A liquid crystal (LC) cell is fabricated by combining a uniformly rubbed substrate and a periodically rubbed substrate. The LC cell is applied to an LC reflective beam deflector. It is theoretically derived that the sawtooth phase profile is achieved under optimum LC molecular orientation conditions. That is, the retardation of the LC cell is one-half the wavelength and the polarization direction of the incident ray makes an angle of ±π/4 with respect to the uniformly rubbed direction. Optical properties of the fabricated LC cell are experimentally investigated. It is revealed that the diffraction efficiencies of two first-order light beams ( m =±1, m denotes diffraction order) and the zeroth-order light beam ( m =0) can be controlled by the applied voltage. Since the strong diffraction of the first-order light beams ( m =±1) can be selected at will, the fabricated LC cell functions as an electrically controllable beam deflector.