| Liquid crystal devices play a very important role in people’s life.Photoelectric liquid crystal materials,such as blue phase liquid crystal and ferroelectric liquid crystal,have been continuously studied and applied in the field of display and optical devices due to their excellent response ability.Among these materials,there is a kind of curved nematic liquid crystal material containing azobenzene fins,which shows excellent photoelectric response characteristics in the industrially manufactured friction-oriented liquid crystal cell,but the texture of the molecular arrangement is bad,and it is not convenient for light-dependent control,so it is difficult to realize application.In this paper,a Pancharatnam-Berry Liquid Crystal device(PBLC)was manufactured using this material based on the polarized lightorientation technology of Liquid Crystal spatial light modulator.It can not only carry out convenient photoelectric control,but also have excellent display effect.The manufacture of the liquid crystal cell is the basic step of the photoalignment experiment,which is carried out in the ultra-clean laboratory.In order to protect the orientation stability at high temperature,the orientation layer manufactured by azo dye BY was coated with RM257 solution as the protective layer.The optical path of the holographic polarization grating was established to conduct the exposure experiment of the interference grating,which was used to detect the orientation effect of the manufactured liquid crystal cell and facilitate the deployment of various parameters.The LCoS used in this paper is one of many spatial Light Modulator(SLM).It is a new digital imaging technology,driven by electric signals,with high resolution and wide range of phase modulation.The optical path is built with LCoS,and the real-time dynamic digital mask is controlled by 8-bit gray image.In a single exposure,the simultaneous orientation of different micro-regions with different polarization directions can be realized.The polarization direction is refined to each pixel micromirror to realize the quasicontinuous pattern orientation such as "circular" and "radial".The photoelectric control experiment of the device was carried out under the polarized light microscope system,and the sample images were collected by the CCD optical sensor lens in real time.The device temperature is kept at 225℃,and the environment is in a state without light interference.An alternating current with a frequency of 100 Hz is applied to the device and Freedericksz transition occurs.When the voltage range reaches the Uth(1V),the sample has an instantaneous state change characterized by color.Under the control of the light field at 365 nm,the liquid crystal molecules undergo trans-cis photoisomerization,and the four color gradients can be realized in 40 seconds.The FT effect is enhanced by the generated light field and the Uth of the electric field is effectively reduced.Under the control of the photoelectric composite field,the device can achieve four state transitions: yellow,gold,green and orange.The color display of the device can be realized by drawing grayscale map and controlling the difference of grayscale value in each micro area of the pattern.The photoelectric phase adjustable liquid crystal devices based on SLM photoalignment have the advantages of simple and efficient manufacture,high resolution,sensitive response,wide color gamut and low cost,and are expected to be applied in the fields of display,optical switch and optical information processing. |
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