Now, Terahertz technology has been widely used in many fields, which is mainly related to imaging detection. While the frequency range of the terahertz-wave is located between microwave and visible light, whether the existing visible light principle is applicable to terahertz-wave should be studied again. Through experiment, we measure the terahertz-wave field amplitude distribution on the receiving plane perpendicular to the direction of propagation in the air and picture out the energy distribution curve; derive an energy decay formula of terahertz wave based on the results; design a terahertz wavelength apparatus using the F-P interferometer theory; test the wavelength between 1 and 3 THz from the SIFIR-50THz laser of American Corehent company; finally analyze the related factors affecting the measurement precision including the beam incident angle, mechanical vibration, temperature fluctuation and the refractive index fluctuation.
In this paper, a three-dimensional relaxation method and a finite difference method (FDM) are used to model the dynamic response behavior of liquid crystal (LC) microlens. Simulations have been done for the focus-swing patterned electrodes structures. The formation of disclination lines in the director orientation can be accurately predicted. Based on the simulation, a careful choice of the device structure and the voltage will help to design better lens. We can expect that the model developed by us can be utilized to design more complex LC microlens or other functioned LC structure.
In this paper, we present a new LC lens with multi-ring patterned electrode, it consists of two ring-shaped sub-electrodes and a circle sub-electrode, each sub-electrode can be driven separately. The two rings have different diameter but the same center, when the two ring-shaped sub-electrodes are driven independently, the LC lens can work as micro convex lens with different clear aperture and its local length can be tunable along optical axis by electrical signal. As the voltage is applied to the circle sub-electrode, it appears like concave lens. With this design, it can achieve two types microlens effect in one structure, and by applying the voltage to the different patterned electrode, it can switch between two types microlens. The optical properties of the LC microlens are also demonstrated experimentally.
In this paper, we present a new LC lens with different pattern electrodes including triangle electrode, square electrode, pentagon electrode, hexagon and octagon electrodes. We demonstrate the focusing process of LC lens, when the electrodes are driven by the voltage signal, all the LC lens with different pattern electrodes have good focusing characters along the optical axis. In addition, a LC lens with different sub-electrode pattern is also introduced, the sub-electrodes are designed to circular pattern and each sub-electrode can be driven separately. If the sub-electrodes are driven by the same voltage signal, the LC lens can focus along the axis, while they are controlled separately, it can make the focus swing off the axis over the focal plane. We show the Interference patterns of LC lens with various pattern electrodes. The different focal spot shapes and the optical properties of LC microlens are also demonstrated experimentally.
In this paper, a three-dimensional relaxation method together with a finite difference method (FDM) are used to
model the dynamic response behavior of liquid crystal (LC) directors filled into a cavity with complex patterned
electrodes. Simulations and analysis have been done for the focus-swing patterned electrodes structures. A new type of
LC micro-structure which has an ability to swing its focus over its focal plane has been designed. The simulation shows
that the new LC structure designed by us has also a strong ability of swing focus over focal plane. We can expect that the
model developed by us can be utilized to design more complex LC microlenses or other functioned LC structures.
In this paper, a three-dimensional (3-D) relaxation method is used to model the dynamic response behavior of liquid crystal (LC) directors in LC micro-optics structures with complex patterned electrodes. The method is based on Frank- Oseen continuum elastic theory by using a vectorial representation. This method can deal with liquid crystal structures with arbitrary patterned electrodes, and it is quite computational stability. Different numerical results obtained according the method are as follows: (1) the nematic LC structures with complex patterned electrodes applied by a constant voltage signal, and (2) the nematic LC structures with different thickness of LC layer, and (3) the nematic LC structures with different signal voltage. The typical results include the distribution of LC directors in LC layers, the distribution of electric potential in LC layers, and the distribution of phase retardation. The results show that the method can be used to effectively predict the formation of disclination lines, which has a strong impact on the performance of LC micro-optics structures.
A liquid crystal (LC) microlens with a new type of electrode pattern is designed. The both bottom and top ITO electrodes of LC microlens are placed face to face, and are separated by glass spacer with the thickness in micron scale, and then LC materials are injected into the cell constructed by them. Because of the two electrodes directly and closely facing the LC layer injected, the design can largely decrease the driving signal voltage for LC lens. The bottom electrode is designed with one round hole pattern. The top electrode is four circle patterns. The diameters of round hole and circle are 500μm and 160μm, respectively. Each circle pattern electrode can be used to focus incident light into different region over the focal plane of LC lens. When the four circle electrodes are driven by different signal at the same time, the focus can be moved off-axis over the focal plane of LC lens, and thus the voltage amplitude can be varied in the range from 0Vrms to 20Vrms. So, we realize a LC microlens with tunable-focus over the focal plane of LC lens driven by low-amplitude voltage signal.
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