To focusing ion beam etching (FIB) machine, the maximum effective processing size in x- and y-direction is still in ~100 micron scale during a single manufacturing cycle, generally. Considering the performances of existing equipments, it is a core operation that a high-precision and small-volume stepping displacement microplatform with a larger manufacturing size of more than that of existing equipments, is constructed effectively for fabricating optical antenna with a size in centimeter scale. The designed setup can be used to conduct a two-dimensional displacement with very high precision of few tens of nanometers for processing sample with structural size scope in centimeter level or even more, is to attach to the working plate of the FIB machine. In this paper, the 80C51 single-chip microcomputer is used as the control setup. Based on the analysis of the three closed-loop DC speed regulation system, the key parameters of the controller are designed according to the dynamic and static performance indicators of the system. Using Matlab's Simulink and Power System toolbox, a three-mode closed-loop DC speed control system for positioning and current generating is built. The model and the key parameter setting of the positioning loop, the speed loop and the current generating loop, are introduced. The simulation model and results of the DC reversible speed control system are given. The simulations verify the model, which can be effectively utilized to correct the parameter setting. It should be noted that the current change rate is suppressed while maintaining a maximum allowable changing rate, so as to make the entire current waveform being closer to the ideal waveform.
In this paper, a new type of electrically controlled liquid-crystal microlens arrays (ECLCMAs) based on plane nonuniform spiral microcoils (PNSMs) is proposed. The microlens array is based on a nematic liquid-crystal material, which presents a special characteristics of optical anisotropy and birefringence, and is fabricated by common ultraviolet lithography and dry ICP etching process to form needed PNSMs pattern. In the ECLCMAs, a glass substrate precoated by a film of indium tin oxide (ITO) on both surfaces of substrate is adopted. The key center electrode for shaping each functioned LC cell is drilled using a laser etching and emery polishing process. Metallic indium particles are selected to connect the upper and lower ITO layers. The design can guarantee the continuity of the upper and lower plates and does not affect the electric and magnetic fields generated by spiral microcoils, which are utilized to drive LC film to present needed functions of further controlling and adjusting incident microbeam distribution, which is preprocessed by main objective lens system. After an AC voltage signal is applied across the microcoil, an effective electromagnetic field can be formed in LC cell so as to drive LC molecules to rotate and thus demonstrates an electrically tuning focus. The simulations show that the design of patterned PNSMs can be effectively used to form a sufficient electric and magnetic fields that are directly used to rotate LC molecules and thus form a gradient refractive index distribution for converging incident microbeams so as to show a higher controlling-light efficiency than that of traditional patterned microelectrodes. The proposed method laid a solid foundation for future smart ECLCMAs.
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