共查询到19条相似文献,搜索用时 656 毫秒
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在栅扫描束流配送系统下, 进行了重离子束对运动靶体进行适形照射的可行性实验研究. 利用实时修正束流扫描参数的方法, 使得束流追踪靶体在横向上的运动; 在纵向上利用一个机械驱动的束流降能装置(称深度扫描器)迅速调节束流
能量, 使得重离子束高剂量的Bragg峰区落在运动靶体需治疗的断层之上. 实验结果表明: 栅扫描器主动补偿靶体横向运动及深度扫描器补偿靶体纵向运动是可行的. 相似文献
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激光二维光机扫描系统设计 总被引:1,自引:0,他引:1
介绍了一种采用八面体转镜与平面摆镜联合实现激光二维光栅轨迹扫描的扫描器,讨论了光学及机构设计中影响扫描精度的因素,及电机频率/相位稳速控制问题,保证了该扫描器的精度和稳定性。 相似文献
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能扫描任意字符的光扫描器 总被引:2,自引:0,他引:2
本文介绍一种用计算全息方法制作的光扫描器,这种扫描器能扫描任意图形例如字符等.文中还介绍了改善聚焦和回扫(扫描方向回转)的方法,并附实验结果. 相似文献
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Sihua Xiang Author Vitae Sihai Chen Author Vitae Xin Wu Xiawei Zheng 《Optics & Laser Technology》2010,42(1):42-46
In the field of lidar system design, there is a need for laser scanners that offer fast linear scanning, are small size and have small a rotational inertia moment. Currently, laser scanners do not meet the above needs. A new laser scanner based on two amplified piezoelectric actuators is designed in this paper. The laser scanner has small size, high mechanical resonance frequencies and a small rotational inertia moment. The size of the mirror is 20 mm×15 mm. To achieve fast linear scanning performance, an open-loop controller is designed to compensate the hysteresis behavior and to restrain oscillations that are caused by the mechanical resonances of the scanner's mechanical structure. By comparing measured scanning waveforms, nonlinearities and scan line images between the uncontrolled and controlled scanner, it was found that the scanning linearity of linear scanning was improved The open-loop controlled laser scanner realizes linear scanning at 250 Hz with optical scan angle of ±12 mrad. 相似文献
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Effects of ramp vibrational states on flexural intrinsic vibrations in Besocke-style scanners 下载免费PDF全文
For both the vibrating and steady supporting surfaces of a scanning disk in a Besocke-style piezoelectric scanner, a theoretical model is given by considering the nonlinear lateral friction at the micro-contact interface between the positioning legs and the supporting surface. Numerical simulations demonstrate that unexpected flexural vibrations can arise from a vibrating ramp, and their frequencies are lower than the eigenfrequencies of the scanner in the linearly elastic regime. The vibrations essentially depend on 1) the vibrational states of the supporting ramp and the steel ball tips on the three piezo- electric positioning legs, and 2) the tribological characteristics of the contacts between the tips and the ramp. The results give an insight into the intrinsic vibrations of the scanners, and are applicable in designing and optimizing piezoelectric scanning systems. 相似文献
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We report an all-fiber-optic scanning, multimodal endomicroscope capable of simultaneous optical coherence tomography (OCT) and two-photon fluorescence (TPF) imaging. Both imaging modalities share the same miniature fiber-optic scanning endomicroscope, which consists of a double-clad fiber with a core operating in single mode at both the OCT (1310 nm) and two-photon excitation (1550 nm) wavelengths, a piezoelectric two-dimensional fiber-optic beam scanner, and a miniature aspherical compound lens suitable for simultaneous acquisition of en face OCT and TPF images. A fiber-optic wavelength division multiplexer was employed in the integrated platform to combine the low coherence OCT light source and the femtosecond two-photon excitation laser into the same optical path. Preliminary imaging results of cell cultures and mouse tissue ex vivo demonstrate the feasibility of simultaneous real-time OCT and TPF imaging in a scanning endomicroscopy setting for the first time. 相似文献
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И. С. Желудев 《Czechoslovak Journal of Physics》1966,16(5):368-381
The necessary and sufficient conditions for the existence of the direct and inverse piezoelectric effect in crystals and textures are deduced. It is found that under certain conditions the piezoelectric properties in crystals of certain classes are richer than those obtained from the piezoelectric tensor. The results are given of the piezoelectric polarization of quartz in the direction of the optical axis and the excitation of oscillations of the plates perpendicular to the optical axis when the field is applied in the direction of the optical axis. 相似文献
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A scanned-cantilever atomic force microscope (AFM) with large scanning range is proposed, which adopts a new design named laser spot tracking. The scanned-cantilever AFM uses the separate flexure x-y scanner and z scanner instead of the conventional piezoelectric tube scanner. The closed-loop control and integrated capacitive sensors of these scanners can insure that the images of samples have excellent linearity and stability. According to the experimental results, the scanned-cantilever AFM can realize maximal 100 × 100 (μm) scanning range, and 1-nm resolution in z direction, which can meet the requirements of large scale sample testing. 相似文献
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The design of optical prism fingerprint scanner with aspheric lens is researched. We propose a modified structure for optical prism fingerprint scanner, which has an asymmetrical aspheric lens on the output plane. It is numerically shown under elliptic valley similar fingerprint model that the optical image qualities of such a scanner are better than the scanner with symmetrical aspheric lens. When the fingerprint range is 15 mm, the results show that the minimum image contrast is 0.49 for an optical prism with asymmetrical aspheric lens, much better than a symmetrical aspheric lens with 0.20. The relative illumination variation is from 0.62 to 1.00 for optical prism with asymmetrical aspheric lens, and for the symmetrical aspheric lens it is 0.35 to 1.00. We conclude that an optical prism with asymmetrical aspheric lens is better than an optical prism with symmetrical aspheric lens. 相似文献
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C.Z. Tan 《Solid State Communications》2004,131(6):405-408
A relationship is proposed between the piezoelectric coefficient and the dielectric constant (or refractive index) based on classical dispersion theory. Piezoelectric lattice vibrations are associated with ionic polarizations at optical frequencies. This relation is applied to study the piezoelectric lattice vibrations in α-quartz, and agreement is found between the calculated and the measured value of the piezoelectric coefficient. No direct experimental method for measurement of piezoelectric coefficients at optical frequencies exists; however, in terms of the proposed relation, piezoelectric coefficients at optical frequencies can be evaluated from infrared reflection measurements. 相似文献
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利用飞秒光频梳、外腔可调谐半导体激光器和法布里-珀罗干涉仪建立了一套压电陶瓷亚纳米级闭环位移控制系统. 将可调谐半导体激光器锁定至光频梳, 通过精确调谐光频梳的重复频率, 实现了半导体激光器在其工作频率范围内的精密调谐. 利用Pound-Drever-Hall锁定技术将带有压电陶瓷的法布里-珀罗腔锁定至半导体激光器, 进而通过频率发生系统控制压电陶瓷产生亚纳米级分辨率的位移. 实验研究发现锁定至光频梳后可调谐半导体激光器1 s的Allan标准偏差为1.68×10-12, 将其在30.9496 GHz范围内进行连续闭环调谐, 可获得压电陶瓷的位移行程约为4.8 μm; 以3.75 Hz的步长扫描光频梳的重复频率, 实现了压电陶瓷的450 pm闭环位移分辨率并测定了压电陶瓷的磁滞特性曲线. 该系统不存在非线性测量误差, 且激光频率及压电陶瓷位移均溯源至铷钟频率源.
关键词:
光频梳
压电陶瓷
法布里-珀罗腔
可调谐半导体激光器 相似文献
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Polarization is a crucial issue for electrical and optical characteristics of the UV AlGaInN light-emitting diodes. The effect of spontaneous and piezoelectric polarization on optical characteristics of the UV AlGaInN light-emitting diodes is investigated numerically. The simulation results indicate that the polarization-related effect for the UV AlGaInN light-emitting diodes is dominated by the piezoelectric polarization. When the UV AlGaInN light-emitting diodes are without piezoelectric polarization, the optical performance is enhanced effectively due to improved overlap of electron and hole wavefunctions, reduced electron leakage current, and increased density of holes in the active region. 相似文献