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微机械谐振式加速度计(MMRA)是通过检测加速度施加前后谐振器谐振频率变化实现对加速度检测的。该传感器具有频率信号输出、稳定性好、灵敏度高、精度高等优点,己成为MEMS传感器的重要发展方向之一。详细讨论了微机械谐振式加速度计设计中的关键技术,难点及对应解决方案、发展趋势。其中,关键技术包括机械结构、激励与检测方式以及谐振器刚度改变方式。分析了谐振器的三种机械结构以及微杠杆工艺误差造成的不对称性;根据谐振器材料的压电特性,可将MMRA分为压电MMRA和非压电MMRA,压电MMRA的激励与检测方式都是压电激励/压电检测,非压电MMRA主要为静电激励/电容检测;讨论了轴向应力和静电刚度这两种谐振器刚度改变方式的原理和适用范围。微机械谐振式加速度计主要存在四个技术难点:机械耦合、温度特性、工艺误差、组装与封装,并针对这四点给出了相应的解决方案。集成,静电刚度,新材料,多轴以及更高的性能指标将是今后微机械谐振式加速度计的主要发展趋势。 相似文献
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无衍射光莫尔条纹被广泛应用在精密测量领域中,实现无衍射光莫尔条纹中心的精确定位是高精度测量的关键。通过对无衍射光莫尔条纹图像特征进行分析,提出了一种无衍射光莫尔条纹的中心定位方法。该方法首先根据光强分布特征,提取莫尔条纹图像中两光斑中心局部同心圆区域;然后进行局部同心圆环检测,确定初始圆心集;再对初始圆心集进行聚类分析确定两光斑中心的初始位置;最后删除异常点并迭代求取两光斑中心较精确的位置,实现无衍射光莫尔条纹两光斑中心的定位目的。理论和实验结果表明该方法能快速、准确地同时确定两光斑中心位置,且误差小于1 pixel。 相似文献
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在某非约束环境下,需要将多束激光准确照射到空间的某点,各激光发射器的支座可单独用手动调节,—旦调至所要求的对准范围,即将支座固定,确保激光光束的方向和位置恒定不变,因而准确测量激光光斑中心相对于靶标中心的位置成为确保瞄准精度的关键环节,为此研制了激光光斑中心位置检测系统。 相似文献
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基于压电换能器技术设计了一种应用于光学相干层析成像的新型内窥式二维光纤扫描探头,即利用两片压电陶瓷片和一片薄导电基片驱动光纤探头.该探头利用光纤悬臂的共振特性,通过对压电陶瓷施加等于光纤共振频率的混频信号,能同时激发光纤悬臂两正交方向上的振动,可以实现光纤悬臂的二维扫描.建立了理论模型并进行了有限元仿真分析,最后搭建了实验系统,验证并获得了扫描图样.实验结果实现了光纤悬臂的二维扫描,扫描范围达到(500×500)μm,调节驱动信号振幅幅值可以调节扫描范围.实验结果与理论分析和仿真相吻合,验证了方案的可行性. 相似文献
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Okamoto H Ito D Onomitsu K Sanada H Gotoh H Sogawa T Yamaguchi H 《Physical review letters》2011,106(3):036801
Carrier-induced dynamic backaction in micromechanical resonators is demonstrated. Thermal vibration of an n-GaAs/i-GaAs bilayer cantilever is amplified by optical band-gap excitation, and for the excitation power above a critical value, self-oscillations are induced. These phenomena are found in the [1[over ˉ]10]-oriented cantilever, whereas the damping (deamplification) is observed in the [1[over ˉ]10] orientation. This optomechanical coupling does not require any optical cavities but is instead based on the piezoelectric effect that is generated by photoinduced carriers. 相似文献
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S. Hirsekorn U. Rabe W. Arnold 《Applied Physics A: Materials Science & Processing》2001,72(7):S87-S92
In dynamic force microscopy the cantilever of an atomic force microscope is vibrated at ultrasonic frequencies in the range of several 10 kHz up to several MHz while scanning a sample surface. The amplitude and phase of the cantilever vibration as well as the shift of the cantilever resonance frequencies provide information about local sample surface properties. In several operation modes of dynamic force microscopy, for example force modulation microscopy, tapping mode or atomic force acoustic microscopy, the sensor tip is in contact with the sample at least during a fraction of its vibration cycle. The periodic indentation of the tip with the sample surface generates ultrasonic waves. In this paper, the ultrasonic radiation of a vibrating cantilever into a sample and its contribution to the damping of the cantilever vibration are calculated. The theoretical results are compared to experiments. 相似文献
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S. Petitgrand R. Yahiaoui K. Danaie A. Bosseboeuf J. P. Gilles 《Optics and Lasers in Engineering》2001,36(2):77
Microscopic interferometry is a powerful technique for the static and dynamic characterization of micromechanical devices. In this paper we emphasize its capabilities for 3D vibration mode shapes profiling of Al cantilever microbeams and Cr micromachined membranes. It is demonstrated that time-resolved measurements up to 800 kHz can be performed with a lateral resolution in the micrometer range and a vibration amplitude detection limit of 3–5 nm. In addition, with reduced image sizes (256×256), quasi-real time (150–500 ms) visualization of the vibration mode 3D profiles becomes possible. These performances were obtained by using stroboscopic illumination with an array of superluminescent LED and an optimized automatic fast Fourier transform phase demodulation of the interferograms. The results are compared with theoretical shapes of the vibration modes and with point measurements of the vibration spectra. 相似文献
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The steady-state response motion of a base excited cantilever beam with circular cross-section excited by a unidirectional displacement will fall along a straight line. However, achieving straight-line motion with a real cantilever beam of circular cross-section is difficult to accomplish. This is due to the fact that nonlinear effects, small deviations from circularity, asymmetric boundary conditions, and actuator cross coupling can induce whirling. The vast majority of previous work on cantilever beam whirling has focused on the effects of system nonlinearities. We show that whirling is a much broader problem in the design of resonant beam scanners in that the onset of whirling does not depend on large amplitude of motion. Rather, whirling is the norm in real systems due to small system asymmetries and actuator cross coupling. It is therefore necessary to control the growth of the whirling motion when a unidirectional beam motion is desired. We have developed a novel technique to identify the two eigen directions of the beam. Base excitation generated by virtual electrodes along these orthogonal eigen axes of the cantilever beam system generates tip vibration without whirl. This leads to accurate open loop control of the motion of the beam through the combined actuation of two pairs of orthogonally placed actuator electrodes. 相似文献
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In this paper, we study the dynamic modes of a scanning near-field optical microscope (SNOM) which uses an optical fiber probe; and the sensitivity of flexural and axial vibration modes for the probe were derived and the closed-form expressions were obtained. According to the analysis, as expected each mode has a different sensitivity and the first mode is the most sensitive mode of flexural and axial vibration for the SNOM probe. The sensitivities of both flexural and axial modes are greater for a material surface that is compliant with the cantilever probe. As the contact stiffness increases, the high-order vibration modes are more sensitive than the lower-order modes. Furthermore, the axial contact stiffness has a significant effect on the sensitivity of the SNOM probe, and this should be noted when designing new cantilever probes. 相似文献
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Two-frequency interferometry for small displacement measurements is examined from a practical point of view. A laser beam that is modulated sinusoidally in intensity by an acousto-optic Bragg cell provides signal and reference optical waves to produce dynamic interference. The output signal of a photodetector receiving the interference is composed of optical homodyne and heterodyne components. The heterodyne component carries a vibrational displacement to be detected on its amplitude. A sinusoidal vibration amplitude is measured down to 0.5 nm. 相似文献
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The bit pattern effect on all-optical clock recovery using tank circuits and birefringent resonators
In this paper we discuss the bit pattern effect on optical clock signals recovered using tank circuits and using birefringent resonators. For the first time we compare the bit pattern dependence of the clock signals recovered from both schemes. We show that a birefringent resonator can recover the clock for the same number of consecutive zeros as the optical tank circuit. We also show quantitatively that the fluctuation of the clock signal amplitude is less for the birefringent resonator than the optical tank circuit. These results are obtained numerically and confirmed experimentally. 相似文献
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采用飞秒激光抽运脉冲激发了Bi_2Te_3薄膜频率为1.856 THz的声子相干振动,并用探测光测量得到了其阻尼振动信号.结合Raman光谱,确定该振动为A~1_(1g)对称振动模式的相干光学声子.为了实现该模式振动的调控,在抽运光路上安装了脉冲整形器,进而控制生成具有不同时间间隔和能量比的两束脉冲激光.研究表明,当两束脉冲的间隔时间为相干光学声子振动半周期的奇数倍时,调整两束脉冲的能量比值,可以实现A~1_(1g)模式振动的完全消除.继而将两束脉冲的能量比值保持不变,得到了振幅随间隔时间的变化曲线,与理论分析符合.结果进一步证实了用超快光谱调控特定晶格振动的可行性,从而为研究材料内部超快能量传递过程提供了有效手段. 相似文献