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New Laser Doppler Velocimetry with Wide Dynamic Range and Clear Directional Discrimination 下载免费PDF全文
We present a new laser Doppler velocimetry based on self-mixing effect using a single longitudinal-mode verticalcavity surface-emitting laser modulated by a dynamic triangular current. It can indicate the direction of velocity without ambiguity in a wide dynamic range of 5.2-479.9minis. The accuracy of velocity measurement is better than 3.1% in the whole velocity range when a diffusing target is used for measurements. More interestingly, it works very well on different diffusing surfaces, even on a black glossy photographic paper. 相似文献
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对双镜头二维三角法测距精度的实验研究表明,在大视角下,双镜头二维测距存在较大的测距误差;通过应用小孔成像代替普通镜头成像进行二维测距研究,证明了大视角非近轴光线的镜头失真是造成该误差的主要原因,并且基于实验提出了一种经验修正公式,明显地提高了系统的测距精度和速度.实验结果表明,在50 mm×50 mm的工作区,对应于80°的大视角下,测距系统在x和y方向的平均定位精度均优于2 mm,平均分辨率分别为0.2 mm和0.1 mm. 相似文献
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A temperature-tunable polarization interference filter (PIF) made of YVO4 crystal has been presented and applied for wavelength locking of a distributed feedback (DFB) semiconductor laser in dense wavelength-division-multiplexing (DWDM) optical communication systems. This new design offers a flexible way to monitor and then lock an operating wavelength of DFB laser to any preselected point without dead spots. The results show that the laser wavelength can be locked with accuracy better than ±0.01 nm with much relaxed requirement on temperature stability of the filter. 相似文献
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应用同步辐射光电子谱(SRPES)表征了一种新的CH3CSNH2/NH4OH溶液体系处理的GaAs(100)表面的成键特性和电子态.结果表明,经过处理的GaAs(100)表面,S既与As成键也与Ga成键,形成了S与GaAs的新界面,这说明CH3CSNH2/NH4OH溶液处理的GaAs(100)表面具有明显的钝化作用.钝化表面退火处理后,发现AS的硫化物不稳定,分解或反应生成Ga-S成分和元素态As;室温下,Mg淀积硫钝化的GaAs表面的实验结果表明,Mg置换GaS的Ga成为金属Ga偏析到表面,而硫以MgS 相似文献
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The effect of speckle pattern on laser Doppler velocimeters is studied theoretically and experimentally. We have found that dynamic speckle patterns can cause error in velocity measurement. Increasing sampling time and using proper signal processing circuits can eliminate this bad effect caused by speckle pattern.The accuracy of velocity measurement is better than 2.1% in a wide velocity range(4.66-468.86 mm/s)when speckle effects are taken into account. 相似文献