共查询到20条相似文献,搜索用时 218 毫秒
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介绍一种测量肌肉震颤频率和幅度的无损伤、非接触光学方法。分析了在直接频率调制下,激光二极管中的光反馈效应,探讨了振动微小位移和速度的理论模型。设计并研制了一套基于光反馈效应的直接频率调制激光二极管光电探测系统。利用该系统对微弱机械振动信号进行了探测,表明该系统能用于肌肉震颤的测量。最后介绍了人体前臂内侧屈肌群紧张收缩时,肌肉震颤的光学测量结果。 相似文献
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调制偏振光在光学相位延迟测量中的频谱分析 总被引:1,自引:0,他引:1
介绍了光调制器的调制原理,在时间域和频率域对其调制特性进行了理论分析,得到了相应的光强分布曲线。基于偏振光调制理论,提出了一种新型光学相位延迟测量方法,并对该方法从时域和频域两方面进行了分析。频谱分析的结果表明,当出射光信号的奇次谐频分量为零时,满足完全补偿条件,此时可由补偿器的补偿量直接得到待测器件的光学相位延迟量。这种方法能够对光学相位延迟量进行直接量的测量,和其他间接测量方法相比有其明显的优势。在理论分析的基础上,还进行了相应的实验,并得到了高精度的实验结果。 相似文献
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为了实现连续稳定、高速、高精度和高灵敏度的光学旋光测量, 考虑到弹光偏振调制技术具有高的调制频率、调制纯度、调制精度和良好的调制稳定度等应用优势, 设计了一种基于弹光调制的旋光测量新方案. 检测激光经起偏器、测量样品、弹光调制器和检偏器到探测器的光路设计, 使得测量系统选用较少的光学器件, 最大化地降低了光学器件可能引入的测量误差; 起偏器和检偏器偏振轴相对于弹光调制器快轴方向分别取0°和45°的光学安排, 并选择弹光调制的二倍频信号作为研究对象, 有效避免了弹光调制器剩余双折射对旋光样品测量的影响, 提高了旋光测量精确度; 将探测器输出调制信号的直流和交流分开输出, 并将交流信号进行前置放大处理, 然后再锁相输出, 进一步提高了测量灵敏度. 设计了将激光调制为圆偏光, 然后精确调节起偏器来替代样品的旋光测量验证试验, 确定了系统旋光测量的比列系数, 并且获得旋光测量灵敏度为3.15×10-7 rad, 测量精度优于0.3%. 所以, 本方案实现了较高灵敏度旋光测量, 有望应用于高灵敏旋光测量领域, 并且本方案的实验可为高灵敏旋光测量系统的定标提供参考. 相似文献
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Liang Lu Longhua Zhai Ke Zhang Jijun Dai Jun Zhu Shenglai Zhen Benli Yu 《Optik》2011,122(20):1840-1842
Laser interferometry based on self-mixing effect widely used to measure displacement, velocity, vibration and distance due to compactness, non-contact, as well as low cost. An important use of the self-mixing effect inside a laser diode is in optical self-mixing vibrometer. We have experimentally investigated self-mixing interference produced by the feedback of light from a vibrated target into a vertical-cavity surface-emitting laser for sensing applications. In this paper, the self-mixing vibrometer employing different feedback regime is discussed and a theoretical analysis is also proposed. Numerical analysis focused on the distortion self-mixing waveform. Numerical analysis and experimental results show that mode-hop occurs when the laser self-mixing vibrometer employing at high feedback level. 相似文献
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K. Döringshoff I. Ernsting R.-H. Rinkleff S. Schiller A. Wicht 《Applied physics. B, Lasers and optics》2008,91(1):49-56
We analyze in detail the frequency noise properties of a grating enhanced external cavity diode laser (GEECDL). This system
merges two diode laser concepts, the grating stabilized diode laser and the diode laser with resonant optical feedback, thus
combining a large tuning range with an excellent short-term frequency stability. We compare the frequency noise spectrum of
a GEECDL to that of a grating stabilized diode laser and demonstrate a 10-fold reduction of the frequency noise linear spectral
density. The GEECDL is phase locked to a similar laser and to a fs-frequency comb with a servo loop providing an open-loop
unity-gain frequency of only 237 kHz, which is a tenth of the bandwidth typically required for grating stabilized diode lasers.
We achieve a residual rms phase error as small as 72 mrad (≈ 200 mrad) for stabilization to a similar laser (to the fs-frequency
comb). We demonstrate that the novel diode laser can phase-coherently track a stable optical reference with an instability
of 1.8×10-16 at 1 s. This laser system is well suited for applications that require phase locking to a low-power optical reference under
noisy conditions. It may also be considered for the implementation of optical clock lasers.
PACS 42.55.Px; 42.60.Jf; 42.50.Gy 相似文献
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The emission frequency of a diode laser submitted to a frequency-dependent optoelectronic feedback is observed to have more than one stable operation point together with a stable power emission. This is, to our knowledge, the first observation of bistability exclusively in the frequency of an optical system. The experiment was carried out with a semiconductor laser coupled to the cesium D2 line by an orthogonally polarized frequency-sensitive optical feedback. 相似文献
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The frequency of an external-cavity diode laser has been stabilized to 1.637 μm by using the reference of absorption lines of methane.The method can be applied to wavelength division multiplexed optical communication,fiber-optic sensing systems,as well as the high-sensitivity detection of methane.The derivative-like error signal yielded by frequency modulation and phase sensitivity detection technology is inputted into the PI feedback loop circuit in order to stabilize the frequency to the line center.After stabilization,the frequency fluctuation of diode laser is held within 5.6 MHz,and the root of Allan variance of error signal reaches a minimum of 1.66×10-10 for an average time of 10 s. 相似文献
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A novel cavity ring-down (CRD) technique, based on the optical feedback effect of Fabry–Perot diode lasers, is developed for accurate reflectivity measurement of highly reflective cavity mirrors. The strong optical feedback, including the direct reflection from the front cavity mirror of a linear ring-down cavity, is re-injected into the oscillator cavity of the diode laser, and large resonant peaks are observed in the ring-down cavity output signals. The diode laser is switched off by a threshold circuit when the amplitude of a resonant peak exceeds a pre-defined threshold. Exponentially decayed signals recorded immediately after switching off the laser are used to determine the cavity decay time. The ultra-high reflectivity of cavity mirrors is measured to be 99.99606% with a reproducibility of 0.00003%. Compared with the previous phase-shift CRD technique, the signal-to-noise ratio of the cavity output signals is improved with an enhancement factor of over 100. 相似文献
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Zhouqiang Zhang Shuhai Jia Fei Wang Yonglin Wang 《Journal of Russian Laser Research》2016,37(3):285-290
We study quartz tuning fork (QTF) characteristics using a 532 nm semiconductor laser with a power of 39 mW and calculate QTF vibrations caused by thermal noise and disturbance of the air using the equipartition theorem; the vibration value is about 1.152 Pm. The signal-to-noise ratio and QTF resonance amplitude acquired experimentally are 104.56 and 214.75 Pm, respectively. In addition, we develop a new photo-acoustic spectroscopic system for detection of trace acetylene using a CW diode laser source with distributed feedback operating near 1,532 nm, measure the absorption spectrum of acetylene employing this system, and show that the method elaborated is more sensitive than photoelectric detectors that provides new directions for research in photo-acoustic spectroscopy. 相似文献
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Ludlow AD Huang X Notcutt M Zanon-Willette T Foreman SM Boyd MM Blatt S Ye J 《Optics letters》2007,32(6):641-643
We demonstrate phase and frequency stabilization of a diode laser at the thermal noise limit of a passive optical cavity. The system is compact and exploits a cavity design that reduces vibration sensitivity. The subhertz laser is characterized by comparison with a second independent system with similar fractional frequency stability (1x10(-15) at 1 s). The laser is further characterized by resolving a 2 Hz wide, ultranarrow optical clock transition in ultracold strontium. 相似文献
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We demonstrate the excellent spectral properties of a diode laser setup that combines good tunability with superb short-term frequency stability and controllability. It is based on merging two concepts, the diode laser with resonant optical feedback and the grating stabilized diode laser. To characterize the short-term performance we beat two essentially identical diode lasers and find a short-term linewidth of ~11 kHz. Phase locking between these lasers is achieved with a servo bandwidth as small as 46 kHz, although an analog phase detector is used that requires subradian residual phase error. Despite small phase error detection range and small servo bandwidth, cycle-slip-free phase locking is accomplished for typically many 10 min, and the optical power is essentially contained in a spectral window of less than 20 mHz relative to the optical reference. Due to the excellent performance this laser concept is well suited for atomic or molecular coherence experiments, which require phase locking of different lasers to each other, and as part of a flywheel for optical clocks. 相似文献
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An active phase-shifting interferometer using current modulation of a laser diode is proposed. Fringe movement in the instrument is detected by a spatial filtering detector whose output is fed back to the injection current of the laser diode to lock the fringes and shift them correctly for phase shifting analysis. Frequency modulation characteristics of the laser diode and frequency response of the feedback system are first investigated. We constructed a portable interferometer head set apart from a mirror under test then measured the shape of a spherical mirror 130 mm in diameter, which was placed on a wooden table subject to vibration. Measurement repeatability of λ/35 was achieved. 相似文献