共查询到20条相似文献,搜索用时 46 毫秒
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Y型光波导分束比和插入损耗测量技术研究 总被引:1,自引:0,他引:1
Y波导在集成光学系统中得到了广泛的应用,并拥有很大的潜力,近年来备受关注。因此了解它的各项指标至关重要。在Y波导的诸多指标中,分束比和插入损耗是2个重要指标。着重介绍了2个指标的测量装置及测量方法。对于分束比,分别采用波长为1300nm和1550nm的激光光源测量Y波导两尾纤的输出光功率。根据公式计算出分束比后,分析影响测量结果的主要因素,进行测量不确定度评定。对于插入损耗,主要是按照测量原理搭建测量装置,从理论上分析影响插入损耗测量的因素。通过对Y波导2个指标的测量,有助于更好地了解Y波导的性能。 相似文献
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大口径元件反射率的镜面扫描精密测量系统 总被引:4,自引:2,他引:2
为了测量高功率激光传输系统中大口径高反射率元件,研制了一种镜面扫描的精密测量系统。介绍了该系统的结构及其工作原理,分析了影响系统测量精度的因素,理论上估算的测量精度为2×10-5。在直腔下对该系统的性能进行了实验测试,分析表明,系统的测量不确定度优于2.052 28×10-5,最大测量误差为3.554 04×10-5,与理论预计结果吻合较好。对大口径元件进行的多次实验扫描测试,结果显示,镀膜加工误差导致反射率分布是关于镜面中心呈旋转对称。该系统的使用大大简化了元件表面反射率分布的测量。 相似文献
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We propose an experiment which demonstrates the undoing of a weak continuous measurement of a solid-state qubit, so that any unknown initial state is fully restored. The undoing procedure has only a finite probability of success because of the nonunitary nature of quantum measurement, though it is accompanied by a clear experimental indication of whether or not the undoing has been successful. The probability of success decreases with increasing strength of the measurement, reaching zero for a traditional projective measurement. Measurement undoing ("quantum undemolition") may be interpreted as a kind of quantum eraser, in which the information obtained from the first measurement is erased by the second measurement, which is an essential part of the undoing procedure. The experiment can be realized using quantum dot (charge) or superconducting (phase) qubits. 相似文献
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差分吸收光谱法(DOAS)是基于朗伯比尔定律的光谱法测量气体的重要方法,按此原理建立的测量系统是测量痕量气体的主要方法。用于测量痕量气体的DOAS系统的关键是其检出限的校准,传统的方法是使用标准气体进行校准。但是由于标准气体自身的量值确定问题,在ppb甚至ppt级的不确定度大于10%,而一般的ppt级的DOAS测量系统本身的不确定度也会高于标准气体,导致传统方法失效。提出一种基于光谱密度的DOAS系统校准方法,利用朗伯比尔定律将DOAS系统的检出限和光谱密度建立关系。由于光谱密度作为光学量值可以测量到10-6甚至更高,所以通过该方法可以实现DOAS系统在ppb乃至ppt级的校准。本方法需要根据待校准的测量系统光学结构的基本参数计算其总的标准光学密度值,然后把标准光学密度片放入测量系统光程中,测得其光学密度值,根据前后两次光学密度计算测量系统的测量偏差,进而分析计算测量系统的标准不确定度和标定的扩展不确定度,所得到的标定的扩展不确定度即为测量系统的检出限。该方法完全基于光学测量,不需引入标准气体评估,基于光学密度的精密测量和测量系统光学结构的装调误差,实现测量系统在较小不确定度水平上的标定,提高检出限标定的精度。本方法在开放光程式的DOAS系统上进行了实验验证。 相似文献
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Mario Bertolotti 《Contemporary Physics》2013,54(2):144-145
‘Flying Triangulation’ (FlyTri) is a recently developed principle which allows for a motion-robust optical 3D measurement of rough surfaces. It combines a simple sensor with sophisticated algorithms: a single-shot sensor acquires 2D camera images. From each camera image, a 3D profile is generated. The series of 3D profiles generated are aligned to one another by algorithms, without relying on any external tracking device. It delivers real-time feedback of the measurement process which enables an all-around measurement of objects. The principle has great potential for small-space acquisition environments, such as the measurement of the interior of a car, and motion-sensitive measurement tasks, such as the intraoral measurement of teeth. This article gives an overview of the basic ideas and applications of FlyTri. The main challenges and their solutions are discussed. Measurement examples are also given to demonstrate the potential of the measurement principle. 相似文献
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Lei Yang Jianchen Luo Xiaowei Song Menglong Li Pengwei Wen Zixiang Xiong 《Entropy (Basel, Switzerland)》2021,23(7)
A robust vehicle speed measurement system based on feature information fusion for vehicle multi-characteristic detection is proposed in this paper. A vehicle multi-characteristic dataset is constructed. With this dataset, seven CNN-based modern object detection algorithms are trained for vehicle multi-characteristic detection. The FPN-based YOLOv4 is selected as the best vehicle multi-characteristic detection algorithm, which applies feature information fusion of different scales with both rich high-level semantic information and detailed low-level location information. The YOLOv4 algorithm is improved by combing with the attention mechanism, in which the residual module in YOLOv4 is replaced by the ECA channel attention module with cross channel interaction. An improved ECA-YOLOv4 object detection algorithm based on both feature information fusion and cross channel interaction is proposed, which improves the performance of YOLOv4 for vehicle multi-characteristic detection and reduces the model parameter size and FLOPs as well. A multi-characteristic fused speed measurement system based on license plate, logo, and light is designed accordingly. The system performance is verified by experiments. The experimental results show that the speed measurement error rate of the proposed system meets the requirement of the China national standard GB/T 21555-2007 in which the speed measurement error rate should be less than 6%. The proposed system can efficiently enhance the vehicle speed measurement accuracy and effectively improve the vehicle speed measurement robustness. 相似文献
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Masashi Ban 《International Journal of Theoretical Physics》1997,36(12):2583-2638
State change, quantum probability, and information gain in the operational phasespace measurement are formulated by means
of positive operator-valued measure (POVM) and operation. The properties of the operational POVM and its marginal POVM which
yield the quantum probability distributions of the measurement outcomes obtained by the operational phase-space measurement
are investigated. The Naimark extension of the operational POVM can be expressed in terms of the relative-position states
and the relative-momentum states in the extended Hilbert space. An observable quantity measured in the operational phase-space
measurement becomes a fuzzy or unsharp observable. The state change of a physical system caused by the operational phase-space
measurement is described by the operation which is obtained explicitly for the position and momentum measurements and for
the simultaneous measurement of position and momentum. Using the results, the entropy change of the measured physical system
and the information gain in the operational phase-space measurement are investigated. It is found that the average value of
the entropy change is equal to the Shannon mutual information extracted from the outcomes exhibited by the measurement apparatus. 相似文献
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大尺度三维几何尺寸立体视觉测量系统实现 总被引:15,自引:2,他引:15
基于立体视觉的大尺度三维几何尺寸测量技术是对外形不规则的大型物体进行几何量测量的有效方法。与传统的视觉测量技术不同,大尺度视觉测量的精度随测量距离的增加而迅速下降,同时大尺度空间下照明条件难以控制,也使得测量变得不稳定。因此如何在大测量尺度的前提下提高测量精度成为这一领域的研究难点。从立体视觉测量系统的原理出发,分析了影响系统精度的各种因素,将相位一致性变换与极线约束条件引入结构光光条中心提取之中,显著提高了图像分析的精度。研制了测量系统的样机并给出了实验结果,现场测试表明该系统可以有效地保证大尺度条件下的测量精度。 相似文献
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Yan Li Shangchun Fan Zhanshe Guo Jing Li Le Cao 《Journal of sound and vibration》2012,331(20):4417-4424
In this paper, frequency measurement methods of resonant vibratory gyroscopes are studied. First, the working principle and dynamic output characteristics of the resonant vibratory gyroscope are introduced, which provide a theoretical analysis base to analyze the dynamic frequency output characteristic of the resonant vibratory gyroscope. Moreover, some relevant frequency measurement methods are introduced, a frequency measurement method based on dynamic output characteristics has been proposed for the purpose of investigating the modulated output signal of resonant vibratory gyroscopes. Finally, in order to verify the feasibility of the proposed frequency measurement method, resonator oscillator and dynamic frequency measurement experiments of the resonant vibratory gyroscopes are built. It is concluded from the resonator oscillator result that the designed and observed resonant frequency of the resonator have a good match, which shows the design of resonator oscillator is feasible. It is concluded from the dynamic frequency measurement result that correlation coefficient of output fitted curve is 99.95%, and the output characteristic of the gyroscope is linear frequency output, which shows the effectiveness of the proposed frequency measurement method. 相似文献
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We present the first experimental demonstration of the maximum confidence measurement strategy for quantum state discrimination. Applying this strategy to an arbitrary set of states assigns to each input state a measurement outcome which, when realized, gives the highest possible confidence that the state was indeed present. The theoretically optimal measurement for discriminating between three equiprobable symmetric qubit states is implemented in a polarization-based free-space interferometer. The maximum confidence in the measurement result is 2/3. This is the first explicit demonstration that an improvement in the confidence over the optimal minimum error measurement is possible for linearly dependent states. 相似文献
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全光纤速度测量仪的研究 总被引:6,自引:0,他引:6
本文提出一种由单膜光纤及其无源器件构成的全光纤速度测量仪。在具体分析该测量仪的工作原理基础上研制了一套实用的速度测量系统,并且将该干涉仪与传统的迈克尔逊速度干涉仪进行了比较。将其应用于喇叭的振动测量中,获得了稳定的、可重复的实验曲线。 相似文献
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介绍了地基测量空间目标光度的两种方式。首先介绍了系统组成及对比测量原理,然后基于工程角度分析提出了宽谱段测量和滤光片测量两种方式,并给出了两种测量方式的误差分析。若G型恒星及空间目标在同一视场可选择宽谱段测量方式,若途经天区G型定标星较少,可以选择滤光片测量方式。外场实验验证表明,宽谱段测量方式信噪比较高,可探测的极限星等为16等星,在天气条件较好的情况下测量精度在0.15星等左右,而滤光片测量方式由于探测到的能量较少,在相同信噪比下可探测极限星等为14等星,天气变化较小条件下测量精度在0.02星等左右,两种测量方式误差相当,但宽谱段测量方式定标恒星数量增加2.4倍,便于数据处理与计算。 相似文献
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In-process measurement has been the requirement of the precision industries, but due to vibrations while manufacturing, in-process measurement has been difficult to achieve. There is little work on in-process measurement using phase shifting interferometry, as phase shifting is extremely sensitive to vibrations. In this work, the advantage of the developed non-mechanical and instantaneous phase shifting interferometry is felt while measuring surface profile of large flat surfaces under vibrating conditions which can be extended for in-process measurement of surface profile. A near common path optical configuration is achieved and the effect of the environment is reduced. Moreover, the measurement of phase is instantaneous which increases the versatility of this technique for measuring vibrating objects. Profile measurements were carried out on a smooth mirror surface excited with vibrations of different frequencies and the technique was found to be immune to vibrations of up to 1000 Hz. 相似文献
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Yutian Wang Longjiang Zheng Peiguo Hou Chunhai Hu 《Optics and Lasers in Engineering》2005,43(10):1145-1150
In this paper an electro-optic current transformer (CT) is designed which is used for measuring the super-high-voltage station's line current. The measurement system utilizes a conventional CT as the sensing probe whose electronics is optically powered. The paper describes the principle of measurement system, including the system design, optically powered sensing probe, the data link measurement signal processing and results showing current measurement by means of CT. 相似文献