与方波合成有关的李萨如图形的实验与理论研究

通过方波与方波、正弦波与方波合成的图形来研究李萨如图形,利用傅里叶级数理论把方波展开为正弦和余弦形式的傅里叶级数,然后利用Matlab软件来合成2列相互垂直的方波与正弦波以及2列方波的李萨如图形,并与实验上观察到的现象进行比较,并分析了两者之间的差异.     

基于基频混频的相位生成载波解调方法研究与改进

对基频混频相位生成载波解调方法的局限性进行了研究与改进.在该方法的基础上,通过引入直流滤波器,滤除了直流成分的影响,使得改进后的算法克服了基频混频相位生成载波解调方法只适用于小信号的局限性;通过引入抗混叠滤波器,保留了有用频谱成分,进一步降低了采样频率.在采样频率一定时,最大限度地提高了系统可解调的动态范围上限,给出了实现改进后算法的硬件实现方案,并用Matlab及数字信号处理器软件开发代码调试器分别进行了仿真验证,证明了这种改进解调方案的可行性.     

Dynamical evolution of Lissajous singularities in free-space propagation

The dynamic evolution of Lissajous singularities in free-space propagation is studied. It is shown that the pair creation and annihilation, handedness reversal and change in the degree of polarization of Lissajous singularities, as well as the rotation and change in the shape of Lissajous figures may appear upon propagation.     

Long distance real-time measurement of multi-points micro-vibration in region by digital holography

Many applications require micro-vibration measurement, especially multi-points detection at long distance in real-time. In this paper, a micro-vibration measurement approach based on digital holographic interferometry is proposed for middle-low frequency detection. It can be used to monitor irregular frequency/amplitude vibration in selected region over 10 m away simultaneously and synchronously. A series of experiments were conducted including real-time measurement of 300 Hz, 1 kHz, 2 kHz and 3 kHz constant frequency/amplitude periodic vibration, precision and frequency response tests with calibration of LDV, 1 kHz irregular amplitude vibration, irregular frequency/amplitude vibration as well as the real-time measurement and simultaneous display of multi-points vibration. The experimental results demonstrate the feasibility of the proposed method and reveal its unique advantages.     

干涉型光纤传感器相位生成载波技术研究与改进

对干涉型光纤传感器的相位生成载波解调技术进行了研究.对PGC算法进行了数学推导和仿真计算,对数字低通滤波器进行了详细分析,给出了其影响PGC解调性能的原因及数字滤波器的设计方法.讨论了传感器干涉光强对PGC算法输出结果的影响,提出了改进的PGC算法,该算法可以有效的实现自动增益控制,消除干涉光强漂移对解调的影响,并大大减小由干涉光强引入的系统噪音;还可以在有限阶数低通滤波器的情况下,极大的增加系统可解调的大信号幅度,提高系统动态范围12 dB以上.     

基于迈克尔逊干涉的光纤弯曲传感器

设计并研制了一种新型的基于迈克尔逊干涉的光纤弯曲传感器.该光纤弯曲传感器由两根光纤组成的光纤带固定于弹性弯曲结构上来产生迈克尔逊干涉信号,用光纤折射率匹配液填充微型腔,并施加音频振荡信号对相位干涉信号实现低频调制.采用相位生成载波技术对相位干涉信号进行调制和解调,实现了对曲率变化高精确度的检测.实验测试了该光纤弯曲传感器的相位干涉信号与光纤带弯曲曲率的关系,并与理论分析对比.结果表明该光纤弯曲传感器具有43.96 rad/m－1的灵敏度及0.004 m－1的高分辨率.     

数字化相位载波解调方案在光纤水听器系统中的实现

本文分析了干涉型光纤水听器内调制相位载波(PGC)调制解调的原理，提出了PGC调制解调的全数字化方案，通过计算机仿真，并在光纤水听器系统中实现了PGC的数字化解调。实验室光纤水听器与标准水听器对比测试以及实际海况试验都证明，数字化PGC解调技术在光纤水听器系统的实现对水声信号的检测是有效的。     

剖析一道经典光学例题的疏忽

在现行光学教材中有一道关于迈克耳孙干涉仪的应用例题,由于忽略了一个极微小的细节,使得计算结果出现了偏差．本文对此问题进行了详细的分析．     

迈克尔逊干涉仪反射镜的调节

本文指出了目前迈克尔逊干涉仪的调节方法只能实现两反射镜相互垂直,但无法确定可移动反射镜与其移动方向垂直的问题。通过研究,我们给出了一种实现两反射镜相互垂直且可移动反射镜与其移动方向垂直的调节方法。     

Research of the polarity characteristic for an optical fiber accelerometer demodulated by phase generated carrier technology

For an accelerometer, it is necessary to distinguish the plus/minus axis rightly before use. Demodulated by phase generated carrier (PGC) technology, a definition of the polarity characteristic for a double-arms optical fiber accelerometer is proposed. It was found that, when the selected modulation depth C > 0, the demodulated result by PGC technology is equal to the optical phase shift in the long arm subtracting the one in the short arm, while opposite result would be obtained when C < 0. Then, a simple model is presented to discuss relations between the output of the accelerometer and relative positions of the two arms and the sound source. We demonstrate that, when C > 0, the response of the accelerometer is coincident with the signal when the long arm is placed pointing to the source, while opposite once the relative positions of the two arms were exchanged. On this condition, the long arm is defined as the plus axis and the short arm to be the minus axis. However, when C < 0, the polarity definition should be opposite. Based on this polarity definition, a combination method is offered to fabricate a three-dimensional optical fiber vector hydrophone (OFVH). Finally, these conclusions are proved by experiments.     

Large Signal Analysis of the Michelson Interferometer with Gires-Tournois Interferometers in its Arms

A mathematical model for the transfer function of the Michelson interferometer with Gires-Tournois interferometers in its arms is presented. The model, basically a sine-series function, can easily yield closed-form expressions for the amplitudes of the harmonic and intermodulation components of the output when the input is formed of large-amplitude multisinusoidal voltage. The special case of two-tone equal-amplitude input voltage is considered in detail. The results show that the third-order intermodulation component is always higher than the third-harmonic component. The results also show that the linearity of the Michelson interferometer with Gires-Tournois interferometers in its arms improves with the increase of the front mirror reflectivity. Moreover, the results show that the third-order intermodulation exhibits a minimum for relatively large values of the front mirror reflectivity. Furthermore, compared with the traditional Mach-Zehnder interferometer, the results show that a reduction of 15 dB in the third-order intermodulation can be achieved even for relatively small values of the front mirror reflectivity.     

Design of a Michelson interferometer for the measurement of electrostrictive strains

In the field of quadratic electrostriction of non-ferroelectric materials, efforts to optimize interferometers for the accurate measurement of small strains are being undertaken because the displacements that have to be measured are very small (10⁻¹³m). Here, a design for a Michelson interferometer is proposed that combines a double-face detection scheme with a null method.     

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介绍了一种新的相位比较技术——傅里叶变换法，并将其成功地应用到了HL-2A装置激光干涉测量等离子体电子密度的计算中。通过对大量实验数据的脱机计算后，将其结果与硬件比较方法、传统软件计算方法的结果进行了对比，证实了傅里叶变换相位比较技术的正确性和可靠性；它不仅能够真实地反映电子密度变化行为，还能一定程度上改善密度曲线起始时刻不归零和跳变行为，但不能够实时计算电子密度是该方法存在的不足。     

压电陶瓷压电系数测量的一种实验改进方法

针对压电陶瓷的压电系数实验测量中仪器调节的困难,通过放置一个三面箱体辅助仪器来改善对光路的调节,同时在给压电陶瓷施加电压的电路中接入电压报警器,有效控制施加在压电陶瓷上的电压大小,以此避免压电陶瓷的疲劳受损乃至被烧坏。     

迈克尔逊干涉仪实验中最佳间隔条纹个数的探讨

用迈克尔逊干涉仪可以测量激光的波长,读取的干涉条纹个数较多时容易引起学生视力的疲劳。因此,本文测量了多组不同的间隔条纹个数时氦氖激光的波长,进而确定它们与波长理论值之间的误差大小,通过比较不同间隔条纹个数时百分差和相对不确定度的大小,最终确定最佳的间隔条纹个数。     

干涉法测量半导体激光频率漂移实验

半导体激光在外调制时将产生频率漂移，将这种调制激光引入Michelson干涉仪，从强度调制和频率调制双重假设出发导出光强干涉方程，通过测量干涉项的相位噪声确定频率漂移值并对实验结果与过程作探讨.     

干涉型光纤传感阵列的电光调制消偏振衰落技术

提出了一种新型的干涉型光纤传感器阵列的消偏振衰落技术。在时分复用系统中,在全保偏传感基元的基础上,使用单模光纤做传输光纤搭建系统,通过对输入偏振态进行高频调制,能够在光强有所下降的情况下较好地解决了系统的偏振衰落问题。理论分析证明,当EOM相位调制的初相位设置为π/4,采样率和相位调制频率设置恰当时,通过PGC内调制解调技术可实现消偏振衰落。在理论分析的基础上进行了MATLAB软件模拟,解调出来的信号与原始信号基本重合。     

电子散斑干涉载频调制形貌测量方法的分析

根据电子散斑干涉载频调制测量物体形貌的基本原理,物体表面的微小偏转可引入包含物体高度信息的载波干涉条纹。将物体的偏转视为变形,对物体变形与载波干涉条纹之间的关系进行了讨论,得出了离面位移引入载波和面内位移引入含有物体高度信息相位的结论。发现利用典型电子散斑干涉系统测量物体形貌效果最好,并通过实验得到了验证。     

The new circular heterodyne interferometer with electro-optic modulation for measurement of the optical linear birefringence

We present a new circular heterodyne interferometer with electro-optic modulation for measurement of the optical linear birefringence. It enables the measurement of not only the phase retardation but also the principal angle. The measurement procedure is carried out in two steps. In the first step of measurements, we use the electro-optic modulated circular heterodyne interferometer and the phase-lock technique to precisely measure the principal axis angle. After rotating the analyzer in the setup, the phase retardation is determined also by the phase-lock technique. The compact configuration requires only a photodetector and two simple phase-lock extractions to determine the principal axis angle and the phase retardation. The validity of the proposed design is demonstrated by measurement of the principal axis angle and phase retardation of a quarter-wave plate sample. The root-mean-square resolutions for the principal axis angle and phase retardation are found to be 0.0396° and 0.0796°, respectively, with corresponding dynamic ranges of 0–180° and 0–180°.     

迈克耳逊干涉仪的调节技巧及常见问题解析

迈克耳逊干涉仪测量光波波长是大学基础物理实验之一。由于该实验操作的复杂性,导致学生完成此实验很容易出现一些问题。根据实际情况列举一些调试技巧,并对经常出现的问题进行了分析与解决。