波片对偏振激光干涉仪非线性误差的影响

利用琼斯矩阵理论,研究了基于偏振移相技术的激光干涉仪中1/4波片和1/2波片的非理想因素导致非线性误差的产生机理和变化规律.理论研究表明:在导致波片处于非理想状态的各个因素中,干涉仪中两个1/4波片的差模延迟角误差Δεq所产生的恒定偏置误差和接收装置中1/4波片的延迟角误差εq3所引起的一次谐波非线性误差,是组成干涉仪非线性误差的最主要的两个部分;波片各种误差源非理想因素导致的非线性误差在小误差情况下经线性叠加后由干涉仪最终输出.     

Measurement of in-plane motions and rotations using a simple electronic speckle pattern interferometer

We describe the construction and operation of a simple electronic speckle pattern interferometer which is sensitive to in-plane motions and rotations. The interferometer is extremely simple and easy to use. It uses a commercial digital still camera for image acquisition, and a personal computer for image storage and analysis. The interferometer was used to measure very small in-plane rotations of a rough surface, and the results were found to be in good agreement with the expected values. We propose to use this system as an instrument for the measurement of small-angle rotations.     

On possibility of using the lowest odd harmonics of the phase modulation frequency in the output signal of the fiber-optic ring interferometer for detection of the sagnac effect

The possibility of using the lowest harmonics of the phase modulation frequency in the output signal of the fiber-optic ring interferometer (FRI) for detection of the FRI rotation angular velocity is considered. It is shown that the use of the third harmonic of the phase modulation frequency is optimal, since, in this case, the effect of insignificant admixture of the second harmonic of the phase modulation frequency on the FRI baseline shift can be completely eliminated. When processing the signal using the first or the fifth harmonic of the phase modulation frequency, it is possible to compensate for the FRI baseline shift because of its weak dependence on the phase modulation amplitude. Upon processing of the FRI output signal using higher odd harmonics of the phase modulation frequency, the signal-to-noise ratio noticeably decreases.     

First step toward a benchtop model of the Laser Interferometer Space Antenna

A technique for simulating large optical path lengths by use of digital delay buffers is presented. This technique is used to generate a synthetic interferometer with one arm having an arbitrary length. The response of the interferometer to phase and frequency modulation is measured and found to be in agreement with predictions. This technique could be used to simulate long-baseline interferometric space missions such as the Laser Interferometer Space Antenna.     

马赫曾德尔单频干涉仪非线性误差分析

 研究了马赫曾德尔单频干涉仪对可调谐激光器进行频率监测时非理想1/4波片和偏振分光镜引入的非线性误差。借助琼斯矩阵对干涉仪建模,理论推导了系统误差公式。理论分析和数值仿真发现：系统的非线性误差为一次谐波误差和二次谐波误差的线性叠加;系统中2个偏振分光镜倾斜角度的非对称主要导致一次谐波误差;波片倾斜角度误差、偏振分光镜倾斜角度误差以及波片相位延迟误差主要导致二次谐波误差,总二次谐波误差近似表现为此3类误差源独立产生的误差的线性叠加;当偏振分光镜消偏比较大时,其产生的误差可忽略。     

Harmonic and Intermodulation Performance of Sagnac Fiber-Optic Interferometer

Abstract

In this article, closed-form expressions are obtained for the amplitudes of the harmonic and intermodulation products generated when driving the fiber-optic Sagnac interferometer by a DC bias voltage plus an equal-amplitude two-tone signal. The results clearly show the strong dependence of the harmonic and intermodulation performance on the DC bias voltage and/or the phase bias of the fiber-optic Sagnac interferometer. The results obtained suggest that the DC bias voltage and/or the phase bias play an important role in deciding the linearity of the fiber-optic Sagnac interferometer and, hence, its suitability for analog applications.     

The theory of nonlinear dispersion interferometers in the constant intensity approximation

The operation of a dispersion interferometer with intracavity location of a medium under study is analyzed in the constant intensity approximation taking into account the reciprocal influence of a harmonic on the phase of the exciting wave. This approximation allows the effects of phase mismatch and losses in a medium on the course of a nonlinear process to be taken into account simultaneously. Intensity minima of the harmonic (as opposed to the constant field approximation) in the constant intensity approximation are shown to depend on dispersion of the refractive index of the medium under study, which makes it possible to determine dispersion of the refractive index of the substance under study directly and accurately     

Modeling of the fringe shift in multiple beam interference for glass fibers

A quadratic model is suggested to describe the fringe shift occurred due to the phase variations of uncladded glass fiber introduced between the two plates of the liquid wedge interferometer. The fringe shift of the phase object is represented in the harmonic term which appears in the denominator of the Airy distribution formula of Fabry-Perot’s interferometer. A computer program is written to plot the computed fringe shifts of the described model. An experiment is conducted using liquid wedge interferometer where the fiber of a nearly quadratic thickness variation is introduced between the two plates of the interferometer. The obtained fringe shift shows a good agreement with the proposed quadratic model. Also, it is compared with the previous theoretical shift based on ray optics of semi-circular shape.      

Step index fibre using laser interferometer

A model is suggested to describe the fringe shift which occurs due to the phase variations of cladded glass fibre introduced between the two plates of the liquid wedge interferometer illuminated with a He–Ne laser. The fringe shift of the phase object which appears in the denominator of the Airy distribution formula of the multiple beam interference is represented in the harmonic term. An experiment is conducted using liquid wedge interferometer where the step index glass fibre of a nearly quadratic thickness variation is introduced between the two plates of the interferometer. The obtained fringe shift shows a good agreement with the proposed quadratic model. The Matlab code is written to plot the interferometer fringes comprising the shift of the step index fibre. Secondly, recognition of elliptical fibres is outlined using tomographic imaging. Finally, results and concluding remarks are given.     

Etude d'impulsions lumineuses breves par interferometrie a deux ondes

We have studied the evolution of the light transmitted through matter in which an optical breakdown is taking place. With a two-waves interferometer made a birefringent plate between polarizers we get informations about the time correlation function of the fields. With an interferometer made of two identical harmonic generating plates separated by a dispersion medium, we learn about the correlation function of the square of the fields. Both systems act as spectral filters with a notch cosine-shaped centered at the incident frequency. We have also observed a transient angular spreading of the beam not previously emphasized which brings a further complication in the picture.     

Zygo interferometer for measuring refractive index of liquids and its application for heavy water analysis

The Zygo interferometer for measuring refractive index of liquids such as heavy water is presented. The accuracy of measurement in the refractive index of liquids is found to be ±0.0002 in the Zygo interferometer. An application of Zygo interferometer for heavy water analysis is also presented. The interferometer is found to be useful for determining the percentage purity of heavy water with an accuracy of ±5% in the purity range of 0–100%.     

Characterization of high-order harmonic radiation on femtosecond and attosecond time scales

We characterize the temporal structure of high-order harmonic radiation on both the femtosecond and attosecond time scales. The harmonic emission is characterized by mixed-color two-photon ionization with an infrared femtosecond laser using a Mach–Zehnder interferometer where both pump and probe arms travel completely separate paths. In a first experiment, we measure the duration and chirp of individual harmonics. In a second experiment, we resolve, for the first time with this type of setup, the attosecond beating of several harmonics generated under conditions similar to the first experiment. We suggest that the results of both measurements can be combined to determine the full attosecond time structure of the harmonic emission. PACS 32.80.Rm; 42.65.Ky     

Experimental test of the nonlinearity of the characteristics of the piezoelectric transducer of the phase modulator of a fiber ring interferometer at small sinusoidal deformations

We show that the level of the second harmonic of sinusoidal modulation resulting from the non-linearity of the characteristics of piezoelectric transducer does not exceed0.005–0.0005% for deformations ranging from10−8 to10−6. The influence of the nonlinearity of the characteristics of a piezoelectric transducer used as a modulator of the optical length of the loop of a fiber ring interferometer on the accuracy parameters of the latter is analyzed. It is shown that the given level of the second harmonic does not lead to a significant shift of the zero of the interference of counterpropagating waves at the interferometer output. Institute of Applied Physics, Russian Academy of Sciences; Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 2, pp. 198–200, February 1999.     

A displacement measurement system, utilizing a Wollaston interferometer

A dual interferometric displacement measurement system is presented where a Wollaston prism interferometer is employed in conjunction with a normal Michelson interferometer. The system operates without the use of external polarizers, apart from those associated with the Wollaston prism interferometer itself. It is shown that an optical path difference induced in the Michelson interferometer can be detected using the Wollaston prism in a normal interferometer arrangement. Further, the interference pattern produced by the Wollaston prism interferometer changes in a measurable, linear fashion as the optical path difference from the Michelson interferometer alters. A simple theoretical analysis of the system is presented and used to derive a computer model of the optical arrangement. Results from an experimental implementation of the system, using a Wollaston prism with a beam separation of 0.5 degrees and a superluminescent diode, of wavelength 825 nm, as a light source, are included and compared to the results from the computer model.     

基于合成波长法的飞秒激光外差干涉测距方法

本文提出了一种基于合成波长法的飞秒激光外差干涉测距方法.系统采用两个带通滤波器产生两个具有一定波长差的单波长,用于产生合成波长.本方法结构简单,能量利用率高.与双频激光干涉仪在40 mm范围内的比对结果表明,该方法比对残差的标准差为91 nm.     

Suppression of dephasing due to a trapping potential and atom-atom interactions in a trapped-condensate interferometer

We propose and demonstrate a novel trapped-condensate interferometer using optical Bragg diffractions in a harmonic magnetic potential, which can realize a long coherence time with low dephasing. Dephasing of wave packets due to the magnetic potential is canceled by setting the interrogation time equal to the oscillation period of the harmonic potential. The harmonic potential also helps to suppress dephasing due to condensate atom-atom interactions. An interference signal with a fringe contrast of 30% is observed at an interrogation time of 58 ms. For a longer interrogation time about 100 ms, the spatial coherence of the condensate is still maintained with low dephasing, although the interference fringe is washed out by external vibrational noise.     

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.     

Frequency measurement of a submillimeter wave gyrotron output

Measurement of frequency spectra of the output of a gyrotron in the millimeter to submillimeter wavelength range using a Michelson interferometer have been made. The results are compared with frequency measurements using a Fabry-Perot interferometer. A correction for mesh transmittance is used to give the true frequency spectrum. The method is used to search for the presence of higher cyclotron harmonics (n=f /f _c=3,4,…) which may be generated along with the more intense fundamentals (n=1) or second harmonics (n=2), and to study mode competition between the fundamental and the second harmonic modes.     

HL-2M 装置 CO2 色散干涉仪研制

研制了一套新型 CO₂ 激光色散干涉仪用于 HL-2M 装置初始放电期间的电子密度测量。该系统采用 基于激光倍频的色散测量原理,能够消除机械振动产生的相位误差。该系统使用全新的调相式信号调制,研发了 相应的数据采集/处理/上传系统。根据实验测量结果表明,CO₂ 激光色散干涉仪和微波干涉仪测量曲线基本一致, 色散干涉仪系统的测量精度约为 2×10¹⁷m⁻³,密度测量上限能达到 10²¹m⁻³。     

光纤连接器端面几何参量自动测量仪

报道了一种高精度测量光纤连接器端面几何参量的自动测量仪。叙述了光纤连接器的端面几何参量的测量原理。由光纤连接器端面形貌和纤芯中心坐标,可以高精度得到曲率半径、顶点偏移量、端面倾斜角和光纤高度等影响连接器性能的关键端面几何参量。该仪器体积小,自动化程度高,用户界面友好,使用方便,可测量物理接触、角度式物理接触等类型的光纤连接器端面几何参量。实际测量证明,该测量仪有很好的重复测量精度。该测量仪与美国Dorc公司ZX-1 mini PMS测量仪和Norland公司NC3000测量仪相比,测量精度水平相当。该仪器样机已通过华东国家计量测试中心的测试。