Fourier Spectrometer based on Wide-range and Phase-locked Michelson Interferometer with Femtosecond Laser Excitation

A wide-range and phase-locked Michelson interferometer technique is described. This technique combined with femtosecond laser is used to measure the spectrum of the rare-earth ion Nd：YVO4, which presents very high signal to noise ratio of interferometric intensity output and higher spectral resolution than traditional grating spectrophotometer.

Experimental research on the feature of an x-ray Talbot–Lau interferometer versus tube accelerating voltage

X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.

Phase-Sensitive Optical Time-Domain Reflectometer Based on a 120°-Phase-Difference Michelson Interferometer

A phase-sensitive optical time domain reflectometer （φ-OTDR） based on a 120°-phase-difference Michelson in- terferometer is proposed. The Michelson interferometer with arm difference of 4m is used to test the phase difference between the Rayleigh scattering from two sections of the fiber. A new demodulation method called the inverse transmission matrix demodulation scheme is utilized to demodulate the distributed phase from the backward scattering along the long fiber, The experimental results show that the 120°-phase-difference inter- ferometer φ-OTDR can detect the phase along the 3km fiber, and the acoustic signal within the whole human hearing range of 20 Hz-20 kHz is reproduced accurately and quickly.

LIGO Experiments Cannot Detect Gravitational Waves by Using Laser Michelson Interferometers—Light’s Wavelength and Speed Change Simultaneously When Gravitational Waves Exist Which Make the Detections of Gravitational Waves Impossible for LIGO Experiments

It is proved strictly based on general relativity that two important factors are neglected in LIGO experiments by using Michelson interferometers so that fatal mistakes were caused. One is that the gravitational wave changes the wavelength of light. Another is that light’s speed is not a constant when gravitational waves exist. According to general relativity, gravitational wave affects spatial distance, so it also affects the wavelength of light synchronously. By considering this fact, the phase differences of lasers were invariable when gravitational waves passed through Michelson interferometers. In addition, when gravitational waves exist, the spatial part of metric changes but the time part of metric is unchanged. In this way, light’s speed is not a constant. When the calculation method of time difference is used in LIGO experiments, the phase shift of interference fringes is still zero. So the design principle of LIGO experiment is wrong. It was impossible for LIGO to detect gravitational wave by using Michelson interferometers. Because light’s speed is not a constant, the signals of LIGO experiments become mismatching. It means that these signals are noises actually, caused by occasional reasons, no gravitational waves are detected really. In fact, in the history of physics, Michelson and Morley tried to find the absolute motion of the earth by using Michelson interferometers but failed at last. The basic principle of LIGO experiment is the same as that of Michelson-Morley experiment in which the phases of lights were invariable. Only zero result can be obtained, so LIGO experiments are destined failed to find gravitational waves.

Photoacoustic Detection in the Michelson Interferometer Cavity

For the first time, we report photoacoustic (PA) signal detection in a cell placed within the Michelson interferometer cavity in an attempt to relate photoacoustic effect to the Michelson fringe shift as a result of changes in the cell. Both detection schemes were investigated using IR absorption and their sensitivities compared. Signals related to Michelson interferometer fringe and PA effect have shown good correlations with each other using different samples including some essential oils and their corresponding plant part from which the essential oil is usually obtained. Results were encouraging and will open the door widely to use the combined Michelson interferometer-photoacoustic spectroscopy (PAS) in trace gas detection for different applications.

Optical Fiber Bragg Grating Michelson Interferometer

A new Michelson interferometer based on fiber Bragg grating（FBG） is demonstrated. FBCs are used as reflectors, and the laser is replaced by a broadband source as input light in this interferometer. To demodulate the signals, a 3 × 3 coupler is used as a splitter. By combining with software demodulation, the outer interference can be obtained from the outputs of the interferometer. This kind of interferometer can also be wavelength-multiplexed easily by composing a series Michelson interferometer. The experiment results show that the clear interference fringe can be obtained by adjusting the path difference to make it less than interference length of FBG. The signals are also demodulated.

Polarization Beam Splitter Based on a Self-Collimation Michelson Interferometer in a Silicon Photonic Crystal

A polarization beam splitter based on a self-collimation Michelson interferometer (SMI) in a hole-type silicon photonic crystal is proposed and numerically demonstrated.Utilizing the polarization dependence of the transmission spectra of the SMI and polarization peak matching method,the SMI can work as a polarization beam splitter (PBS) by selecting an appropriate path length difference in the structure.Based on its novel polarization beam splitting mechanics,the polarization extinction ratios (PERs) for TM and TE modes are as high as 18.4 dB and 24.3 dB,respectively.Since its dimensions are only several operating wavelengths,the PBS may have practical applications in photonic integrated circuits.

Present Status of EUV Interferometer Development at the Research Center for Soft X-ray Microscopy

A new interferometer for extreme ultraviolet (EUV) radiation with a laser produced plasma (LPP) laboratory source is under construction. The LPP source is operated with a Sn solid rod target on which pulsed YAG laser is focused to produce high temperature plasma emitting EUV radiation. The source is equipped with a newly designed debris stopper protecting a condenser multilayer mirror from the particle debris of the target. The condenser mirror focuses the light onto an EUV beam-splitter to form transmitted and reflected paths for producing interference fringes of a sharing type. The optical configuration is of a common path based on a triangular path type with a focusing at the beam-splitter, which is enabled to produce fringes by a low coherence radiation with a standard optical quality beam-splitter. The fringes are recorded by an imaging plate with pixels as small as 25μm. The dynamic range of linearity in detection of the EUV light was found to be more than 10 4 with sensitivity of 10 4 photons/pixel, enough for the purpose of interferogram recording, possibly with one laser shot.

X-ray phase-sensitive microscope imaging with a grating interferometer:Theory and simulation

A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer,which simultaneously enables the high spatial resolution imaging and the improved image contrast.By using this theory,several key parameters of phase contrast imaging can be predicted,for instance,the fringe visibility and period,and the conversion condition from the differential phase imaging(DPI)to the phase difference imaging(PDI).Additionally,numerical simulations are performed with certain x-ray optical components and imaging geometry.Comparison with the available experimental measurement[Appl.Phys.Lett.113063105(2018)]demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.

Reviewing Michelson Interferometer Experiment and Measuring the Speed of Starlight

The wave-aether model was proposed long time ago. We study Michelson interferometer experiment and find that its theoretical calculation erroneously neglected the aether drag effect. We take the drag effect into account and reanalyze the theoretical interference pattern shift. The result is null because the drag coefficient of aether is zero. Such that the wave-aether model fulfills all light propagation characteristics. We design and implement a system to measure the starlight speed by comparing to that from a local source. We observe that the arrival times are different. It implies the apparent speeds of starlights are not equal to c.

The Light Timing Calculations of the Interferometer in the Quest to Detect Light Speed Anisotropy and a Case Study of the Michelson-Morley and Miller Mt Wilson Experiments

This paper formulates the light timing calculations for each interferometer arm;one that is parallel to the direction of motion of the interferometer through space and the other that is perpendicular. The calculations are done for a vacuum-mode interferometer and then for a gas-mode interferometer. The calculations show that no light timing difference is detectable in a vacuum-mode interferometer, but once an optical medium is present in the light path down the arms of the interferometer, this is no longer the case and a timing difference is detectable. Further to this, the timing equations obtained from the analysis are used to model the historical experiments of Michelson-Morley and Miller (Mt Wilson) and predictions are made by the model that accurately match the actual recorded results from those experiments. Thus, this timing analysis confirms that there is a light speed anisotropy in a reference frame that is moving through space, indicating the presence of a preferred Aether reference frame through which the Earth is moving.

Quantitative coherence analysis of dual phase grating x-ray interferometry with source grating

Dual phase grating x-ray interferometry is compatible with common imaging detectors,and abandons the use of an absorption analyzer grating to reduce the radiation dose.When using x-ray tubes,an absorbing source grating must be introduced into the dual phase grating interferometer.In order to attain a high fringe visibility,in this work we conduct a quantitative coherence analysis of dual phase grating interferometry to find how the source grating affects the fringe visibility.Theoretical analysis shows that with the generalized Lau condition satisfied,the fringe visibility is influenced by the duty cycle of the source grating and the transmission through the grating bar.And the influence of the source grating profile on the fringe visibility is independent of the phase grating type.Numerical results illustrate that the maximum achievable fringe visibility decreases significantly with increasing transmission in the grating bar.Under a given transmission,one can always find an optimal duty cycle to maximize the fringe visibility.These results can be used as general guidelines for designing and optimizing dual phase grating x-ray interferometers for potential applications.

Strain measurement using frequency modulation fiber optic interferometer

The method for measuring the strain of an object using an optical fiber and a frequency modulation(FM) coupled cavity semiconductor laser is proposed.This method uses the coherent FM heterodyne principle of the Michelson interferometer and can avoid the π/2 nonreciprocal phase bias and phase shifting problem existing in general fiber optic interferential sensors, the maximum detection range is limited by the coherent length of the semiconductor laser and its relative factor.

Classifying Vibration Modes Generated by The Michelson Interferometer Using Machine Learning Methods

In this paper, we explore the classification of vibration modes generated by handwriting on an optical desk using deep learning architectures. Three deep learning models—Long Short-Term Memory (LSTM) networks with attention mechanism, Video Vision Transformer (ViViT), and Long-term Recurrent Convolutional Network (LRCN)—were evaluated to determine the most effective method for analyzing time series patterns generated by a Michelson interferometer. The interferometer was used to detect vibration modes created by handwriting, capturing time-series data from the diffraction patterns. Among these models, the LSTM-Attention network achieved the highest validation accuracy, reaching up to 92%, outperforming both ViViT and LRCN. These findings highlight the potential of deep learning in material science for detecting and classifying vibration patterns. The powerful performance of the LSTM-Attention model suggests that it could be applied to similar classification tasks in related fields.

Michelson干涉仪式光纤空气声传感器

介绍了一种用于直升机等低空目标探测的光纤空气声传感器.该传感器基于光纤Michelson干涉仪的原理,结合弹性盘片的应力应变理论分析和光纤粘接的工艺设计,采用相位载波解调技术进行信号解调.对比实验测试验证了这种声音探测技术可行性.传感器理论灵敏度为2.38rad/Pa,实测灵敏度为1.5rad/Pa,采用PGC相位解调理论最小可探测的最小声信号为6.7μPa,即9.5dB.传感器在20～300Hz范围内响应基本平坦.结合声音传播规律分析并肯定其在实用中的可行性.

基于Michelson干涉仪的光纤分布式扰动传感器(英文)

提出并研究了基于Michelson干涉仪的应用于检测时变扰动的光纤分布式传感器。所提出的光纤传感器由两个Michelson干涉仪和一个光纤延迟环组成。扰动作用在传感光纤上,引起传输光波相位的调制作用,可以通过该传感器进行检测并得到扰动的位置信息。通过光电探测器对干涉信号进行接收。对接收到的信号进行隔直,并通过求取峰峰值的方法对隔直后的信号进行预处理。通过希尔伯特变换、相位去包裹和三角函数运算可以提取出预处理信号中包含的相位信息。最后,通过频谱分析和相应的数学运算可以实现扰动的定位。在20 km的监测距离内通过实验验证了传感器的可行性。所提出的光纤传感器具有实时性好、抗偏振性、低成本的独特优势。

光纤Michelson干涉仪干涉条纹对比度的研究

通过实验测定了光纤Michelson干涉仪输出的干涉信号,并由此计算了干涉条纹对比度。从条纹对比度的拟合曲线出发,分析了可能影响光纤干涉仪干涉信号对比度的主要因素,为实验中条纹对比度的进一步提高提供有益的参考。

Michelson干涉型光纤弱磁场传感器信号检测电路研究

针对Michelson光纤弱磁场传感器的特点,设计和实现了控制和信号检测系统。着重对传感器信号检测部分的电路进行了分析和研究,采用了相位自跟踪锁定放大技术进行微弱信号检测;针对磁致伸缩材料的非线性响应特点,设计了定偏闭环反馈系统,使探头始终工作在最佳偏置磁场下。经实验验证,系统灵敏度高,抑制噪声能力强。

光纤光栅Michelson干涉仪

提出了一种基于光纤布拉格光栅(光纤光栅)的光纤Michelson干涉仪.它使用光纤光栅作为干涉仪的反射器,宽带光代替激光作为光源,是一种可以波分复用的Michelson干涉仪.用3×3耦合器作为分光器,并结合软件解调技术从干涉仪的输出信号中解调出了外部振动信号.

基于Michelson干涉解调技术的光纤光栅传感系统

介绍了一种基于M ichelson干涉解调技术的光纤光栅传感系统,将包含被测应变信息的FBG波长信号转变成相位信号,通过单片机系统检测相位的变化,得到被测应变的大小。系统可检测静态应变和动态应变,具有高分辨力、大测量范围等特点。