Comparative research and its significance of deformation measurements by technologies of laser real-time holographic interferome-try and radar differential interferometry

The principles and applications of laser real-time holographic interferometry （LRTHI） and radar differential interferometry （RDI） technologies are described in this paper, respectively. By using LRTHI, we can observe the deformation of samples under pressure in the lab and study the anomaly characteristics relating to different strain fields in different fracture-developing areas; while by using RDI, we can observe the landform and surface deformation. The results of deformation observed before and after the Ms=7.9 Mani earthquake （Tibet） and Ms=6.2 Shangyi-Zhangbei earthquake in China are obtained. It is pointed out that LRTHI and RDi are similar, which study the characteristics of anomalous deformation field by fringe variations for both of them. Therefore, the observation of deformation field in the seismogenic process, especially in the period impending an earthquake by RDI, and the comparative study in the lab by LRTHI are of great significance.

Measurement of Liquid Concentration Fields Near Interface with Cocurrent Gas-Liquid Flow Absorption Using Holographic Interferometry

Real-time laser holographic interferometry was applied to measure liquid concentrations of CO2 in the vicinity of gas-liquid free interface under the conditions of cocurrent gas-liquid flow for absorption of CO2 by ethanol. The influences of the Reynolds number on the measurable interface concentration and on the film thickness were discussed. The results show that CO2 concentration decreases exponentially along the mass transfer direction,and the concentration gradient increases as Reynolds number of either liquid or gas increases. CO2 concentrations fluctuate slightly along the direction of flow; on the whole, there is an increase in CO2 concentration. The investigation also demonstrated that film thickness decreases with the increase of Reynolds number of either of the two phases. Sherwood number representing the mass transfer coefficient was finally correlated as a function of the hydrodynamic parameters and the physical properties.

Measurement of Liquid Diffusion Coefficients of Aqueous Solutions of Glycine, L-Alanine, L-Valine and L-Isoleucine by Holographic Interferometry

The diffusion coefficients of aqueous solutions ofglycine, L-alanine, L-valine and L-isoleucine at 298.15 K were determined by holographic interferometry with accuracy and promptness while without disturbance. The density and viscosity of these solutions were also determined. According to original Gordon model, a model for correlating the diffusion coefficients of amino acids in aqueous solutions was developed and applied. The results showed that this model provided significant convenience in correlation of diffusion coefficients for amino acids system.

Measurement of Liquid Concentration Fields Near Interface with Cocurrent Gas-Liquid Flow Absorption Using Holographic Interferometry

Real-time laser holographic interferometry was applied to measure liquid concentrations of CO2 in the vicinity of gas-liquid free interface under the conditions of cocurrent gas-liquid flow for absorption of CO2 by ethanol. The influences of the Reynolds number on the measurable interface concentration and on the film thickness were discussed. The results show that CO2 concentration decreases exponentially along the mass transfer direction, and the concentration gradient increases as Reynolds number of either liquid or gas increases. CO2 concentrations fluctuate slightly along the direction of flow; on the whole, there is an increase in CO2 concentration. The investiga- tion also demonstrated that film thickness decreases with the increase of Reynolds number of either of the two phases. Sherwood number representing the mass transfer coefficient was finally correlated as a function of the hy- drodynamic parameters and the physical properties.

THE THREE-DIMENSIONAL ANALYSIS OF THE SELF-VIBRATIONAL CHARACTERI-STICS OF THE 2050MM HOT-STRIP MILL HOUSING BY MEANS OF LASER HOLOGRAPHIC INTERFEROMETRY AND FINITE ELEMENT METHOD

According to the theory of similarity, a three-dimensional simulation study on the self-vibrational characteristics of the 2050mm hot-strip finishing mill housing at Baoshan Iron and Steel Complex has been carried out. The analysis of the main vibrational modes of the first three orders has also been done by means of holographic interferometry. In addition, the authors have carried out the numerical analysis of finite elements in three dimensions. The comparison of the results of both analyses (simulation analysis and numerical analysis of finite element) shows that they are consistent.

HIGH RESOLUTION,REAL-TIME LINE-FIELD FOURIER-DOMAIN INTERFEROMETRY

To increase the application potential in manufacturing process,such as monitoring the processing performance,the profile measurement should be provided in real-time display and with high resolution simultaneously.We propose a line-field Fourier-domain interferometric method(LFI),which combines the line-field microscope with spectral interferometer,for the surface cross-sectional profile measurement with no scan needed.The white light and objectives are employed to offer high axial and lateral resolution,respectively.In our system setup,the measurement could be implemented in real-time display of 10 frame/s,and the resolutions of the LFI system in X;Y,and Z directions are~8μm,~3.2μm,and~1.4μm,respectively.As a demonstration,the cross-sectional profiles of a microfluidic chip are tested.The graphics processing unit is also used to accelerate the reconstruction algorithm to achieve the real-time display of the cross-sectional profiles.

Measuring the Object Deformation by Real Time Holographic Interferometry with Automatically Calculating Hologram

Used Ar + laser as a light source,BSO(Bi 12 SiO 20 ) crystal as a hologram recording material,CCD camera as a detector,and a holographic setup controlled by a computer,we have realized real time holographic interferometry in terms of 3-interfe-rogram method.The deformation of a plate is measured under a pressure.

Reconstruction of 3-D Temperature Field in Holographic Interferometry

The tomography technique is commonly used for the reconstruction of holographic interferometry. However, the current reconstruction method doesn’t consider the measurement errors which are non-avoidable in the measurement and will degrade the reconstruction quality. The factors affecting the reconstruction quality are analyzed and the distribution law of the reconstruction error with experimental errors is discussed. Finally, a method to improve the reconstruction quality—the Kalman filter method is presented.

Surface Deformation Measurement by Phase-Shift Holographic Interferometry

In this paper, the principle of phase-shift interferometry is first briefly introduced. Then it is used as an illustration to measure small surface deformation, and the measurement accuracy of 0.02μis obtained. This demonstrates that the technology has great significance for strain analysis in experimental mechanics.

Holographic Deformation Measurement by a Spatial Carrier Fringe Technique

A carrier fringe techrtique for measuring surface deformation is described and verified by experiments. In contrast to conventional holography and fringe analysis, this holographic system is based on fibre optics and automatic spatial carrier fringe pattem analysis techniques Single-mode optic fibres are used to transfer both the object and reference beams. Carrier fringes are generated by simply translating the object beam between two exposures The Fourier transform is applied to the carrier fringe pattern to convert it to the spatial frequency domain, where it is processed The results are given for a centrally loaded disk, including a 3-D perspective plot of the out of plane deformation field, phase map, grey level map and contour map.

Phase-shifting digital holography in image reconstruction

A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A reverse-transform algorithm is employed to reconstruct the object wave on its original position of unknown distance or the imaging position from the object wave information on the holographic plane. To get the clearest reconstruction the exact registration of the unknown distance is determined by applying the intensity sum as the auto-focusing function, The spatial resolution of the reconstruction image is also investigated for a variety of affecting factors. Laboratory results of reconstruction images under deformation are presented.

Possibility to break through limitation of measurement range in dual-wavelength digital holography

By using the beat frequency technique,the dual-wavelength digital holography(DWDH)can greatly increase the measurement range of the system.However,the beat frequency technique has a limitation in measurement range.The measurement range is not larger than a synthetic wavelength.Here,to break through this limitation,we propose a novel DWDH method based on the constrained underdetermined equations,which consists of three parts:(i)prove that the constrained underdetermined equation has a unique integer solution,(ii)design an algorithm to search for the unique integer solution,(iii)introduce a third wavelength into the DWDH system,and design a corresponding algorithm to enhance the anti-noise performance of DWDH.As far as we know,it is the first time that we have discovered that the problem of DWDH can belong in a problem of contained underdetermined equations,and it is also the first time that we have given the mathematical proof for breaking through the limitation of the measurement range.A series of results is shown to test the theory and the corresponding algorithms.More importantly,since the principle of proposed DWDH is based on basic mathematical principles,it can be further extended to various fields,such as dual-wavelength microwave imaging and dual-wavelength coherent diffraction imaging.

Measurement of the Optical Coherence of a Femtosecond Pulsed Laser by Shearing Interferometry with a Double-Frequency Grating

Shearing interferometry of an ion-etched holographic double-frequency grating is used to measure the optical coherence of femtosecond pulsed lasers.The experimental results show that the optical coherence of the femtosecond light beam is not only related to the spectral width and size of the light source but is also related to the pulse duration and mode-locked laser state.The results of theoretical analysis and numerical calculation are also given.Application of this research is also discussed.

Real-time pupil tracking backlight system for holographic 3D display(Invited Paper)

We propose an automatic three-dimensionM （3D） pupil tracking backlight system for holographic 3D display system with large image size and full-parallax accommodation effect. The proposed tracking module is applied to a holographic 3D display system with two sets of directional holographic imaging module composed of 2 × 2 large scale lens array and 22-inch high-resolution liquid crystal display 3D panel. System architecture is described and experimental results are presented.

Measuring Vibration of Body with Speckle Interferometry

Speckle interferometry is an efficient method to analyze a vibration. In certain conditions, this technique has some outstanding advantage, and need not strict shock--proof condition, compared with the holographic method for measuring vibration. Therefore,it is suitable to analyze a vibration with a large amplitude.Real-time interferometry is a rapid and simple method for measuring vibration of a body, gives speckle pattern containing amplitude distribution of body-surface. By means of time-averaged method, the speckle pattern is recorded in Fourier transform plane, or vibration lines are seen directly with eyes, so as to analyze efficiently amplitude, phase, and model of a vibration. This paper deduces the intensity distribution function with real-time method, and gives experimental demonstration of vibration body-the vibration lines with different frequencies.

Measurement of mass diffusion coefficients of O_2 in aviation fuel through digital holographic interferometry

The experimental apparatus to measure the mass diffusion coefficients of O2 in aviation fuel was constructed based on the digital holographic interferometry method. The theory of mass diffusion coefficient and interference image processing were introduced in detail. The accuracy of the experiment was verified by measuring the mass diffusion coefficient of 0.33 mol/L KCl in aqueous solution at 298.15 K. The mass diffusion coefficients of O_2 in RP3 and RP5 aviation fuels were measured at temperature from 278.15 K to 333.15 K, and the Arrhenius equation was employed to fit the experimental data. In terms of the Stokes-Einstein equation, the viscosities of these two aviation fuels were tested to estimate the correlation among mass diffusion coefficient, viscosity and temperature. A uniform polynomial calculation correlation was proposed to predict the mass diffusion coefficients of O_2 in both RP3 and RP5 aviation fuels, and its accuracy is considerably higher than that of the Stokes-Einstein equation.

Real-time human blood pressure measurement based on laser self-mixing interferometry with extreme learning machine

In this paper, we present a method based on self-mixing interferometry combing extreme learning machine for real-time human blood pressure measurement. A signal processing method based on wavelet transform is applied to extract reversion point in the self-mixing interference signal, thus the pulse wave profile is successfully reconstructed. Considering the blood pressure values are intrinsically related to characteristic parameters of the pulse wave, 80 samples from the MIMIC-II database are used to train the extreme learning machine blood pressure model. In the experiment, 15 measured samples of pulse wave signal are used as the prediction sets. The results show that the errors of systolic and diastolic blood pressure are both within 5 mm Hg compared with that by the Coriolis method.

APPLICATION OF PULSE-LASER HOLOGRAPHIC INTERFEROMETRY TO THE RESEARCH ON ROCK MECHANICS

In research on rock mechanics, deformation measurement at every point on the surface of a rock specimen, that is, observation of a deformation field, is frequently required. For example, in the research on rock mechanics associated with earthquake prediction, an important problem is to know the temporal and spacial variation during the process of earthquake fault formation. The laser holographic interferometry is

Studies on the liquid-liquid interfacial mass transfer process using holographic interferometry

This paper aims at the interfacial phenomena of liquid-liquid mass transfer and its characteristic.By using the real-time holographic technique,the concen-tration distributions on the aqueous side were obtained according to holographic diagrams of mass transfer of ethanol through the interface of oil and water at different initial concentrations.Furthermore,the concentrations near the interface and the mass transfer coefficients were attained.A correlation of concentration near the interface to the concentration of the solute in the oil side was proposed.An approach of interfacial energy with solute concentration was established,and the calculated results are at good agreement with the experimental data.It is indicated that the liquid-liquid mass transfer process is approximately in accordance with two-film theory,the interfacial performance may be changed by the addition of the solute,and the interface of liquid-liquid is non-equilibrium thermodynamically during the mass transfer process.

岩石压剪耦合破坏过程的实时监测研究

将实时激光全息干涉光路布置与岩石力学压剪加载装置组构成光学-力学最优匹配测量系统,通过数据图像采集系统,实时动态捕获了压剪应力作用下花岗岩岩样压剪耦合破坏全过程的实时全息干涉图;根据全息干涉条纹解释原理和图像处理计算,试样表面动态干涉条纹的分布与移动规律高精度直观地揭示了岩石压剪耦合破坏过程中局部变形场分布、微破裂微裂纹的演化路径与速率以及岩石失稳破裂的力学性状。结果表明,该方法能够为岩石损伤与断裂力学问题的研究提供有效的试验技术支持。