Holographic Interferometry Technique Research Articles

Temperature Sensing in Space and Transparent Media: Advancements in Off-Axis Digital Holography and the Temperature Coefficient of Refractive Index

An off-axis digital holographic interferometry technique integrated with a Mach–Zehnder interferometer based setup is demonstrated for measuring the temperature and temperature profile of a transparent medium. This technique offers several advantages: it does not require precise optomechanical adjustments or accurate definition of the frequency carrier mask, making it simple and cost-effective. Additionally, high-quality optics are not necessary. The methodology relies on measuring the phase difference between two digitally reconstructed complex wave fields and utilizing the temperature coefficient of the refractive index. In this way, we presented an equation of the temperature as a function of phase changes and the temperature coefficient of refractive index. This approach simplifies the calculation process and avoids the burden of complicated mathematical inversions, such as the inverse Abel transformation. It also eliminates the need for additional work with the Lorentz–Lorentz equation and Gladstone–Dale relation and can be extend for 3D measurements.

Self-stabilized holographic interferometry for the measurement of two-dimensional vibrations

In this paper, we focus on the features of a self-stabilized holographic recording system with a photorefractive crystal as a vibration optical sensor. With it and the time-average holographic interferometry technique, high quality vibration maps of a thin plate were obtained. The results show that the system is capable of phase control in low diffraction efficiency conditions and under high disturbances.

Investigation of cloud droplets velocity extraction based on depth expansion and self-fusion of reconstructed hologram.

The velocity of cloud droplets has a significant effect on the investigation of the turbulence-cloud microphysics interaction mechanism. The paper proposes an in-line digital holographic interferometry (DHI) technique based on depth expansion and self-fusion algorithm to simultaneously extract particle velocity from eight holograms. In comparison to the two-frame exposure method, the extraction efficiency of velocity is raised by threefold, and the number of reference particles used for particle registration is increased to eight. The experimental results obtained in the cloud chamber show that the velocity of cloud droplets increases fourfold from the stabilization phase to the dissipation phase. The measurement deviations of two phases are 1.138 and 1.153 mm/s, respectively. Additionally, this method provides a rapid solution for three-dimensional particle velocimetry investigation of turbulent field stacking and cloud droplets collisions.

Visualization study of a cryostat with a large diameter flow channel for flowing high-pressure cryogenic fluid

For abundant cryogenic experiments, systems, and so on, visualization is necessary to observe the cryogenic fluid. Therefore, the visualization methods of cryogenic fluid have been widely studied, such as shadowgraph technique, schlieren technique, and laser holographic interferometry technique. A cryostat for visualization study must have optical windows to meet the requirement of various image acquisition equipment. Due to the difference of shrinkage between transparent glass and device materials at low temperatures, especially at large diameter flow channels, it is difficult to meet the requirement of visualization. This paper studies a kind of cryogenic visualization device with an inner diameter of 200 mm, which can meet the visualization requirements of cryogenic fluid with the maximum working pressure at 0.7 MPa and the lowest temperature at 77 K. Liquid nitrogen was used to test the visualization of the device at low temperatures. The device was also subjected to vibration conditions to test the ability of the device to withstand harsh environments. The results show that the device has good sealing performance and can meet the visualization requirements well.

Concealing information in security hologram using interferometry

A new method utilizing holographic interferometry technique is described to conceal information in security holograms for enhancing their anti-counterfeiting ability. This concealed information can only be imitated if security hologram is illuminated through correct decoding wavefront generated through a key hologram. In decoding process, three spatially separated focus spots emerge at predefined positions which upon divergence further generate interferometric fringes modulated with concealed information in them. When security hologram is perfectly aligned, interferometric fringes disappear and concealed information becomes visible. The advantage of encoding through this technique lies in the fact that relative repositioning of key and security hologram becomes much easier and also additionally brings multifold improvement in the security level of the verification systems.

Digital holographic study of vapor transport of heavy hydrocarbon from heated well cavity

Thin film evaporative cooling is one of the liquid cooling technologies, capable of removing high heat flux with lower junction temperature due to the utilization of latent heat of vaporization. To understand the various transport processes involved in vapour phase during thin film evaporation, evaporation from a heated well cavity of diameter 3 mm and height 2 mm is studied using Digital holographic interferometry technique. A flat disk-shaped vapour cloud is appeared for heated as well as not- heated well surface case. This signifies radial outward natural convection instead of pure diffusion. A higher vapour concentration is obtained at each time instants for heated surface case due to the higher evaporation rate as compared to non-heated, ambient case.

Experimental study of thermal convection in dry air by holographic interferometry method

The convection of humid and dry air was studied experimentally. The observed fluid convection involves two mechanisms of heat and mass transfer: thermal convection produced by temperature gradient and concentration convection occurred due to the inhomogeneous vapor distributions induced by evaporation and condensation of water. The convection stability of humid air was described in terms of two (thermal and concentration) Rayleigh numbers. Laboratory experiments were performed using holographic interferometry and thermocouple techniques. Experimental holograms were processed numerically in order to calculate the space distribution of the refractive index in relation to temperature and vapor concentration. The results show that the difference between moist convection and dry convection can be measured even in the absence of evaporation and condensation. The experimental interferograms for dry air (intentionally dried up to 4 % relative humidity) are given. The justification of this research requires an additional quantitative comparison with the measurements obtained for humid air (with 100 % relative humidity) undergoing the first-order phase transition of the “gas-liquid” type.

Determination of the Diffusion Coefficient of Urea Solution Using Double Exposure Digital Holographic Interferometry (DEDHI) to Study Plant Growth-=SUP=-*-=/SUP=-

In this paper, we have used the double exposure digital holographic interferometry (DEDHI) technique to determine the diffusion coefficient of urea in pure distilled water at 27oC (room temperature) and it is used further to predict urea movement in soil by considering the concentration of urea solution and diffusion coefficient to study early plant growth. We have recorded several consecutive digital holograms of diffusing solutions of urea and pure distilled water at different times instantaneously on the CCD chip and processed them with H-Digital numerical reconstruction software on the computer. It is observed that as the concentration of urea solution increases from 0 to 4 M, diffusion coefficient 'D' of urea slightly increases from 12.2 to 13.8 × 10^-6 cm^2/s, which considerably affects the growth of the plants.

Investigations of defects in ceramic tiles using Double Exposure Digital Holographic Interferometry (DEDHI) technique

Glazed ceramic flooring tiles have a protective layer that rests over the material, making them impervious to water and stain penetration. A typical defect found in the ceramic tile is delamination. This paper describes the problem of detecting delamination and defects of typical ceramic tiles by using Double Exposure Digital Holographic Interferometry (DEDHI), as a non-destructive technique. The specimen tiles of different qualities (defected) having dimensions 10 cm × 12 cm are used as the sample tiles. These tiles are subjected to mechanical and thermal stressing and their double exposure digital interferograms are recorded. Digital reconstructed images show various fringe patterns. It is found that the defected samples show the irregularity in the fringe patterns and the shape of the fringes changes accordingly the defect, crack and debonds present in the samples. The compared fringe patterns, with fringe patterns of high quality on ceramic samples give reasonably interesting results.

Surface Deformation of Cadmium Selenide Thin Films By DEHI Technique

Abstract Here, the Double Exposure Holographic Interferometry (DEHI) technique is used to study the surface deformation of CdSe films electrodeposited on stainless steel substrate. The electrodeposition of CdSe thin films is carried out by varying the time of deposition. The deposition potential of the compound was studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited films have been studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and optical absorption technique respectively. Also the contact angle measurements are carried out. The DEHI technique is used to determine, thickness of thin films, mass deposited, fringe width and stress to substrate of electrodeposited CdSe thin films for various deposition time with different solution concentrations. With increasing deposition time fringe width was decreased due to the reduction in film stress

Surface Deformation Study of the Electrodeposited Nanostructured Bi2Te3 and Sb2Te3 Thin Films by Double‐Exposure Digital Holographic Interferometry

Bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thin films are successfully deposited on stainless steel (SS) substrate by the potentiostatic mode of electrodeposition. Herein, the focus is on surface deformation during the electrodeposition process under the effect of deposition time. This study is carried out using double‐exposure digital holographic interferometry (DEDHI) technique and the prepared optimized films are characterized for their physico‐chemical properties. The deposition potential is found out by cyclic voltammetry; it is −170 and −260 mV for Bi2Te3 and Sb2Te3, respectively. The hologram fringes are recorded during the electrodeposition of films and the variations in the number of fringes, deposited mass, thickness of film, and stress to surface with respect to deposition time are studied.

Experimental investigation of convective heat transfer between corrugated heated surfaces of rectangular channel

The convective heat transfer between corrugated heat transfer surfaces in the rectangular channel have been investigated experimentally. The optical measurement technique of holographic interferometry is used to visualize the temperature fields between heat transfer surfaces. Studies were carried out for the triangular, trapezoidal and wing corrugated heat transfer surfaces, comparing them to a smooth surface. The cooling air is sucked in between heated surfaces at different flow rates of 5, 10, 15 and 20 m3/h, which corresponds to the Reynolds numbers in the 732 to 3,020 range. The wall temperature was held constant at 318.15 K. The effects of the different corrugated channels and different heights of the gaps between heated surfaces (H = 40, 50 mm) and Reynolds numbers on heat transfer characteristics are discussed. Experiments were performed to determine local and mean heat transfer coefficients, Nusselt numbers, ratio j/f and thermal performance η. The results showed that the trapezoidal offset with 40 mm gap height and the Reynolds number Re = 3,020 achieved the highest values of mean Nusselt numbers (Num´ = 26.97) in comparison with smooth and other corrugated channels. The mean Nusselt number Num´ with raising of Re increased by 102 % for trapezoidal offset with gap H = 0.04 m. When considering heat transfer and pressure drop in the channel (ratio j/f), the trapezoidal offset with gap H = 0.05 m (j/f = 0.0104) is the most optimal case.

Surface deformation studies of MnO2 film by double exposure digital holographic interferometry technique

In the present paper, the MnO2 films have been deposited on stainless steel support by potentiostatic mode of electrodeposition at different times. The x-ray diffraction, Fourier transform infrared spectroscopy along with Energy-dispersive x-ray spectroscopy analysis confirmed formation of amorphous MnO2 coating. The surface analysis by field emission scanning electron microscope indicated development of fractures with increasing film thickness. The in situ measurement of stress to the substrate and MnO2 film thickness during deposition is performed by non-destructive double exposure digital holographic interferometry (DEDHI) technique. It was observed that the stress to the substrate decreases with increasing MnO2 film thickness. This study opens application of DEDHI for non-destructive measurement using simple mathematical interpretation.

Electrochemical and surface deformation studies on electrodeposited nanostructured Bi2Te3 thin films

In this article, we have used double exposure digital holographic interferometry (DEDHI) technique for surface deformation study and hologram recording during synthesis of the Bi2Te3 thin films by electrodeposition method. The synthesized Bi2Te3 thin films were characterized structural, morphological, electrochemical, wettability and surface deformation study. Further the holograms are recorded during the electrodeposition process by varying the concentration of electrolyte. From the recorded fringes the stress, deposited mass and thickness have been calculated. It is observed that the fringe width, mass of deposited thin films, and stress to substrate changes with the concentration of electrolyte. The DEDHI technique is found more reliable for thickness measurement in electrodeposition process. The EIS study confirms that the deposited material is highly conducting.

Natural convection heat transfer from a horizontal cylinder using holographic interferometry

AbstractThe natural convection heat transfer from a horizontal cylinder with a uniform wall temperature in an infinite space was experimentally investigated. Infinite fringe interferograms of the cylinder heated from 295.15 to 355.15 K were recorded using the holographic interferometry technique. The temperature field around the cylinder was reconstructed based on phase difference recovery using a MATLAB code. The distributions of the local and average Nusselt numbers over the cylinder were then obtained. A correlation of the average Nusselt number was proposed for a Rayleigh number range of 2.7–6.0 × 104. The experimental results are in good agreement with previous correlations, with a deviation of ±10%. The holographic interferometry technique was found to be satisfactory and reliable for heat transfer analyses.

Digital holographic interferometry for cultural heritage structural diagnostics: A coherent and a low‐coherence optical set‐up for the study of a marquetry sample

AbstractCultural heritage conservation is an active field of research, where there is an ever‐growing demand for nondestructive and noninvasive diagnostic techniques, for performing remote analysis and diagnosis of the condition of historical structures and pieces of art, often of very high cultural and historical value. In this context, holographic interferometry is a very well‐established optical technique for research in cultural heritage, which brings together some very basic and critical properties such as contactless examination and nondestructivity, accuracy, repeatability, and a wide range of applicability. In this paper, the optical technique of digital holographic interferometry is tested on mock‐up, art‐related targets, with 2 different light sources, in an attempt to expand the technique towards a new approach that will profit from an easy‐to‐operate, inexpensive, and tunable source, offering a broad spectrum and wavelength selectivity, according to the needs of the experiments. Examples are presented, and the results demonstrate the effectiveness of the proposed modified experimental scheme for defect mapping, to be used in structural documentation reports, and for its exploitation in future hybrid optical diagnostic systems and data processing.

Determination of Young’s Modulus of Aluminium, Copper, Iron, Brass and Steel Alloys by Using Double Exposure Holographic Interferometry (DEHI) Technique

Double Exposure Holographic Interferometry (DEHI) technique has wide applications in the field of science and engineering. DEHI can be used to determine very small surface changes in an object at very small interval of time. In present case, DEHI technique is used to record the hologram of the same object at different times subjected to different loads. This method has been advantageously used to determine Young’s Modulus (Y) of Aluminium, Copper, iron, brass and some steel alloys. It is found that the values of Y obtained by using DEHI technique are in close agreement with standard values of Y available for respective metals and their alloys. The method is also used to make standard relation between effect of carbon composition and Y of steel alloys.

Gravitational Level Effects on the Coupling Phenomena between Mass Transfer and Morphological Variation Rate

Gravitational Level Effects on the Coupling Phenomena between Mass Transfer and Morphological Variation Rate T. Nishida 1) , K. Nishikawa 1) , H. Matsushima 1) , T. Wakatsuki 1) , T. Homma2) , M. Rosso 3) and Y. Fukunaka4) 1) Dept. of Energy Sci. & Tech., Kyoto University 2) Dept. of Applied Chemistry, Waseda University 3) Ecole Polytecnique, Paris 4) Nanotechnology Research Center, Waseda University e-mail: hirofukunaka@gmail.com Development of advanced battery is the key for future space engineering field. Long life cycling must be maintained as well as the safety issue. Moreover, battery life must be predicted to reduce the number of space debri. Such technology achievements in space engineering field should be fed-back to the terrestrial applications including large scale energy storage devices. Generally speaking, battery reversibility is frequently governed by electrode surface flatness. Metal electrodeposition may generate irregular deposits with various morphologies. Coupling phenomena between the morphological or microstructural variations and ionic mass transfer rate must be fully understood to tailor the interface to create the unique physical properties as well as the ultra-high energy storage capacity. It is also indispensable for us to prolong the charging/discharging operation of secondary battery after longer term utilization under various environments. For liquid electrolyte, a precise study of these morphologies may be complicated by convective motion caused by gravitational force of buoyancy. Now the coupling phenomena are discussed in the case of Li in organic solvent PC or ionic liqid and Ag (or Cu) in AgNO3 (CuSO4) aqueous solution because they have been employed as negative electrode in space application as well as commercial use. The dendrite growth behavior of Li metal galvanostatically electrodeposited on Ni substrate in LiClO4-PC electrolyte was in-situ observed by a laser scanning confocal microscope. A Li dendrite precursor is stochastically evolved on Ni substrate probably through SEI. The initiation period of dendrite precursor becomes shorter with increasing current density and decresing LiClO4 concentration. Once it has been initiated, the ionic mass transfer rate starts to control the growth process of dendrite arm length, exceeding over the surface chemistry determining step. In order to excule the complexities due to SEI formation during the dendrite formation process, more simplified coupling behavior was studied in aqueous solution. 3M AgNO3aqueous solution was contained in a quasi-two dimensional electrolytic cell. Holographic interferometry technique was employed to monitor the ionic mass transfer rate. The thickness of electrolyte layer sandwiched by two slides glasses was measured to be 55 to 70 micrometer. The concentration profiles were formed around dendrite tips of silver electrodeposited at extremely high current densities. A uniform diffusion layer was formed along the cathode surface at the start of electrolysis. Electrochemical nucleation and growth phenomena on a substrate is expected under a considerably high overpotential. Following a certain incubation period, several dendrite tips began to protrude into the diffusion layer. The growth rates of these dendrites were related to concentration gradients around the tips, diffusivity, and transfer number of Ag+ ion. Giant-Macro step flow accompanied with dendritic growth of electrodeposited Ag in AgNO3 solution was dynamically observed in the image of Laser Confocal Scanning Microscope. These experiments must be engaged in microgravity facility which provides an ideal environment to built the physical model on electrolyte/electrode interfacial coupling phenomena without natural convection.

Digital holographic interferometry applied to the investigation of ignition process.

We use the digital holographic interferometry (DHI) technique to display the early ignition process for a butane-air mixture flame. Because such an event occurs in a short time (few milliseconds), a fast CCD camera is used to study the event. As more detail is required for monitoring the temporal evolution of the process, less light coming from the combustion is captured by the CCD camera, resulting in a deficient and underexposed image. Therefore, the CCD's direct observation of the combustion process is limited (down to 1000 frames per second). To overcome this drawback, we propose the use of DHI along with a high power laser in order to supply enough light to increase the speed capture, thus improving the visualization of the phenomenon in the initial moments. An experimental optical setup based on DHI is used to obtain a large sequence of phase maps that allows us to observe two transitory stages in the ignition process: a first explosion which slightly emits visible light, and a second stage induced by variations in temperature when the flame is emerging. While the last stage can be directly monitored by the CCD camera, the first stage is hardly detected by direct observation, and DHI clearly evidences this process. Furthermore, our method can be easily adapted for visualizing other types of fast processes.

Structural, morphological, optical and hologram recording of the CdS and ZnS thin films by double exposure digital holographic interferometry technique

In this paper, we have used double exposure digital holographic interferometry (DEDHI) technique for hologram recording of electrochemical synthesis of the CdS and ZnS thin films materials. As synthesis CdS and ZnS thin films are characterized by different characterization techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), optical band gap, and contact angle measurement. Further recording of the holograms has been carried out with different deposition time of CdS and ZnS thin films, and we have used mathematical relation between stress, mass deposited thickness of thin film and fringe width. It is seen that the fringe width, mas of deposited samples, stress to substrate changes with the time of deposition.