Double Exposure Digital Holographic Interferometry Research Articles

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 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.

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.

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.

Evaluation of the holographic parameters by electrosynthesized CdXZn1−XS (X=0.3) thin films using double exposure digital holographic interferometry technique

In this paper, we have reported the optical non destructive technique, which uses double exposure digital holographic interferometry (DEDHI) together with simple mathematical interpretation, which instantly situates to the thickness of thin films, deposited mass, stress to substrate and fringe width for different deposition times. Here, the stainless steel substrate was exposed for different intervals of time. It is observed that the fringe width, stress to substrate changes with changing the time of deposition. This effect is due to the increase in thickness of CdXZn1−XS (X=0.3) thin films. Thus, holographic studies show sensitivity to deposition time and concentrations of solution.

Method for calculating the dynamic phase delay in holographic interferometry without phase unwrapping

A method for calculating the difference between two arbitrary spatial phase distributions reconstructed from digital holograms is presented. The method is promising for application in double-exposure digital holographic interferometry, especially for the evaluation of phase variations in heavily noised or speckle-structure-modulated digital holograms, because it does not use the phase unwrapping procedure for each reconstructed spatial phase distribution. Instead, by analogy with classical double-exposure holographic interferometry, an interference pattern formed by two reconstructed object waves is calculated first. The interferogram thus obtained is then processed as a digital hologram by the same method that was used for reconstruction of physically recorded holograms. The advantages of the proposed method are demonstrated by both by the numerical computation of the difference of the phase distributions of speckle-structure-modulated wavefronts and the experimental observation of the laser-induced temperature gradients in an aqueous solution of a photosensitizer.

Comparative study with double-exposure digital holographic interferometry and a shack-hartmann sensor to characterize transparent materials.

We compare wave-front measurements using double-exposure digital holography and a Shack-Hartmann sensor. A voltage-driven liquid-crystal wedge modulates the optical wave front and provides a refractive-index gradient typical of interesting transparent materials. Measurement accuracy and reliability are similar for both methods. In our opinion, digital holographic interferometry has several advantages for both laboratory and field environments. When compared with Shack-Hartmann methods, these advantages include hardware simplicity and robustness, relative insensitivity to sample dynamic range, and less computational demanding and more straightforward data evaluation algorithms. We believe that digital holography provides the methodology of choice for field studies of transparent materials such as microgravity protein crystal growth experiments.