Phase-shifting Holographic Interferometry Research Articles

Simultaneous measurement of optical inhomogeneity and thickness variation by using dual-wavelength phase-shifting photorefractive holographic interferometry

Abstract A method to measure thickness variation and optical inhomogeneity simultaneously with a dual-wavelength phase-shifting photorefractive holographic interferometer is proposed. This method has no special requirements on the sample surfaces, and additional operations such as coating refractive index matching liquid on surfaces is not needed. With the help of photorefractive holographic interferometry, the wavefront distortion caused by the interferometer system is compensated automatically. Compared with other methods, this method is simpler and more accurate. Computer simulation and optical experiment have verified its feasibility and reliability.

Application of digital phase-shift holographic interferometry to weak shock waves propagating at Mach 1.007

Digital phase-shift holographic interferometry was applied to visualize weak shock waves and related phenomena quantitatively. This method of interferometry is an improved version of double-exposure holographic interferometry using digital image processing and a phase shift method. The obtained interferograms were analyzed using the Carre method. To evaluate the applicability of the interferometry to quantitatively visualize the phenomena, density profiles behind weak spherical shock waves generated with 500 μg of silver azide were examined. The results of the numerical analysis performed with the hydrocode AUTODYN were compared with those of the experiment. The Mach number of visualized shock waves was estimated to be 1.007 ± 0.001 at the pressure transducer near the test section. At the shock fronts, the density difference between the experimental and numerical results was within 0.3%.

A general form for calculating residual stresses detected by using the holographic blind-hole method

A general form used for analyzing residual stresses measured using the holographic blind-hole method is introduced in this paper. Adopting the general form presented, the residual stresses can be obtained using three relative displacements measured from a single interference fringe pattern. Even for the case in which phase-shifting holographic interferometry is not employed, interpolating calculations for determining the fringe orders are not needed, since the choice of data points becomes more flexible when using this general form. Two experiments, the first one carried out by the authors and the second one published previously, are used to illustrate the applicability and usefulness of this general form. Suggestions for the applications of this general form are also established via the upper bound error estimations.

Effect of composition distribution on holographic temperature measurement of a diffuse flame

The application of phase shift holographic interferometry to non-intrusive temperature measurement of a laminar, axisymmetric, propane diffuse flame is investigated. In our previous work the effect of composition changes on the holographic temperature measurement of reacting flows was experimentally studied for cases with axisymmetric, propane, laminar premixed lean flames (PLFs) and partially premixed flames (PPFs). To further examine this effect, in this work the effect of the diffuse flame (DF) is investigated. It has been shown that for the DF, the composition distribution is the most complicated and the composition effect is more severe than that of the PLF and the PPF. In order to obtain accurate and satisfactory holographic results, it is necessary to measure the species concentration at lower flame heights, and to use linear interpolation of the molar refractivity at higher test sections.

Phase-shifting holographic interferometry for breast cancer detection

Using a mild pressure stressing device and a pulsed ruby-laser system, we apply phase-shifted holographic interferometry to the detection of breast cancer. We compare a four-step algorithm and a Carré algorithm for their ability to evaluate the interferograms. The results show the feasibility of holographic interferometry in the detection of anomalies in the human female breast.

Holographic temperature measurement on axisymmetric propane-air, fuel-lean flame

Instead of using conventional interferometry, the whole field temperature distribution of a laminar, axisymmetric, propane-air, fuel-lean flame is measured by using an advanced digital interferometric technique, namely digital phase-shifting holographic interferometry. The measurement technique effectively improves the accuracy of conventional interferometric measurement as it circumvents the limitation of fringe counting interpolation. The results obtained by this technique are compared with those measured by conventional holographic interferometry (using interpolation) in order to evaluate the effect of interpolation on measurement accuracy. A modified dual reference beam holographic recording system is set up for this experiment and fast Fourier transformation is used for Abel inversion. The structure of the test flame is analysed by holographic visualization and measured temperature distribution. In addition, the interferometric temperature distributions are compared with thermocouple measurements. Errors introduced in the measurement are analysed and discussed.

Temperature measurements of reacting flowfield by phase-shifting holographic interferometry

Application of phase-shift holographic interferometry to the temperature measurement of an axisymmetrically premixed flame was experimentally investigated. The test apparatus is an axisymmetric Bunsen burner. Commercial nature hydrocarbon gases were used as the gaseous fuel. A fast Fourier transform for Abel inversion was used to reconstruct the axisymmetric temperature field from the interferometric data. The temperature distribution was compared with thermocouple measurements. The comparison shows that the proposed technique is satisfactory. Errors introduced in the measurement are analyzed and discussed.

Digital phase shift holographic interferometry and its application in the experimental flow study

The application of digital phase shift holographic interferometry to flow-visualization and flow temperature measurement of a 2D thermal flow field was experimentally investigated. An improved recording system for two reference beam phase shift holographic interferometry is set up for this experiment, and details of this experimental technique are described. The phase distribution obtained by this technique presents an excellent picture of flow visualization. From this phase image, temperature distribution of the 2D thermal flow field is also calculated and compared with some measured values obtained using thermocouple probes.

Phase-shifting holographic interferometry for measuring three-component distributions of displacement vectors

A method for measuring displacement vectors is discussed in this paper. The method realizes the measurement by observing the object through three or more points on a single hologram and by using a phase-shift technique to detect accurate path differences. This paper also presents experiments for displacement on a plane and discusses methods of improving measuring accuracy.

The inspection of solder joints on printed circuit boards by phase-shift holographic interferometry

The principle of inspecting solder joints on printed circuit boards (PCBs) by phase-shift holographic interferometry is described. By using this technique, defective solder joints can be easily distinguished from good ones without analysing complicated holographic interferograms. Experiment shows that most defects in solder joints, such as breaks and voids, can be detected successfully.

The inspection of solder joints on printed circuit boards by phase-shift holographic interferometry

The principle of inspecting solder joints on printed circuit boards (PCBs) by phase-shift holographic interferometry is described. By using this technique, defective solder joints can be easily distinguished from good ones without analysing complicated holographic interferograms. Experiment shows that most defects in solder joints, such as breaks and voids, can be detected successfully.

The application of digital image processing technique in industry production non-destructive testing Senyuan, Zhu; Chenggui, Yi; Peng, Yang; Zongfa, Zhang; Lin, Li; Jianhuan, Li; Xuhui, Wang Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands), 23–28 Apr. 1989, Vol. 2, pp. 1308–1311. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989

The principle of inspecting solder joints on printed circuit boards (PCBs) by phase-shift holographic interferometry is described. By using this technique, defective solder joints can be easily distinguished from good ones without analysing complicated holographic interferograms. Experiment shows that most defects in solder joints, such as breaks and voids, can be detected successfully.