This paper presents a digital holographic method for measurement of periodic asymmetric temperature fields. The method is based on a modified Twyman-Green setup having double sensitivity. For measurement only one precisely synchronized and triggered digital camera is used. The periodicity and self-similarity of each cycle of the measured phenomenon combined with the precisely synchronized camera capture allow one to obtain data later used for three-dimensional (3D) measurement. The reconstruction of 3D temperature field is based on tomographic approach.
15N NMR spectra of twelve neat ionic liquids derived from 1,3-disubstituted imidazolium salts were measured, and effects of nitrogen atoms substitution, type of anions and influence of solvents used for dilution of neat ionic liquids were studied. Changes in charge distribution are discussed.
A method for the measurements of the out-of-plane displacement on the surface of vibrating object is presented herein. This method is based on frequency-shifted time-averaged digital holographic interferometry, employing the principle of phase shifting. This approach allows for significant noise reduction, which results in high sensitivity of measurements. This method makes it possible to measure vibrations with amplitudes in the nanometer range over the whole measured surface. This method was applied to the visualization of the out-of-plane vibration modes of piezoelectric transformers. The amplitude and modal shapes were measured with a very high resolution. Furthermore, aspects influencing the measurement errors are discussed and the measurement results by holographic method were compared with the well-established single-point laser interferometry measurement method.
Abstract. The measurement of properties of so called phase objects is being solved for more than one Century starting probably with schlieren technique 1. Classical interferometry served as a great measurement tool for several decades and was replaced by holographic interferometry, which disposes with many benefits when compared to classical interferometry. Holographic interferometry undergone an enormous development in last decade when digital holography has been established as a standard technique and most of the drawbacks were solved. The paper deals with scope of the huge applicability of digital holographic interferometry in heat and mass transfer measurement from micro to macro scale and from simple 2D measurement up to complex tomographic techniques. Recently the very complex experimental setups are under development in our labs combining many techniques leading to digital holographic micro tomography methods.
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