Viscosity measurement of Newtonian liquids using the complex reflection coefficient

This work presents the implementation of the ultrasonic shear reflectance method for viscosity measurement of Newtonian liquids using wave mode conversion from longitudinal to shear waves and vice versa. The method is based on the measurement of the complex reflection coefficient (magnitude and phase) at a solid-liquid interface. The implemented measurement cell is composed of an ultrasonic transducer, a water buffer, an aluminum prism, a PMMA buffer rod, and a sample chamber. Viscosity measurements were made in the range from 1 to 3.5 MHz for olive oil and for automotive oils (SAE 40, 90, and 250) at 15 and 22.5degC, respectively. Moreover, olive oil and corn oil measurements were conducted in the range from 15 to 30degC at 3.5 and 2.25 MHz, respectively. The ultrasonic measurements, in the case of the less viscous liquids, agree with the results provided by a rotational viscometer, showing Newtonian behavior. In the case of the more viscous liquids, a significant difference was obtained, showing a clear non-Newtonian behavior that cannot be described by the Kelvin-Voigt model.     

Accurate measurement of the refractive indices of solids and liquids by the double-layer interferometer

The rings of equal inclination of the double-layer interferometer disappear in their common center if a plane-parallel glass plate is rotated inside one of the interferometer gaps that is filled with a liquid. Knowledge of the ring count and the rotated angle allows the refractive indices of both the rotated plate and the liquid to be found from a new analytical formula accurate to ?0.0004. The experimental results for glass, distilled water, and methanol are fitted to the Sellmeier dispersion function to determine their quantum parameters such as the absorption wavelengths in the ultraviolet side of the spectrum and the atomic number densities contributing to these absorption bands.     

Co-flowing of partially miscible liquids for the generation of monodisperse microparticles

Liquid templating is a well-established method for the fabrication of monodisperse microparticles. Nearly all liquid templating methods use totally immiscible liquids for the generation of monodisperse liquid droplets. With this approach, it is difficult to mass produce monodisperse droplets in the submicron range. The approach also suffers from some common difficulties associated with the use of small openings or channels required for the generation of small sized droplets including high back pressures and frequent blockage of the flow channels. Aimed at overcoming these difficulties, this paper presents a new co-flowing method that uses partially miscible liquids for the generation of a monodisperse liquid template. The results show that addition of a co-solvent in the inner phase that makes the liquid systems partially miscible changes the bulk and interfacial properties of the liquids that facilitate the generation of smaller droplets. They also confirm that the co-solvent concentration in the inner phase can be used as an additional tool to manipulate the mean size of the resultant droplets and solid particles.     

1st International comparison measurement on assessing the diffusion coefficient of radon

Radon diffusion coefficient is a material parameter which is usually used in the radon mitigation measures design. There are different approaches used for radon diffusion coefficient measurement and assessment. The International comparison measurement which was jointly organised by National Radiation Protection Institute and Faculty of Civil Engineering CTU Prague in 2009 and 2010 has registered 11 laboratories from all over the world. Three sets of samples of polyethylene damp-proof membranes were sent to these laboratories for measurement. Till today, the organisers received only five sets of results. The results showed a great variability among laboratories involved.     

Photon diffusion coefficient in an absorbing medium

A number of investigators have recently claimed, based on both analysis from transport theory and transport-theory-based Monte Carlo calculations, that the diffusion coefficient for photon migration should be taken to be independent of absorption. We show that these analyses are flawed and that the correct way of extracting diffusion theory from transport theory gives an absorption-dependent diffusion coefficient. Experiments by two different sets of investigators give conflicting results concerning whether the diffusion coefficient depends on absorption. The discrepancy between theory and the earlier set of experiments poses an interesting challenge.     

Absolute distance measurement with an optical feedback interferometer

An important use of the self-mixing effect inside a frequency-modulated single-mode laser diode is in laser velocimetry and range-finding applications. The optical beam reflected by a target and injected into the laser diode cavity modulated by a reshaped current is mixed with the light inside the cavity, causing variations of the optical output power. A theoretical analysis of this effect is proposed, based on the determination of the beat frequencies of the optical power variations, to improve the accuracy of laser distance measurement. A resolution of ?1.5 mm from 50 cm to 2 m is obtained when thermal effects are taken into account.     

Two-wavelength heterodyne interferometer with an expanded measurement range

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 39–40, August, 1992.     

Determination of the coefficient of volume expansion for liquids

We present a theoretical method for an approximate determination of the coefficient of volume expansion for liquids at the saturation line. The theory of similarity and the molecular characteristics of the materials serve as the basis for the derivation of quantitative relationships.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 16, No. 6, pp. 1034–1038, June, 1969.     

Michelson interferometer for precision angle measurement

An angle-measuring technique based on an optical interferometer is reported. The technique exploits a Michelson interferometric configuration in which a right-angle prism and a glass strip are introduced into a probe beam. Simultaneous rotation of both components along an axis results in an optical path difference between the reference and the probe beams. In a second arrangement two right-angle prisms and glass strips are introduced into two beams of a Michelson interferometer. The prisms and the strips are rotated simultaneously to introduce an optical path difference between the two beams. In our arrangement, optimization of various parameters makes the net optical path difference between the two beams approximately linear for a rotation as great as +/-20 degrees . Results are simulated that show an improvement of 2-3 orders of magnitude in error and nonlinearity compared with a previously reported technique.     

Characterization and use of an optical fiber interferometer for measurement of the electric wind

An optical fiber interferometer of the Mach-Zehnder type has proved to be a convenient and accurate method for measuring the electric wind in the active region of a corona discharge. The technique relies on the cooling effect of the wind on a small heated region of one arm of the interferometer, which has been remotely heated with an infrared CO(2) laser beam. Wind speeds of up to 5.5 m s(-1) have been measured near the generation region, and by the use of a mesh electrode, the wind has been detected on the axis up to 0.5 m away from the gap. A number of characterization experiments that show the interferometer to be a useful diagnostic tool in the quantitative analysis of the CO(2) laser beam have also been carried out, and good agreement between experimental results and theoretical calculations based on a simple heat-power balance equation for the fiber exists.     

White-light interferometer with dispersion: an accurate fiber-optic sensor for the measurement of distance

We present a fiber-optical sensor for distance measurement of smooth and rough surfaces that is based on white-light interferometry; the sensor measures the distance from the sample surface to the sensor head. Because white light is used, the measurement is absolute. The measurement uncertainty depends not on the aperture of the optical system but only on the properties of the rough surface and is commonly approximately 1 microm. The measurement range is approximately 1 mm. The sensor includes no mechanical moving parts; mechanical movement is replaced by the spectral decomposition of light at the interferometer output. The absence of mechanical moving parts enables a high measuring rate to be reached.     

Double-grating interferometer for measurement of cylinder diameters

We describe a double-grating interferometer for the measurement of cylinder diameters. The unique characteristic of this interferometer is that one can freely change the period of the interference fringes by turning the grating, which permits the measurement range of the interferometer also to be changed freely according to the cylinder diameter to be measured. A clear image of the cylinder can be obtained because the aperture diaphragm blocks the beams diffracted from the edge of the cylinder. The outside and inside diameters of the M4 x 0.7 mm hand tap are measured with this double-grating interferometer.     

Scanning laser differential-heterodyne interferometer for flying-height measurement

With conventional optical interferometry flying-height testing, a stationary measurement beam and a two-axis moving stage are used to measure slider-disk spacing at different points on the slider. Pitch angle or roll angle is calculated on the basis of the measurement results. We report on a scanning differential-heterodyne interferometer, which measures the continuous flying-height variation along the edge of a slider with two continuously scanning laser beams. Pitch angle or roll angle can be obtained directly from the scanning measurement. The system can also measure points individually to obtain the absolute flying height at different locations on the slider. Experiments were performed to demonstrate the concept of scanning measurement. The flying-height variation along the slider edge was measured by continuous scan and by point-to-point moving. The measurement results from continuous scan coincided with those of conventional methods.     

Method for path imbalance measurement of the two-arm fiber-optic interferometer

The path imbalance (PI) of the two-arm fiber-optic interferometric sensor is a substantial parameter; a precise value of millimeters is required. Currently the precision reflectometry and the millimeter optical time-domain reflectometry are used to measure the tiny optical path difference, but the performances of these measurements are limited from the length and the resolution of the PI. We propose a new method accomplished by interferometer to accurately measure millimeters to within a few decimeters of the PI.     

Plano-concave microcuvette for measuring the absorption coefficient of highly absorbing liquids

A powerful and simple method based on the use of a plano-concave microcuvette was investigated for measuring the absorption coefficient of highly absorbing liquids. A plano-convex lens put on a plane-parallel plate formed a microcuvette with small, continuously varying thicknesses. This microcuvette was filled with liquid and illuminated by a homogeneous beam. The parabolic variation of the liquid thickness generates a Gaussian spatial intensity distribution behind the cuvette. This Gaussian profile, detected by a CCD camera, was used to determine the absorption coefficient of the liquid. An absorption coefficient as high as 1.54 x 10(4) cm(-1) was measured by use of high-concentration malachite green dye solutions. A comparison of the results with data extrapolated from those of conventional methods showed good agreement.     

A biosensor in the time domain based on the diffusion coefficient measurement: intermolecular interaction of an intermediate of photoactive yellow protein

A new type of biosensor is presented for the first time. This method is based on the diffusion measurement in the time domain by the transient grating method. As the first demonstration of this new method, various intermolecular interactions with a reaction intermediate of photoactive yellow protein, such as the protein-protein interaction, protein-DNA interaction, and protein-small molecule binding are detected. The characteristic advantages and limitations are summarized.     

Vibration compensating beam scanning interferometer for surface measurement

Light beam scanning using a dispersive element and wavelength tuning is coupled with fiber-optic interferometry to realize a new surface measurement instrument. The instrument is capable of measuring nanoscale surface structures and form deviations. It features active vibration compensation and a small optical probe size that may be placed remotely from the main apparatus. Active vibration compensation is provided by the multiplexing of two interferometers with near common paths. Closed loop control of a mirror mounted on a piezoelectric transducer is used to keep the path length stable. Experiments were carried out to deduce the effectiveness of the vibration compensation and the ability to carry out a real measurement in the face of large environmental disturbance.     

Measuring the refractive indices of liquids with a capillary tube interferometer

A theoretical analysis of the fringe pattern produced by a capillary tube interferometer is presented, which is expected to be two-beam interference, and a computer program to simulate the interference fringe pattern is established. By comparing the simulated fringe pattern and the experimental fringe pattern, the refractive index of the liquid can be given when the two fringes coincide best. The results of this method are close to those of the Abbe refractometer.