Measurement of Microscopic Deformation in a Cualni Single Crystal Alloy by Nanoindentation with a Heating Stage

Thermally induced recovery of nanoindents in a CUAINi single crystal shape memory alloy was studied by nanoindentation in conjunction with a heating stage. Nanoindents formed by a Berkovich indenter at room temperature were heated to 40, 70 and 100 degrees C. Partial recovery was observed for the nanoindents. The recovery ratio depended on the heating temperature. Indentation of CuAlNi can induce inelastic deformation via dislocation motion and a stress-induced matensitic transformation. The percentages of dislocation-induced plastic strain would affect the thermal deformation of CuAlNi, because the induced dislocations could stabilize stress-induced martensite plates even when the temperature above austenite finish temperature, A(f). When the applied indentation load is low (less than 10,000 mu N), the shape recovery strain is predominant, compared with the dislocation-induced plastic strain. Therefore, the degree of indent recovery in the depth direction, delta(D), is high (about 0.7-0.8 at 100 degrees C).

Measurement of instantaneous temperature in shock-loaded nonmetallic solids

The feasibility of direct measurement of temperature in shock-loaded, nonmetallic solids within microseconds using a foil thermocouple of 200 Å thickness has been studied over a range of pressure from 0.5 to 4 GPa. The foil thermocouple and thermopile (200 Å thickness) were designed and used to measure the temperature rise in shock-compressed polymethylmethacrylate (PMMA). The method used to manufacture the gauges is spelled out in detail in this paper. The results agree with calculated PMMA temperatures when the shock pressure is below 2.2 GPa. Above this pressure the measured temperature rise is far higher than the calculated values. This result appears to be very similar to that obtained earlier by Bloomquist and Sheffield.

Simultaneous measurement of temperature, density and velocity in gas-flows by modulated photoluminescence

A novel possibility to determine the temperature, density and velocity simultaneously in gas flows by measuring the average value, amplitude of modulation and phase shift of the photoluminescence excited by a temporally or spatially modulated light source is investigated. Time-dependent equations taking the flow, diffusion, excitation and decay into account are solved analytically. Different experimental arrangements are proposed. Measurements of velocity with two components, and temporal and spatial resolutions in the measurements are investigated. Numerical examples are given for N z with biacetyl as the seed gas. Practical considerations for the measurements and the relation between this method and some existing methods of lifetime measurement are discussed.

A thin liquid film and its effects in an atomic force microscopy measurement

Recently, it has been observed that a liquid film spreading on a sample surface will significantly distort atomic force microscopy (AFM) measurements. In order to elaborate on the effect, we establish an equation governing the deformation of liquid film under its interaction with the AFM tip and substrate. A key issue is the critical liquid bump height y(0c) at which the liquid film jumps to contact the AFM tip. It is found that there are three distinct regimes in the variation of y(0c) with film thickness H, depending on Hamaker constants of tip, sample and liquid. Noticeably, there is a characteristic thickness H* physically defining what a thin film is; namely, once the film thickness H is the same order as H* , the effect of film thickness should be taken into account. The value of H* is dependent on Hamaker constants and liquid surface tension as well as tip radius.

Measurement of velocity profiles in a rectangular microchannel with aspect ratio α = 0.35

In this work, we measured 14 horizontal velocity profiles along the vertical direction of a rectangular microchannel with aspect ratio alpha = h/w = 0.35 (h is the height of the channel and w is the width of the channel) using microPIV at Re = 1.8 and 3.6. The experimental velocity profiles are compared with the full 3D theoretical solution, and also with a Poiseuille parabolic profile. It is shown that the experimental velocity profiles in the horizontal and vertical planes are in agreement with the theoretical profiles, except for the planes close to the wall. The discrepancies between the experimental data and 3D theoretical results in the center vertical plane are less than 3.6%. But the deviations between experimental data and Poiseuille's results approaches 5%. It indicates that 2D Poiseuille profile is no longer a perfect theoretical approximation since a = 0.35. The experiments also reveal that, very near the hydrophilic wall (z = 0.5-1 mu m), the measured velocities are significantly larger than the theoretical velocity based on the no-slip assumption. A proper discussion on some physical effects influencing the near wall velocity measurement is given.

Development And Application Of Flexible Substrate Sensors In Instantaneous Heat Flux Measurement

A new type of sensor with the flexible substrate is introduced. It is applicable in measuring instantaneous heat flux on the model surface in a hypersonic shock tunnel. The working principle, structure and manufacture process of the sensor are presented. The substrate thickness and the dynamic response parameter of the sensor are calculated. Because this sensor was successfully used in measuring the instantaneous heat flux on the surface of a flat plate in a detonation-driven shock tunnel, it may be effective in measuring instantaneous heat flux on the model surface.

Direct measurement of entrainment in plasma jets

The entrainment rate of ambient gas into a turbulent argon plasma jet generated by plasma torch is directly measured using a “porous-wall chamber” technique. It is shown that with the increase of the mass flow rates of argon at the jet inlet, the mass flow rate of entrained gas increases. The normalized mass flow rate decreases with the increasing inlet mass flow rates of plasma torch. The entrained gas mass flow rate increases with increasing chamber length, but less depends on the arc current of the plasma torch at higher flow rates. The effects of different ways of inflowing gas into plasma torch on entrainment characteristics of plasma jet are also examined in this paper.

Influence of birefringence dispersion on distributed measurement of polarization coupling in birefringent fibers

A white light interferometer is developed to measure the distributed polarization coupling in high-birefringence polarization-maintaining fibers (PMFs). Usually the birefringence dispersion between two orthogonal eigenmodes of PMFs is neglected in such systems. Theoretical analysis and experimental results show that the birefringence dispersion becomes a nonnegligible factor in a long-fiber test. Significant broadening of interferograms and loss of longitudinal coherence are observed. The spatial resolution and measurement sensitivity of the system decrease correspondingly. Optimum spectrum width selection is presented for better spatial resolution and measurement range. c 2007 Society of Photo-Optical Instrumentation Engineers.

Aberration measurement of projection optics in lithographic tools based on two-beam interference theory

The degradation of image quality caused by aberrations of projection optics in lithographic tools is a serious problem in optical lithography. We propose what we believe to be a novel technique for measuring aberrations of projection optics based on two-beam interference theory. By utilizing the partial coherent imaging theory, a novel model that accurately characterizes the relative image displacement of a fine grating pattern to a large pattern induced by aberrations is derived. Both even and odd aberrations are extracted independently from the relative image displacements of the printed patterns by two-beam interference imaging of the zeroth and positive first orders. The simulation results show that by using this technique we can measure the aberrations present in the lithographic tool with higher accuracy. (c) 2006 Optical Society of America.

Aberration measurement of projection optics in lithographic tools by use of an alternating phase-shifting mask

As a critical dimension shrinks, the degradation in image quality caused by wavefront aberrations of projection optics in lithographic tools becomes a serious problem. It is necessary to establish a technique for a fast and accurate in situ aberration measurement. We introduce what we believe to be a novel technique for characterizing the aberrations of projection optics by using an alternating phase-shifting mask. The even aberrations, such as spherical aberration and astigmatism, and the odd aberrations, such as coma, are extracted from focus shifts and image displacements of the phase-shifted pattern, respectively. The focus shifts and the image displacements are measured by a transmission image sensor. The simulation results show that, compared with the accuracy of the previous straightforward measurement technique, the accuracy of the coma measurement increases by more than 30% and the accuracy of the spherical-aberration measurement increases by approximately 20%. (c) 2006 Optical Society of America.

Measurement technique for in situ characterizing aberrations of projection optics in lithographic tools

As the feature size decreases, degradation of image quality caused by wavefront aberrations of projection optics in lithographic tools has become a serious problem in the low-k1 process. We propose a novel measurement technique for in situ characterizing aberrations of projection optics in lithographic tools. Considering the impact of the partial coherence illumination, we introduce a novel algorithm that accurately describes the pattern displacement and focus shift induced by aberrations. Employing the algorithm, the measurement condition is extended from three-beam interference to two-, three-, and hybrid-beam interferences. The experiments are performed to measure the aberrations of projection optics in an ArF scanner. (C) 2006 Optical Society of America.

Quantitative measurement of domain inversion in RuO2 : LiNbO3 crystal by digital holographic interferometry

We quantitatively study the domain inversion in a RuO2:LiNbO3 crystal wafer by the digital holographic interferometry. The crystal wafer is placed into one arm of a Mach-Zehnder-type interferometer to record a series of holograms. Making use of the angular spectrum backward propagation algorithm, we reconstruct the optical wave field in the crystal plane. The extracted phase difference from the reconstructed optical wave field is a well linear function of the applied external voltage. We deduce that the linear electro-optic coefficient of the detected RuO2:LiNbO3 crystal sample is 9.1x10(-12) m/V. An unexpected phase contrast at the antiparallel domain wall is observed and the influence of the applied external voltage on it is studied in detail. Also the built-in internal field is quantitatively measured as 0.72 kV/mm. (c) 2006 American Institute of Physics.

Distributed measurement of birefringence dispersion in polarization-maintaining fibers

A new method to measure the birefringence dispersion in high-birefringence polarization-maintaining fibers is presented using white-light interferometry. By analyzing broadening of low-coherence interferograms obtained in a scanning Michelson interferometer, the birefringence dispersion and its variation along different fiber sections are acquired with high sensitivity and accuracy. Birefringence dispersions of two PANDA fibers at their operation wavelength are measured to be 0.011 ps/(km nm) and 0.018 ps/(km nm), respectively. Distributed measurement capability of the method is also verified experimentally. (c) 2006 Optical Society of America.

Influence of birefringence dispersion on distributed measurement of polarization coupling in birefringent fibers

A white light interferometer is developed to measure the distributed polarization coupling in high-birefringence polarization-maintaining fibers (PMFs). Usually the birefringence dispersion between two orthogonal eigenmodes of PMFs is neglected in such systems. Theoretical analysis and experimental results show that the birefringence dispersion becomes a nonnegligible factor in a long-fiber test. Significant broadening of interferograms and loss of longitudinal coherence are observed. The spatial resolution and measurement sensitivity of the system decrease correspondingly. Optimum spectrum width selection is presented for better spatial resolution and measurement range. c 2007 Society of Photo-Optical Instrumentation Engineers.