Interferometry Microscopy Research Articles

Correlation of the holes quality with the force signals in a microdrilling process of a sintered tungsten-copper alloy

Holes quality errors are an undesired but unavoidable consequence in drilling operations. Due to the small dimensions involved in the microdrilling processes, quality measurement and control must be carried out offline, by using microscopy or other high precision measurement devices. This paper presents a study about the correlation between the holes quality and the force signals in the microdilling process of 0.1 mm and 0.5 mm-diameter holes in a sintered tungsten-copper alloy. The surface of the obtained holes was scanned by means of an interferometry microscope and the error of the holes was computed from the scanned data. The three components of the forces were measured during all the drilling process. The behavior of these signals, in three different intervals (tool entrance, forward motion and backward motion) was described by wavelet package analysis. The features having higher correlation with the holes quality error were the average power of the axial component of the forces in the frequency bands of 0~391 Hz and 3906~4297 Hz, during the backward motion. With these features, a statistical regression model was fitted. The main outcomes of this study are the basement for obtaining reliable models for monitoring systems in microdrilling operations.

Enhanced bone healing around nanohydroxyapatite-coated polyetheretherketone implants: An experimental study in rabbit bone.

To investigate the bone response to threaded polyetheretherketone (PEEK) implants coated with nanohydroxyapatite. A total of 39 PEEK implants were coated with nanocrystalline hydroxyapatite and 39 uncoated implants were used as controls. The implant surface was characterized by optical interferometry and scanning electron microscope. The implants were inserted in the tibia and femur of 13 rabbits. After 6 weeks of healing, quantitative and qualitative analyses were performed. The test implants showed significantly higher removal torque test values compared with the control group. Histomorphometric evaluation demonstrated higher bone-to-implant contact for the test implants; however, there were no differences in bone area between the groups. Qualitative histological analyses demonstrated inflammatory cellular reactions in close vicinity of both implant surfaces. A two-cell layer of foreign body giant cells was observed irrespective of sample type. Our findings demonstrate that implants with a threaded design render good stability to PEEK in both coated and uncoated implants. Nanohydroxyapatite-coated PEEK implants demonstrated improved bone formation compared with uncoated controls.

In-situ atomic force microscopy study of the mechanism of surface relief grating formation in photosensitive polymer films

When photosensitive azobenzene-containing polymer films are irradiated with light interference patterns, topographic variations in the film develop that follow the local distribution of the electric field vector. The exact correspondence of e.g., the vector orientation in relation to the presence of local topographic minima or maxima is in general difficult to determine. Here, we report on a systematic procedure how this can be accomplished. For this, we devise a new set-up combining an atomic force microscope and two-beam interferometry. With this set-up, it is possible to track the topography change in-situ, while at the same time changing polarization and phase of the impinging interference pattern. This is the first time that an absolute correspondence between the local distribution of electric field vectors and the local topography of the relief grating could be established exhaustively. Our setup does not require a complex mathematical post-processing and its simplicity renders it interesting for characterizing photosensitive polymer films in general.

Friction and wear performances of hot filament chemical vapor deposition multilayer diamond films coated on silicon carbide under water lubrication

Tribological properties of chemical vapor deposition (CVD) diamond films greatly affect its application in the mechanical field. In this paper, a novel multilayer structure is proposed, with which multilayer diamond films are deposited on silicon carbide by hot filament CVD (HFCVD) method. The different micrometric diamond grains are produced by adjusting deposition parameters. The as-deposited multilayer diamond films are characterized by scanning electron microscope (SEM) and white-light interferometry. The friction tests performed on a reciprocating ball-on-plate tribometer suggest that silicon carbide presents the friction coefficient of 0.400 for dry sliding against silicon nitride (Si3N4) ceramic counterface. With the water lubrication, the corresponding friction coefficients of silicon carbide and as-deposited multilayer diamond films further reduce to 0.193 and 0.051, respectively. The worn surfaces indicate that multilayer diamond films exhibit considerably high wear resistance.

激光全息干涉测定微通道内气液传质

激光全息干涉测定微通道内气液传质

Experimental investigation of flash weakening in limestone

Flash heating and weakening could operate during earthquake nucleation and propagation. We performed 27 friction experiments in a compression-torsion apparatus on ring-shaped limestone samples at sub-seismic to seismic slip rates ≤340 mm/s, centimetric displacements and normal stresses of ≤8 MPa. Friction decreases dramatically at slip rates of 50–150 mm/s. Flash weakening was contemporaneous with a peripheral temperature rise of ∼90 °C measured with an infrared camera. The peripheral temperature yields a lower limit to the slipping zone temperature.The decrease in friction may result from weakening of the asperity contacts due to decarbonation of calcite induced by (1) flash heating or (2) mechanically-activated reactions. However, X-Ray powder diffraction and Raman Spectroscopy analyses do not reveal the presence of decarbonation products in the slipping zone. Instead, White Light Interferometry and Field Emission Scanning Electron Microscope observations reveal the presence of a smooth sliding surface made of nanometric-particles. The mechanical data can be fit by the rate- and state-dependent friction model or by a quadratic model (the latter proposed for powder lubrication). We conclude that flash heating and weakening and powder lubrication may operate together to decrease dynamic friction in limestone in experiments and, for the conditions investigated here, in nature.

Visually guided 3D micro positioning and alignment system

This paper presents a Visually Guided Micro Positioning and Alignment System that employs Scanning White Light Interferometry (SWLI). An Interferometry microscope is integrated with a magnetically suspended motion stage to achieve alignment of micro objects in 3D. Based on the SWLI measurement an integrated control scheme is presented which enables the alignment of micro objects in 3D space. A demonstration of 3D micro alignment and manipulation was designed to show the capabilities of the integrated system. Alignment and docking of two silicon micro cantilevers is demonstrated using the magnetically suspended stage and the 3D sensing ability of the SWLI. Experimental results show that cantilever docking can be achieved with less than 30nN force sensitivity.

Single and reciprocal friction testing of micropatterned surfaces for orthopedic device design

The use of micropatterning to create uniform surface morphologies has been cited as yielding improvements in the coefficient of friction during high velocity sliding contact. Studies have not been preformed to determine if these micropatterns could also be useful in biomedical applications, such as total joint replacement surfaces, where the lower sliding velocities are used. In addition, other factors such as lubricant viscosities and materials used are more tightly constrained. In this study, the effect of pattern geometry, feature size and lubricant on contact friction and surface damage was investigated using 316L steel in sliding contact with a stainless steel and polyethylene pins. Using a novel proprietary forming process that creates millions of microstructures in parallel, a variety of micropatterned surfaces were fabricated to study the influence of shape (oval, circular, square), geometry (depressions, pillars) and feature size (10, 50 and 100 mm) on both contact friction and surface damage. All samples were 316L stainless steel and the static and dynamic coefficients of friction when in contact with either a stainless steel or polyethylene counterface were measured in dry and lubricated conditions. All samples were characterized for surface uniformity and pattern aspect ratio using white light interferometry and optical microscope image analysis, and the coefficients of friction were measured for each surface/lubricant/pin system using a CETR scratch testing system. Results showed that round depressions with diameters of 10 μm had a significantly lower steady state coefficient of friction than the non-patterned substrates or substrates with greater diameter depression patterns. In addition, our results showed that the single-pass coefficient of friction measurements were not good predictors of the steady state coefficient of friction values measured.

Ultraslow growth rates of giant gypsum crystals

Mineralogical processes taking place close to equilibrium, or with very slow kinetics, are difficult to quantify precisely. The determination of ultraslow dissolution/precipitation rates would reveal characteristic timing associated with these processes that are important at geological scale. We have designed an advanced high-resolution white-beam phase-shift interferometry microscope to measure growth rates of crystals at very low supersaturation values. To test this technique, we have selected the giant gypsum crystals of Naica ore mines in Chihuahua, Mexico, a challenging subject in mineral formation. They are thought to form by a self-feeding mechanism driven by solution-mediated anhydrite-gypsum phase transition, and therefore they must be the result of an extremely slow crystallization process close to equilibrium. To calculate the formation time of these crystals we have measured the growth rates of the {010} face of gypsum growing from current Naica waters at different temperatures. The slowest measurable growth rate was found at 55 °C, 1.4 ± 0.2 × 10(-5) nm/s, the slowest directly measured normal growth rate for any crystal growth process. At higher temperatures, growth rates increase exponentially because of decreasing gypsum solubility and higher kinetic coefficient. At 50 °C neither growth nor dissolution was observed indicating that growth of giant crystals of gypsum occurred at Naica between 58 °C (gypsum/anhydrite transition temperature) and the current temperature of Naica waters, confirming formation temperatures determined from fluid inclusion studies. Our results demonstrate the usefulness of applying advanced optical techniques in laboratory experiments to gain a better understanding of crystal growth processes occurring at a geological timescale.

Parallel two-step phase-shifting microscopic interferometry based on a cube beamsplitter

Parallel two-step phase-shifting interferometry for microscopy is presented, and the recording condition for generalized two-step phase-shifting interferometry is discussed. A 45° tilted cube beamsplitter enables to replicate the orthogonally linear polarized object and reference waves into two parallel beams, respectively. As a consequence, two interferograms with quadrature phase shift are obtained along the two beams, and phase reconstructed with an improved algorithm. To reconstruct the phase distribution from the two-step phase-shifting interferograms, a certain recording condition should be satisfied. However, the recording condition has not ever been discussed before. In this paper, the recording condition for the two-step phase-shifting interferometry is derived and that is: the intensity of reference wave should be no less than two times object wave intensity.

Interlaminate Deformation in Thermoplastic Composite Laminates: Experimental-Numerical Correlation

The interlaminar deformation behaviors of thermoplastic AS4/PEEK composite laminates subjected to static tensile loading are investigated by means of microscopic moire interferometry with high spatial resolution. The fully three- dimensional orthotropic elastic-plastic analysis of interlaminar deformation for the thermoplastic laminates is developed in this paper, and used to simulate the stress-strain curves of tensile experiment for its angle-ply laminates. Under uniaxial tensile loading, the 3D orthotropic elastic-plastic FE analysis and microscopic moire interferometry of interlaminar deformations are carried out for the (±25)S4 laminates. The quantitative local-filed experimental results of interlaminar shear strain and displacements at free- edge surface of the laminate are compared with corresponding numerical results of the orthotropic elastic-plastic FE model. It is indicated that the numerical tensile stress- strain curves of angle-ply laminates computed with 3D orthotropic elastic-plastic model are agree with experimental results. The numerical interlaminar displacement U and shear strainxz are also consistent with the experimental results obtained by moire interferometry. It is expected the elastic-plastic interlaminar stresses and deformations analysis for the optimal design and application of AS4/PEEK laminates and its structures.

显微干涉术在血红细胞光相位场定量测量中的应用

显微干涉术在血红细胞光相位场定量测量中的应用

白色光干渉顕微鏡による表面トポグラフィ測定

白色光干渉顕微鏡による表面トポグラフィ測定

Long-working-distance Linnik microscopic interferometry for measuring the surface profile of microstructures

The surface profile is an important specification that influences the performance and stability of a microelectromechanical system device. Microscopic interferometry is, up to now, the most widely used technique for surface profiles of microstructures. A long working distance is needed when it is necessary to place components such as probes or transparency windows between microstructures and the objective. In this paper, a long-working-distance Linnik microscopic interferometer system was developed for meeting above requirements. Because it is difficult to ensure that the sample and the reference objectives are completely identical, the surface profile is modulated by unmatched optical path length between measurement and reference arms. This paper puts forward compensation process for demodulating the surface profile. Experiment results show that this method can provide correct measurement of the surface profile of microstructures effectively.

Dynamic out-of-plane profilometry for nano-scale full-field characterization of MEMS using stroboscopic interferometry with novel signal deconvolution algorithm

A dynamic 3D nano-scale surface profilometer using stroboscopic white-light interferometry with novel signal deconvolution was developed to deliver dynamic surface profilometry with a measurement bandwidth of up to a MHz scale and a vertical resolution reaching 1 nm. Previous work using stroboscopic microscopic interferometry for dynamic characterization of micro-(opto)electromechanical systems (M(O)EMS) has been limited in measurement bandwidth of less than a few hundred kHz due to physical length limitation of stroboscopic light. For high-resonance mode analysis, the stroboscopic light pulse is too lengthy to capture the moving fringes from dynamic motion of the detected structure. In view of this need, a novel deconvolution algorithm using correction of the light response was developed for removing potential image blurs caused by the unavoidable vibration of the tested parts. With this advance in technology, the bandwidth of dynamic measurement can be significantly increased without sacrificing measurement accuracy. A microcantilever beam used in AFM was measured to verify the capability of the system in accurate characterization of dynamic behaviors of M(O)EMS.

A high precision profilometer based on vertical scanning microscopic interferometry

A profilometer used for 3 dimension measurement of micro-surface topography is presented. The instrument is based on the vertical scanning microscopic interferometry (VSMI). A Linnik type interference microscope is used and the interferograms which present changes of surface profile are recorded with a CCD camera. A developed nano-positioning work stage with an integrated optical grating displacement measuring system realizes the precise vertical scanning motion during profile measurement. By a white-light phase shifting algorithm of arbitrary step, frames of interferograms are processed by a computer to rebuild and evaluate the measured profile. Because of the specialty of VSMI, the profilometer is suitable for both smooth and rough surface measurement. It can also be used to measure curved surfaces, dimension of micro electro mechanical systems (MEMS), etc. The vertical resolution of the profilometer is 0.5 nm, and lateral resolution 0.5 μm.

마이크로 무아레 간섭계를 이용한 초정밀 변형 측정

Moire interferometry is an optical method, providing whole field contour maps of in-plane displacements with high resolution. The demand for enhanced sensitivity in displacement measurements leads to the technique of microscopic moire interferometry. The method is an extension of the moire interferometry, and employs an optical microscope for the required spatial resolution. In this paper, the sensitivity of moire interferometry is enhanced by an order of magnitude using an immersion interferometry and the optical/digital fringe multiplication(O/DFM) method. In fringe patterns, the contour interval represents the displacement of 52 ㎚ per fringe order. In order to estimate the reliability and the applicability of the optical system implemented, the measurements of rigid body displacements of grating mold and the coefficient of thermal expansion(CTE) for an aluminium block are performed. The system developed is applied to the measurement of thermal deformation in a flip chip plastic ball grid array package.

A Scanning White-Light Interferometric Profilometer for Smooth and Rough Surface

A profilometer for micro-surface topography measurement is presented. The instrument is based on the scanning white-light microscopic interferometry (SWLMI). A Linnik type interference microscope is used and the interferograms which present changes of surface profile are recorded by a CCD camera. A developed nano-positioning work stage with integrated optical grating displacement measuring system realizes the precise vertical scanning motion during profile measurement. By white-light phase shifting algorism of arbitrary steps, frames of interferograms are processed by computer to rebuild and evaluate the measured profile. Because of the specialty of SWLMI, the profilometer is suitable for both smooth and rough surface measuring. It also can be used for the measurement of curved surface, dimension of MEMS etc. The vertical resolution of the profilometer is 0.5nm, lateral resolution 0.5+m.

Optical properties of synthetic crystals of brushite (CaHPO 4·2H 2O)

The principal refractive indices of brushite (CaHPO 4·2H 2O) crystals for sodium light, 589 nm, have been determined by a combination of several methods: microscopic interferometry, retardation measurements with an Ehringhaus 6 λ compensator, and determination of the angle 2 V between optic axes from the measurements of extinction directions using a spindle stage and evaluating the data with the computer program EXCALIBRW. The following values were found: n α =1.54089, n β =1.54620, n γ =1.55191, and 2 V=88.2°. The standard deviations of the three indices lie in the range 7–8×10 −5. The results are regarded valuable in connection with studies of crystal growth kinetics in biological mineralization and related fields.

PZT thick films on different ceramic substrates; piezoelectric measurements

The piezoelectric, microstructural and electrical characteristics of thick PZT films on relatively inert alumina substrates and on two LTCC tapes, i.e., Du Pont 951 and Electro Science Labs 41020 were studied. A thick-film paste was prepared from the pre-reacted PZT powder (PbZr0.53Ti0.47O3) and printed and fired on LTCC tapes and on alumina substrates, respectively. Dielectric permittivities, dielectric losses, remnant polarizations and coercive fields were measured. The dielectric constants (100–150) of thick films fired on LTCC substrates are low. The piezoelectric coefficients d33 were measured by different methods, i.e. Berlincourt piezometer, interferometry and piezoresponse force microscope (PFM). The d33 values on LTCC substrates are low (30–70 pm/V) as compared with values obtained on alumina substrates (around 120 pm/V). Lower dielectric constants and piezoelectric coefficients d33 of films on LTCC substrates are attributed to the formation of phases with a low permittivity due to the diffusion of silica from LTCC substrates into PZT films. The d33 constants of samples with different thicknesses of PZT layers (from 20 to 160 μm) at first increase with the increasing thickness of PZT layers and then decrease for thicker films. As the cracks in the structure were not observed the reason for the decreasing d33 values for thicker films is still unclear.