Confocal Profilometer Research Articles

Genetic and Developmental Basis for Increased Leaf Thickness in the Arabidopsis Cvi Ecotype.

Leaf thickness is a quantitative trait that is associated with the ability of plants to occupy dry, high irradiance environments. Despite its importance, leaf thickness has been difficult to measure reproducibly, which has impeded progress in understanding its genetic basis, and the associated anatomical mechanisms that pattern it. Here, we used a custom-built dual confocal profilometer device to measure leaf thickness in the Arabidopsis Ler × Cvi recombinant inbred line population and found statistical support for four quantitative trait loci (QTL) associated with this trait. We used publically available data for a suite of traits relating to flowering time and growth responses to light quality and show that three of the four leaf thickness QTL coincide with QTL for at least one of these traits. Using time course photography, we quantified the relative growth rate and the pace of rosette leaf initiation in the Ler and Cvi ecotypes. We found that Cvi rosettes grow slower than Ler, both in terms of the rate of leaf initiation and the overall rate of biomass accumulation. Collectively, these data suggest that leaf thickness is tightly linked with physiological status and may present a tradeoff between the ability to withstand stress and rapid vegetative growth. To understand the anatomical basis of leaf thickness, we compared cross-sections of Cvi and Ler leaves and show that Cvi palisade mesophyll cells elongate anisotropically contributing to leaf thickness. Flow cytometry of whole leaves show that endopolyploidy accompanies thicker leaves in Cvi. Overall, our data suggest that mechanistically, an altered schedule of cellular events affecting endopolyploidy and increasing palisade mesophyll cell length contribute to increase of leaf thickness in Cvi. Ultimately, knowledge of the genetic basis and developmental trajectory leaf thickness will inform the mechanisms by which natural selection acts to produce variation in this adaptive trait.

Genetic Architecture and Molecular Networks Underlying Leaf Thickness in Desert-Adapted Tomato Solanum pennellii.

Thicker leaves allow plants to grow in water-limited conditions. However, our understanding of the genetic underpinnings of this highly functional leaf shape trait is poor. We used a custom-built confocal profilometer to directly measure leaf thickness in a set of introgression lines (ILs) derived from the desert tomato Solanum pennellii and identified quantitative trait loci. We report evidence of a complex genetic architecture of this trait and roles for both genetic and environmental factors. Several ILs with thick leaves have dramatically elongated palisade mesophyll cells and, in some cases, increased leaf ploidy. We characterized the thick IL2-5 and IL4-3 in detail and found increased mesophyll cell size and leaf ploidy levels, suggesting that endoreduplication underpins leaf thickness in tomato. Next, we queried the transcriptomes and inferred dynamic Bayesian networks of gene expression across early leaf ontogeny in these lines to compare the molecular networks that pattern leaf thickness. We show that thick ILs share S. pennellii-like expression profiles for putative regulators of cell shape and meristem determinacy as well as a general signature of cell cycle-related gene expression. However, our network data suggest that leaf thickness in these two lines is patterned at least partially by distinct mechanisms. Consistent with this hypothesis, double homozygote lines combining introgression segments from these two ILs show additive phenotypes, including thick leaves, higher ploidy levels, and larger palisade mesophyll cells. Collectively, these data establish a framework of genetic, anatomical, and molecular mechanisms that pattern leaf thickness in desert-adapted tomato.

Multilayered diamond mechanical seal rings under biodiesel lubrication and the full sealing conditions of pressurized water

A mechanical sealing tribosystem based on multilayer microcrystalline/nanocrystalline diamond (MCD/NCD) coatings is proposed. The tribological behaviour was investigated in ring–on–ring self–mated planar contact configuration. Tests were carried out under biodiesel lubrication and pressurized water (2bar) sealing conditions. A 3D optical confocal profilometer was used to obtain for the first time the wear coefficients of seal rings, revealing a value of k=6.3×10−10mm3/N.m for biodiesel lubrication that is two orders of magnitude lower than for reciprocating sliding ball-on-flat experiments. The advantage of the multilayer strategy was demonstrated in the sealing of pressurized water, where full sealing conditions were achieved within the P×V range of 0.75–5.5MPams−1. For these coatings, full delamination is prevented due to structural discontinuity at the MCD/NCD interfaces whereas for a MCD monolayer coating, premature failure takes place and sealing is not reached.

Measurement uncertainty associated with chromatic confocal profilometry for 3D surface texture characterization of natural human enamel

ObjectiveTo investigate the measurement performance of a chromatic confocal profilometer for quantification of surface texture of natural human enamel in vitro. MethodsContributions to the measurement uncertainty from all potential sources of measurement error using a chromatic confocal profilometer and surface metrology software were quantified using a series of surface metrology calibration artifacts and pre-worn enamel samples. The 3D surface texture analysis protocol was optimized across 0.04mm2 of natural and unpolished enamel undergoing dietary acid erosion (pH 3.2, titratable acidity 41.3mmolOH/L). ResultsFlatness deviations due to the x, y stage mechanical movement were the major contribution to the measurement uncertainty; with maximum Sz flatness errors of 0.49μm. Whereas measurement noise; non-linearity’s in x, y, z and enamel sample dimensional instability contributed minimal errors. The measurement errors were propagated into an uncertainty budget following a Type B uncertainty evaluation in order to calculate the Standard Combined Uncertainty (uc), which was ±0.28μm. Statistically significant increases in the median (IQR) roughness (Sa) of the polished samples occurred after 15 (+0.17 (0.13)μm), 30 (+0.12 (0.09)μm) and 45 (+0.18 (0.15)μm) min of erosion (P<0.001 vs. baseline). In contrast, natural unpolished enamel samples revealed a statistically significant decrease in Sa roughness of −0.14 (0.34) μm only after 45min erosion (P<0.05s vs. baseline). SignificanceThe main contribution to measurement uncertainty using chromatic confocal profilometry was from flatness deviations however by optimizing measurement protocols the profilometer successfully characterized surface texture changes in enamel from erosive wear in vitro.

Microstructure, tensile properties and wear resistance correlations on directionally solidified Al-Sn-(Cu; Si) alloys

The development of alloys suitable for engine bearings demands not only reducing the amount of wear as well as increasing the load carrying capability due to both engines stop/start systems and sudden rise in load or velocity. Al-Sn based alloys are well-known for having excellent tribological and mechanical properties fulfilling these requirements: Sn is a self-lubricating component and addition of third elements should increase the strength of the Al-rich matrix. The current study focuses on interrelations of microstructure of directionally solidified Al-Sn(Cu; Si) alloys and mechanical/tribological properties. In order to analyze the influence of alloy Sn content on the tribological behavior of these ternary alloys, ball-on-disc wear tests were performed under dry sliding conditions. Correlations between tensile strength, elongation and wear volume and the primary dendritic arm spacing (λ1) have been determined. The worn samples were analyzed by scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and the wear scar topographies by a confocal profilometer. The analysis of the worn surfaces revealed a change from abrasive to adhesive wear mechanism for Al-Sn-Cu alloys and only adhesive one for Al-Sn-Si alloys. For Al-Sn-Cu alloys, the best wear resistance was observed to be related to coarser microstructures whereas refined microstructures improved the tensile properties, indicating an inverse trend between tensile and tribological properties. The wear resistance of the Al-Sn-Si alloys were shown not to be affected by the size of λ1, however the tensile strength is shown to increase significantly with the decrease in λ1.

A new high-resolution 3-D quantitative method for identifying bone surface modifications with implications for the Early Stone Age archaeological record

Bone surface modifications have become important indicators of hominin behavior and ecology at prehistoric archaeological sites. However, the method by which we identify and interpret these marks remains largely unchanged despite decades of research, relying on qualitative criteria and lacking standardization between analysts. Recently, zooarchaeologists have begun using new technologies capable of capturing 3-D data from bone surface modifications to advance our knowledge of these informative traces. However, an important step in this research has been overlooked and after years of work, we lack both a universal and replicable protocol and an understanding of the precision of these techniques. Here we propose a new standard for identifying bone surface modifications using high-resolution 3-D data and offer a systematic and replicable approach for researchers to follow. Data were collected with a white-light non-contact confocal profilometer and analyzed with Digital Surf's Mountains® software. Our data show that when methods are standardized, results between researchers are statistically indistinguishable. Multivariate analyses using the measured parameters allow discrimination between stone tool cut marks and mammalian carnivore tooth marks with 97.5% accuracy. Application of this method to fossil specimens resulted in 100% correspondence with identifications made by an experienced analyst using macroscopic observations of qualitative features of bone surface modifications. High-resolution 3-D analyses of bone surface modifications have great potential to improve the reliability and accuracy of taphonomic research, but only if our methods are replicable and precise.

Measuring profile of large hybrid aspherical diffractive infrared elements using confocal profilometer

The discrete profiles of large hybrid aspherical diffractive infrared elements (HADIEs) are measured using a confocal profilometer, and are extracted using a polynomial regression method. In this study, a HADIE with a diameter of 80 mm is measured using a confocal profilometer with maximum horizontal and vertical measurement ranges of 120 mm and 12 mm, respectively. The experimental results indicate that the confocal profilometer can compensate for the fabrication error of the HADIE, which can be reduced from 7.20 µm to 1.05 µm. Furthermore, a profile error of 0.64 µm (measured peak-to-valley (P-V)) is obtained after correcting for the curvature error. The confocal profilometer is a nondestructive tool that can be used to measure the profile of HADIEs, and is particularly suitable in compensating for the fabrication error of fine optical elements.

On the tribological behavior of retrieved hip femoral heads affected by metallic debris. A comparative investigation by stylus and optical profilometer for a new roughness measurement protocol

In this study, 35 retrieved ceramics femoral heads with evidence of metallic dark lines on the surface were analyzed. The surface roughness of these femoral heads was acquired using both a stylus contact profiler and an optical non-contact profilometer. The metallic deposition on hip ball surface, also known as Metal Transfer (MT), appeared as dark metallic and can occur during the surgery or during the reduction of a dislocated prosthesis. In this study, we validate a new protocol to measure surface roughness on retrieved femoral heads, by using the aforementioned two different acquisition techniques and also to investigate the hypothesis that such metal transfer retrieved ceramic femoral head is associated with increased surface roughness.All femoral components of this investigation showed remarkable differences in roughness values between MT-affected and MT-unaffected areas. The two acquisition procedures – conventional stylus and 3D confocal profilometer – confirmed a satisfying agreement, even considering the obvious resolution difference.

Topological characterization of antireflective and hydrophobic rough surfaces: are random process theory and fractal modeling applicable?

The random process theory (RPT) has been widely applied to predict the joint probability distribution functions (PDFs) of asperity heights and curvatures of rough surfaces. A check of the predictions of RPT against the actual statistics of numerically generated random fractal surfaces and of real rough surfaces has been only partially undertaken. The present experimental and numerical study provides a deep critical comparison on this matter, providing some insight into the capabilities and limitations in applying RPT and fractal modeling to antireflective and hydrophobic rough surfaces, two important types of textured surfaces. A multi-resolution experimental campaign using a confocal profilometer with different lenses is carried out and a comprehensive software for the statistical description of rough surfaces is developed. It is found that the topology of the analyzed textured surfaces cannot be fully described according to RPT and fractal modeling. The following complexities emerge: (i) the presence of cut-offs or bi-fractality in the power-law power-spectral density (PSD) functions; (ii) a more pronounced shift of the PSD by changing resolution as compared to what was expected from fractal modeling; (iii) inaccuracy of the RPT in describing the joint PDFs of asperity heights and curvatures of textured surfaces; (iv) lack of resolution-invariance of joint PDFs of textured surfaces in case of special surface treatments, not accounted for by fractal modeling.

Note: development of high speed confocal 3D profilometer.

A high-speed confocal 3D profilometer based on the chromatic confocal technology and spinning Nipkow disk technique has been developed and tested. It can measure a whole surface topography by taking only one image that requires less than 0.3 s. Surface height information is retrieved based on the ratios of red, green, and blue color information. A new vector projection technique has developed to enhance the vertical resolution of the measurement. The measurement accuracy of the prototype system has been verified via different test samples.

Wear mechanisms and in-service surface modifications of a stellite 6B Co-Cr alloy

In the present paper, the in-service wear mechanisms and cross-sectional microstructural evolution of a Stellite 6B cobalt-based alloy subjected to sliding contact conditions are analysed. The analysis is carried out using focused ion beam (FIB), transmission electron microscopy (TEM), 3D confocal profilometer and nanoindentation techniques. Samples under investigation consisted of a lip-seal adopted in a Tunnel Boring Machine (TBM). In the working conditions, the lip-seal is in sliding contact with a rubber seal in a pressurised oil environment. In those conditions, an unexpected low wear resistance was observed during service. As a consequence, a long machine downtime was necessary to replace the damaged component. Results of FIB-SEM/EDS characterisation showed severe grooving due to the presence of sand (SiO2) particles embedded in the rubber seal in the contact area. In addition, three body abrasive wear is observed immediately outside the contact area. Microstructural evaluation of Stellite 6 B Co-based alloy of the cross-section also showed the presence of a nano-crystalline hardened layer with diffuse presence of stacking faults. The presence of a tribo-film with a complex structure was also clearly observed. It is concluded that wear resistance of such components could be significantly enhanced either by a proper control of abrasive contaminant particles in the lubricant oil or by introducing a proper protective coating (e.g. a thermal sprayed thick coating).

Relationships between 3D roughness parameters and visuotactile perception of surfaces of maritime pinewood and MDF

Abstract The objective measurement and subjective estimation of the surface quality by the consumers are important issues for furniture production and marketing. The objective of the present study is to find suitable (objective) roughness parameters that are linked to human sensation. Maritime pinewood and medium-density fiberboard (MDF) made from the same species are in focus. The roughness was measured by means of a 3D confocal profilometer and 13 independent 3D roughness parameters were computed. The quality of surfaces was modified through sanding, whereas the grit size of sand papers ranged between P60 and P320. The applied pressure and sanding time were controlled. The subjective estimation of the surface aspects was performed by several individuals through sensorial analysis. Biplots of several roughness parameters versus tactile rank revealed in the case of MDF a significant correlation to arithmetical average roughness S a and valley material component S r2. For pinewood, the parameters arithmetical average roughness S a and texture aspect ratio S tr correlated best to tactile rank.

Picosecond Laser Micromachining of Ultra-Hard AlMgB&lt;sub&gt;14&lt;/sub&gt; Thin Films

Ultra-hard AlMgB14 (30-50 GPa) thin films were deposited on silicon substrate for a nominal thickness of 100 nm using a pulsed excimer laser and then subjected to direct micromachining using a 532 nm, 30 picosecond pulsed Nd:YAG laser. The application is targeted towards synthesizing an artificial nacre material composed of hexagonal bricks and particle bridges of superhard AlMgB14 thin film and mortars of Ti thin film that biomimic the hierarchical architecture of natural nacre. The effects of pulse energy (0.1 to 1 μJ) and laser scanning speed (0.5 to 1.5 m/sec) on ablation depth and quality of scribed channels were evaluated. The morphology of the channels was characterized using confocal microscope and optical profilometer. Results indicated a clean material removal process characterized by absence of heat affected zone, high-speed scribing and small feature size. The energy fluence for the removal of 100 nm thin film without affecting the silicon substrate was 0.3 J/cm2. An interesting observation is that particulate matter present in the thin film was not ablated suggesting a size effect. Analysis of thermal transport reveals that the material removal has occurred via spallation and phase explosion mechanisms. The picosecond laser thus offers a high-speed energy source for precisely ablating ultra-hard thin films that in turn will allow the potential for fabrication of novel artificial nacre with exceptional strength and toughness.

On the use of femtosecond laser ablation to facilitate spectroscopic depth profiling of heterogeneous polymeric coatings

Spectroscopic depth profiling of organic coatings is useful for characterizing the nature and spatial distribution of weather-induced aging on a coating system. Due to their highly heterogeneous compositions and general opacity, high-solids organic coatings can be extremely difficult to depth profile using established techniques. This work evaluates the feasibility of using femtosecond time-scale laser pulses as a method for preparing coating samples for the purpose of depth-resolved spectroscopic analysis. Samples were prepared by ablating square regions of various depths in military coating samples. Ablated regions were characterized morphologically using a custom scanning confocal profilometer and spectroscopically using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) and dispersive Raman spectroscopy. Depth profiles collected from ablated samples were compared with profiles of the same material collected using a cross-sectional transmission-mode FTIR technique. A threshold level was found, below which a compound-selective ablation process was observed. Additional ether cross-linking was found to occur at moderate/high energy levels. Material in the residual interaction volume showed indications of reconstituted urethane functionality.

Chromatic confocal microscopy by means of continuum light generated through a standard single-mode fibre

In this paper a confocal profilometer using longitudinal chromatic aberration is presented. The system uses a novel polychromatic illumination source generated by means of non-linear effects in a standard single-mode optical fibre. A wavelength–height codification is realized using the chromatic aberration of a Fresnel lens. The height decoding is obtained by the spectral analysis of the detected light, identifying the most intense spectral component coming from the sample. The height sensitivity of the profilometer is variable and it is related to the full width half maximal value (FWHM) of the system's spectral response. From 700 to 938 nm the experimental value of the FWHM changes from 10.78 to 3.9 µm respectively.

Acousto-optic lens with very fast focus scanning

We propose and experimentally demonstrate an acousto-optic cylindrical lens with a very fast (400-kHz) focal scanning. The lens is realized by use of two adjacent acousto-optic scanners with counterpropagating acoustic waves that have the same frequency modulation but a pi phase difference. This scheme completely suppresses the lateral scan but adds the linear chirp of the two waves and thus functions as a fast focal-scan lens. We also demonstrate the use of this scanning lens in a very fast confocal profilometer.

The importance of surface texture for bone integration of screw shaped implants: an in vivo study of implants patterned by photolithography.

The aim of the present study was to investigate the influence of different properties inherent in surface topography on the integration of an implant in bone. Using a photolithography technique, a specific surface pattern was produced on the screw flanks of threaded titanium oral implants. Surface topography was qualitatively assessed by scanning electron microscopy (SEM) and a confocal laser scanning profilometer. Quantitative analysis with the confocal laser profilometer derived parameters for surface roughness and surface roughness together with waviness. The chemical composition of the implant surfaces was analyzed by Auger electron spectroscopy. The patterned and control (turned) implants were inserted in New Zealand White rabbits with a healing period of 3 months. Bone fixation was evaluated with resonance frequency analysis (RFA), peak removal torque analysis (RTQ), and by histomorphometry. No statistically significant differences were seen in the fixation, with respect to bone-to-implant contact, between the patterned and control implants.

Nontranslational three-dimensional profilometry by chromatic confocal microscopy with dynamically configurable micromirror scanning

A confocal microscope profilometer, which incorporates chromatic depth scanning with a diffractive optical element and a digital micromirror device for configurable transverse scanning, provides three-dimensional (3D) quantitative measurements without mechanical translation of either the sample or the microscope. We used a microscope with various objective lenses (e.g., 40x, 60x, and 100x) to achieve different system characteristics. With a 100x objective, the microscope acquires stable measurements over a 320 microm x 240 microm surface area with a depth resolution of 0.39 microm at a 3-Hz scan rate. The total longitudinal field of view is 26.4 microm for a wavelength tuning range of 48.3 nm. The FWHM value of the longitudinal point-spread function is measured to be 0.99 microm. We present 3D measurements of a four-phase-level diffractive element and an integrated-circuit chip. The resolution and the accuracy are shown to be equivalent to those found with use of conventional mechanical scanning.