High Entropy Alloys (HEAs) coatings obtained by laser melting (LM) technique were studied through a multiscale topographical surface analysis using a focus variation microscope. The laser melting ...creates a multiscale topography from under-powder size (incomplete or complete powder melting) to upper-powder size (process conditions). The surface topography must be optimized because of the significant influence on friction and material transfer during sliding wear. The analyses were shown that different pre-melting zone interactions were present. Statistical analysis based on covariance analyses is allowed to highlight the different process melting scales. The best LM parameter values to minimize Surface Heterogeneity were laser power (Pw) of 55 W, laser exposition time (te) of 1750 µs, and distance between two pulses (dp) of 100 µm.
The surface of tissue paper is relatively complex compared to other paper grades and consists of several overlapping structures like protruding fibres, crepe and fabric-based patterns at different ...spatial frequencies. The knowledge of tissue surface characteristics is crucial when it comes to improvement with respect to surface softness and the perceptual handfeel of tissue products. In this work we used the optical based, non-contact measurement principle of focus variation for surface characterization of dry-creped, textured and through air dried (TAD) tissue. Based on the three tissue grades, a procedure which includes the characterization of the whole tissue surface throughout different scales within one setup, was developed. Surprisingly, focus variation was rarely used in tissue-related research, as it provides robust and reliable 3D surface information which can be used for further areal surface analysis. Special attention was given to the preparation and discussion of the raw data up to the final analysis including several spatial filtering steps. Enhanced surface parameters like the developed interfacial area ratio (Sdr) and the power spectral density (PSD) were used to describe the surface adequately. The surface roughness of the three tissue grades was compared, with the textured tissue showing the highest roughness in Sdr and PSD analysis. Although both methods are based on different principles, a high correlation in terms of evaluated roughness is evident. Regular structures like crepe and patterns are obtainable as peaks at the respective frequency with a certain intensity in the PSD evaluation. Apart from topography in terms of structures and roughness, the wide field of view of the focus variation measurement also allows assessment of effects related to flocculation and sheet formation. The developed procedure could also be appropriate for other fibre based materials and/or fabrics, which are similar to tissue with respect to optical properties such as for example nonwovens.
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•Macro photography is a cheap alternative for microscopy.•Different light sources are useful for the identification of materials.•Focus stacking allows 3D surface visualisation of ...large curved samples.•High resolution imaging (2D/3D) is useful for e.g. fractography analysis.
The goal of this study was to show the potential of the inexpensive macro photography technique for application in various fields of contemporary dental materials science. The method was used for studying surface characteristics for fractographic evaluation, topography analysis, and for the measurement of optical properties such as translucency and opalescence.
The variable test setup consisted of a digital camera with macro or microscopic objectives (combined with a lens tube and an objective adapter). The distance between object surface and objectives was controlled by an automatic stacking unit with a software-controlled mobile object slide. The exposure was carried out by LED light sources and a standard illuminant (D55).
Highly resolved pictures with fine details, high focal depth, flexible imaging by adjusting the illuminates in different angles, and the possibility of 3D topography imaging are the main reasons why macro photography proved to be a suitable imaging method for fractographic analyses. The automatic focal stacking technique was a powerful tool for imaging distinct topographies in high-resolution with nearly unlimited focal depth and 3D surface visualisation. Translucency as well as opalescence, measured with the macro photography produced differed from the measurements performed with a conventional spectrophotometer.
The modular structure of the cost-effective macro photography setup enables diverse applications such as identification of material groups, fractography analysis, and 3D surface visualisation. Quantification of colour, translucency, as well as opalescence under condition of the microscopic scale requires further research.
Fast and accurate in-line areal surface topography measuring instruments are required to control the quality of microscale manufactured components, without significantly slowing down the production ...process. Full-field areal optical surface topography measurement instruments are promising for in-line or on-machine measurement applications due to their ability to measure quickly, to access small features and to avoid surface damage. This paper presents the development and integration of a compact optical focus variation sensor for on-machine surface topography measurement mounted on to a hybrid ultraprecision machine tool. The sensor development is described and a case study involving the on-machine dimensional measurement of the depth of hydrophobic microscale features, including microchannels and micro-dimples, is presented. Comparisons of results between the on-machine measurements obtained by the developed sensor and a desktop focus variation microscope are presented and discussed. The comparison results show that the developed focus variation sensor is able to perform on-machine dimensional measurement of microscale features within sub-micrometre accuracy.
The appearance of portable artistic objects during the Upper Palaeolithic is characterised by a combination of a wide choice of techniques, use of different materials and a diversity of iconographic ...expression, with many objects made of bone and antler decorated with animal representations. Taphonomic and experimental approaches have been systematically applied in an effort to understand the technical and artistic procedures followed. In this study, we applied a new combination of 3-dimensional microscopy (focus variation optical microscope) and micro-CT scanning to the analysis of two Magdalenian engraved specimens: a reindeer antler from the site of Neschers (France), engraved with the partial image of a horse in left profile, and a horse metatarsal from Courbet Cave, Penne (France), engraved with a horse head also in left profile. Results of the analysis suggest that both the Neschers and Courbet Cave engravings had been prepared before being carved. The overall contours of the horse body/head were incised first, while anatomical features were added afterwards. In the Neschers case, the incision resulted from the repeated scratching of a previously made incision in order to enlarge the engraving, possibly reflecting the engraver's aesthetic sense. The combination of the techniques used in this study is applicable to fragile or unique archaeological specimens. Micro-CT scanning, in particular, provides non-invasive means for identifying engravings that are obscured by encrusted sediment. The application of these techniques can potentially open new avenues for the authentication, technical and gestural recognition and interpretation of incised forms and artistic creativity.
► Two Magdalenian specimens engraved with a horse image have been re-discovered at the Natural History Museum (London, UK). ► The incisions were recorded using different non-destructive imaging and analytic techniques. ► The technical and artistic procedures used in the engraving of the Neschers and Courbet Cave artefacts have been compared. ► A protocol for the study of fragile or sediment-encrusted engraved objects has been detailed.
The purpose of this study was to characterize compact surfaces (surface roughness) and study its potential importance to the intrinsic dissolution rate (IDR) as determined by dissolution imaging. To ...this end, the effect of varying compaction pressures and the use of two stainless-steel surfaces with different textures/roughness on the intrinsic dissolution were investigated. Ketoprofen (KET), paracetamol (PAR) and ibuprofen (IBU) were compacted and a focus variation microscope used to determine the surface topology of the compacts. IDR determination was conducted using a surface dissolution imaging apparatus with the flow-through set up in phosphate buffer at pH 7.2 and at 37 °C. The results indicated a general decrease in the surface area of the drug compacts with an increase in compaction force (p values < 0.05 for IBU and PAR but not KET). This change in surface area was measured using the Sdr parameter, which can be defined as the developed interfacial area. The smoother stainless-steel plate insert produced significantly smoother compacts for KET (Sdr decreased from 0.30% to 0.07%). However, PAR and IBU compacts showed an increase in their Sdr values from 3.94% to 17.90% and from 0.60% to 0.83%, respectively, suggesting the changes in surface properties to be drug specific relating to poor compaction properties and elasticity. The dissolution studies suggested that low compaction forces were not suitable for PAR. Overall changes in the surface topology did not have a significant effect on the obtained IDR values.
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The rapidly advancing trend towards miniaturization in the series production of gears confronts quality assurance with new challenges. In this context, metrological technologies as well as expertise ...from the field of macro gears can only be transferred to a limited extent. Inline integration of metrology into micro gear production has not yet been implemented in a practicable way. This publication extends the current limits of micro gear quality assurance to date by qualifying the optical method of focus variation technology for complete inline measurements of micro gears in series production time. In detail, this work includes the development of a measurement program by means of Design of Experiments, the establishment of a practicable cleaning process, the evaluation of resulting measurement uncertainties, and a process capability analysis. Consequently, the focus variation technology is qualified for fast, three-dimensional measurements of micro gears with respectively low measurement uncertainties.
The paper aims to analyze the InfiniteFocus system for the capability to measure macrogeometry of tooth models manufactured using two material extrusion techniques, i.e. MEM and FFF, and analyze the ...accuracy of manufacturing the said models. To achieve the goals it was needed to carry out two studies. The first one focused on estimating the measurement error of the microscope in the course of digitalizing geometry with the use of a rotary table. The research involved samples of cylindrical and spherical geometries. In the result further measurements of tooth model in the second stage were decided to be performed using vertical resolution 10 µm and overlap 70 %. For these settings, the absolute values of the mean measurement error for the MEM and FFF samples were about 0.01 mm. From 95 % to 98 % of points measured for all the tooth models were contained in the assumed tolerance range of ±0.25 mm for dental models.
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