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Geomaterials (i.e. rock, sand, soil and concrete) are increasingly being encountered and used in extreme environments, in terms of the pressure magnitude and the loading rate. Advancing the understanding of the mechanical response of materials to impact loading relies heavily on having suitable high-speed diagnostics. One such diagnostic is high-speed photography, which combined with a variety of digital optical measurement techniques can provide detailed insights into phenomena including fracture, impact, fragmentation and penetration in geological materials. This review begins with a brief history of high-speed imaging. Section  2 discusses of the current state of the art of high-speed cameras, which includes a comparison between charge-coupled device and complementary metal-oxide semiconductor sensors. The application of high-speed photography to geomechanical experiments is summarized in Sect.  3 . Section  4 is concerned with digital optical measurement techniques including photoelastic coating, Moiré, caustics, holographic interferometry, particle image velocimetry, digital image correlation and infrared thermography, in combination with high-speed photography to capture transient phenomena. The last section provides a brief summary and discussion of future directions in the field.

Fringe Pattern Analysis for Optical Metrology: Theory, Algorithms, and Applications The main objective of this book is to present the basic theoretical principles and practical applications for the classical interferometric techniques and the most advanced methods in the field of modern fringe pattern analysis applied to optical metrology. A major novelty of this work is the presentation of a unified theoretical framework based on the Fourier description of phase shifting interferometry using the Frequency Transfer Function (FTF) along with the theory of Stochastic Process for the straightforward analysis and synthesis of phase shifting algorithms with desired properties such as spectral response, detuning and signal-to-noise robustness, harmonic rejection, etc.

Introduction For ideal occlusion and passive fit of implant-retained prosthetic restorations minimal tolerance of the position of the abutment in the implant after dis- and reassembly is essential. Methods to examine the three-dimensional (3D) positional stability of implant-abutment connections (IAC) vary and their accuracy and applicability have not been assessed. The aim of this study was to evaluate non-contact optical measurement devices for 3D-feasibility, accuracy, repeatability, time efficiency and complexity of use. Methods Five devices capable of contactless, optical methods (Profile Projector; Digital Image Correlation (DIC); Profilometer; Confocal Technology; Coordinate Measuring Machine (CMM)) were examined regarding their 3D-feasibility, accuracy, repeatability, time efficiency and complexity. The parameters were quantified and scored using a decision matrix. In an experimental set-up the method (device) with the highest score was used to measure the position stability as follows: four implants with a butt joint (BJ) and a conical (CON) IAC were embedded in an aluminum block and dis- and reassembled ten times with the abutment screw being hand-tightened (∑1–5) and torque-tightened (∑6–10). Results The CMM achieved the highest score in the decision matrix with 40/50 points (range: 10–50 points; 10 requirements not met, 50: requirements fully met) while the Profile Projector, the DIC, the Profilometer and the Confocal Technology achieved 30, 32, 34, 38 points, respectively. Using the CMM the mean rotational freedom in BJ vs. CON was 0.32° ± 0.16° vs. 0.21° ± 0.25° (hand-tightened) and 0.36° ± 0.09° vs. 0.20° ± 0.22° (ratchet), respectively. The maximum vertical deviation of the abutment position after re-assembly was 7.2 μm ± 2.1 μm (BJ) and 24.4 μm ± 2.1 μm (CON). Conclusion The data acquired suggest that the CMM with its non-contact, optical measurement method is the most appropriate to investigate the 3D positional stability of the IAC in different implant systems. As previously described distinct differences between BJ and CON IACs were found. CON connections exhibit a higher vertical deviation when the system specific torque value was applied.

Significant effort has been devoted in this work to convert bare glass substrate with high transmittance, into reflective layers to know its suitability for modern applications. The glass substrate has been carefully chosen for its durability, high permeability, and ability to withstand any external stresses as a result of the accumulation of layers that reduce its permeability to convert it with the thin films coated on it into reflective materials. In parallel, the thin layer to be coated on the substrate is selected from films that can withstand external influences and their great optical properties, not to mention that they are cheap and can produce highly reflective surfaces. The optical measurements (transmittance and reflectance spectra) have been performed in the UV, Vis and NIR regions of the spectrum, that is, in the range between 300 and 1200 nm. Such measurements have been made for the bare glass substrate, the glass substrate with the Al (top side), and the glass substrate with Ag on it (bottom side), and then the optical measurements have been made for the three layers. The corresponding optical parameters of each layer have been calculated and ultimately a reflective layer with high electrical conductivity and excellent optical properties has been obtained that can be adapted for different application purposes.

A material strength investigation along with a detailed microfractography analysis of fractures formed during static tensile tests of steel Armstal 550 was performed. The tests in this research were conducted in a temperature range of 298 to 973 K. In addition, during tensile tests at ambient temperature, optical measurements of strain maps and the curvature of the neck were performed. The minimum cross-sectional diameter and the radius of the neck curvature during tensile tests were obtained. The data can be directly used to obtain the true stress–strain curve. The material property analysis confirmed the high strength of the Armstal 550 alloy. The ultimate strength at room temperature equals 2.14 GPa, whereas the yield point equals 1.65 GPa. A decrease in the strength parameters along with an increase in temperature was noted. This is a typical phenomenon related to a change in the density and thermal expansion of steel under the influence of the temperature increase. For example, at a temperature of 500 °C, the ultimate strength is more than 50% less than at room temperature. An in-depth analysis of the metallography and microfractography of fractures resulting from static tensile tests showed the formation of atypical nano- and microstructures with an elongated shape. Local nano- and microstructures were observed at different levels of intensity for different temperatures. The largest clusters of nanoparticles were present on the surfaces of the specimens examined at a temperature of 973 K. Scanning microscopy analysis confirmed the presence of molybdenum oxides.

This book covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding modern phase estimation methods. The book first focuses on phase retrieval from image transforms using a single frame. It then examines the local environment of a fringe pattern, the phase estimation approach based on local polynomial phase modeling, temporal high-resolution phase evaluation methods, and methods of phase unwrapping. It also discusses experimental imperfections liable to adversely influence the accuracy of phase measurements.

Multisensor CMMs are systems with an established position on the market, but their popularity still grows, as they provide access to the advantages offered by tactile and contactless measurement methods. Yet there are still questions of the comparability of results obtained using the optical and tactile operation modes of multisensor system. This phenomenon can be assessed by measuring appropriate gauges, most often reference rings or spheres. Due to the completely different nature of probing processes for tactile and contactless measurements, the material from which reference object is made may significantly affect measurement results. In order to assess the influence of this factor on measurement accuracy, three reference spheres made from different materials were measured on optical multisensor CMMs. Measurements involved tactile measurements as well as optical measurements made using different probing systems: a video probe and white light sensor. Results obtained from performed experiments show large differences depending on the material used for spherical standard production. On the basis of obtained results, it can be stated that the best material for a reference object that can be used for comparability tests of tactile and optical measurements is a composite of alumina with at least one oxidic additive.

With the increasing aperture as well as the observation frequency of radio telescopes in the current period, the deformation caused by time-varying loads such as temperature and wind has been emphasized. Existing methods for measuring deformations often fall short in meeting the demands of full attitude coverage, quasi-real-time response, and high accuracy. This study introduces a novel geometric-optical measurement approach based on light-tracing. Diverging from traditional methods, this approach doesn’t directly measure the surface deformation of the main reflector. Instead, it creates a more easily measurable variable and establishes a mapping relationship between this variable and the main reflector deformation. In this innovative scheme, multiple laser modules are strategically positioned on the main reflector, treating the sub reflector as a spot projection surface. When the panel is displaced, the spot on the projection surface will follow and be displaced. In practice, the main reflector deformation can be solved by recording the position change of the light spots on the projection surface and utilizing the inverse reconstruction model. Besides, effective strategies are proposed to improve the robustness of the scheme. Next, the accuracy and real-time performance of the proposed method are verified through simulations and experiments. Results indicate that the proposed approach presents a fresh perspective to enhance the efficiency and precision of deformation measurements for large-aperture antennas.

Nowadays, the optical measuring approach is widely used in the precision machining industry due to high measurement efficiency. In the industry, measuring devices play a crucial role in the field of quality assurance. In practical engineering, the green measurement approach indeed plays an important role in the industry currently. In this study, a state-of-the-art green technique for three-dimensional (3D) optical measurements without environmental pollution is demonstrated, which is an environmentally friendly optical measurement method. This method can perform precise optical measurement without matte coatings. This work dealt with the possibility of measuring four metal components that were not sprayed with anything. The differences in the optical measurement results between with and without matte coatings were investigated and analyzed. It was found that the research result has practical value in the precision machining industry because average size errors of the four measurement objects with different surface properties can be controlled at about 3 µm, 0.1 µm, 0.5 µm, and 9 µm. A technical database with industrial value was established for optical measurements of metal components with different surface properties without matte coatings, which can serve as an alternative to the conventional 3D optical measurement.

The electron-hole pair created via photon absorption in organic photoconversion systems must overcome the Coulomb attraction to achieve long-range charge separation. We show that this process is facilitated through the formation of excited, delocalized band states. In our experiments on organic photovoltaic cells, these states were accessed for a short time (< 1 picosecond) via infrared (IR) optical excitation of electron-hole pairs bound at the heterojunction. Atomistic modeling showed that the IR photons promote bound charge pairs to delocalized band states, similar to those formed just after singlet exciton dissociation, which indicates that such states act as the gateway for charge separation. Our results suggest that charge separation in efficient organic photoconversion systems occurs through hot-state charge delocalization rather than energy-gradient-driven intermolecular hopping.