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We report on a dynamic metalorganic aerosol deposition (dyna-MAD) technique, that allows dynamic growth control of thin film heterostructures with complex oxide constituents. This method enables the deposition of gradient (or ‘graded’) heterostructures of (LaMnO3)x/(SrMnO3)y. In situ optical ellipsometry reveals a modified electronic and optical material’s response with changing amount of gradient. Structure and microstructure are characterized by means of x-ray diffraction and atomic force microscopy measurements, which confirm epitaxial thin film growth.

We develop the method for determining the Mueller matrix elements using standard photometric ellipsometer. Small ellipsometer design changes give an opportunity to completely determine all elements of the Mueller matrix. It is shown how the values of Mueller matrix elements can be obtained from the measurements at different azimuthal positions of optical units.

Changes in the optical properties of samples of aluminum-alloy mirrors caused by ion bombardment with ions from a deuterium plasma, which imitates conditions that can exist upon the operation of the first mirrors for diagnostics of plasma in an ITER, have been investigated. The basic methods of studying the mirror surfaces were ellipsometry and reflectometry; as an additional procedure, Auger electron spectroscopy was used. It has been found that the coefficient of reflection of mirrors decreases as a result of irradiation by ions with an energy of ∼1 keV, but it can be restored by the subsequent irradiation by ions with a lower energy (∼60 eV). The complex of experimental studies that were performed was used as a base for the selection of a mathematical model for a correct interpretation of ellipsometric data. The results of multiple-angle and spectral ellipsometry were analyzed in terms of the models of a clean surface and single-layer films. On the basis of the analysis of experimental data and simulation of the effective medium, we proposed a mechanism, which explains the results of the experiment; this mechanism is based on (1) the chemical processes in the surface layer in the first cycle of “degradation-restoration” and (2) the development of roughness as a result of a sequence of procedures of “degradation-restoration.”

Naturally birefringent crystals are fundamental components of devices with many fields of application, from high energy physics and biomedical devices, to lasers. Crystals functional properties are related to their quality. Non-destructive tests are mandatory to check and improve the quality of these expensive materials as well as to control the growth process. In this paper, a set of methods are presented, based on photoelasticity. The classical diffuse light Photoelasticity, laser Conoscopy and laser Sphenoscopy are discussed and compared. Each technique has shown reliability and sensitivity to the crystal stress condition. The work discusses the main characteristics of these techniques; from the simple optical set-up of the diffuse light technique, limited to volume measurements, to the extremely high resolution of the laser Conoscopy achieved through a more complex optical lay-out and, finally, to the fast and easy data analysis of Sphenoscopy.

To understand the dynamics of ultrashort-pulse laser ablation, the interpretation of ultrafast time-resolved optical experiments is of utmost importance. To this end, spatiotemporally resolved pump-probe ellipsometry may be utilized to examine the transiently changing dielectric function of a material, particularly when compared to two-temperature model simulations. In this work, we introduce a consistent description of electronic transport as well dielectric function for bulk aluminum, which enables unambiguous quantitative predictions of transient temperature and density variations close to the surface after laser excitation. Potential contributions of these temperature and density fluctuations to the proposed optical model are investigated. We infer that after the thermal equilibrium of electrons and lattice within a few picoseconds, the real part of the dielectric function mostly follows a density decrease, accompanied by an early mechanical motion due to stress confinement. In contrast, the imaginary part is susceptible to a complicated interaction between time-varying collision frequency, plasma frequency, and a density dependency of the interband transitions. The models proposed in this study permit an outstanding quantitative prediction of the ultrashort-pulse laser ablation’s final state and transient observables. Consequently, it is anticipated that in the future, these models will provide a quantitative understanding of the dynamics and behavior of laser ablation. Graphical abstract

Titanium nitride film was deposited on a glass substrate by reactive magnetron sputtering. The composition and structure of the film were studied by SEM, XRD and XPS. The results show that the atomic ratio of titanium to nitrogen in the film is TiN1.05, and the crystal orientation of the film is mainly TiN (111). The optical properties of titanium nitride films in the wavelength range from 380nm to 2500nm were studied in detail using a spectral ellipsometer. Four commonly used dispersion models including Gaussian and Lorentz are compared to resolve the fitting effect of the ellipsometry spectrum of titanium nitride films. The fitting results were validated by reflection and transmission spectra. The results show that the Lorentz model combined with the Drude model is the best fit for the elliptic spectrum of titanium nitride films over the entire range of bands tested.

This review presents the state-of-the-art of optical sensors for determination of biogenic amines (BAs) in food by publications covering about the last 10 years. Interest in the development of rapid and preferably on-site methods for quantification of BAs is based on their important role in implementation and regulation of various physiological processes. At the same time, BAs can develop in different kinds of food by fermentation processes or microbial activity or arise due to contamination, which induces toxicological risks and food poisoning and causes serious health issues. Therefore, various optical chemosensor systems have been devised that are easy to assemble and fast responding and low-cost analytical tools. If amenable to on-site analysis, they are an attractive alternative to existing instrumental analytical methods used for BA determination in food. Hence, also portable sensor systems or dipstick sensors are described based on various probes that typically enable signal readouts such as photometry, reflectometry, luminescence, surface-enhanced Raman spectroscopy, or ellipsometry. The quantification of BAs in real food samples and the design of the sensors are highlighted and the analytical figures of merit are compared. Future instrumental trends for BA sensing point to the use of cell phone–based fully automated optical evaluation and devices that could even comprise microfluidic micro total analysis systems.

This study employs zinc acetate as the precursor for synthesizing pure zinc oxide thin films through the sol–gel process. Comprehensive characterization and analysis were conducted using X-ray diffraction, field-emission scanning electron microscopy, ultraviolet–visible-infrared spectrophotometry, ellipsometry, and photoluminescence. The X-ray diffraction study confirms the hexagonal wurtzite polycrystalline structure of zinc oxide. Increasing the zinc precursor concentration resulted in a decrease in the observed intensity of diffraction lines, as revealed by XRD studies. Microstructural parameters such as crystallite size and micro-strain were determined using the Scherrer equation and the Williamson–Hall method. The Williamson–Hall method indicated an increase in crystallite size values from 28.3 to 36.9 nm, while micro-strain values decreased from 1.192 × 10 −3 to 1.12 × 10 −3 with an increase in zinc acetate concentration from 0.1 M to 0.5 M. Scanning electron microscopy images displayed connected microstructures with wrinkle network architectures influenced by the concentration of zinc acetate, consistent with the texture coefficient results. Optical characteristics were investigated in the 300–2500 nm range through transmission measurements and subsequent photoluminescence measurements. The optical band-gap energy was found to decrease from 3.33 to 3.21 eV and the band tail width (Urbach energy) decreased from 0.344 to 0.105 eV with an increase in zinc concentration.

We present a study on femtosecond laser treatment of amorphous hydrogen-containing carbon coatings (a-C:H). The coatings were deposited on silicon wafers by a plasma-assisted chemical vapour deposition (PA-CVD), resulting in two different types of material with distinct properties (referred to as “absorbing” and “semi-transparent” coatings in the following). The samples were laser-treated with single fs-laser pulses (800 nm center wavelength, 35 fs pulse duration) in the ablative regime. Through a multi-method approach using topometry, Raman spectroscopy, and spectroscopic imaging ellipsometry, we can identify zones and thresholds of different fluence dependent effects and have access to the local dielectric function. The two coating materials react significantly different upon laser treatment. We determined the (non-ablative) modification threshold fluence for the absorbing coating as$$3.6\\times {10}^{-2}$$3.6 × 10 - 2  Jcm −2 and its ablation threshold as 0.22 Jcm −2 . The semi-transparent coating does not show such a low-fluence modification but exhibits a characteristic interference-based intra-film ablation mechanism with two distinguishable ablation thresholds at 0.25 and 0.28 Jcm −2 , respectively. The combination of tailored layer materials and correlative imaging spectroscopic methods delivers new insights into the behaviour of materials when treated with ultrashort-pulse laser radiation. Graphical abstract