LiDAR (Light Detection and Ranging) is thought to be one of the necessary sensors for automatic driving systems and advanced driver assistance systems. Recently, the LiDAR of the automotive vehicle is installed in the grille or near the headlights. These installed positions are very weak for a variety of pollutions. One of the measures to keep the LiDAR window surface clean is the use of anti-fingerprint coating. In this study, the hybrid optical coating for automotive LiDAR window (BK7 glass) which have the multifunction of UV-VIS absorption, NIR transmission, mechanical hardness and easy cleanability was developed. The surface hardness of the whole front coating and performance of anti-fingerprint coating were measured. The several reliability tests were performed. The coated window passed all tests.
For chalcogenide-based infrared glass materials, the need was emphasized along with the spread of thermal imaging cameras in COVID 19 environment. Commercial Ge-As-Se glass system exhibits a dispersion value of 100~180 and a refractive index of 2.5 or more, and is suitable for the glass molding process, so it is used as an aspherical infrared lens for various thermal imaging cameras. However, some compositions are not suitable for glass molding process. In this study, the composition of the long wavelength infrared glass melting was designed based on the Ge-As-Se system with a Ge composition range of 0~35 at%, As composition range of 20~40 at%, and Se composition range of 25~60 at%. As a result of XRD analysis for each Ge-As-Se-based composition, it was confirmed that all amorphous grains were obtained in the developed composition area. For the Ge-As-Se glass-forming composition region, the glass transition temperature ranged from 180 to 425°C. The refractive index was measured using the prism method in the 3 to 12 μm wavelength band. The refractive index (λ=10 μm) of Ge5As40Se55 and Ge5As35Se60 was 2.6913 and 2.6538, respectively. Moldability test was performed using a glass molding press. As a result of observing whether the lens has internal defects and microcracks after molding, it was confirmed that there was no abnormality and that it was suitable for glass molding process.
A diamond-like carbon thin film was deposited on the outer face of the germanium (Ge) window to protect the infrared lenses from a harsh environment in automotive application. Infrared transmittance and residual stress of a tetrahedral amorphous carbon (ta-C) thin film by a filtered cathodic vacuum arc (FCVA) source were investigated to increase the lifetime of a Ge window. They were found to have a trade-off relation about the change of the substrate pulse voltage. By introducing methane gas in FCVA deposition process, a hydrogenated ta-C (ta-C:H) thin film of which both IR transmittance and residual stress was improved could be obtained. A Ge window coated with ta-C:H thin film with 1.43 μm thickness showed anti-reflective effect in long-wave infrared. The hardness of ta-C:H thin film on Ge window was higher than 30 GPa. Adhesion, severe abrasion, temperature, humidity and salt solubility tests were carried out in accordance with MIL-C-48497A.
In the present study, zinc molybdenum tellurite glasses with the molar composition of (1−x)TeO2−yMoO3−xZnO and (1−x)TeO2−yMoO3−xZnO, where x = 10, 20, and 30 mol%, and y = 10 and 20 mol%, were prepared by a high temperature melt quenching technique and studied their thermal, thermo-mechanical and mechanical properties. From the thermal analysis, it was found that the glass transition (Tg), crystallization (Tx) and stability parameters slightly increased with increase in ZnO content in both series of glasses. Thermal expansion coefficient decreases from 16.56 to 14.67×10-6/K as the ZnO content increases from 10 to 30 mol%. Knoop hardness slightly decreases from 307 to 290 kgf/mm2 with increase in ZnO content from 10 to 30 mol% for 10 mol% of MoO3 content, whereas it increases for 20 mol% of MoO3. Based on the results, it concludes that the number of bridging oxygens and network compactness of tellurite matrix increased with increase in ZnO content varied from 10 to 30 mol%.
A series of Er3+/Yb3+ co-doped fluorophosphate glasses with varying YbF3 concentration were prepared by a high temperature melt quenching technique. The effect of sensitization on various spectroscopic properties of Er3+-doped fluorophosphate glasses was investigated. Using the Judd-Ofelt theory, the intensity parameters (Ωλ, λ = 2, 4 and 6) were evaluated from the absorption spectra of glasses. Absorption and emission cross-sections were determined by using the McCumber theory. The dependence of Er3+ ions near infrared emission (1.54 μm) on the Yb3+ concentration was investigated. The upconversion studies were also carried out at room temperature and low temperatures. The wider bandwidth (78 nm), larger emission cross-section (9.86 x 10-21 cm2) and longer fluorescence lifetime (12.37 ms) were noticed for the 4I13/2 → 4I15/2 transition of ABS3Er4Yb glass. The temperature sensing behavior of the ABS3Er5Yb glass was studied by using the fluorescence intensity ratio technique in the temperature range from 100 K to 280 K. The sensitivity and temperature of the maximum sensitivity were found to be of the order of 15 x 10−4 K−1 and 271 K, respectively. The results suggested that the present glass composition has possibilities for optical applications.
KEYWORDS: Copper indium gallium selenide, Laser induced breakdown spectroscopy, Thin film solar cells, Manufacturing, Solar cells, Chemical elements, Statistical analysis, Thin films, Gallium, Analytical research
The characteristics of laser-induced breakdown spectroscopy (LIBS) such as short measurement time and no sample preparation provide clear advantages over other analytical techniques for rapid elemental analysis at manufacturing sites where the composition of products need to be determined in real-time for process monitoring or quality control. Thin film solar cells based on CuIn1-xGaxSe2 (CIGS), polycrystalline compound semiconductor material, have unique advantages of high efficiency (>20%), long-term stability, and low manufacturing cost over other types of solar cell. The electrical and optical properties of the thin CIGS films are closely related to the concentration ratios among its major constituent elements Cu, In, Ga and Se such as Ga/(Ga + In) and Cu/(Ga + In), and thus an accurate measurement of the composition of CIGS thin films has been an issue among CIGS solar cell researchers, requiring a fast and reliable technique for composition analysis. This paper presents the results of nanosecond (ns) and femtosecond (fs) laser based LIBS analysis of thin CIGS films. The critical issues for LIBS analysis of CIGS thin films such are discussed in comparison with ns- and fs-LIBS measurement results. The calibration of LIBS signal intensity ratios with respect to reference concentration data is carried out and the results of optimal line selection for LIBS analysis, depth profiling capability, and reproducibility are discussed.
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