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The experimental results demonstrate that the proposed method can reduce the storage capacity of the guide star catalog, and improve its uniformity, integrity, and average brightness.Modern grating manufacturing techniques suffer from inherent issues that limit their peak efficiencies. The anisotropic etching of silicon facilitates the creation of custom gratings that have sharp and atomically smooth facets, directly addressing these issues. We describe work to fabricate and characterize etched silicon echelles optimized for the far ultraviolet (FUV; 90-180 nm) bandpass. We fabricate two echelles that have parameters similar to the mechanically ruled grating flown on the Colorado High-resolution Echelle Stellar Spectrograph sounding rocket. We demonstrate a 42% increase in peak order efficiency and an 83% decrease in interorder scatter using these gratings. We also present analysis on where the remaining efficiency resides. These demonstrated FUV echelle improvements benefit the faint source sensitivity and high resolution performance of future UV observatories.Today, there are strict requirements for the quality inspection of mobile phone cameras, as the design tolerance is getting critically tighter. In order to avoid unnecessary disposal of lens components when testing and assembling the complete cameras, testing the quality of each single lens group in advance before the final assembly is effective. However, as part of a whole camera, a single lens group cannot generate a sharp image independently; it needs to be combined with other elements in the testing system and assembled precisely. In order to address this challenge, we propose a fast testing method based on spatial light modulators (SLMs). By taking advantage of the programmable feature of the SLM, the assembly misalignments caused by fixing the lens group to be tested into the testing system are dynamically scanned and compensated at a fast speed. A design criterion of the phase map pattern to be loaded on the SLM is also verified by simulation and is applied on the testing system. In this way, the proposed method significantly reduces the positioning requirement of the lens under test, and thus improves efficiency. The passed yield of tested lens groups reaches 92.6%.Laser-generated ultrasonic wave characteristics in the rail foot weld were simulated and reported for qualitative analysis and evaluation of sub-millimeter-level crack growth. Numerical analyses using the finite element method (FEM), the propagation characteristics, and displacement field distribution of a laser-generated ultrasonic wave after the interaction with cracks were fully demonstrated. By calculating displacement amplitude distribution, the optimal sensing position and area were the laser incident point and the upper surface, respectively. STC-15 supplier Crack growth degree toward the rail bottom and axial direction can be confirmed by analyzing time and amplitude of the echoes originating from the rail bottom and crack surface reflection. By combining time with peak intensity of the echo reflection from the rail bottom, the sub-millimeter-level crack growth process inside the rail foot weld is capable of acquiring and evaluating. The results justify that the laser ultrasonic technique, characterized by laser excitation and laser detection, is a competitive nondestructive testing technique for sub-millimeter-level crack growth evaluation and detection inside the rail foot weld.The ability to measure micro-starting torque is pivotal for micromechanical equipment, which has wide usage in mechanical manufacturing, electrical, electronic, and other industries. However, the measurement range of existing methods is about N⋅m or mN⋅m. There is not much research on the measurement of micro-torque starting in the µN⋅m. In this paper, a novel micro-gear starting torque measurement system, to the best of our knowledge, is proposed based on an optical lever with a long range from 1 to 10µN⋅m. The system device consists of the optical lever, cantilever, and position sensitive device. A micro-gear was used to assess the performance of the proposed method. The standard deviation of the measured starting torque is 1.2µN⋅m. The external factors that can contribute to the uncertainty of the measurement system, such as force measurement, arm of force, and repeatability, have been analyzed and quantified. The relative combined uncertainty is estimated at 3.0%, approximately.Pharmacokinetic parameter estimation with the support of dynamic diffuse fluorescence tomography (DFT) can provide helpful diagnostic information for tumor differentiation and monitoring. Adaptive extended Kalman filtering (AEKF) as a nonlinear filter method has the merits of high quantitativeness, noise robustness, and initialization independence. In this paper, indirect and direct AEKF schemes combining with a commonly used two-compartment model were studied to estimate the pharmacokinetic parameters based on our self-designed dynamic DFT system. To comprehensively compare the performances of both schemes, the selection of optimal noise covariance matrices affecting estimation results was first studied, then a series of numerical simulations with the metabolic time ranged from 4.16 min to 38 min was carried out and quantitatively evaluated. The comparison results show that the direct AEKF outperforms the indirect EKF in estimation accuracy at different metabolic velocity and demonstrates stronger stability at the large metabolic velocity. Furtherly, the in vivo experiment was conducted to achieve the indocyanine green pharmacokinetic-rate images in the mouse liver. The experimental results confirmed the capability of both schemes to estimate the pharmacokinetic-rate images and were in agreement with the theory predictions and the numerical simulation results.Time-domain diffuse optical tomography can efficiently reconstruct both absorption and reduced scattering coefficients but is heavily limited by the ill-posedness in its inverse problem and low spatial resolution. To deal with these adversities, the truncated singular value decomposition (TSVD)-based whole-weighting-matrix inversion scheme can be a particularly suitable implementation. Unfortunately, TSVD is subject to a storage challenge for three-dimensional imaging of a bulk region, such as breast. In this paper, a multi-scale mesh strategy based on computed tomography (CT) anatomical geometry is adopted to solve the storage challenge, where a fine mesh is used in forward calculation to ensure accuracy, and a coarse mesh in the inversion process to enable TSVD-based inversion of the whole-weighting matrix. We validate the proposed strategy using simulated data for a single lesion model from clinical positron emission tomography images of a breast cancer patient, and further, for a complex model that is constructed by setting dual lesions at different separations in the CT breast geometry.As a representative method of optical non-interference measurement, digital image correlation (DIC) technology is a non-contact optical mechanics method that can measure the displacement and deformation of the whole field. However, when the measurement range of the field is too large, the existing DIC method cannot measure the full-field strain accurately, which limits the application of the DIC measurement in the case of a large size and wide-field view. To address this issue, a DIC measurement method for large-scale structures based on adaptive warping image stitching is proposed in this paper. First, multiple adjacent high-resolution images are collected at different locations of large-scale structures. Secondly, the collected images are stitched by applying the adaptive warping image stitching algorithm to obtain a panoramic image. Finally, the DIC algorithm is applied to solve the whole deformation field. In the experiments, we first verify the feasibility of the proposed method for image matching and fusion through the numerical simulation of a rigid body translation experiment. Then the accuracy and robustness of the proposed method in practical application are verified by rigid body translation and a three-point bending experiment. The experimental results demonstrate that the measurement range of DIC is improved significantly with the adaptive warping image stitching algorithm.Demultiplexers play an important role in wavelength division multiplexing optical transmission systems and constitute an essential component of future terahertz integrated circuits. In this work, we propose a terahertz spoof surface plasmonic demultiplexer, which is capable of distinguishing between three different frequencies by exploiting the band-stop effect of the waveguide units. The waveguide units are composed of metallic pillars of different sizes, where the transmission of spoof surface plasmons in the terahertz range is strongly influenced by the pillar size. The frequency-splitting feature can be achieved by selecting waveguide units with proper parameters that allow the passbands of the waveguides to be completely non-overlapping. As the effective working section, the length of the band-stop units is 1 mm, and extinction ratios of 21.5 dB, 18.0 dB, and 23.9 dB are obtained at 0.578 THz, 0.632 THz, and 0.683 THz, respectively. The proposed band-stop unit and its tunable characteristics have important applications for further development of terahertz integrated communication systems and terahertz on-chip plasmonic circuity.Sudden cardiac death (SCD) caused by cardiovascular disease is the greatest hidden danger to human life, accounting for about 25% of the total deaths in the world. Due to the early concealment of SCD and the heavy medical burden of long-term examination, telemedicine combined with home monitoring has become a potential medical alert method. Among all the existing human cardiac and electrophysiology monitoring methods, optics-based sensors attract the widest attention due to the advantages of low delay, real-time monitoring, and high signal-to-noise ratio. In this paper, we propose an optical sensor with the capabilities of long-term monitoring and real-time analysis. Combining an R-peak recognition algorithm, Lorenz plots (LP), and statistical analysis, we carried out the consistency analysis and result visualization of ECG sequences over 1 h. The results of 10 subjects show that the R-peak recognition accuracy of the optical ECG monitor is higher than 97.99%. The optical system can display abnormal heart rhythm in real-time through LP, and the readability is good, which makes the system suitable for self-monitoring at home. In addition, this paper provides a detailed long-term monitoring assessment method to effectively guide the practical clinical transformation of other optical wearable devices.A novel, to the best of our knowledge, bionic coaxial micro-displacement sensor based on the shadow method is developed and experimentally demonstrated inspired by the water strider walking on the water. The water is used as the sensitive element to measure the micro- displacement. A meniscus is formed by the superhydrophobic circular plate subjected to a coaxial displacement excitation. Then a shadow is formed because of the refraction when the parallel light illuminates the meniscus. A maximum coaxial displacement sensitivity of 62 nm/pixel over the displacement range of 50 µm is achieved experimentally. The linearity error in the measurement range was 1.58%. Therefore, it is expected that this displacement sensor can be used in many important ultraprecision measurement fields because of the advantages of the easy structure and high resolution.
Read More: https://www.selleckchem.com/products/stc-15.html
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