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Chest muscles X-ray Bone Reductions regarding Enhancing Group of Tuberculosis-Consistent Studies.
To achieve optical differential operation based on the cross-polarization effect at the optical interface, one just needs an optical interface composed of two uniform media with different refractive indices. When certain conditions are satisfied, the reflection co-efficient of the light field at the interface conforms to the form of the spatial spectrum transfer function required by the spatial differentiation, the spatial analog operation can be achieved with a single interface. In this paper, based on the optical differentiation of Brewster effect, we propose a tunable optical differentiation based on the cross-polarization effect at the optical interface. We theoretically derive the tunable optical differentiation and then conduct an experiment to demonstrate theoretical results. It is found that the differentiator can achieve the tunable optical differentiation by adjusting the polarization of output beam. While getting the clear edge of the object, we can also observe the imaging of the middle part to different degrees, which realizes the multi-degree of freedom imaging for the measured target. This provides a potential way to develop devices more suitable for microscopic imaging and target detection.Hybrid methods combining the geometrical-optics and diffraction-theory methods enable designing diffractive optical elements (DOEs) with high performance due to the suppression of stray light and speckles and, at the same time, with a regular and fabrication-friendly microrelief. DNA Damage inhibitor Here, we propose a geometrical-optics method for calculating the eikonal function of the light field providing the generation of a required irradiance distribution. In the method, the problem of calculating the eikonal function is formulated in a semi-discrete form as a problem of maximizing a concave function. For solving the maximization problem, a gradient method is used, with analytical expressions obtained for the gradient. In contrast to geometrical-optics approaches based on solving the Monge-Ampére equation using finite difference methods, the proposed method enables generating irradiance distributions defined on disconnected regions with non-smooth boundaries. As an example, we calculate an eikonal function, which provides the generation of a "discontinuous" irradiance distribution in the form of a hexagram. It is shown that the utilization of the hybrid approach, in which the obtained geometrical-optics solution is used as a starting point in iterative Fourier transform algorithms, enables designing DOEs with a quasi-regular or piecewise-smooth microrelief structure. The calculation results are confirmed by the results of experimental investigations of a DOE generating a hexagram-shaped irradiance distribution.Shack-Hartmann wavefront sensors (SHWS) are generally used to measure the wavefront shape of light beams. Measurement accuracy and the sensitivity of these sensors are important factors for better wavefront sensing. In this paper, we demonstrate a new type of SHWS with better measurement accuracy than the regular SHWS. The lenslet array in the regular SHWS is replaced with an array of coded phase masks, and the principle of coded aperture correlation holography (COACH) is used for wavefront reconstruction. Sharper correlation peaks achieved by COACH improve the accuracy of the estimated local slopes of the measured wavefront and consequently improve the reconstruction accuracy of the overall wavefront. Experimental results confirm that the proposed method provides a lower mean square wavefront error by one order of magnitude in comparison to the regular SHWS.As a high-performance optical material, fused silica is widely applied in high-power laser and photoelectric systems. However, laser induced damage (LID) of fused silica severely limits the output power and performance of these systems. Due to the values in strong field physics and improving the load capacity and performance of high power systems at UV laser, LID at 355 nm of fused silica has attracted much attention. It has been found that, even be treated by advanced processing technologies, the actual damage threshold of fused silica at 355 nm is far below the intrinsic threshold. It means that there is an absorption source near 355 nm in fused silica. However, to date, the absorption source is still unknown. In this paper, a absorption source near 355 nm is found by first-principles calculations. We find that the absorption source near 355 nm is neutral oxygen-vacancy defect (NOV, ≡Si-Si≡) and this defect originates from the oxygen deficiency of fused silica. Our results indicate that NOV defect can be taken as a damage precursor for 355 nm UV laser, and this precursor can be obviously reduced by increasing the ratio of oxygen to silicon. Present work is valuable for exploring damage mechanisms and methods to improve the damage threshold of fused silica at UV laser.A novel modulation format recognition (MFR) scheme based on multiple Stokes sectional planes images by generative adversarial network (GAN) is proposed and demonstrated to adapt to next-generation elastic optical network (EON). The application of the encoder, along with the suitable loss function, is able to achieve better performance with regards to MFR of GAN. Experimental verifications were performed for the polarization division multiplexing (PDM)-EON system at a symbol rate of 12.5GBaud. Five modulation formats, including PDM-BPSK, PDM-QPSK, PDM-8PSK, PDM-8QAM, PDM-16QAM, were recognized by our scheme under the condition of practical optical signal-to-noise ratio (OSNR) over both back-to-back transmission and 25km standard signal-mode fiber (SSMF). Specifically, the minimum required OSNR of PDM-16QAM signal to achieve 100% MFR success rate is 18 dB, which is lower than its corresponding 7% forward error correction (FEC) threshold. Results show that, compared with three other machine learning algorithms, the proposed scheme obtains the higher recognition accuracy in the case of the same OSNR. Moreover, the training data required by the proposed scheme is less than the traditional convolutional neural network (CNN) in MFR task, which means the training cost of the neural network is greatly reduced by using GAN.Wavefront aberration is one important parameter for objective lenses. When the NA (Numerical Aperture) of the objective lens becomes larger than 0.8, wavefront aberration measurement with high accuracy and low cost is difficult to realize because of the lack of a reference sphere. In this paper, a new method is proposed to measure the wavefront aberration of a high NA objective lens. A cat-eye retroreflector with a plane mirror is used to reflect the wavefront. The plane mirror is tilted in at least three different directions by certain tilt angles to collect sufficient information of the wavefront aberration under test. Specific grid-combined Zernike polynomial is built for each set of tilt angles and directions to fit the corresponding returned wavefronts. The wavefront aberration can be reconstructed from the fitting results of the returned wavefronts. The measurement accuracy is influenced by the tilt angle, tilt angle error, NA, defocus amount of the plane mirror, detector's resolution, and other random noise. The tilt angle error is the main source of the measurement error. The relative measurement error is within 5% and 1% when the relative tilt angle error is below 0.5% and 0.1% respectively. The feasibility of the proposed method is verified experimentally by measuring the wavefront aberrations of 0.14 NA, 0.65 NA, and 0.9 NA objective lenses. Wavefront aberration measurement for a high NA objective lens with high accuracy and low cost is achievable through this method.We present an optical transduction method adapted to the detection of low frequency thermal perturbations and implemented for photothermal trace gas detection. The transducer is a π-phase shifted fiber Bragg grating, stabilized and interrogated by the Pound-Drever-Hall method. The principle of detection is based on the frequency shift of the narrow optical resonance, induced by the temperature variations. In temperature measurement mode, the stabilization leads to an estimated limit of detection of 1 µK at room temperature and at a frequency of 40 Hz. When the fiber transducer is placed in a gas cell, CO2 is detected by photothermal spectroscopy with a limit of detection of 3 ppm/H z. This novel method, based on a single fiber, offers robustness, stabilized operation and remote detection capability.In the present work, a discrete flexure for silicon carbide (SiC) deformable mirror (DM) with Lead-Magnesium-Niobate (PMN) stacked-actuators is designed using topology and size optimizations. In order to fulfill the designated surface strokes of the SiC mirror without adhesive failure, discrete flexures are adopted between the mirror faceplate and the actuators. As the same design process for the flexure of the final DM model, which has a 140 mm diameter mirror faceplate and 489 channels of piezoelectric PMN-30PT single crystal multilayer actuators, the topology and the sizes of the flexure for the 5×5 engineering DM model are optimized. The topology and the size optimizations are conducted by GTAM and DesignXplorer in ANSYS based on finite element method (FEM). The prototype of the designed model is built and the test results show appropriate mirror deformations comparing with the simulated results without adhesive failure.We extend a recent theoretical work [Phys. Rev. A101, 053856 (2020)10.1103/PhysRevA.101.053856] by replacing disorders characterized by varied atomic densities with defects characterized by vacant lattice cells to evaluate again three-color reflection in a one-dimensional optical lattice filled with cold 87Rb atoms. This is based on the consideration that trapped atoms may escape from some lattice cells and effects of vacant cells on light propagation are of major importance from both fundamental and applied research viewpoints. We consider two types of defective atomic lattices where vacant cells are randomly or continuously distributed among filled cells. Numerical results show that the wider reflection band in a large detuning region of negligible off-resonance absorption is quite sensitive to, while the narrower reflection bands in two near-resonant regions of electromagnetically induced transparency are rather robust against, the number of random vacant cells. In contrast, all three reflection bands exhibit strong robustness against the number of continuous vacant cells. Note, however, that both narrower reflection bands may become widened and exhibit a blue shift when continuous vacant cells appear in the front of our atomic lattice due to the joint contributions of Bragg scattering and quantum interference.We demonstrate an adaptive super-resolution based contact imaging on a CMOS chip to achieve subcellular spatial resolution over a large field of view of ∼24 mm2. By using regular LED illumination, we acquire the single lower-resolution image of the objects placed approximate to the sensor with unit magnification. For the raw contact-mode lens-free image, the pixel size of the sensor chip limits the spatial resolution. We develop a hybrid supervised-unsupervised strategy to train a super-resolution network, circumventing the missing of in-situ ground truth, effectively recovering a much higher resolution image of the objects, permitting sub-micron spatial resolution to be achieved across the entire sensor chip active area. We demonstrate the success of this approach by imaging the proliferation dynamics of cells directly cultured on the chip.
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