numerical aperture
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Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Lei Chen ◽  
Saima Kanwal ◽  
Binbin Yu ◽  
Jijun Feng ◽  
Chunxian Tao ◽  
...  

Abstract Bessel beam arrays are progressively attracting attention in recent years due to their remarkable non-diffracting nature and parallel manipulation capabilities in diverse applications. However, the poor phase discretization of conventional approaches such as spatial light modulators leads to low numerical aperture (NA) beam arrays due to the limitation imposed by the Nyquist sampling theorem and poor uniformity of the beam intensity. The key contribution of this study is to experimentally demonstrate the generation of high-uniformity and high-resolution Bessel beam arrays by utilizing all-dielectric metasurfaces. This is attained by optimizing the design of the supercell of a Dammann grating, particularly decreasing each supercell of the grating to a proper size. We demonstrate a 4 × 4 array of Bessel beams with a subwavelength transverse dimension (570 nm, ∼0.9λ) and a large NA of 0.4 for each beam in the array, while maintaining a relatively high uniformity intensity (52.40%) for the array. Additionally, the Bessel beam arrays are generated in a broadband range through the proposed all-dielectric metasurfaces. Our results are of great significance and particularly useful for applications of metasurface-based Bessel beam arrays in multidisciplinary fields such as laser fabrication, biomedical imaging, data storage, and multi-particle trapping.


Author(s):  
Harry Jay Levinson

Abstract High-NA extreme ultraviolet (EUV) lithography is currently in development. Fabrication of exposure tools and optics with a numerical aperture (NA) equal to 0.55 has started at ASML and Carl Zeiss. Lenses with such high NA will have very small depths-of-focus, which will require improved focus systems and significant improvements in wafer flatness during processing. Lenses are anamorphic to address mask 3D issues, which results in wafer field sizes of 26 mm × 16.5 mm, half that of lower NA EUV tools and optical scanners. Production of large die will require stitching. Computational infrastructure is being created to support high-NA lithography, including simulators that use Tatian polynomials to characterize the aberrations of lenses with central obscurations. High resolution resists that meet the line-edge roughness (LER) and defect requirements for high-volume manufacturing (HVM) also need to be developed. High power light sources will also be needed to limit photon shot noise.


Author(s):  
A. A. AlKelly ◽  
Ibrahim G. H. Loqman ◽  
Hassan T. Al-Ahsab

Focus shaping of cylindrically polarized vortex beams (CPVBs) by linear axicon is studied theoretically. Vector diffraction theory has been used to derive the expressions of the light field in the focal region. It is shown that a different intensity distribution in the focal region can be obtained by adjusting the topological charge, the polarization rotation angle and the numerical aperture maximal angle. A focal spot, a dark channel and a flat-topped shapes are formed by choosing proper values of parameters. A controllable polarization state of dark channel is obtained. The different focal region shapes may find wide applications such as material processing and optical tweezers.


Author(s):  
Muhammad Arif Bin Jalil

Abstract: Optical fiber is a medium that made by silica or plastic, and widely used in transmitting information over longer distance especially in communication system. There are three types of fiber optic used in this project which are single mode stepindex (SMSI), multimode step-index (MMSI), and multimode graded-index (MMGI) in optical communication system. There are three objectives in this project in order to get the suitable optical fibers in the communication system. First objective is to simulate the result by using Excel and Origin software. The data and the formula of fiber optics will be key in through Excel software while the graph will be analyzed by using Origin software. The second objective is to compare the different types of fiber optics in communication system by comparing the several of their characteristics such as numerical aperture (NA), acceptance angle (θ(a)) and propagation constant (β). The performance of all types fiber optics are analyzed from the result using the standard communication wavelength of 1550 nm. The core diameter for SMSI, MMSI, and MMGI are 9, 200 and 50 μm respectively while the cladding diameter for SMSI and MMGI is 125 μm and 240 μm for MMSI. This diameter also been analyzed by using the standard value for optical communication system. Then, the comparison between SMSI, MMSI and MMGI will be made to choose the more suitable for optical communication system based on their characteristics. From the results, MMSI and MMGI give best performance compared to SMSI. After that, the third objective is to make the comparison between MMSI and MMGI in term of intermodal dispersion to compare the efficiencies of fiber optics. MMGI give the better result in terms of efficiencies for communication system compared to MMSI. Keyword: Single Mode Step-Index (SMSI), Multimode Step-Index (MMSI), Multimode Graded-Index (MMGI), Communication System, Excel and Origin Software


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Ruo-Peng Zheng ◽  
Shu-Bin Liu ◽  
Lei Li

Due to the limitation of numerical aperture (NA) in a microscope, it is very difficult to obtain a clear image of the specimen with a large depth of field (DOF). We propose a deep learning network model to simultaneously improve the imaging resolution and DOF of optical microscopes. The proposed M-Deblurgan consists of three parts: (i) a deblurring module equipped with an encoder-decoder network for feature extraction, (ii) an optimal approximation module to reduce the error propagation between the two tasks, and (iii) an SR module to super-resolve the image from the output of the optimal approximation module. The experimental results show that the proposed network model reaches the optimal result. The peak signal-to-noise ratio (PSNR) of the method can reach 37.5326, and the structural similarity (SSIM) can reach 0.9551 in the experimental dataset. The method can also be used in other potential applications, such as microscopes, mobile cameras, and telescopes.


Author(s):  
Nina Artioukhina

The article is devoted to the theory of calculating mirror systems with anastigmatic properties, namely, the area of research in terms of developing methods for parametric calculation of dimensions and aberration correction. The such systems can correct three third-order aberrations. Mirror anastigmats allow developing the angular field of view of devices while maintaining a high numerical aperture, which allows them to be used in optoelectronic equipment operating in a wide spectral range. Complete absence of chromatic aberrations, high resolution, permissible wave criteria for image quality provide excellent opportunities for using mirror anastigmatic systems. General methodological approaches have been developed that can be applied to the creation of detailed engineering and technical methods for calculating a group of mirror anastigmatic systems. A serious drawback of reflective optics is center without central screening, which degrades image quality. To eliminate it, rotations or displacements of the mirrors are intro-duced, but non-elementary aberrations of even orders appear, which must be corrected. The creation of compositions with decentered catoptric elements requires further development of the calculation and methodological base. Mathematical solutions to the problem of creating basic models of non-centered mirror systems are presented. Accurate formulas are obtained for the calculation of real rays from the conditions of astigmatism and coma correction for the given angles of incidence of the chief ray on the mirror surfaces and the «oblique» thickness  , which determines their relative position. Based on the proposed formulas, a new method for parametric calculation of decentered mirror systems has been created, which allows one to compose algorithms and design both basic models and complex mirror systems from off-axis mirrors. The development of new algorithms for two- and three-mirror decenter lenses will increase the accumulated potential of computational optics. The scope of the proposed technique can be expanded in terms of the number of components.


2021 ◽  
pp. 1-12
Author(s):  
Neelam Barak ◽  
Vineeta Kumari ◽  
Gyanendra Sheoran

Maintaining telecentricity and zooming in microscopic systems with prolonged depths of focus is a difficult challenge because these properties degrade while moving to different axial planes in the extended focal depth. In this paper, we propose the proof of concept for an automated dual-mode microscopic system that combines two electrically tunable lenses (ETLs) with a variable numerical aperture controller placed. It acts as a viable solution to allow both multiplane microscopic zooming and telecentricity with consistent image resolution throughout the objective's extended focal depth. The image plane remains fixed for both the modes of operation, namely telecentricity and multiplane zooming. To validate the performance of the proposed idea, both simulations and experiments are carried out at various ETL curvature ranges. Over the whole zoom distance range, the experimental zoom ratio is determined to range from −2.723X to −34.42X. The experimental and simulation findings are compared and found to be quite similar, with magnification error percentages of 2.26% for zoom mode and 1.27% for telecentric mode. The comprehensive explanation of simulation and experimental results demonstrate the feasibility of the proposed method for both multiplane zoom and telecentric operations on a single platform in microscopic applications.


Author(s):  
Yong-Qiang Liu ◽  
Zhongru Ren ◽  
Yingchao Shu ◽  
Lujun Wu ◽  
Jinhai Sun ◽  
...  

Abstract Broadband metalenses consist of sub-wavelength phase gradient elements are indispensable in modern science and technology. So far, several broadband optical metalenses are demonstrated but mostly with either small NA or relatively low focusing efficiency. Herein, an ultra-thin broadband microwave metalens (frequency range from 8.0GHz to 10.5GHz) with both high-efficiency above 40% and large NA more than 0.6 is presented. The metalens is also fabricated and the measurement results agree with the simulations very well. The performances of the presented broadband metalens can surpass nowadays microwave metalens largely and open up new vistas for low-profile, low-cost and light-weight microwave components.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lihua Dai ◽  
Ben Wang ◽  
Xuemin Cheng ◽  
Qin Wang ◽  
Junchang Yu

Abstract In order to discuss the application and mode of the forced modulation function in a sensor, the optical fibre emphasis function was established by referring to the geometric method, the tilt factor and the shape factor of the reflecting surface. These were introduced for the first time, and the corresponding mathematical model was established. The method of numerical simulation is systematically studied and multimode optical fibre parameters (including optical fibre of axial spacing, optical fibre core diameter and numerical aperture) are adopted. The reflective surface inclination and shape factors on the RIM–FOS intensity modulation characteristics are studied according to the obtained light quasi-Gaussian distribution model, establishing a general three-intensity modulation function of fibre optic sensor. The results show that the intensity modulation characteristic of specular reflection is obviously better than that of the diffuse reflection surface, and the peak value of the modulation function is five times that of diffuse reflection. The intensity modulation characteristic decreases with increase in the roughness of the reflection surface. The system can not only complete the RIM–FOS characteristic simulation and characteristic testing functions, but can also start-up the test and not be affected by the ambient light interference and power fluctuation of the light source. The test stability is good with high repeatability.


2021 ◽  
Author(s):  
Ning Zhang ◽  
Qingzhi Li ◽  
Jun Chen ◽  
Feng Tang ◽  
Jingjun Wu ◽  
...  

Abstract Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They achieve the effect of focusing through phase control under a sub-wavelength scale, named metalens. They are poised to revolutionize optics by enabling complex low-cost systems. However, there are monochromatic severe aberrations in the metasurfaces. In this paper,the long-wave infrared optical system coma is eliminated through a single-layer metasurface. By changing the phase function,this metalens have a numerical aperture of 0.89,a focal length of 150 μm,and a field of view of 120° (0.4@60lp/mm) that enables diffraction-limited monochromatic imaging along the focal plane at a wavelength of 10.6μm. And the designed metasurface maintains a favorable MTF value at different angles. This equipment can be widely used in imaging and industrial processing.


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