Design Of Optical System Research Articles

AUTOMATED SYNTHESIS OF FAST LENSES FOR MODERN NIGHT VISION DEVICES

This article is devoted to research of the possibilities of automated design of fast and high-quality multi-lens objectives intended for use in night vision devices with modern image intensifier tubes of generation 4 and 4+, which have photocathodes with a diameter of up to 18 mm. Such image intensifier tubes are characterized by extended spectral sensitivity, high signal-to-noise ratio, and increased resolution. The computer program PODIL, developed earlier for the automated design of arbitrary optical systems, was applied to find out prescription data of fast lenses. For the parametric synthesis of optical systems, the modified evolutionary algorithm implemented in the program was used. The article presents the general methodology and results of automated parametric synthesis of a series of optical systems of objectives with different focal lengths, which contain from 7 to 9 lenses with spherical surfaces. The synthesized lenses provide angular field of view of 10°, 37° and 60° without any vignetting of axial and peripheral beams. The correspondent F numbers are 1.5, 1.33, and 1.4. The working spectral range of the designed lenses is determined by the spectral sensitivity of the photocathodes of the image intensifier tubes. In this research, it covers wavelengths from 0.45 to 0.9 μm. The longitudinal size of the designed optical systems (i.e. the distance from the first optical surface to the photocathode’s plane) is found within the range from 80 to 106 mm. The presented results of aberration analysis confirm the high image quality of the obtained optical systems. In particular, the maximum spatial frequencies of the evaluated polychromatic diffraction modulation transfer functions of the lenses over the entire field in both meridional and sagittal planes exceed 50 mm-1. The maximum values of relative distortion of the lenses are obtained within the range from 1% to 2%.

Secure and Efficient Federated Learning for Smart Optical Cable Monitoring Systems

This study presents a pioneering federated multi-modal data classification model tailored for smart optical cable monitoring systems. By harnessing federated learning techniques, the model ensures data privacy while achieving performance on par with centralized models. Through comprehensive experiments spanning various modalities, including vision and auditory data, our approach showcases promising outcomes, as evidenced by accuracy and precision metrics. Furthermore, comparative analyses with centralized models highlight the superior data security and reduced network strain offered by federated learning. Moreover, we delineate the design and deployment of a smart optical cable monitoring system leveraging edge computing, accentuating the pivotal role of information technology in elevating operational efficiency within the cable monitoring domain. Through meticulous analysis and simulations, our proposed system adeptly monitors environmental variables, thereby bolstering safety and efficiency in smart optical cable monitoring applications.

Measurement of nonlinear refraction and absorption coefficient in BaGa2GeSe6 crystal

The coefficients of nonlinear absorption and nonlinear refraction of the quaternary barium chalcogenide crystal BaGa2GeSe6 at a wavelength corresponding to half the band gap, as well as their dependence on the pulse repetition rate and peak on-axis irradiance, were measured for the first time. The third-order nonlinear optical properties were studied using the single-beam Z-scan technique. An Nd: YLF laser at 1.053 μm with a pulse duration of approximately 5.2 ns was used as a radiation source. In addition, a thermal Z-scan was carried out to investigate thermal lensing in the BaGa2GeSe6 crystal, employing a continuous wave Nd: YAG laser at 1064 nm. These studies represent an important step in comprehending the nonlinear optical properties of barium chalcogenide crystals and their behavior at different pulse intensities. The results might be significant for the modelling and design of mid-infrared optical systems.

Underwater target laser polarization suppression scattering detection technology and verification.

The underwater laser polarization detection technology integrates the polarization characteristics of light into the detection and identification of underwater targets. Addressing the challenge of poor accuracy in identifying targets in strong underwater scattering environments, this article proposes an overall scheme for a laser polarization underwater detection device that suppresses scatter using polarized pulse signals. By overcoming key technological barriers in the design of polarization-preserving optical detection systems and utilizing the method of differential amplitude to measure polarization, a laser polarization underwater detection device was developed and underwater polarization detection experiments were conducted, achieving precise detection of underwater targets. The results indicate that the underwater detection device we designed has a root mean square error of less than 5.7% to detect the polarization of the target, demonstrating the accuracy and precision of the underwater detection device.

Design and implementation of a physical layer optical fiber security communication system based on a ZUC stream cipher

In this work, we have proposed a new physical layer encryption scheme to improve the security of optical fiber communication systems. The secrecy scheme is based on disturbance of the data cluster under the ZUC algorithm (named for Zu Chongzhi, a famous mathematician in ancient China), which is generated by optical XOR using a dual-drive Mach–Zehnder modulator (DD-MZM). A base scrambling pseudo random binary sequence (PRBS) generated by the ZUC stream cipher is introduced, which results in a better scrambling effect and randomness in the key stream of the block encryption structure. A simulation setup conducted in an encrypted transmission of the 64×64 grayscale image over 80 km of optical fiber shows that the authorized user can successfully decrypt the received signal, while the eavesdroppers cannot derive useful information with a bit error rate (BER) at approximately 0.5. In the simulation, after setting the delay compensation to 3.125 ps, a correct signal with a Q-factor as high as 11.3642 and a BER as low as 3.14295−30 can be obtained.

Dual-channel aperture-splitting snapshot spectral imaging detection system

The contemporary spectral imaging detection systems commonly employed, such as pushbroom and stare systems, often necessitate motion-based imaging mechanisms such as scanning motors. This reliance on motion renders the imaging process vulnerable to platform vibrations, resulting in intricate post-image correction procedures and precluding dynamic target detection. Consequently, the advent of snapshot spectral imaging detection systems has ensued. Currently, there are significant challenges in the miniaturization design and rapid data acquisition aspects of snapshot spectral imaging systems. In this study, linear variable filters were employed as spectral components, and, through optical system simulation and design, the design of the nonspherical monolithic lens system and telescope system in the dual-channel aperture-splitting snapshot spectral imaging detection system were separately completed. The spectral range covered 400–1000 nm, with a spectral resolution of 27.3 nm, and each channel had a spatial sampling of 409×409 pixels. Additionally, based on the optical system design results, the system structure design and assembly were completed. Performance testing and preliminary spectral image fusion research were conducted on the assembled prototype. The instrument demonstrated excellent spectral imaging performance, thereby enhancing the efficiency of spectral imaging detection in snapshot spectral imaging.

Optical Design of a Hyperspectral Remote-Sensing System Based on an Image-Slicer Integral Field Unit in the Short-Wave Infrared Band.

Grating-type spectral imaging systems are frequently employed in scenes for high-resolution remote-sensing observations of the Earth. However, the entrance of the grating-type spectral imaging system is a slit or a pinhole. This structure relies on the push broom method, which presents a challenge in capturing spectral information of transiently changing targets. To address this issue, the IFU is used to slice the focal plane of the telescope system, thereby expanding the instantaneous field of view (IFOV) of the grating-type spectral imaging system. The aberrations introduced by the expansion of the single-slice field of view (FOV) of the IFU are corrected, and the conversion of the IFU's FOV from arcseconds to degrees is achieved. The design of a spectral imaging system based on an image-slicer IFU for remote sensing is finally completed. The system has a wavelength range of 1400 nm to 2000 nm, and a spectral resolution of better than 3 nm. Compared with the traditional grating-type spectral imaging system, its IFOV is expanded by a factor of four. And it allows for the capture of complete spectral information of transiently changing targets through a single exposure. The simulation results demonstrate that the system has good performance at each sub-slit, thereby validating the effectiveness and advantages of the proposed system for dynamic target capture in remote sensing.

Design of a zoom head-up display optical system based on a nodal aberration theory

We propose a zoom dual-path augmented reality head-up display optical system. The system uses two image generation units to display the basic and interactive information. Based on the node aberration theory, the aberration evaluation function was constructed. By solving the optimal solution of the aberration evaluation function, the initial structure of the interactive information display optical path was obtained. In order to solve the vergence-accommodation conflict in the process of vehicle speed change, the interactive information optical path was designed as a zoom optical path. The zoom distance is 10–20 m, and the basic information optical path will not be interfered with in the process. In addition, the tolerance analysis of the system was carried out to prove the machinability and stability of the system. This study makes the imaging of the augmented reality head-up display system more in line with the characteristics of the human eye and improves driving comfort.

Design and implementation of a lightweight hybrid optical system for aircraft head-up display

Design and implementation of a lightweight hybrid optical system for aircraft head-up display

A science-driven approach to optimize the design for a biological small-angle neutron scattering instrument

Biological small-angle neutron scattering (SANS) instruments facilitate critical analysis of the structure and dynamics of complex biological systems. However, with the growth of experimental demands and the advances in optical systems design, a new neutron optical concept is necessary to overcome the limitations of current instruments. This work presents an approach to include experimental objectives (i.e. the science to be supported by a specific neutron scattering instrument) in the optimization of the neutron optical concept. The approach for a proposed SANS instrument at the Second Target Station of the Spallation Neutron Source at Oak Ridge National Laboratory, USA, is presented here. The instrument is simulated with the McStas software package. The optimization process is driven by an evolutionary algorithm using McStas output data, which are processed to calculate an objective function designed to quantify the expected performance of the simulated neutron optical configuration for the intended purpose. Each McStas simulation covers the complete instrument, from source to detector, including realistic sample scattering functions. This approach effectively navigates a high-dimensional parameter space that is otherwise intractable; it allows the design of next-generation SANS instruments to address specific scientific cases and has the potential to increase instrument performance compared with traditional design approaches.

Implementing green optical waveform system using hybrid cognitive methods for QAM transmission scheme

Abstract This study proposes a hybrid approach combining Energy Detection (ED) and Matched Filter (MF) spectrum sensing techniques to enhance power spectrum density (PSD) in optical Nonorthogonal Multiple Access (NOMA) systems. Optical NOMA has emerged as a key technology for boosting spectral efficiency in optical communication networks. However, optimizing PSD remains a critical challenge due to various factors including signal detection and noise interference. The hybrid ED–MF spectrum sensing method aims to address these challenges by leveraging the strengths of both techniques. Energy Detection (ED) offers simplicity and robustness in detecting primary users, making it suitable for initial spectrum sensing in cognitive radio networks. Matched Filter (MF) spectrum sensing, on the other hand, provides superior signal detection and noise rejection capabilities, particularly in low signal-to-noise ratio (SNR) environments. By integrating these two techniques, we aim to achieve improved sensitivity and accuracy in spectrum sensing, thus enhancing spectral efficiency and system performance in optical NOMA networks. The effectiveness of the proposed hybrid approach is evaluated through theoretical analysis and simulation experiments. Results demonstrate significant enhancements in spectral efficiency and system reliability compared to conventional spectrum sensing methods, highlighting the potential of the hybrid ED–MF approach for enhancing PSD in optical NOMA systems. This research contributes to advancing the design and optimization of optical communication systems for future high-capacity and high-speed data transmission applications. The PSD values −920 are obtained and it confirmed that the proposed algorithm outperforms the standard algorithms.

Simulation method for multi-source information fusion space target

Current space target simulation systems suffer from limitations, such as a single simulated spectral band, inability to allocate spectral ratios between bands, and poor imaging quality of multi-spectral simulated images. We propose a multi-source information fusion spatial target simulation method system that features a “series-parallel” hybrid connection. We optimize the design of a multi-spectral common aperture optical system and experimentally verify the proposed method. The experimental results show that the proposed system can simulate a wide range of spectral bands ranging from ultraviolet to long-wave infrared. Furthermore, it achieves precise control over the ratio of simulated radiant energy among spectral bands, with a spectral simulation error of less than 4.8%. Notably, it effectively images stars against the cosmic background and spacecraft across different spectral bands. This system serves as a theoretical cornerstone and provides crucial technological support for performance testing and rapid iterative development of multi-source information fusion space exploration systems.

Improvement of optical wave propagation simulations: the scaled angular spectrum method for far-field and focal analysis

In the field of optics, accurately simulating wave propagation is essential for both theoretical insights and practical applications. This study introduces the scaled angular spectrum method (Sc-ASM) for simulating far-field and focal patterns, overcoming the limitations inherent in the standard angular spectrum method (ASM) by allowing variable sampling intervals between source and observation planes. Comparative analysis with the Rayleigh–Sommerfeld integral demonstrates Sc-ASM's superior accuracy in estimating the far-field patterns of beams with complex phase structures. Our results underscore Sc-ASM’s potential to set a new benchmark in optical simulations, significantly advancing optical system design and the study of wave propagation.

Electronic, magnetic, elastic and optical properties of Ba2CoTaO6 double perovskite oxide: A DFT study

In this study, the computational functionals GGA and mBj of density functional theory (DFT) were employed to explore the electronic structure of tantalum based double perovskite oxide Ba2CoTaO6. Computed tolerance (t) and octahedral (µ) factors deduce the cubic stability of the perovskite crystal. Negative formation energy indicates that the system is thermodynamically stable. The elastic constants satisfy the conditions for cubic stability and the Pagh’s index (B/G) evinces the brittle nature. The band structure and total density of states reveal the half-metallic nature with a 4.7 eV insulator indirect energy band gap at the Fermi level in the spin up direction. An integer-valued (4µB) magnetic moment is observed to favor the half-metallic ferromagnetism in the double perovskite oxide Ba2CoTaO6. Optical properties play a significant role in the design and functionality of optical devices and systems. In this aspect, the two parts of the dielectric function (real and imaginary) and the related parameters have been explored. The observed properties provide insights into possible applications of this system in spintronics and optoelectronics.

Design method for lens desensitization adapted to refractive index error

The design of optical systems not only considers the imaging performance but also the manufacturing difficulty and feasibility of the system. In practice, errors in the manufacturing process of glass materials and deviations in glass material parameters introduced in complex environments can both lead to degradation in the imaging quality of optical systems. Optical systems that are sensitive to glass material errors face increased manufacturing difficulty and reduced stability. This paper, based on geometrical optics theory, establishes an evaluation function for refractive index error sensitivity and analyzes its relationship with optical parameters and glass materials. It proposes a design method to reduce the refractive index sensitivity of optical systems. Through simulation verification and analysis using examples, the validity of the desensitization design method is confirmed.

Research on electronic optical monitoring technology and system design for vacuum electron beam welding process

Electron beam welding technology is increasingly used in industrial manufacturing due to its high power density and the purity of welded joints. In vacuum environments, traditional optical and machine vision monitoring methods are susceptible to contamination by metal vapors, which hinders the monitoring effect. Due to the limitations of optical monitoring methods, electronic optical imaging technology is a new alternative monitoring method that has been introduced into the electron beam processing in recent years, but the complexity of the industrial electron beam welding environment makes it relatively less studied in the field of electron beam welding. In this study, a YAG scintillator detector is proposed to collect the backscattered electron information generated by the interaction of electrons with the sample, and an FPGA real-time processing system is used to realize the weld quality monitoring in the industrial electron beam welding processes. The distribution law of backscattered electrons in space is simulated by Monte Carlo method, and the results show that the number of distribution in the 40°∼60° angle region is more, the backscattering coefficient increases with the increase of the incident angle of the electron beam, and the backscattering coefficient of the samples with large atomic numbers is relatively high. The field monitoring experiments show that the designed system exhibits good sensitivity to the characteristic morphology, and the imaging resolution reaches more than 200 μm, and the weld hole defects are clearly visible. A good linear correlation between the current change curve during scanning and the actual shape profile is shown, while the image resolution is better when the spot current is 1 mA.

Continuously Geometrical Tuning to Boost Circular Dichroism in 3D Chiral Metamaterials

AbstractChiral metamaterials possess unique optical chiral responses, and the attainment of remarkable intrinsic chirality typically necessitates the disruption of their mirror symmetry to facilitate cross‐coupling between electric and magnetic dipoles. However, achieving such symmetry breaking in a flexible and controllable manner remains challenging due to the limited range of applications afforded by available methodologies. Here, a method is proposed for fabricating robust three‐dimensional (3D) chiral metamaterials by projecting arbitrary planar chiral metasurfaces onto on‐demand height‐tunable 3D silicon structures, thereby effectively modulating their optical chiral responses through continuously tuning the degree of cross‐coupling between dipoles. Experimental and simulation results demonstrate this approach's ability to precisely control circular dichroism (CD) from a non‐chiral state to various activated and enhanced chirality. Enhancing CD with high precision and continuous control manners can naturally provide an advanced opportunity and platform for the future design and actual applications of chiral optical systems.

An analytic expression for the field dependence of three-order Zernike aberrations in decentered and/or tilted optical systems

The double Zernike polynomials can describe the aperture dependence and field dependence of non-coaxial optical system aberrations simultaneously, and characterize the complex optical aberrations, which are of great value in the optical system design and alignment. In this paper, the specific analytic forms of all third-order double Zernike aberrations in decentered and/or tilted optical systems are derived based on the nodal aberration theory. This paper realizes the orthogonalization of the third-order aberrations with different aperture dependence and field dependence. The calculation process of the third-order double Zernike aberrations is presented. The ray tracing of the Cassegrain telescope verifies the analytic derivation of the double Zernike aberrations.

Compact off-axis reflective optical system design combining freeform mirror and freeform detector

Minimizing system size and weight without sacrificing the desired imaging performance is a crucial and challenging goal in the design of off-axis optical systems. In this paper, we propose a design concept that combines freeform mirror and freeform detector to achieve more compact off-axis optical systems. Initially, by applying nodal aberration theory, the optimal focal surface shape for off-axis systems is demonstrated to be an off-axis paraboloid or even a freeform surface, rather than the commonly assumed spherical shape. Subsequently, we show the ability of the design concept to reduce off-axis system volume through a design example of a fast and wide-field off-axis three-mirror system. Results indicate that, under the same design parameters and imaging quality, the design with a freeform detector is 80% smaller than that with a flat detector in terms of volume. Finally, the bending capability of the freeform detector presented in this paper is ensured through finite element analysis, and its surface accuracy is achievable based on the current precision level of curved detector fabrication. The proposed design concept holds promise for application in planetary science, where the imaging performance of the instrument is highly required and the size and weight are strictly limited.

Bidirectional trifunctional splitter with two sided microstructure

This paper proposes a bidirectional trifunctional splitter with a bilayer ridge structure for polarization-selective and polarization-insensitive outputs at the wavelength of 1550 nm. The configuration can realize a four-port output for both polarizations and TE-two/TM-three output. In the upper part of the bidirectional trifunctional splitter, for TE polarization, two outputs exhibit diffraction efficiencies greater than 49%, while for TM polarization, three outputs exhibit diffraction efficiencies greater than 32%. Furthermore, for the lower part of this beam splitter, under both TE and TM polarization, the diffraction efficiencies of four outputs exceed 24%. Compared to the previous beam splitter, the bidirectional trifunctional splitter exhibits superior uniformity and is capable of simultaneously achieving polarization-selective and polarization-insensitive outputs. Furthermore, the configuration is theoretically resistant to the geometric dimensions, which greatly reduces the difficulty of fabrication. This work exhibits a novel approach to the design of energy-splitting devices and optical communication systems with multiple outputs.