Mirror Surface Research Articles (Page 1)

The off-axis reflective system exhibits severe off-axis aberrations due to its non-rotational symmetry. Traditional design methods compensate for off-axis aberrations by complicating the mirror surfaces. To address this issue, this paper proposes optimizing the off-axis four-mirror system through computational imaging to achieve high-quality imaging. First, most of the current mainstream optical design software relies on the selection of the initial structure. We propose an improved particle swarm optimization algorithm (PSO-GA) combined with cosine annealing and a genetic algorithm (GA) to obtain the off-axis four-mirror initial structure for subsequent optimization. To improve the restoration effect and effectively compensate for off-axis aberrations, we introduce a generative adversarial network model (ES-GAN), which combines the attention mechanism and spatially gated feedforward network for image restoration. This method achieves high-quality restoration of blurred images without increasing the complexity of the surfaces. By comparing the peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) between the restored and original images, the results indicate that the PSNR of the restored image increased by 19.43%, and the SSIM increased by 19.32%. This verifies the effectiveness of the proposed computational imaging method and provides a reference for the simplification tasks of complex surface-type systems.

Achieving uniform intensity distribution is essential for various laser applications such as material processing. This paper presents the design, simulation, and experimental validation of a segmented beam-shaping integrator mirror aimed at transforming an incident laser beam into a uniform line-shaped spot. The mirror surface is composed of multiple connected parabolic segments. A geometric optics computational method, implemented using Python code, was developed to determine the unique parameters and boundaries for each segment, based on input specifications including the working distance (f), the input aperture size (D), the target spot size (d), and the number of segments (s). For a design case with D=49.5mm, f=350mm, d=20mm, and s=7, the segment parameters were calculated. The calculated design was modeled in SolidWorks, and its performance was simulated using Zemax ray tracing, predicting a shaped spot closely matching the 20mm target size in the segmented direction and an expected size (approx. 1.4mm) in the orthogonal direction. Experimental validation was conducted using a 4kW fiber laser equipped with a fiber core diameter of 400µm and a numerical aperture of 0.15, along with a collimating lens with a 100mm focal length. The measured spot size at the target plane was 20.39mm×1.41mm (1/e2 width), showing excellent agreement with both the design specification and the simulation results. This work successfully demonstrates the effectiveness of the integrator mirror design method and fabrication process for creating high-performance beam-shaping integrator optics for high-power laser systems.

High purity aluminum in its bulk form has intrinsicallyhigh reflectancein the far-ultraviolet (FUV) regime and finds utility in astrophysicalinstrumentation applications. However, bulk Al oxidizes rapidly inthe atmosphere, and its native oxide strongly absorbs and severelydegrades the observed FUV properties relative to bare Al. Varioustechniques have been investigated to produce coatings that inhibitaluminum oxide formation and lead to high FUV mirror reflectance.This work examines the development and use of a uniquely modified,hybrid plasma-enhanced atomic layer deposition (PEALD) system to passivatealuminum mirrors with metal fluoride films. This system combines twoplasma sources in a commercial atomic layer deposition (ALD) reactor.The first is a conventional inductively coupled plasma (ICP) sourceoperated as a remote plasma, and the second is an electron beam (e-beam)driven plasma near the mirror surface. To establish the operatingconditions for the in situ e-beam plasma source, the effects of samplegrounding, SF6/Ar flow, and sample temperature on resultingAlF3 films were investigated. Optimal operating conditionsproduced mirrors with excellent FUV reflectivity, 92% at 121 nm and42% at 103 nm wavelengths, which is comparable to state-of-the-artAlF3-based passivation coatings and matches that of previouslyreported ex situ e-beam plasma-processed mirrors. This optimized insitu e-beam process, along with XeF2 passivation, is thenexplored to produce a clean seed layer (unoxidized Al surface) forsubsequent PEALD of AlF3. Both approaches are demonstratedas valid pretreatments before PEALD of AlF3, showing apromising pathway for the deposition of other fluoride-based layers,such as MgF2 or LiF, with ALD or PEALD.

The largest biaxial dual-trough collector system in China was constructed at Bayan Oilfield. This system features a biaxial dual-trough collector with a tracking accuracy of up to 0.015° and a heat collection efficiency as high as 85%, maximizing the utilization of solar radiation resources within a limited land area. However, research on the wind load effect of biaxial dual-trough collectors remains sparse. This paper presents contour plots of average wind pressure and pulsating wind pressure distributions obtained through numerical simulations of the biaxial dual-trough collector model. It analyzes the factors influencing wind pressure distribution and compares them with the wind pressure distribution of a uniaxial trough collector. The results indicate that the extreme wind pressure values for the biaxial dual-trough collector mainly occur at the edge corner areas of the mirror surface. The maximum wind pressure coefficient appears at a vertical elevation angle of 60°, predominantly in the upstream area of the mirror surface. Additionally, due to the gap between the two mirrors of the biaxial structure, columnar vortices are more likely to form on the mirror surface.

Fingermark development on silver mirror surfaces: A comparative study between mirror chemical delamination assessment and established techniques

In this paper, the fixed aberration corrector is combined with the wavefront sensorless adaptive optical system to solve the problem of large dynamic aberration in the aspherical dome optical system with a large field of regard (FOR) of ±60°. We constructed a conversion matrix between Zernike polynomial coefficients and the voltage of the deformable mirror actuator, reducing the number of optimization variables to eight. The genetic algorithm based on the Zernike model controls deformable mirror (DM) surface shape and corrects residual aberrations in the system. The simulation results show that the optimization speed is increased by more than 95%. At the same time, we established an experimental validation platform. Experimental results show that the optimization method can successfully eliminate the introduced wavefront aberration. Therefore, the aberration correction method of the aspherical dome optical system based on Zernike polynomial coefficients designed in this paper is feasible.

In this paper, the optical efficiency and output thermal power of the heliostat mirror field are analyzed and optimized by constructing a geometric model and an optimization algorithm for the optimal design of the heliostat mirror field of a tower-type solar photovoltaic power plant. First, based on the solar position model and the optical efficiency model of the heliostat mirror field, the annual average optical efficiency, the annual average output thermal power, and the annual average output thermal power per unit mirror area of the heliostat mirror field are calculated. Secondly, the EB layout was used to optimize the heliostat field, and the parameters of heliostat size and mounting height were optimized by genetic algorithm and particle swarm algorithm to maximize the annual average output thermal power per unit mirror surface area. The results show that the optimized heliostat mirror field significantly increases the annual average output thermal power per unit mirror area under the condition of achieving the rated power, which provides theoretical basis and technical support for the design and operation of the tower solar thermal power plant.

The TPS Phase III soft x-ray beamlines, designated as 33, 35, and 43, employ bendable mirrors to achieve the required optical performance across a broad energy range. All mirrors, except for the grating mirrors, are designed with adjustable height and position to optimize alignment. The mirrors are secured to the bending mechanism using specially designed clips and bolt joints. During bending, the mirror surface deformation can be approximated by second- and third-order polynomial terms, which must be removed to minimize optical aberrations. After applying these corrections, the residual slope error in the useful optical area must remain below ±1.5 × 10-6rad to meet performance criteria. Therefore, the design of the mirror clip and the precise application of bolt joint forces are critical to achieving high-accuracy figure control. This study systematically investigates how varying bolt joint forces at the mirror clip can compensate for high-order residual deformations. Finite element method simulations were conducted to determine optimal force distributions, providing guidance for experimental setup and safe mounting conditions. In experiments, the bolt joint forces were adjusted using a calibrated torque wrench, while the long trace profiler continuously measured the slope error to identify the configuration yielding the widest functional optical area with minimal residual error.

The utilization of smooth optical surfaces represents a critical approach for suppressing backscattering in spaceborne gravitational wave telescopes, such as those employed in the TianQin project. The bidirectional reflectance distribution function (BRDF) serves as an effective physical parameter for characterizing light scattering properties and has been extensively applied in stray light suppression research. This study employs surface scattering theory to quantitatively analyze the impact of three major stray light sources - surface roughness, defects, and contamination-on telescope system backscattering. Based on this analysis, we establish specific performance requirements for single mirror surface roughness, defect tolerance, and cleanliness levels.

We present a direct measurement of the nanoscale dynamics of plasma mirrors using wavefront measurement techniques. This two-dimensional measurement, performed via pump-probe diagnostics, enables the reconstruction of the three-dimensional plasma mirror surface with nanometer axial, micrometer transverse, and femtosecond temporal resolution.

Fast computer-generated hologram calculation algorithm for mirror images reflected on mirror surface of Bézier surfaces using subdivision

Orthogonal polynomials are indispensable in optical engineering for aberration control and surface machining, yet their application in non-circular apertures remains a persistent challenge. While Zernike polynomials effectively decompose wavefront errors into physically meaningful terms within circular domains, their orthogonality fails in arc-shaped apertures-a critical geometry for extreme ultraviolet lithography (EUVL) systems employing curved fields to avoid light obscuration. This breakdown severely limits high-precision surface correction and aberration control in freeform optics. To address the breakdown of orthogonality for traditional orthogonal polynomials in irregular domains, this study employs the principle of topological homeomorphic transformation to establish a bidirectional mapping function between irregular and regular regions, thereby extending the orthogonality domain of conventional orthogonal polynomials. Taking the irregular effective aperture in EUVL objective lens systems as an example, we derived arc-shaped Legendre orthogonal polynomials (ALOP) and verified their advantages over traditional polynomials through two distinct application scenarios. The introduction of ALOP into the optical design of the six-mirror system has led to a further enhancement of the system's imaging quality, and the wavefront aberration root mean square (RMS) has been optimized from the original 0.148 nm to 0.098 nm. In the context of surface figure refinement applications, we simultaneously established a deterministic mapping between the ALOP parameters of individual mirror surfaces and optical aberrations. This mapping enabled the reduction of the full-field wavefront aberration RMS in the projection optical system from 1.77 nm to 1.05 nm via single-mirror refinement, achieving a refinement efficiency exceeding 40%. Furthermore, the methodology established in this study-linking irregular domains with regular domains through topological homeomorphic transformation-addresses the challenges posed by non-conventional geometries and pupils in advanced optical systems, and provides fresh perspectives for the design and fabrication of future high-precision, highly complex optical systems.

Near-unstable cavities hold promise for reducing thermal noise in next-generation gravitational wave detectors and for enhancing light–matter interactions in quantum electrodynamics. However, operating close to the edge of geometrical stability presents significant challenges, including increased coupling to higher-order modes and heightened sensitivity to small cavity length changes and mirror imperfections. This study employs Finesse v3 simulations to systematically investigate the modal behavior of a plano-concave cavity as it approaches instability, incorporating measured mirror surface defects and anisotropic curvature to replicate realistic conditions. The simulations highlight the degradation of beam purity and control signals as the cavity approaches instability. By validating the simulations against experimental data, we confirm Finesse’s reliability for modeling cavities while identifying critical limitations in regimes close to the edge of stability. These findings provide essential guidance for optimizing cavity designs in future gravitational wave detectors, balancing performance gains against the challenges of operating at the stability edge.

High-throughput surface measurements and inspection are crucial for a wide range of applications, from reflective optical components to very large-scale integrated (VLSI) circuits. Reflective Fourier ptychographic microscopy (RFPM) has been previously reported as a solution for imaging reflective surfaces at high resolution. Prior approaches have used epi-illumination for bright-field and either a ring array or parabolic mirror for dark-field illumination, which can be bulky and require demanding calibration compared to standard transmission FPM setups. In this work, we present a novel, to the best of our knowledge, deep ultraviolet (DUV) RFPM method that utilizes a single LED matrix as the illumination source. The system achieves a simpler and more compact reflective FPM setup, enabling a 1.6 mm field of view, 690 nm spatial resolution, and nanometer-scale height profiling using a 5×, 0.12 NA DUV objective lens. We demonstrate the DUV RFPM experimental setup and present measurement results on wafer standards and a machined concave mirror surface.

Smooth copper foils contribute to reduced high-frequency signal loss and enhanced performance in lithium-ion batteries, making them essential for next-generation electronic devices and energy technologies. In this study, we achieved surface smoothing by instantaneously compressing copper foils onto a smooth metal mirror plate using underwater shock waves generated by explosives, thereby replicating the topography of the mirror surface. As a result, the surface roughness was reduced from 81.05 nm to 6.69 nm in a single step. Although the applied pressure was an order of magnitude lower than that typically used in laser shock processing, the stress concentrated on surface protrusions and the longer pressure duration enabled plastic deformation exclusively at the foil surface, leading to effective smoothing. The low applied pressure prevented the propagation of plastic waves into the foil interior, resulting in no reduction in thickness. Furthermore, the mirror plate exhibited no deformation and retained its surface integrity, allowing for repeated use. This method offers high scalability, as the treatment area can be expanded by tailoring the shape of the explosive charge, making it a promising technology for large-area applications.

Passive support systems for astronomical telescope optical mirrors effectively suppress gravitational deformation, yet the absence of reliable mounting stress compensation remains the primary factor causing surface deformation errors. For mid-sized optical mirrors, conventional designs employing nonlinear kinematic pairs and unidirectional optomechanical interfaces reduce mounting stress at the expense of inducing nonlinear effects, thereby limiting overall system performance. This study develops a fully constrained passive support mechanism that achieves system linearization via flexible mirror-support coupling while innovatively implementing axial micro-displacement vectors applied through lateral support mounting interfaces to counteract connection-induced stresses. The compensation strategy is structured as follows: First, utilize axial micro-displacement vectors at the mounting interfaces of lateral support mechanisms to calibrate low-order Zernike aberration coefficients and solve the transfer matrix. Next, decompose the mirror surface deformation caused by lateral support installation into low-order Zernike aberration terms. Then compute axial micro-displacement vectors through the transfer matrix and apply them to the mounting interfaces of lateral support mechanisms to achieve compensation for mounting stress. Experimental validation on a 1200mm Zerodur mirror demonstrated surface error reduction to root mean square values of λ/42 (λ=632.8nm) and λ/33 in vertical and horizontal orientations, respectively, accomplished through low-order Zernike aberration calibration and precision micro-displacement array adjustment.

Touchscreen, as an important medium for human‐computer interaction, has been widely used in the civilian market. With the development of touch technology, touch design is also gradually being adopted in the airborne cockpit display system. In order to meet the application requirements of special display, it is necessary to reduce the reflectivity of the resistive touch screen and improve its reliability. In this paper, based on the principle of polarization and phase deflection of light, the combination strategy of circular polarizer and quarter‐wave plate was used to reduce reflected light of the five‐wire resistive touch screen. The results of performance tests show that the proposed design of the resistive touch screen has lower surface haze and mirror reflection, better electromagnetic compatibility effect than the conventional resistive touch screen. Moreover, the low‐reflection touch screen was fully bonded to the LCD screen by using liquid optical adhesive, which greatly reduced the impact of vibration on the overall structure of the touch screen. This work optimizes the structure of the five‐wire resistive touch screen and achieves an acceptable effect to realize low reflection and high reliability in the airborne cockpit display system.

The far-UV (FUV) reflectance of the state-of-the-art, broadband UV/optical/IR mirrors of XeF2-passivated LiF on Al (Al + XeLiF) is promising for future space telescope missions. To reach their potential, dependable cleaning procedures and storage methods for such reflective surfaces need to be developed. First Contact™ polymer (FCP) formulations have proven to be a reliable method for cleaning conventional mirror surfaces coated with oxides or bare metal and for protecting them in storage. We report here on studies of the cleaning and storage of Al + XeLiF samples using customized FCP formulations designed by Photonic Cleaning Technologies. Cleaning of such mirrors is demanding since fluoride coatings are softer than oxides and can be moisture sensitive. Any damage that marks the overcoat can lead to catastrophic loss of FUV reflectance due to surface roughening and formation of aluminum oxide, which is FUV opaque. We discovered that one formulation could be successfully applied to and removed from Al + XeLiF coatings multiple times. The coatings retained low roughness, minimal aluminum oxide thickness, and high far-UV reflectance. Another of the four FCP formulations successfully cleaned the Al + XeLiF coatings several times. Variable-angle, spectroscopic ellipsometry, tapping-mode atomic force microscopy, x-ray photoelectron spectroscopy, and FUV reflectance allowed us to observe any changes in reflectance and surface roughness, the formation of aluminum oxide, and damage to coating integrity. From the studies of the range of FCP-fluoride interactions, we noted that too much polymer-to-surface adhesion or exposure to trace water in the polymer can result in coating damage.

Abstract The X-ray mirror surface requires high spatial resolution image measurement, a task for which the white light interferometer stitching method is most commonly used in the X-ray optical measurement lab. The measurement stage design, a crucial part of this method, includes two linear axes and two rotation axes, each with specific travel ranges. The 1200 mm travel range axis is the X axis, and the 390 mm travel range axis is the Y axis. The measurement head travel range is 390 mm along the Z axis. The rotation axes are the X-axis and the Y-axis, and each rotation range is ± 1.5 degrees. The accuracy of the rotation axes is 2.87 x10−3 degrees. The linear axes stage X, Y, and Z-axis scales accuracy ±1 µm for up to 1 m. In this study, the measurement head is ZYGO Nexview NX2, which has one rotation axis to the Y-axis. The Nexview NX2 measurement sensor array pixels are 1000 * 1000 and 1X objective head with an 8.69 * 8.69 mm field of view. Thus, each pixel’s spatial resolution is about 8.69 μm for the white light interferometer stitching measurement with 1X objective. Therefore, the stage linear direction accuracy is good enough to support the different snapshot images for stitching.

Abstract The development of X-ray mirrors has been stated in three major areas: optical, mechanical, and thermal designs. The last topic deals with modelling and controlling thermal expansion due to the absorption of the incident beam, as well as heat transfer through radiation and contact among the parts. Such control is important ensuring the mirror surface deformation caused by the power load remains within specification. Peltier devices are reliable and user-friendly thermal control actuators coping with smaller total power load, which were developed for the CARCARÁ, MOGNO, and SABIÁ beamline mirrors as an alternative to designs such as cryogenic or water/vacuum interfaces. The Peltier effect is a well-known thermoelectric phenomenon occurring when an electrical current flows through a p-type and an n-type junction. This effect can be used to transfer heat from one side of the junction to the other, resulting in a temperature difference. A Peltier dispositive was integrated in a PID control-loop associated with platinum resistance temperature sensors attached to the mirror mechanism. Here we describe the thermal design process and modelling established for a mirror mechanism and some commissioning results are discussed in terms of temperature and mechanical stability and minimized thermal deformation.