Mirror Parameters Research Articles

Thermal optimization of a high heat load liquid-metal-bath cooled mirror at the Hefei Advanced Light Facility.

Within the beamlines of diffraction-limited storage rings, the liquid-metal-bath cooling scheme is a prevalent choice for the cooling of high-heat load mirrors. This study employs the finite element analysis method to evaluate the thermal deformations of liquid-metal-bath horizontally deflecting mirrors in the Hefei Advanced Light Facility. In particular, we introduce a novel optimization strategy to obtain the optimal thermal deformation scenario, which also satisfies mechanical design requirements. Moreover, a concurrent optimization approach across multiple structural parameters of mirrors is adopted to attain globally optimal thermal deformation. Following the optimization of the mirror's structural parameters, the curvature radius increases to 227 km, while the residual slope error decreases to 36.3 nrad at 6eV in the meridian direction. The ray tracing analysis of the beam demonstrates a considerable reduction in the influence of thermal deformation on the beam's focal point. This work proposes an optimization method for designing cooling schemes under mechanical constraints.

Improved BP Neural Network Algorithm for Predicting Structural Parameters of Mirrors

Addressing the nonlinear correlations between input variables and output responses, in addition to the time-consuming nature of finite element analysis in mirror design, this study introduces an enhanced back-propagation (BP) neural network (BR-TLDBO-BPNN) employing Bayesian regularization and an optimized dung beetle algorithm. This novel approach facilitates rapid and efficient parameter estimations, significantly reducing the computational overhead. Utilizing an integrated analysis platform, the study obtained training and test samples, and the BR-TLDBO-BPNN model is used to predict the reflector’s mass and root mean square (RMS). The optimization mathematical model is built, and the nonlinear planning function (fmincon) is utilized to solve the problem and find an ideal set of structural parameters. The outcomes demonstrate that the prediction model is accurate enough to predict the mirror characteristics to optimize the mirror structural parameters. Empirical validation demonstrates that the proposed model achieves an over 99% accuracy in predicting mirror characteristics against finite element simulations. As a result, the BR-TLDBO-BPNN algorithm studied in this article not only broadens the application scope of neural networks, but also provides a new practical technique for engineering design.

Parametric optimization of rearview mirror structure based on a multi-island genetic algorithm

To quickly find the structural parameters of a particular mirror that produces the least amount of aerodynamic noise, the rearview mirror of a passenger car is taken as the research object and an optimization platform is established based on Isight software in this paper. The mirror structure is parameterized in Sculptor, and several sample models are constructed using the optimal Latin hypercube design (OLHD). Then, by simulating each sample model, the sound pressure level of the Curle source at the side window surface monitoring point was obtained. The relationship between the mirror structure and the wind noise at the point is fitted using the Kriging approximation model after the calculation is completed. Finally, the values at each point decreased when the changes at positions 1, 2, 3, and 4 were 2.5 mm, 3.91 mm, 4.5 mm, and 3.6 mm, and the sound pressure level at monitoring point 4 decreased the most, with a reduction of 3.76 dB in wind noise compared with the original model.

Optical characterization of a fiber Fabry-Perot cavity: precision measurement of intra-cavity loss, transmittance, and reflectance

We propose and demonstrate a method for characterizing the individual mirror parameters of a fiber Fabry–Perot cavity (FFPC). By measuring the reflection and transmission spectra of the FFPC with an incident laser propagating from the two mirrors of the FFPC and considering several normal or unique losses, the transmittance, reflectance, and intra-cavity loss of the individual mirrors can be determined. Due to the intrinsic limitation of cavity length, traditional powerful methods, such as the cavity ring-down technique, are not applicable to FFPCs for characterizing the parameters of individual mirrors. This scheme provides a dependable method for assessing FFPC mirrors and provides a significant capability for the implementation of strong-coupling cavity quantum electrodynamics based on FFPCs.

Numerical analysis and validation of an optical parametric oscillator considering crystal thermal effects

In this paper, a calculation model is proposed for the optical parametric oscillation (OPO) process considering the crystal thermal effects. Based on existing models, we combine a set of three-wave coupled equations with the Sellmeier equation. In order to optimize the calculation of the nonlinear process, a temperature variable t is introduced to describe the heat generated by the laser crystal during operation. The waveforms under different pump powers are analyzed. The effects of the reflectivity of the output mirror on the OPO threshold and inverse conversion are investigated. In addition, the optimal reflectivity under different pump powers can be estimated. Based on the simulation results, experiments are also performed in the near-infrared 1.57 µm band and mid-infrared 3.15 µm band. The experimental results are compared with the results of this model and a model that does not consider crystal thermal effects. The experimental results are consistent with the improved theoretical results, affirming that the proposed theoretical model can simulate the energy conversion process of OPO. This provides a theoretical basis for optimizing the parameters of the OPO output mirror and improving the efficiency of the parametric wave conversion.

Simulation analyses and configuration optimizations of an LD pumped 3.1 µm Co/Er:PbF2 MIR laser

The demand for mid-infrared physics technology is increasing, and it is still a difficult process from growing excellent laser crystals to performing laser experiments. In this paper, we consider the energy transfer process between Co2+ and Er3+, and present the theoretical simulation results of the output power of the 3.1 µm Co/Er:PbF2 MIR laser. Based on the setup of a LD pulse pumped laser system, the effects of beam waist radius, resonator parameters and crystal length on the output are discussed in detail. The calculation results show that under good cavity mirror conditions, we can obtain a 3.1 µm laser with an output slope efficiency of 43.4%, whose output energy reaches 2.19 mJ at an input of 5 mJ. This provides guidance include the cavity mirror parameters and crystal parameters for laser experiments.

Optimization Design of Large-Aperture Primary Mirror for a Space Remote Camera

Lightweight, high stability, and high-temperature adaptability are the primary considerations when designing the primary mirror of a micro/nano satellite remote sensing camera. In this paper, the optimized design and experimental verification of the large-aperture primary mirror of the space camera with a diameter of Φ610 mm is carried out. First, the design performance index of the primary mirror was determined according to the coaxial tri-reflective optical imaging system. Then, SiC, with excellent comprehensive performance, was selected as the primary mirror material. The initial structural parameters of the primary mirror were obtained using the traditional empirical design method. Due to the improvement of SiC material casting complex structure reflector technology level, the initial structure of the primary mirror was improved by integrating the flange with the primary mirror body design. The support force acts directly on the flange, changing the transmission path of the traditional back plate support force, and has the advantage that the primary mirror surface shape accuracy can be maintained for a long time when subjected to shock, vibration, and temperature changes. Then, a parametric optimization algorithm based on the mathematical method of compromise programming was used to optimize the design of the initial structural parameters of the improved primary mirror and the flexible hinge, and finite element simulation was conducted on the optimally designed primary mirror assembly. Simulation results show that the root mean square (RMS) surface error is less than λ/50 (λ = 632.8 nm) under gravity, 4 °C temperature rise, and 0.01 mm assembly error. The mass of the primary mirror is 8.66 kg. The maximum displacement of the primary mirror assembly is less than 10 μm, and the maximum inclination angle is less than 5″. The fundamental frequency is 203.74 Hz. Finally, after the primary mirror assembly was precision manufactured and assembled, the surface shape accuracy of the primary mirror was tested by ZYGO interferometer, and the test value was 0.02 λ. The vibration test of the primary mirror assembly was conducted at a fundamental frequency of 208.25 Hz. This simulation and experimental results show that the optimized design of the primary mirror assembly meets the design requirements of the space camera.

Automatic Feedback System for X-ray Flux at BL08U1A Soft X-ray Spectromicroscopy Beamline of Shanghai Synchrotron Radiation Facility

An online automatic feedback system has been successfully installed and commissioned at the BL08U1A Soft X-ray Spectromicroscopy Beamline of Shanghai Synchrotron Radiation Facility, which can monitor the incident X-ray beam in real time by measuring the blade-edge signals of the exit slit and automatically adjust the elliptical cylindrical mirror parameters to achieve beam calibration and maintain the optimal X-ray flux of the sample. This work provides a comprehensive description of the hardware composition, system implementation, feedback logic, function and software design, system optimization and commission, as well as the online experimental results supported by the system. The experimental results demonstrated that the online automatic feedback system is capable of effectively maintaining the optimal X-ray beam flux for X-ray absorption spectroscopy experiments. Its success can provide valuable technique assistance for the design, construction and optimization of similar systems at various beamlines in synchrotron sources in the future.

Particle contamination simulation of Einstein probe follow-up X-ray telescope focusing mirror

Particle contamination can greatly affect the performance of X-ray focusing mirror. In this paper, we analyze the influence of particle contamination on X-ray focusing mirror. The model of interaction between contaminant particles and incident light is established from Mie scattering theory in the wavelength range of X-ray. And the relationship between them is mainly influenced by the complex refractive index of the particles <inline-formula><tex-math id="M1">\begin{document}$m$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20230301_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20230301_M1.png"/></alternatives></inline-formula> and the scale factor <inline-formula><tex-math id="M2">\begin{document}$\alpha$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20230301_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20230301_M2.png"/></alternatives></inline-formula>. Therefore, the reaction cross section and scattering function of particle contamination are calculated. Then, in order to obtain the effect of particle contamination on Einstein probe follow-up X-ray telescope (EP-FXT) focusing mirror, we carry out Monte Carlo simulation based on the design parameters of EP-FXT focusing mirror. Finally, the relationships among effective area, HEW, W90 and particle contamination density are calculated to characterize the influence of particle contamination on the performance of the focusing mirror. In this paper, structural and thermal model (STM) and qualification model (QM) are simulated simultaneously to make full use of their test data. By comparing the simulation results of STM effective area with the measured results, we find that the simulation results of STM effective area are accurate. When the EP-FXT is in orbit (the contamination amount is limited to less than 1.1 × 10<sup>–3</sup>), the effective area and angle resolution (HEW) meet the development requirements of EP-FXT. For the simulation of HEW, both QM and STM are in good agreement with the test results. The simulation results of HEW and effective area can be used to quantitatively analyze the effect of particle contamination on the performance of the focusing mirror. These quantitative analysis results provide a theoretical basis for the contamination prevention requirements of EP-FXT.

Design of Matching Imaging on Agile Satellite with Wide-Swath Whiskbroom Payloads along the Coastal Zone

The non-linearly curved coastal zone is very long and wide. The traditional satellite can’t cover the whole coastal zone in a single scan. So, the method of matching imaging combining the adjustment of satellite attitude and the scanning of the swing mirror are proposed. Firstly, based on the position of feature points of the coastal zone, the attitude when the optical axis of the satellite always points to the feature points is calculated. According to the width of the sea and land on both sides of the coastline, the parameters of the swing mirror of wide-swath whiskbroom payloads are analyzed. Secondly, the velocity vector model considering time-varying satellite attitude and the dynamic scanning of the swing mirror is constructed. The schemes of matching imaging such as adjustments of yaw angle and detector are developed. Finally, the precise experiment is designed to verify the correctness of the matching imaging. The experimental results show that the resolution of the matching imaging is less than 1 pixel and its modulation transfer function (MTF) is greater than the human eye’s minimum MTF of 0.026. The method of matching imaging using the adjustment of satellite attitude and the scanning of the swing mirror can realize wide imaging along the coastline and improve the temporal resolution at the same time.

One-dimensional image scaling with a reflecting X-ray mask

The work deals with the issue of miniaturization of template images using X-ray radiation. The compression method is based on the fact that X-ray radiation is directed at a specific template that reflects X-ray radiation at an grazing angle and a one-dimensional compressed image is recorded on a plane not parallel to the plane of the template. The advantage of this method of image compression is the relative simplicity of its implementation. The paper proposes the use of X-ray multilayer mirrors as reflective X-ray masks (RXM) for one-dimensional image compression. Control of the structural parameters of multilayer mirrors was carried out on a DRON- 3M X-ray diffractometer. The RXM template was formed by sputtering an absorbing WC layer with a thickness of ~0.2 μm through a certain stencil on the surface of a multilayer mirror. The test of the RXM with mirrors based on a pair of WC/Si materials in synchrotron radiation (l~3.5 nm) was carried out. A 14-fold compression of the reflective segments of the RXM with a size of ~50 μm was obtained. Theoretically, the principle possibility of obtaining compression of reflective segments to submicron sizes is shown.

Design of a compact off-axis freeform three-mirror system in a circular configuration.

A compact off-axis three-mirror system, especially with a wide field of view and small f-number, continues to present challenges in the optical design field. To design a compact off-axis three-mirror system based on a freeform surface, an optimization method with a circular configuration and four parameters is proposed. In the proposed method, the f-number and angles of mirrors are combined to optimize and achieve high-quality imaging, which means the modulation transfer function is close to the diffraction limit. To evaluate the performance of the proposed method, four design examples with different fields of view (4∘×4∘, 6∘×6∘) and f-numbers (2, 1.75) were created. The results showed that the compact off-axis three-mirror system based on a freeform surface can be designed with a wide field of view, small f-number, and high-quality imaging using the proposed method. Unlike other design methods, the surface parameters of mirrors are obtained with only one calculation and are close to the final optimization results, which saves both time and resources for optimization. The findings indicate that the method is accurate and effective for designing compact off-axis three-mirror systems with freeform surfaces.

Performance Simulation for Adaptive Optics Technique Using OOMAO Toolbox

The Adaptive Optics technique has been developed to obtain the correction of atmospheric seeing. The purpose of this study is to use the MATLAB program to investigate the performance of an AO system with the most recent AO simulation tools, Objected-Oriented Matlab Adaptive Optics (OOMAO). This was achieved by studying the variables that impact image quality correction, such as observation wavelength bands, atmospheric parameters, telescope parameters, deformable mirror parameters, wavefront sensor parameters, and noise parameters. The results presented a detailed analysis of the factors that influence the image correction process as well as the impact of the AO components on that process.

Enhancing the temporal contrast and peak power of femtosecond laser pulses.

It is shown that a nonlinear polarization interferometer and a chirped mirror enable enhancement of the contrast of high-power laser pulses with a duration of tens and hundreds of femtoseconds by several orders of magnitude and simultaneously a several-fold reduction of their duration. Different variants of interferometers based on cubic nonlinearity in KDP and DKDP crystals are considered. The interferometer and chirped mirror parameters are optimized aimed at enhancing the peak power of the compressed pulse.

Low voltage quasi floating gate current mirror with improved output impedance

Current mirror with a wide variety of application has become a basic block of analogue circuits. The main parameters affecting its performances are linearity range, input compliance voltage, input and output impedance and bandwidth. In this paper, a quasi floating gate-based current mirror design is modified in terms of increasing the output impedance. An improvement was achieved without affecting the other performance parameters of current mirror. The proposed current mirror uses the gate driven quasi floating bulk technique which results in effective transconductance as the sum of gate and scaled body transconductance. This increased transconductance boosts the output impedance from 800 kilo ohms to 3 mega ohms without degrading any of the other current mirror performance parameters. The complete analysis of the proposed current mirror is done using HSpice simulator on 0.18 um twin-well CMOS technology at a supply voltage of ±0.5 V.

CGHS Black Hole Analog Moving Mirror and Its Relativistic Quantum Information as Radiation Reaction.

The Callan–Giddings–Harvey–Strominger black hole has a spectrum and temperature that correspond to an accelerated reflecting boundary condition in flat spacetime. The beta coefficients are identical to a moving mirror model, where the acceleration is exponential in laboratory time. The center of the black hole is modeled by the perfectly reflecting regularity condition that red-shifts the field modes, which is the source of the particle creation. In addition to computing the energy flux, we find the corresponding moving mirror parameter associated with the black hole mass and the cosmological constant in the gravitational analog system. Generalized to any mirror trajectory, we derive the self-force (Lorentz–Abraham–Dirac), consistently, expressing it and the Larmor power in connection with entanglement entropy, inviting an interpretation of acceleration radiation in terms of information flow. The mirror self-force and radiative power are applied to the particular CGHS black hole analog moving mirror, which reveals the physics of information at the horizon during asymptotic approach to thermal equilibrium.

Relativistic theory of aberrations of electrostatic electron-optical systems

Using the central particle method, within the framework of a unified mathematical formalism, the equations of trajectories of charged particles in electrostatic electron mirrors and lenses, including cathode lenses, are obtained, taking into account relativistic effects, with an accuracy of the third order of smallness inclusive. On the basis of the obtained equations, the conditions for the spatial focusing of beams of charged particles in such systems and their coefficients of geometric aberrations of the third order and chromatic aberrations of the second order are determined with full account for relativistic effects. By means of numerical calculations, parameters of the three-electrode electrostatic mirror of rotational symmetry, which provide conditions for simultaneous elimination of spherical and axial chromatic aberrations with allowance for relativistic effects, are determined.

Structure of Multiple Mirror System From Kaleidoscopic Projections of Single 3D Point.

This paper proposes a novel algorithm of discovering the structure of a kaleidoscopic imaging system that consists of multiple planar mirrors and a camera. The kaleidoscopic imaging system can be recognized as the virtual multi-camera system and has strong advantages in that the virtual cameras are strictly synchronized and have the same intrinsic parameters. In this paper, we focus on the extrinsic calibration of the virtual multi-camera system. The problems to be solved in this paper are two-fold. The first problem is to identify to which mirror chamber each of the 2D projections of mirrored 3D points belongs. The second problem is to estimate all mirror parameters, i.e., normals, and distances of the mirrors. The key contribution of this paper is to propose novel algorithms for these problems using a single 3D point of unknown geometry by utilizing a kaleidoscopic projection constraint, which is an epipolar constraint on mirror reflections. We demonstrate the performance of the proposed algorithm of chamber assignment and estimation of mirror parameters with qualitative and quantitative evaluations using synthesized and real data.

Method for optimizing the errors of the wavefront of recorded radiation for large-size information-measuring optical systems

The article proposes a new method for increasing the information content of the image by minimizing the errors of the optical system of a large telescope using the redistribution of errors over the image field. Variation of the parameters of the secondary mirror is carried out to solve the optimization problem of uniform distribution of aberrations over the image field of a large telescope using the example of a cryotelescope with a diameter of 12 m in the Zemax-EE package. The results of calculations of optical schemes by the traditional method and by the method of optimization of the errors of the radiation wavefront are presented. The advantages and disadvantages are considered.

Novel method of improving beam quality of thin-wall tube laser based on right-angle cone deformable mirror

Aiming at improving the beam quality of thin-wall tube laser, a novel method based on the right-angle cone deformable mirror is proposed. In the method, a reflector with inner right-angle conical surface is used, and the annular laser beam successively passes through the opposite sides of the tube, compensating for the off-axis aberrations of the annular laser beam. Next, the residual aberrations are corrected by the deformation of the right-angle cone mirror to further improve the beam quality. The physical model of the right-angle cone deformable mirror is built up by using the finite element analysis method, followed by optimizing the structural parameters of the right-angle cone deformable mirror. The preliminarily optimized right-angle cone deformable mirror drived by 48 actuators with a radius of 1.5 mm for each actuator and an interval of 11 mm between actuators is then utilized to correct the beam quality of the thin-wall tube laser. Results indicate that the output beam quality of the thin-wall tube laser degrades rapidly with the increasing of the tube’s concentricity error, parallelism error, taper error and source’s parallelism error. Fortunately, the beam quality is significantly improved by using the right-angle cone deformable mirror and the <i>β</i> factor greatly decreases. In addition, the performance of the non-ideal right-angle cone deformable mirror with a 20-μrad taper error and a 10-mrad collimation error is compared with that of the ideal mirror, and the results show that the <i>β</i> factor is controlled within 1.14 after having been corrected by the non-ideal right-angle cone deformable mirror. Therefore, the simulation results theoretically prove that the novel method can effectively eliminate the typical aberrations caused by the errors from fabrication and alignment and correct the wavefront distortion of the large-aperture thin-wall tube laser, thus significantly improving the beam quality.