Mirror Parameters Research Articles

Isolated attosecond pulse in the water window from many-cycle laser-driven plasma mirrors without pulse engineering

High-order harmonic generation from relativistic laser-driven plasma mirrors is an attractive route to produce highly energetic attosecond pulses in the extreme ultraviolet to x-ray regime. To achieve an isolated attosecond pulse (IAP) driven by many-cycle intense laser pulses, pulse engineering techniques such as polarization modulation and wavefront rotation, are usually needed. Here we show that it is possible to generate an IAP without pulse engineering. Through particle-in-cell simulations, it is found that plasma mirrors can be rapidly heated and deformed in a relatively long preplasma regime. Intense IAP in the high-frequency spectral region is given rise once when the mirror parameters are suitable. The results may offer a new route to generate a bright IAP source for various applications such as bio-imaging and electronic dynamic studies.

Cost-effective plane-grating monochromator design for extreme-ultraviolet application.

The optical design of a plane-grating monochromator mainly intended for high resolution in the extreme ultraviolet and soft x-ray is presented. The configuration has three optical elements. It uses a uniform line-spaced plane grating illuminated in the converging light coming from a focusing concave mirror and an additional plane mirror that is needed to change the grating subtended angle to keep the system in focus on a fixed slit. The parameters of the focusing mirror are determined to introduce a coma that compensates for the coma given by the grating. A monochromator for the 12-50eV region is designed for application to high-order laser harmonics.

Development and testing of glass substrate Wolter-1 X-ray focusing mirror

The wolter-1 X-ray focusing mirror can reflect grazing incidence X-ray to the focal plane, which plays an important role in the astronomical detection and other fields due to its good image detecting capability. A geometric model of the optical system is established for theoretically deriving the optical path equations which is useful in this glass based focusing mirror designing, all the design parameters of the focusing mirror can be obtained by solving these equations. In the manufacturing process, the D263T glass is chosen to be the structural material of the focusing mirror due to its light weight and super smooth surface, after a slumping process, the flat glass mirror will have the shape of Wolter-1 X-ray focusing mirror. This slumping process has been used successfully in the manufacturing process of an American mission named The Nuclear Spectroscopic Telescope Array, which was launched in 2012. According to X-ray reflecting theory, the reflectivity of the Wolter-1 mirror can be improved significantly by coating metal film on the surface of the mirror. In this work, an iridium film is coated on the surface of the glass mirror through a vacuum evaporating process. In order to learn the influence of the focal spot caused by the mirror shape tolerance, the morphology of the mirror is tested by using a 3-D laser scan instrument. The results show that 50% of the total test points are located in the tolerance range of-10-10 m, in which the tolerance represents the difference between the actual lens profile and the ideal lens profile. Then the focal spot test is carried out with the help of a visible light test system:a laser collimator is installed in front of focusing mirror as an incidence light source, and a charge coupled device (CCD) is placed in the focal plane to gather the image of the focal spot, by calculating the gray level distribution of the focal spot image taken by the CCD, the energy distribution characteristic of focal spot can be obtained. The experimental results show that the focal length of the focusing mirror is 1.6 m, and the half-power surrounding diameter of the focal spot is 0.33 mm, corresponding to the angular resolution of 0.7 arc min.

Dynamic properties of an adaptive optics system versus parameters of the flexible mirror and the way of affecting the mirror

Dynamic properties of an adaptive optics system versus parameters of the flexible mirror and the way of affecting the mirror

Adaptation strategies for tracking constraints under plant-model mismatch

Optimal operating conditions for a process plant are typically obtained via model-based optimization. However, due to modeling errors, the operating conditions found are often sub-optimal or, worse, they can violate critical process constraints. Hence, model corrections become a necessity and are done by exploiting measured process data. To this end, either model parameters are adapted and/or correction terms are added to the model-based optimization problem. The modifier-adaptation methodology does the latter by adding bias and gradient correction terms that are called modifiers. The role of modifiers and model parameters are often seen as competing, and which one of the two is better suited to track the optimality conditions is an open problem. This paper attempts to shed light on finding a synergy between the model parameters and the modifiers in the case when tracking constraints is sufficient for near-optimal performance. We demonstrate through the simulation study of a batch-to-batch optimization problem that a set of model parameters can be selected that mirror the role of modifiers. The modifiers are then added only when there is insufficient number of mirror parameters for independent constraint tracking.

Optical levitation of a mirror for reaching the standard quantum limit.

We propose a new method to optically levitate a macroscopic mirror with two vertical Fabry-Pérot cavities linearly aligned. This configuration gives the simplest possible optical levitation in which the number of laser beams used is the minimum of two. We demonstrate that reaching the standard quantum limit (SQL) of a displacement measurement with our system is feasible with current technology. The cavity geometry and the levitated mirror parameters are designed to ensure that the Brownian vibration of the mirror surface is smaller than the SQL. Our scheme provides a promising tool for testing macroscopic quantum mechanics.

Improving the accuracy of mirror measurements by removing noise and lens distortion

Telescope mirrors determine the imaging quality and observation ability of telescopes. Unfortunately, manufacturing highly accurate mirrors remains a bottleneck problem in space optics. One main factor is the lack of a technique for measuring the 3D shapes of mirrors accurately for inverse engineering. Researchers have studied and developed techniques for testing the quality of telescope mirrors and methods for measuring the 3D shapes of mirrors for centuries. Among these, interferometers have become popular in evaluating the surface errors of manufactured mirrors. However, interferometers are unable to measure some important mirror parameters directly and accurately, e.g. the paraxial radius, geometry dimension and eccentric errors, and these parameters are essential for mirror manufacturing. In this paper, we aim to remove the noise and lens distortion inherent in the system to improve the accuracy of a previously proposed one-shot projection mirror measurement method. To this end, we propose a ray modeling and a pattern modeling method. The experimental results show that the proposed ray modeling and pattern modeling method can improve the accuracy of the one-shot projection method significantly, making it feasible as a commercial device to measure the shapes of mirrors quantitatively and accurately.

Technique for measuring the three-dimensional shapes of telescope mirrors

Telescope mirrors determine the imaging quality and the observation ability of the telescopes. Unfortunately, manufacturing highly accurate mirrors remains a bottleneck problem in space optics. One primary cause is the lack of a technique to robustly measure the three-dimensional (3-D) shapes of mirrors for inverse engineering. After centuries of study, researchers developed different techniques for testing the quality of telescope mirrors and proposed different methods for measuring the 3-D shapes of mirrors. Among them, interferometers become popular in evaluating the surface errors of the manufactured mirrors. However, interferometers could not measure some important mirror parameters, e.g., paraxial radius, geometry dimension, and eccentric errors, directly and accurately although these parameters are essential for mirror manufacturing. For those methods that could measure these parameters, their measurement accuracies are far beyond satisfactory. We present a technique for robust measurement of the 3-D shapes of mirrors with single-shot projection. Experimental results show that this technique is significantly more robust than state-of-the-art techniques, which makes it feasible for commercial devices to measure the shapes of mirrors quantitatively and robustly.

DABAM: an open-source database of X-ray mirrors metrology.

An open-source database containing metrology data for X-ray mirrors is presented. It makes available metrology data (mirror heights and slopes profiles) that can be used with simulation tools for calculating the effects of optical surface errors in the performances of an optical instrument, such as a synchrotron beamline. A typical case is the degradation of the intensity profile at the focal position in a beamline due to mirror surface errors. This database for metrology (DABAM) aims to provide to the users of simulation tools the data of real mirrors. The data included in the database are described in this paper, with details of how the mirror parameters are stored. An accompanying software is provided to allow simple access and processing of these data, calculate the most usual statistical parameters, and also include the option of creating input files for most used simulation codes. Some optics simulations are presented and discussed to illustrate the real use of the profiles from the database.

Decreasing effective reflectivity of the output coupler in the power scaling of fiber lasers

Increasing power leads to the spectral broadening of fiber laser beams. In this effect the spectral line width of the laser beam becomes broader than that of the output coupler (OC) due to power scaling. Therefore, the effective reflectivity of the OC mirror decreases. In this paper, this phenomenon is investigated theoretically and experimentally. A Liekki Application Designer V3.3 was used for the theoretical investigation and the experiments were conducted during the fabrication of a 630W fiber laser. Given the excellent agreement between the simulation and the experimental results, a decrease in the effective reflectivity of the OC mirror was proved. The decrease in the effective reflectivity of the OC mirror changes some of the laser parameters, such as optical efficiency, longitudinal distribution of population inversion and the backward power inside the resonator. This may also lead to power instability. The effects of a decrease in the reflectivity of the OC on the mentioned parameters of the fiber laser are investigated in the present paper. Finally, recommendations for choosing appropriate OC mirror parameters in high-power (kW class) fiber lasers are suggested.

Design of an ellipsoidal mirror for freewave characterization of materials at microwave frequencies

Free-wave characterization of the electromagnetic properties of materials at microwave frequencies requires that scattering at the edges of the samples and/or holder be minimized. Here, an ellipsoidal mirror is designed and characterized in order to decrease the size of the beam, thereby avoiding the scattering problems, even when relatively small samples are used. In the experimental configuration, both the emitting antenna and sample are located at the mirror focuses. Since both the emitted and reflected (focused) beams are Gaussian in nature, we make use of Gaussian beam theory to carry out the design. The mirror parameters are optimized by numerical simulations (COMSOL Multiphysics®) and then experimentally tested. An experimental setup is presented for dielectric, magnetic and chiral measurement in the 4.5–18 GHz band.

Improving the spectral resolution of flat-field concave grating miniature spectrometers by dividing a wide spectral band into two narrow ones

In this study, a new flat-field concave grating miniature spectrometer is proposed with improved resolution across a wide spectral band. A mirror is added to a conventional concave grating spectrometer and placed near the existing detector array, allowing a wide spectral band to be divided into two adjacent subspectral bands. One of these bands is directly detected by the detector, and the other is indirectly analyzed by the same detector after being reflected by the mirror. These two subspectral bands share the same entrance slit, concave grating, and detector, which allows for a compact size, while maintaining an improved spectral resolution across the entire spectral band. The positions of the mirror and other parameters of the spectrometer are designed by a computer procedure and the optical design software ZEMAX. Simulation results show that the resolution of this kind of flat-field concave grating miniature spectrometer is better than 1.6 nm across a spectral band of 700 nm. Experiments based on three laser sources reveal that the measured resolutions are comparable to the simulated ones, with a maximum relative error between them of less than 19%.

Hyperbola-parabola primary mirror in Cassegrain optical antenna to improve transmission efficiency.

An optical model with a hyperbola-parabola primary mirror added in the Cassegrain optical antenna, which can effectively improve the transmission efficiency, is proposed in this paper. The optimum parameters of a hyperbola-parabola primary mirror and a secondary mirror for the optical antenna system have been designed and analyzed in detail. The parabola-hyperbola primary structure optical antenna is obtained to improve the transmission efficiency of 10.60% in theory, and the simulation efficiency changed 9.359%. For different deflection angles to the receiving antenna with the emit antenna, the coupling efficiency curve of the optical antenna has been obtained.

A single eye 3D image perception device using vertical double ring resonator construction

ABSTRACTA single eye three‐dimensional (3D) imaging perception using a single 3D imaging pixel is designed and manipulated, which is the interesting device configuration that can be used for various applications. The device configuration is consisted of double conjugate mirrors that can be vertically fabricated, which can be used to form the 3D image using a single pixel configuration, from which the large area device construction is also possible. By adjusting the microconjugate mirror parameters, then the matching between both microconjugate mirrors can lead to obtain the required 3D images. Results obtained have shown that the 3D image outputs can be achieved and used for 3D pixel imaging. The 3D image output can be confirmed by the four‐wave mixing output balancing profile, which is achieved. In applications, the large area 3D images can be constructed using the large area 3D imaging device, from which the large area can be coverage by the microconjugate mirror array, which can be useful for various applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1802–1805, 2015

Aberrational properties of a thin mirror–lens component in a convergent pencil of rays

Analytical relationships are obtained that determine the structural and aberrational parameters of a thin mirror–lens component consisting of a single lens with a back surface that reflects inwards, located in a convergent (divergent) pencil of rays.

变形镜结构参数对高功率激光相位特性的影响

变形镜结构参数对高功率激光相位特性的影响

Spectrum splitting using multi-layer dielectric meta-surfaces for efficient solar energy harvesting

We designed a high-efficiency dispersive mirror based on multi-layer dielectric meta-surfaces. By replacing the secondary mirror of a dome solar concentrator with this dispersive mirror, the solar concentrator can be converted into a spectrum-splitting photovoltaic system with higher energy harvesting efficiency and potentially lower cost. The meta-surfaces are consisted of high-index contrast gratings (HCG). The structures and parameters of the dispersive mirror (i.e. stacked HCG) are optimized based on finite-difference time-domain and rigorous coupled-wave analysis method. Our numerical study shows that the dispersive mirror can direct light with different wavelengths into different angles in the entire solar spectrum, maintaining very low energy loss. Our approach will not only improve the energy harvesting efficiency, but also lower the cost by using single junction cells instead of multi-layer tandem solar cells. Moreover, this approach has the minimal disruption to the existing solar concentrator infrastructures.

A time-of-flight mass reflectron with controlled ion-energy spread in the packet generated by an ion source

A new principle is proposed for eliminating the energy spread of ions in a packet generated by the ion source of a time-of-flight (TOF) mass reflectron. The ion source is treated as an element of the optic tract, in which the ion trajectories are conjugated with those in the electrostatic mirror, while the primary temporal focus near the source is absent. By properly selecting parameters of the emission-reflection system comprising a combination of the ion source and electrostatic mirror, the total time of ion flight from the source to detector can be controlled so as to be independent of the ion energy. Numerical simulations have been used to find the optimum parameters of a three-electrode electrostatic mirror possessing rotational symmetry, which simultaneously ensure the TOF control (to within third-order terms) and the spatial focusing of ions in the detector plane.

Absorption recovery dynamics in 2 µm GaSb-based SESAMs

The interplay between growth and design parameters of GaSb-based quantum-well semiconductor saturable absorber mirrors (SESAMs) and their corresponding absorption recovery time is investigated. The analysis proves an inherently rapid absorption recovery time of GaSb SESAMs operating at a 2 µm wavelength range, which is surprisingly independent of the growth temperature for a large temperature range from 350 to 530 °C. Moreover, SESAMs incorporating InxGa1−xAsySb1−y quantum wells exhibit a weak variation of the absorption recovery time with changing indium content and with varying lattice strain. The strongest reduction of the absorption recovery time is observed upon placing the quantum wells in the proximity of the SESAM's top layer, and applying an antireflection coating to enhance the interaction with the optical field. Stable mode-locking of a Tm : YAG laser at 2 µm is obtained with an antireflection coated sample incorporating a single surface quantum well.

Is dark matter made of mirror matter? Evidence from cosmological data

We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly made of mirror matter. We consider scalar adiabatic primordial perturbations at linear scales in a flat Universe. The speed of the simulations allows us for the first time to use Markov Chain Monte Carlo analyses to constrain the mirror parameters. A Universe with pure mirror matter can fit very well the observations, equivalently to the case of an admixture with cold dark matter. In both cases, the cosmological models estimate the presence of a consistent amount of mirror dark matter, 0.06≲Ωmirrorh2≲0.12.