Elliptical Mirror Research Articles

Modeling electric charge distribution on insulator under electron bombardment: Case of rectangular surface implantation

Despite progress in the study of dielectric properties and the formation of secondary electrons images and especially in the understanding of their mirror curve shape, since the first models for mirror equation were developed, an exact quantitative prediction of the mirror curve for most materials has remained an unsolved problem. In this paper, recent development in the characterization of charge trapping ability of insulators using the scanning electron microscope mirror method (SEMMM) is reviewed. All this work has resulted in unprecedented insights into the early stage of dielectric study and it is also relevant for a deeper understanding of this anomalous effect (mirror effect) as well as for discussion of the factors affecting it. So the dependency of elliptic mirror and the anisotropic effect in the trapping phenomena of charge is highlighted.

Ultra-precise characterization of LCLS hard X-ray focusing mirrors by high resolution slope measuring deflectometry

We present recent results on the inspection of a first diffraction-limited hard X-ray Kirkpatrick-Baez (KB) mirror pair for the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). The full KB system - mirrors and holders - was under inspection by use of high resolution slope measuring deflectometry. The tests confirmed that KB mirrors of 350mm aperture length characterized by an outstanding residual figure error of <1 nm rms has been realized. This corresponds to the residual figure slope error of about 0.05µrad rms, unprecedented on such long elliptical mirrors. Additional measurements show the clamping of the mirrors to be a critical step for the final - shape preserving installation of such outstanding optics.

P-G2-9 球面収差補正用の楕円曲率可変ミラー(P-G2 マイクロナノ材料・構造,ポスターセッション論文)

Spherical aberration (SA) compensation of a laser beam is necessary in order to maintain the recording and reading quality in the Blu-ray disc^<TM> system. We have already demonstrated the principle of the microelectromechanical systems (MEMS) deformable mirror as a spherical aberration compensator. The deformable mirror is a smaller and less costly alternative to the conventional moving lens system. However, for practical use, an important issue still needs to be addressed: how to make the deformation of an elliptical parabolic mirror correspond to the obliquely incident laser beam. In this report, we proposed and demonstrated a elliptical deformable mirror that is applied for an obliquely incident laser beam.

A Horn-to-Horn Power Transmission System at Terahertz Frequencies

A horn-to-horn power transmission system at Terahertz frequencies has been designed and tested. Power is generated at microwave frequencies and then frequency multiplied to the band 799-938 GHz. The resultant signal is radiated by a diagonal horn and redirected by two identical elliptical mirrors to another diagonal horn located far away. Useful design equations have been derived for the proposed system. The concept has been proven by careful measurements and utilized for the local oscillator injection in the Atacama Large Millimeter Array (ALMA) Band-10 receiver.

ALMA Band 10 tertiary optics

The ALMA Band 10 (787–950 GHz) receiver is a dual-polarization heterodyne system based on NbTiN superconducting technology. The coupling of energy from the secondary mirror of the ALMA Cassegrain antenna to the Superconductor–Insulator–Superconductor (SIS) mixers used for down-conversion is achieved by a frequency-independent optical system composed of two elliptical mirrors to focus and redirect the incoming radiation, a wire-grid to separate orthogonal linear polarizations and two corrugated horns, one for each polarization and SIS mixer. In this paper, we present the ALMA Band 10 tertiary optics design and evaluate its performance by quasi-optical techniques, Physical Optics simulations and measurements. Detailed results of secondary aperture efficiency and beam-squint are provided. The characterization procedure described in this paper can be used for any optical system at around 1 THz.

Instrumento para la medición de la temperatura de las personas a distancia

Se presenta una nueva aplicaciòn basada en un pirómetro a baja radiación para medir la temperatura del cuerpo humano. El instrumento se basa en una termopila de bajo costo como detector y un sistema óptico consistente en un espejo cóncavo elíptico. Fue especialmente diseñado para medir la temperatura de la frente de una persona. El instrumento ha sido caracterizado usando un cuerpo negro construido para este propósito. La precisión del instrumento es de 0.19°C.

Fabrication of nested elliptical KB mirrors using profile coating for synchrotron radiation X-ray focusing

This paper describes fabrication methods used to demonstrate the advantages of nested or Montel optics for micro/nanofocusing of synchrotron X-ray beams. A standard Kirkpatrick-Baez (KB) mirror system uses two separated elliptical mirrors at glancing angles to the X-ray beam and sequentially arranged at 90° to each other to focus X-rays successively in the vertical and horizontal directions. A nested KB mirror system has the two mirrors positioned perpendicular and side-by-side to each other. Compared to a standard KB mirror system, Montel optics can focus a larger divergence and the mirrors can have a shorter focal length. As a result, nested mirrors can be fabricated with improved demagnification factor and ultimately smaller focal spot, than with a standard KB arrangement. The nested system is also more compact with an increased working distance, and is more stable, with reduced complexity of mirror stages. However, although Montel optics is commercially available for laboratory X-ray sources, due to technical difficulties they have not been used to microfocus synchrotron radiation X-rays, where ultra-precise mirror surfaces are essential. The main challenge in adapting nested optics for synchrotron microfocusing is to fabricate mirrors with a precise elliptical surface profile at the very edge where the two mirrors meet and where X-rays scatter. For example, in our application to achieve a sub-micron focus with high efficiency, a surface figure root-mean-square (rms) error on the order of 1nm is required in the useable area along the X-ray footprint with a ∼0.1mm-diameter cross section. In this paper we describe promising ways to fabricate precise nested KB mirrors using our profile coating technique and inexpensive flat Si substrates.

Improvement of ECRH Elliptical Mirror Antenna for GAMMA 10

Horizontally steerable ECRH antenna system of central cell on GAMMA 10 is developed for efficient electron heating. The steering mirror antenna can shift horizontally absorption position at the resonance surface in the range of -7.3 ~ +7.3 mm from standard position without significant power reduction which is examined with both calculation and cold power test. As a result of the plasma experiments of the antenna position scan, it is found the horizontally optimized position for ECRH. The spilled RF from mirror(the stray RF) seems to deteriorate the hot ion confinement. The newly installed efficient antenna system which has higher transmission efficiency of ~90% has shown improved heating performance.

An electrostatic elliptical mirror for neutral polar molecules

Focusing optics for neutral molecules finds application in shaping and steering molecular beams. Here we present an electrostatic elliptical mirror for polar molecules consisting of an array of microstructured gold electrodes deposited on a glass substrate. Alternating positive and negative voltages applied to the electrodes create a repulsive potential for molecules in low-field-seeking states. The equipotential lines are parallel to the substrate surface, which is bent in an elliptical shape. The mirror is characterized by focusing a beam of metastable CO molecules and the results are compared to the outcome of trajectory simulations.

New optical mount design for Canadian Light Source far infrared beamline

The Canadian Light Source far infrared (IR) beamline uses seven mirrors to transport the IR light to the spectrometer experimental station (May et al. 2006). A new mirror mount provides more stability and precision control of mirror alignment. The design uses a gimbal arrangement that reflects the IR beam through 90°. Internal motor actuators for 2° of angular rotation (pitch and roll) and 1° of translation drive the mount. The two independent rotation axes intersect at the mirror centre to minimize translation offset when rotated. Translation along the incoming beam axis allows focus adjustment of the elliptical mirrors mounted. Beam steering using closed loop control with position feedback is precise and repeatable. Piezo-actuator tilting mirrors in an active optics system use this gimbal design for mounting. The design is compact and scales to the size of the mirror to be mounted; this allows installing new components into the existing chambers. We present features of the mount that include in-vacuum operation (Ultra High Vacuum (UHV) possible with change of motor type), economic materials and ability to handle heavy elements of 33 kg or more.

Neutron beam focusing using large-m supermirrors coated on precisely-figured aspheric surfaces

We have developed a 1-dimensional elliptic mirror combining a supermirror coated with ion-beam sputtering and precise elliptic surface figured with the numerically-controlled local wet etching process. In this study, NiC/Ti supermirror (m = 4) was deposited on a precisely figured surface of synthesized quartz glass over 90 mm × 40 mm. Wideband neutrons of λ > 3.64Å were focused with focal spot size down to 0.25 mm, peak intensity gain up to 6 without significant diffuse scattering. Time-of-flight measurements suggest that wideband neutrons are effectively focused to the focal point.

One-dimensional Wolter optics with a sub-50 nm spatial resolution

We studied an imaging system consisting of an elliptical mirror and a hyperbolic mirror [i.e., one-dimensional (1D) Wolter optics] to realize an achromatic full-field hard x-ray microscopy with a resolution better than 50 nm. We report the performance of this 1D Wolter optical system when the mirrors were ultraprecisely figured by elastic emission machining. Experiments to form a demagnified image (demagnification factor of 385) of a 10 μm slit were conducted at an x-ray energy of 11.5 keV at BL29XUL of SPring-8. The system could form a demagnified image with a resolution better than 50 nm over a 12.1 μm field.

A beam-shaping system for TIMEX beamline

FERMI@Elettra is a Free Electron Laser (FEL) user facility currently under construction at Sincrotrone Trieste in Italy. It will provide a spatially coherent and transform-limited photon beam in the sub-ps regime, covering the VUV/Soft X-ray range (from 100 down to 1.33 nm). Thanks to its high fluence this 4th generation light source will be able to create and probe warm dense matter (WDM) inside the TIMEX end-station. Since the WDM state has a short lifetime (a few ps), measurement of basic physical quantities, such as temperature and density, is a challenge and new approaches are needed. For this reason a new method has been proposed for measuring temperature using a slowly responding pyrometric probe (Principi et al., 2010 [1]). However, the technique does require the spatial photon beam profile to be properly shaped at the sample. This can be done using an active optic (i.e. a deformable plane mirror) placed before the elliptical focusing mirror. Ray-tracing simulations and metrology measurements on a prototype have been performed and the results are presented here.

Fabrication of Ultraprecision Millimeter-Thick Elliptical Neutron Focusing Mirror Substrate by Local Wet Etching

Numerically controlled local wet etching (NC-LWE) is a novel technique to fabricate the ultraprecision optical components and/or finishing the functional materials. In this technique, a figuring is performed by controlling the dwelling time of the combination nozzle, which consists of a supply and a suction part of an etchant, on the workpiece. In this paper, we proposed fabrication process of millimeter-thick elliptical neutron focusing mirror substrate by applying NC-LWE figuring involving CeO2 slurry polishing. We fabricated a millimeter-thick elliptical neutron focusing mirror substrate with a figure error of less than 0.2 μm and obtained a surface roughness of less than 0.15 nm rms.

Distributions of Noise Sources in Heated and Cold Jets: Are They Different?

The axial extent of the high-speed flow region in a heated jet is much longer than its counterpart in an unheated jet at fixed Mach number. This trend has led some to believe that the source distributions would be different. Two specific questions are addressed in this study: (1) is the noise source distribution different for heated jets? and (2) is the distance to the true farfield longer for heated jets? The second question has practical significance as it impacts the measurement and processing of spectra. The assumption of a point source located at the nozzle exit plane is invoked in many tests – the condition for its validity is established for heated jets. Source distributions for heated and unheated jets have been measured with an elliptic mirror, for jets with a Mach number range of 0.5 to 1.9. The effect of jet temperature on the peak source location for the noise radiated to all the inlet angles in the range of 90° to 150° is negligible, both for the overall sound pressure level and individual frequencies. The effect of jet mach number is pronounced, with the peak source location moving downstream with increasing Mach number. Different approaches have been adopted for the establishment of the minimum distance to the true farfield for heated and unheated jets: microphone arrays at different distances together with nozzles of various diameters, microphones set at normal and grazing incidence, and the elliptic mirror. Both subsonic and supersonic jets have been considered. It is shown from detailed analyses that the distance to the true acoustic and geometric farfield is the same for heated and unheated subsonic jets, and is ∼37D (D is the jet diameter). The polar response characteristics of condenser microphones are examined to explain the observed good agreement of spectra between microphones located at ∼37D and larger distances. Finally, a minimum distance of ∼40D and a desirable distance of 50D or longer are recommended for true farfield measurements for subsonic jets. The minimum distance for supersonic jets is more nuanced: for unheated jets, a distance of 45D has been shown to represent the farfield. For highly heated supersonic jets, 45D again represents the farfield for the lower polar angles ≤∼100°. Rapid change in source directivity in the angular range of ∼100° to ∼125° dictates that a minimum distance of ∼70D for angles ≥∼100° might be prudent even though a shorter distance might be adequate for angles ≥∼130°. A good understanding of the source distributions and the radiation characteristics for different jet operating conditions, coupled with prudent test planning should help eliminate the nearfield effects in acoustic measurements.

蜂窝椭圆反射镜的孔结构设计研究

Design of lightweight hole of honeycombed elliptical mirror is investigated by means of finite element method.Divisional errors of different divisional element sizes are studied,and the effects of hole array and hole diameter on different performance of honeycombed elliptical mirror is analyzed.The results show that smaller divisional error is acquired with divisional element size of 6 mm;weight,inert moment and pressure displacement are significantly influenced by hole diameter; hole array and hole diameter have great effect on thermal displacement than gravity displacement; the third hexagonal hole array with hole diameter of 80 mm is selected out as optimum hole design.

Explicit formulas for the fundamental mode of a linear resonator with elliptic mirrors and construction of higher order modes

A linear resonator bounded by elliptic (hyperbolic) mirrors with noncoinciding principal curvature directions is considered. Explicit analytic formulas describing the fundamental mode of such resonator are derived in the principal approximation. A procedure of constructing higher order modes is developed. The potentialities of the technique are exemplified by considering a resonator with mirrors whose shapes are close to spheres and a resonator with elliptic mirrors whose shapes are close to each other.

Focusing a helium atom beam using a quantum-reflection mirror

We demonstrate one-dimensional (1D) focusing of a thermal helium atom beam by quantum reflection from a cylindrical concave quartz mirror at near-grazing incidence. The smallest width of the focus achieved is 1.8 μm, essentially limited by spherical aberration. The various effects that contribute to the finite focal width have been investigated. We propose to apply near-grazing reflection from two concave elliptical mirrors in a Kirkpatrick–Baez arrangement for two-dimensional (2D) focusing of a helium atom beam, paving the way for a helium atom microprobe.

Optimal two-mirror system for laser radiation focusing

An optical system for laser radiation focusing, which consists of parabolic and elliptic mirrors, is considered. It is shown by the method of elementary reflections that the maximum concentration of laser radiation on the target can be achieved at a certain position of these mirrors.

Simulation study of four-mirror alignment of advanced Kirkpatrick−Baez optics

We have studied four-mirror alignment for an advanced Kirkpatrick−Baez optics system that consists of two sets of mirrors made up of an elliptical mirror and a hyperbolic mirror. To develop an achromatic hard X-ray imaging system, the tolerance limits for alignment errors to form an image without degrading the resolution were calculated using a wave-optics simulation. A four-mirror alignment procedure is proposed based on the results obtained.