Characteristic investigation of Golay9 multiple mirror telescope with a spherical primary mirror

The sparse aperture provides a novel solution to the manufacturing difficulties of modern super large telescopes. Golay configurations are optimal in the sparse aperture family. Characteristics of the Golay9 multiple mirror telescope having a spherical primary mirror are investigated. The arrangement of the nine sub-mirrors is discussed after the planar Golay9 configuration is analyzed. The characteristics of the entrance pupil are derived by analyzing the sub-aperture shapes with different relative apertures and sub-mirror sizes. Formulas about the fill factor and the overlay factor are deduced. Their maximal values are presented based on the derived tangency condition. Formulas for the point spread function (PSF) and the modulation transfer function (MTF) of the Golay9 MMT are also deduced. Two Golay9 MMT have been developed by Zemax simulation. Their PSF, MTF, fill factors, and overlay factors prove that our theoretical results are consistent with the practical simulation ones.     

球面镜真空紫外光谱反射率的高精度测量

为了实现对球面镜真空紫外光谱反射率的直接测量,构建了一套真空紫外光谱反射率测试系统。该系统以氟化镁窗口氘灯与Seya-Namioka凹面光栅单色仪产生单色光源,反射式调制器与参考探测器做光学补偿,内径80mm的荧光积分球与精密转台作为接收系统。光学补偿消除单色光源不稳定性,荧光积分球消除了两次测量光斑不同对探测器响应的影响,且减少了系统的能量损失。利用该系统测量了115～180nm球面镜的反射率,测试结果表明测量重复性优于±0.3%;按国际通用不确定度评估规范,对系统进行不确定度分析,相关不确定度小于1.3%。实现了球面镜反射率的高精度测量。     

Radiation field calculations of pulsed ultrasonic transducers: Part 2: spherical disc- and ring-shaped transducers

The exact equation to describe the propagation of ultrasonic pressure waves in a lossless, homogeneous medium was evaluated assuming pulse-excited radiators.Acoustical field patterns were studied using the dimensions and shape of the transducer, the ultrasonic frequency and number of cycles within the pulse as parameters. The results emphasize the influence of the piston shape on interference phenomena within the near — and far-field and on beam-narrowing effects in the intermediate range between near- and far-field. The following transducer shapes are studied: spherical disc and spherical ring.     

平面电磁波对导体的辐射压强

当单色平面电磁波垂直入射到可导电的平面镜上时,理论分析了电磁波给平面镜施加的安培力作用以及由此产生的辐射压强.并得到了辐射压强的具体表达式.     

Radiation from slot antennas through a nonlinear plasma layer

Based on a numerical solution of the nonlinear Helmholtz equation, we consider the increasedpower radiation through a layer of plasma from a slot antennas excited by an H-wave. The cases of positive (/|E|>0) and negative (/|E|<0) nonlinearities are analyzed. The effect of restriction of the transmitted power is investigated for negative nonlinearity and the formation of the self-supported waveguide channel is considered for positive nonlinearity. The existence of bistability with variation in the feeding power is shown. The plasma structure near the antenna is analyzed for the high level of the radiated power.Energy Institute, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 5, pp. 436–443, May, 1995.     

反应烧结碳化硅球面反射镜的光学加工与检测

介绍了250mm口径、4200mm曲率半径的反应烧结碳化硅球面反射镜光学加工和检测的工艺流程;并按照流程依次介绍了在研磨成型、细磨抛光和精抛光过程中使用的机床、磨具、磨料及采用的工艺参数和检测方法。介绍了在光学加工和检测各个步骤中应注意的问题。展示了加工后250mm口径反应烧结碳化硅球面反射镜的实物照片,并给出了面形精度和表面粗糙度的检测结果:面形精度(95%孔径)均方根值(RMS)为0.037波长(λ=632.8nm),表面粗糙度RMS值达到1.92nm(测量区域大小为603.6ⅹ448.4μm)。     

Demonstration of the Golay3 multiple-mirror telescope with a spherical primary mirror

The sparse aperture system is a novel solution to design larger telescope of high angular resolution by utilizing several small sub-apertures to displace the full aperture. The system is of light weight and low cost. Multiple-mirror telescope (MMT) is one type of sparse aperture systems. We have analyzed the Golay3 MMT with a spherical primary mirror to obtain the relationships between the sub-mirrors on the primary mirror and the shapes of sub-apertures on the entrance pupil with different relative aperture by investigating the entrance pupil characteristics. The maximum fill factor and the maximal overlay factor were derived, and the tangency condition when sub-mirrors of the Golay3 MMT are tangency was also given out. The expressions of the point spread function (PSF) and the modulation transfer function (MTF) of the Golay3 MMT were deduced. The characteristics of both the PSF and the MTF were obtained based on the deduced formulas and Matlab simulating patterns. Two Cassegrain telescopes of a spherical primary mirror with the Golay3 configuration and with an aspherical secondary mirror were designed. Based on the relationships between the fill factor and the overlay factor, the optimal parameters of sub-mirrors on the primary mirror were selected. The PSFs and MTFs of Cassegrain telescopes with the Golay3 MMT were designed by Zemax simulation. The simulation results are consistent with the theoretical results.     

Three-dimensional study of planar optical antennas made of split-ring architecture outperforming dipole antennas for increased field localization

Optical antennas are of fundamental importance for the strongly localizing field beyond the diffraction limit. We report that planar optical antennas made of split-ring architecture are numerically found in three-dimensional simulations to outperform dipole antennas for the enhancement of localized field intensity inside their gap regions. The computational results (finite-difference time-domain) indicate that the resulting field localization, which is of the order of many thousandfold, in the case of the split-ring resonators is at least 2 times stronger than the one in the dipole antennas resonant at the same operating wavelength, while the two antenna types feature the same gap size and tip sharpness.     

诺莫图法在薄透镜和球面镜成像分析中的应用

在满足近轴光线的条件下,可以利用成像公式和光路图法分析薄透镜或球面镜的物像关系,而本文介绍的这种诺莫图法,可以在直角坐标系上用坐标图示法分析薄透镜和球面镜的物像关系,不仅可以精确求得实物或虚物的成像位置,还可以判断出像的性质,具有简单、直观等特点,可以作为分析物像关系的一种补充手段.     

q软X光多层镜反射率在同步辐射源上的标定

软X光多层镜反射率标定实验在北京同步辐射装置上进行,利用BSRF-3W1B 束线及其反射率计靶室(主靶室)标定不同材料的多层镜样品的反射率.多层镜的标定采用波长扫描法,以得到样品反射率随波长变化的曲线.给出了21°-B4C/Si,21°-B4C/Mo,10°-Cr/Ti,15°- B4C/W,10°- B4C/W以及6.86°-B4C/W等6块多层镜在50～1 500 eV能段上的反射率标定曲线,并将其与理论计算结果进行比较.结果表明标定曲线与理论曲线很好地符合.影响标定结果的总不确定度的主要因素是光子能量不确定度,其次是角度不确定度,测量不确定度的影响很小.     

软X光多层镜反射率在同步辐射源上的标定

 软X光多层镜反射率标定实验在北京同步辐射装置 上进行,利用BSRF-3W1B 束线及其反射率计靶室(主靶室)标定不同材料的多层镜样品的反射率。多层镜的标定采用波长扫描法,以得到样品反射率随波长变化的曲线。给出了21°-B₄C/Si,21°-B₄C/Mo,10°-Cr/Ti,15°- B₄C/W,10°- B₄C/W以及6.86°-B₄C/W等6块多层镜在50～1 500 eV能段上的反射率标定曲线,并将其与理论计算结果进行比较。结果表明：标定曲线与理论曲线很好地符合。影响标定结果的总不确定度的主要因素是光子能量不确定度,其次是角度不确定度,测量不确定度的影响很小。     

Focused aperture microwave antennas operating in the near field zone

Focusing a microwave antenna is often convenient in order to produce a Fraunhofer-type pattern at short distance from the aperture. The characteristics of the radiation patterns produced by some specimens were experimentally tested and compared with theoretical predictions. Basic criteria are given to design focused antennas, once their radiation pattern characteristics are specified.     

Two-dimensional spherical oscillator in a constant magnetic field

We study the equations of motion of a spherical oscillator model suggested by Bellucci and Nersessian, in the presence of a constant magnetic field. This model is shown to be exactly solvable classically in contrast to the Higgs oscillator which is not exactly solvable in magnetic fields.     

Electric field effects on Nano-Scale bio-membrane of spherical cells

Various properties of Nano-Scale cell bio-membranes or vesicle membranes in an external electric field and free salt environment are studied and reviewed in a theoretical and computational framework. This is done by calculating the radial forces acting on cells generated as the result of an applied electric field and the ensuing charge re-distribution. Our results could help to shed light on mechanisms responsible for the observed deformation and fusion of cells which can be designed by biotechnological devices.     

Wave field synthesis of a sound field described by spherical harmonics expansion coefficients

Near-field compensated higher order Ambisonics (NFC-HOA) and wave field synthesis (WFS) constitute the two best-known analytic sound field synthesis methods. While WFS is typically used for the synthesis of virtual sound scenes, NFC-HOA is typically employed in order to synthesize sound fields that have been captured with appropriate microphone arrays. Such recorded sound fields are essentially represented by the coefficients of the underlying surface spherical harmonics expansion. A sound field described by such coefficients cannot be straightforwardly synthesized in WFS. This is a consequence of the fact that, unlike in NFC-HOA, it is critical in WFS to carefully select those loudspeakers that contribute to the synthesis of a given sound source in a sound field under consideration. In order to enable such a secondary source selection, it is proposed to employ the well-known concept of decomposing the sound field under consideration into a continuum of plane waves, for which the secondary source selection is straightforward. The plane wave representation is projected onto the horizontal plane and a closed form expression of the secondary source driving signals for horizontal WFS systems of arbitrary convex shape is derived.     

Gravitational field of spherical domain wall in higher dimension

An exact solution of Einstein’s equations is found describing the gravitational field of a spherical domain wall with nonvanishing stress component in the direction perpendicular to the plane of the wall. Also we have studied the motion of test particle around the domain wall.     

Optomechanical entanglement between a movable mirror and a cavity field

We show how stationary entanglement between an optical cavity field mode and a macroscopic vibrating mirror can be generated by means of radiation pressure. We also show how the generated optomechanical entanglement can be quantified, and we suggest an experimental readout scheme to fully characterize the entangled state. Surprisingly, such optomechanical entanglement is shown to persist for environment temperatures above 20 K using state-of-the-art experimental parameters.