New figuring model based on surface slope profile for grazing‐incidence reflective optics

Surface slope profile is widely used in the metrology of grazing‐incidence reflective optics instead of surface height profile. Nevertheless, the theoretical and experimental model currently used in deterministic optical figuring processes is based on surface height, not on surface slope. This means that the raw slope profile data from metrology need to be converted to height profile to perform the current height‐based figuring processes. The inevitable measurement noise in the raw slope data will introduce significant cumulative error in the resultant height profiles. As a consequence, this conversion will degrade the determinism of the figuring processes, and will have an impact on the ultimate surface figuring results. To overcome this problem, an innovative figuring model is proposed, which directly uses the raw slope profile data instead of the usual height data as input for the deterministic process. In this paper, first the influence of the measurement noise on the resultant height profile is analyzed, and then a new model is presented; finally a demonstration experiment is carried out using a one‐dimensional ion beam figuring process to demonstrate the validity of our approach.     

一种CCD辅助测量基模(TEM_(00))激光光斑尺寸的方法

激光光束是一种振幅和等相位面都在变化的高斯球面光波 ,其最小光斑的位置和大小不易确定 ,本文在实践的基础上提出一种测量基模 ( TEM0 0 )激光光斑尺寸的方法 ,解决了这一问题     

Orthogonal-polarization compensation method for measuring unsteady vertical force of a bumblebee in a wind tunnel

It is important to measure the unsteady vertical force of an insect in a wind tunnel for studying the flight performance of insects. Optical method can measure it with high accuracy, but it is affected by air turbulence. An orthogonal-polarization compensation (OPC) method is developed for measuring the beating force of a bumblebee in a wind tunnel and compensating the error due to beam fluctuations induced by air turbulence. The applicability of the OPC method was confirmed by using a piezo translator to generate the tilt angle variation. The results show that by using the OPC method, the error in tilt angle measurement due to air turbulence can be decreased by about 80% compared with that using the conventional angle measurement method. The OPC method was then applied to measure the tilt angle variation caused by the beating motion of a bumblebee attached to one end of a sensor block in a wind tunnel for a wind velocity of 1.1 ms⁻¹. The results confirmed the effectiveness of this new method.     

Analytic design of an anamorphic optical system for generating anisotropic partially coherent Gaussian Schell-model beams

The analytic design of anamorphic optical system for transforming the coherent Gaussian beam of a He–Ne laser to a partially coherent Gaussian Schell-model beam with an anisotropic cross-section and an anisotropic degree of coherence is described. Design equations are formulated and some design examples are presented.     

STM study of successive Ge growth on “V”-stripe patterned Si (0 0 1) surfaces at different growth temperatures

The self-assembly process of Ge islands on patterned Si (0 0 1) substrates is investigated using scanning tunneling microscopy. The substrate patterns consist of one-dimensional stripes with “V”-shaped geometry and sidewalls inclined by an angle of 9° to the (0 0 1) surface. Onto these stripes, Ge is deposited in a step-wise manner at different temperatures from 520 °C to 650 °C. At low temperature, the Ge first grows nearly conformally over the patterned surface but at about 3 monolayers a strong surface roughening due to reconstruction of the surface ridges as well as side wall ripple formation occurs. At 600 °C, a similar roughening takes place, but Ge accumulates within the grooves such that at a critical thickness of 4.5 monolayers, 3D islands are formed at the bottom of the grooves. This accumulation process is enhanced at 650 °C growth, so that the island formation starts about 1 monolayers earlier. At 600 and 650 °C, all islands are all aligned at the bottom of the stripes, whereas at 550 °C Ge island form preferentially on top of ridges. The experimental observations are explained by the strong temperature dependence of Ge diffusion over the patterned surface.     

Oxygen deficiency effect on resistive switching characteristics of copper oxide thin films

In this Letter, bilayered Cu₂O/CuO thin films were grown on Nb doped SrTiO₃ (Nb:STO) substrates by plasma assisted molecular beam epitaxy. The current-voltage characteristics of Pt/Cu₂O/CuO/Nb:STO devices show reproducible and pronounced current-voltage hysteresis which was induced by the CuO/Nb:STO junctions. By comparing the current-voltage curves of the bilayered and single-layered CuO thin films, we attribute the prominent switching behavior to the oxygen-vacancies-mediated-carriers-trapped-detrapped process with the aid of the applied forward (reversed) bias voltage.     

Ionenstrahlätzen – Verfahren und Ausrüstungen für die Mikrostrukturierung

Ion beam techniques are widely used jur modification as well us analysis of materials in development and production of VLSI circuits and their importance is continuously increased in course of the reduction of structure dimensions. Some possibilities and problems connected with the application of ion beams of low energy in the pattern transfer are- described and the stage of development achieved in the Central Institute of Isotope and Radiation Research is outlined.     

Frequency doubling of Nd:YAG- and GaAs-lasers by KNbO3: Ta crystals

Abstract

For KNb_1-xTa_xO₃ crystals the influence of the Ta-concentration on the phase-matching properties for optical second harmonic generation (SHG) was measured. For non-critical phase matched SHG of the Nd:YAG-laser (1064nm) the coefficient d₃₁ of the tensor of the nonlinear susceptibility was applied, while for the GaAs-laser (905 nm) the coefficient d₃₂ was used. For both laser wavelengths the phase-matching temperature decreases with increasing Ta-concentration. Non-critical phase-matching at room temperature can be reached with the GaAs-laser for a Ta-concentration of ≈9%. The corresponding value for the Nd:YAG-laser is ≈14%.     

TEM study of ion implanted GaAs after pulsed electron beam annealing

Abstract

(001) GaAs single crystals were implanted with 150 keV Cr⁺ ions using a dose of 5 × 10¹⁵ ions cm^?2. The amorphized surface layers were subjected to pulsed electron beam annealing at energy densities in the range 0–1.3 J cm^?2. A detailed TEM investigation of the damaged and annealed surface layer was conducted. These observations were correlated with backscattering results.     

Generating and shifting a spherical focal spot in a 4Pi focusing system illuminated by azimuthally polarized beams

We aim to theoretically investigate the focusing property of a 4Pi configuration under the illumination of azimuthally polarized high-order Bessel–Gaussian beams. The radial component is produced in the focal region through the introduction of a spiral phase plate. The focal region differs from the zero radial intensity component of the azimuthally polarized beams without the spiral phase plate. The spherical focal spot is generated by selecting an appropriate annular obstruction. The position of the focal spot can be shifted.