Thermal luminescence water monitor

A thermal luminescence (TL) spectroscopy method for detecting organic impurities in water solution is presented. Infrared emissions by the dissolved organic matter are measurable, once a thermal gradient between it and the water medium is established, at those TL frequencies that are absorbed by the contaminant, following irradiation by a pulsed microwave beam. This detection window of opportunity closes as the liquid reaches thermal equilibrium at elevated temperatures and on collapse of the gradient. TL radiance liberated by a suspected contaminated water sample is scanned interferometrically about the maximum thermal gradient event, where N interferograms are acquired and grouped into contiguous sets of two, with N/2 interferogram elements per set. The coadded averages of these sets enhance the sensitivity of measurement to a small variance in emissivity and are Fourier transformed, and the adjacent spectra are subtracted. The difference spectrum is preprocessed with linear baseline, noise filtration, scaling, and parity operators to reveal a clear emissions band signature of the solute of dimethylmethylphosphonate to concentrations of parts per 10(3) and less. An artificial neural network facilitates detection of the contaminant by pattern recognition of the contaminant's infrared band signature.     

Design and characterization of a microchannel optical interconnect for optical backplanes

The design, modeling, and experimental characterization of a microchannel-based free-space optical interconnect is described. The microchannel interconnect was used to implement a representative portion of an optical backplane that was based on field-effect transistor, self-electro-optic device smart-pixel transceivers. Telecentric relays were used to form the optical interconnect, and two modes based on two different optical window clusterings were implemented. The optical system design, including the optical geometry for different degrees of clustering of windows supported by a lenslet relay and the image mapping associated with a free-space optical system, is described. A comparison of the optical beam properties at the device planes, including the spot size and power uniformity of the spot array, as well as the effects of clipping and misalignment for the different operating modes, is presented. In addition, the effects of beam clipping and misalignment for the different operating modes is presented. We show that microchannel free-space optical interconnects based on a window-clustering scheme significantly increase the connection density. A connection density of 2222 connections/cm(2) was achieved for this prototype system with 2 x 2 window clustering.     

Surface contamination detection by means of near-infrared stimulation of thermal luminescence

A method for remotely detecting liquid chemical contamination on terrestrial surfaces is presented. Concurrent to irradiation by an absorbing near-infrared beam, the subject soil medium liberates radiance called thermal luminescence (TL) comprising middle-infrared energies (upsilon(mir)) that is scanned interferometrically in beam duration tau. Cyclic states of absorption and emission by the contaminant surrogate are rendered from a sequential differential-spectrum measurement [deltaS(upsilon(mir), tua)] of the scanned TL. Detection of chemical warfare agent simulant wetting soil is performed in this manner, for example, through pattern recognition of its unique, thermally dynamic, molecular vibration resonance bands on display in the deltaS(upsilon(mir), tau) metric.     

A Numerical Study of the Thermal Characteristics of an Air Cavity Formed by Window Sashes in a Double Window

Given that the Korean government is implementing what has been termed the energy standards and labelling program for windows, window companies will be required to assign window ratings based on the experimental results of their product. Because this has added to the cost and time required for laboratory tests by window companies, the simulation system for the thermal performance of windows has been prepared to compensate for time and cost burdens. In Korea, a simulator is usually used to calculate the thermal performance of a window through WINDOW/THERM, complying with ISO 15099. For a single window, the simulation results are similar to experimental results. A double window is also calculated using the same method, but the calculation results for this type of window are unreliable. ISO 15099 should not recommend the calculation of the thermal properties of an air cavity between window sashes in a double window. This causes a difference between simulation and experimental results pertaining to the thermal performance of a double window. In this paper, the thermal properties of air cavities between window sashes in a double window are analyzed through computational fluid dynamics (CFD) simulations with the results compared to calculation results certified by ISO 15099. The surface temperature of the air cavity analyzed by CFD is compared to the experimental temperatures. These results show that an appropriate calculation method for an air cavity between window sashes in a double window should be established for reliable thermal performance results for a double window.     

力平衡式三轴微加速度计的设计与分析

设计了一种具有单一检测质量的力平衡式三轴微加速度计．采用硅-硅键合工艺形成作为单一检测质量块的硅片组合。利用全差分电容检测法实现对加速度三轴分量的检测．通过提高检测质量的重心，有效增加了X、Y轴的灵敏度．利用ANSYS仿真软件对该微加速度计进行了模态及静力学分析，提出了优化设计参数．3个检测模态（1阶、2阶和3阶模态）的频率分别为1．329kHz、1．345kHz和2．174kHz．通过优化设计，提高了3阶模态和4阶模态的频率差距，降低了其他高阶模态的干扰．在100g（g为重力加速度）的Z向加速度作用下，悬臂梁所受的最大应力为46MPa。小于单晶硅的弯曲极限值70-200MPa．静力学分析表明，加速度计的悬臂梁结构参数能够满足加速度计的力学性能要求．     

New generalized Bessel-Gaussian beams

Analytical expressions are derived for a new set of optical beams, in which the radial dependence is described by a sum of Bessel distributions of different orders, modified by a flat-topped Gaussian function expressed in the form 1 - [1 - exp(-xi2)]M, where xi is a dimensionless parameter and M(> or = 1) is a scalar quantity. The flat-topped Gaussian function can be readily expanded into a series of the lowest-order Gaussian modes with different parameters; this situation makes it possible to express the optical beam as a series of conventional Bessel-Gaussian beams of different orders. The propagation features of this new set of optical beams are investigated to reveal how a windowed Bessel beam passes progressively from a smooth Gaussian window toward the hard-edge limit.     

相移掩模和离轴照明在ArF浸没式光刻中对工艺窗口的影响

研究了交替型相移掩模及离轴照明对65nm分辨率ArF浸没式光刻的影响,在3／4环形照明和3／4四极照明方式下,分别选用传统掩模和交替型相移掩模,研究65nm线宽的密集线条、半密集线条、孤立线条在较大的曝光系统参数范围内,对光刻工艺窗口的改善。并对在不同的照明方式、掩模结构下获得的工艺窗口进行了比较,结果表明：①在较大焦深(DOF)范围内,满足光刻性能要求可以有较大范围的曝光系统参数配置;②相时于传统照明和传统掩模,采用交替型相移掩模或者离轴照明,焦深均可提高100％-150％。     

Three-dimensional calculation of high-power, annularly distributed, laser-beam-induced thermal effects on reflectors and windows

Based on the three-dimensional transient heat conduction equation and the elastic stress-strain equation, the temperature rise, distortion, and equivalent stress distributions of a high-reflectivity silicon reflector and a white bijou window irradiated by a high-power sloped annularly distributed laser beam are simulated using a three-dimensional finite element model (FEM). The effects of laser intensity, output duration, beam obscure ratio, and laser intensity spatial gradient on the results are especially investigated. The effects of mirror and window thermal distortion on laser beam phase aberrations are also evaluated. This noncylindrosymmetric three-dimensional FEM can be used to evaluate high-power, high-energy, laser beam-induced thermal effects on optical components.     

Fingerprint-Based Millimeter-Wave Beam Selection for Interference Mitigation in Beamspace Multi-User MIMO Communications

Millimeter-wave communications are suitable for application to massive multiple-input multiple-output systems in order to satisfy the ever-growing data traffic demands of the next-generation wireless communication. However, their practical deployment is hindered by the high cost of complex hardware, such as radio frequency (RF) chains. To this end, operation in the beamspace domain, through beam selection, is a viable solution. Generally, the conventional beam selection schemes focus on the feedback and exhaustive search techniques. In addition, since the same beam in the beamspace may be assigned to a different user, conventional beam selection schemes suffer serious multi-user interference. In addition, some RF chains may be wasted, since they do not contribute to the sum-rate performance. Thus, a fingerprint-based beam selection scheme is proposed to solve these problems. The proposed scheme conducts offline group-based fingerprint database construction and online beam selection to mitigate multi-user interference. In the offline phase, the contributing users with the same best beam are grouped. After grouping, a fingerprint database is created for each group. In the online phase, beam selection is performed for purposes of interference mitigation using the information contained in the group-based fingerprint database. The simulation results confirm that the proposed beam selection scheme can achieve a signal-to-interference-plus-noise ratio and sum-rate performance which is close to those of a fully digital system, and having much higher energy efficiency.     

Stress analysis in thermal barrier coatings subjected to long-term exposure in simulated turbine conditions

In recent years, ruby fluorescence spectroscopy has been demonstrated as a powerful technique for monitoring residual stress evolution in the thermally grown oxide scale in thermal barrier coating (TBC) systems. The measured residual stresses, in turn, can be used to monitor evolution of damage in the coatings. Effective use of this technology for real-time damage monitoring requires the identification of trends in measured stresses that can be used as indicators of damage evolution. The present work focuses on studying the evolution of residual stresses in TBC systems during long-term exposure to turbine operating conditions. The coatings are electron beam physical vapor deposited (EBPVD) and atmospheric plasma sprayed (APS) zirconia. The stress evolution in both EBPVD and APS coatings is analytically modeled by an approach that takes into consideration contributions due to both thermal mismatch and oxide growth. Microstructural changes in the TBC system are correlated with measured stress trends through comparison with the modeled stresses. The stress measurements and modeling provide insight into failure modes and mechanisms, and to identify critical features in the measured stress data that can be used as indicators of failure in TBCs.     

Vibrating wires for beam diagnostics

A new approach to the technique of particle beam scanning by wires has been developed. The novelty of the method is that the wire heating quantity is used as a source of information about the number of interacting particles. The wire heating measurement is performed as a change of the wire natural oscillation frequency. The excitation of wire natural oscillations is provided by interaction of a current through the wire with a permanent magnetic field. A shift in the wire natural oscillation frequency characterizes the change in the conditions of wire irradiation by the measured beam. By the rigid fixing of the wire ends on the support an unprecedented sensitivity of the frequency to the temperature and to the corresponding flux of colliding particles is obtained. The range of frequencies used (about 10 kHz) and characteristic time of heat transfer limit the speed characteristics of the proposed scanning method; however, the high sensitivity makes it a prospective one for investigation of beam halo and weak beam scanning. Traditional beam profile monitors generally focus on the beam core and loose sensitivity in the halo region where a large dynamic range of detection is necessary. The scanning by a vibrating wire can also be used in profiling and detecting of neutron and photon beams.     

Determination of the feasibility of using attenuated total reflectance Fourier transform–infrared spectroscopy to evaluate thermal ageing of enamel-coated magnet wire

A study was initiated to determine the feasibility of employing attenuated total reflectance Fourier transform–infrared spectroscopy (ATR/FT–IR) to detect changes resulting from thermal ageing in the enamel of copper magnet wire. Polyamideimide (SX-81002) was cured on a zinc selenide (ZnSe) internal reflection element (IRE) coated with a thin film of metallic copper. The coated IRE was inserted in a Circle cell housed in a heating jacket and maintained at 250°C on the optical bench of an infrared spectrometer to simulate thermal ageing of enamel-coated magnet wire. Evaluation of the infrared spectra in the fingerprint region suggested that the polymer experienced chemical degradation within a 23 day period of thermal ageing. Through comparisons with controls containing no copper coatings, and ageing studies carried out at 28°C, it was determined that ageing at elevated temperature caused more pronounced chemical changes in the polymer than did exposure to the copper. These results indicate that ATR/FT–IR may be a useful tool to detect enamel fatigue after a short period of thermal ageing.     

A transparent vacuum window for high-intensity pulsed beams

The HiRadMat (High-Radiation to Materials) facility [1] will allow testing of accelerator components, in particular those of the Large Hadron Collider (LHC) at CERN, under the impact of high-intensity pulsed beams. To reach this intensity range, the beam will be focused on a focal point where the target to be tested is located. A 60 mm aperture vacuum window will separate the vacuum of the beam line which is kept under high vacuum 10⁻⁸ mbar, from the test area which is at atmospheric pressure. This window has to resist collapse due to beam passage. The high-intensity of the beam means that typical materials used for standard vacuum windows (such as stainless steel, aluminium and titanium alloy) cannot endure the energy deposition induced by the beam passage. Therefore, a vacuum window has been designed to maintain the differential pressure whilst resisting collapse due to the beam impact on the window. In this paper, we will present calculations of the energy transfer from beam to window, the design of the window and associated mechanical calculations.     

Thermal Image Degradation Through a Heated Sapphire Window

Optical windows are indispensable for monitoring industrial processes under vacuum or high pressure by using thermal imagers and radiation thermometers. When a thermal imager observes a sample through an infrared window at elevated temperatures, the window emits additional thermal radiation and increases the background signal of the thermal images, which results in image degradation. Standard four-bar images with various radiance temperature differences were measured using a thermal imager with a spectral band from 3 ??m to 5 ??m through a UV-grade sapphire window. The four-bar images are given by a blackbody collimator with various image patterns. The window was indirectly heated in a furnace and then rapidly placed on the optical path between the collimator and the thermal imager. The four-bar image degradation was measured as a function of the window temperature and the radiance temperature difference of the four-bar pattern. A simple equation which describes the contrast of the four-bar image by using the transmittance and reflectance of the sapphire window was proposed. It was confirmed that the model can properly predict the window temperature when the appearance of the four-bar pattern cannot be determined.     

Circular dichroism thermal lens microscope for sensitive chiral analysis on microchip

A novel chiral detector, a circular-dichroism thermal lens microscope (CD-TLM), was developed to realize sensitive and selective detection of small volume chiral samples on a microchip. To realize chiral recognition on TLM, an excitation beam was phase-modulated at a frequency of 1.2 kHz, and left-circularly polarized light (LCPL) and right-circularly polarized light (RCPL) were generated. Then, the differential light absorption between LCPL and RCPL, which is the CD effect, was detected as thermal lens signal intensity and phase. As a standard sample, optically active tris(ethylenediamine)cobalt(III) [Co-(en)3]3+I3- aqueous solutions were used for performance evaluations. First, we verified the basic principle for selective chiral analysis by comparing the signals in intensity-modulation and phase-modulation modes of the excitation beam. Also, we found that the g-factor, which is significant for determining enantiomeric excess, agreed well with the value obtained by the CD spectrometer. The limit of detection (LOD) for enantiopure [Co-(en)3]3+I3- was 6.3 x 10(-5) M (1.9 x 10(-7) abs) for (-)-Co(en)3(3+), and the sensitivity in absorbance units was more than 250 times higher than that in a CD spectrophotometer. Finally, we demonstrated enantiomeric excess determination on a microchip. The LOD was 1.7% (8.5 x 10(-7) abs) for (-)-Co(en)3(3+) and at least one order superior to the LOD of a CD spectrometer. The applicability of CD-TLM for sensitive chiral analysis on a microchip was verified, and CD-TLM is expected to be promising for microchip-based chiral synthesis and analysis systems.     

Role of evanescent waves in power calculations for counterpropagating beams

A general expression is obtained for the time-average power passing through a plane transverse to the direction of propagation for two counterpropagating electromagnetic beams. Each beam is represented by its plane-wave spectrum, which contains both propagating and evanescent plane waves. The expression clearly shows that, under certain conditions, the evanescent plane waves contribute to the time-average power passing through the plane. This is in contrast to the case of a single electromagnetic beam, in which only the propagating plane waves contribute to the time-average power passing through the plane. The utility of the expression is demonstrated with a practical example: a line current placed over a dielectric slab. Here the counterpropagating beams are the incident and reflected fields in the region between the current and the slab. The expression is applied to a plane in this region, and it is used to determine the time-average power associated with the evanescent waves passing through this plane. This power is then shown to be equal to the time-average power carried by the guided modes of the slab.     

Diagnostic ultrasound-induced membrane damage in phagocytic cells loaded with contrast agent and its relation to Doppler-mode images

Cell membrane damage induced by diagnostic ultrasound exposure with contrast agent was examined and related to the display of stimulated acoustical emission in Doppler images. Monolayers of mouse macrophage-like cells were cultured on the inside of one window of an exposure chamber. The monolayers were incubated with 5% Optison/sup /spl reg// (Mallinckrodt, Inc., St. Louis, MO) for 15 minutes then rinsed to remove unattached gas bodies. A Spectra Plus scanner (Diasonics GE Medical Systems, Inc., Cincinnati, OH) in B-scan or Doppler-imaging modes exposed the chamber 3.5 cm away in a 37/spl deg/C water bath. The cells were scored either for uptake of fluorescent Dextran (sonoporation), or for trypan blue dye exclusion (cell death). No significant effect was seen for exposure in any mode without a contrast agent. Significant effects with contrast agent included 5.8% (2.3% standard deviation, SD) fluorescent cells and 33.4% (7.7% SD) trypan blue-stained cells in Doppler-imaging modes, compared to 0.0% and 2.2% (1.7% SD), respectively, in sham exposures. Frames of the power Doppler image were analyzed for pixel brightness to quantify the brief flash in the Doppler window. Although both membrane damage and the flash brightness increased with increasing pressure amplitude, there did not appear to be a direct correlation between the two phenomena.     

Current density distribution in a large cross-section beam in an electron accelerator with a multiaperture plasma cathode

An electron accelerator with a multiaperture plasma cathode with grid stabilization of the boundary of emission plasma based on a low-pressure arc discharge generating a large cross-section (750 × 150 mm²) beam with its ejection into the atmosphere or high-pressure gas through the exit foil window is described. A comparatively simple method for decreasing the nonuniformity of the current density distribution over the beam cross section using a mask with variable-diameter holes is proposed and experimentally tested. In this case, the higher the plasma concentration in the emission region, the smaller the diameter of the holes in the mask. When this mask was used, the nonuniformity of the current density distribution was decreased from ±15 and ±10% to ±10 and ±5% on the long and short sides of the beam cross section, respectively.     

Laser beam melting of aluminum alloys with hull-core build strategy by using an initial meso-scale simulation

Laser beam melting (LBM) of aluminum alloys is gaining a wide popularity in different industrial applications as an alternative technology for the production of individual and complex parts. A long build time and the high amount of experimental work for optimizing or finding new process parameters are two of the current challenges for reaching an industrial maturity. This paper proposes an efficient way to determine new process parameters for aluminum alloy aluminum-silicon10-magnesium with highest build-up rates by using a 3D finite element model on the mesoscopic level. High laser power in combination with the hull-core build strategy was used to increase the build-up rate without impairing the part accuracy. The influences of high laser power, laser diameter and scan speed on the melt pool were studied by using a thermal simulation of single laser tracks. Based on the simulation results the process window could be derived and was tested on a laser beam melting (LBM) system. The achieved reduction of the build time of up to 31 % without loss in part accuracy proved the novel approach for the prediction of the required process window as an efficient method to reduce costly and time-consuming experimental work.     

Adaptive beam shaping by controlled thermal lensing in optical elements

We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.