一种应用于超声波测量的混频检相方法研究

为了提高超声波测量系统的精度，加快检测速度，对超声波测量系统提出了一种混频检相方法并完成了混频检相器设计。采用混频方法将两路有一定相位差的被测信号与另一个有较小频差的信号混频，混频后通过低通滤波电路滤除高频成分，得到保留原信号相位差的两路低频信号，通过整形电路获得两路方波信号，由D触发器设计的检相电路对两路方波信号进行相位差检测。对该混频检相方法进行了仿真和多组相位差实验验证，结果表明采用该混频检相方法具有电路简单、测量精度高、成本低等优点。     

基于自动数字检相技术的激光测距仪设计

设计了一个基于自动数字检相技术的相位式激光测距系统。该系统采用DDS技术产生所需要的测距信号,提高了信号的频率稳定度,消除了信号源频率漂移引起的测距误差;该系统还对自动数字检相技术进行了改进设计,改进后的自动数字检相器能够消除波形变换零点漂移及高频干扰引起的检相误差,提高了检相精度。实际测距实验表明该系统具有较好的测量精度。对测试结果进行了分析,指明了今后研究的方向。     

数字式混频器

在红外激光测距中，一般是通过测量发射连续激光脉冲和被测目标回波信号的相位差而求得被测距离的。为了得到高测距精度，常把两信号分别同基准信号混频得到两个抵频信号再进行检相。传统的频率变换方法是利用晶体管的非线性来实现的，我们在研究JMX－1型精密激光测距仅中，采用数字集成电路，做成了数字式混频器，并取得高的测量精度。     

数字式混频器

在红外激光测距中，一般是通过测量发射连续激光脉冲和被测目标回波信号的相位差而求得测距离的。为了得到高测距精度，常把两信号分别同基准信号混频得到两个低频信号再进行检相。传统的频率变换方法是利用晶体管的非线性来实现的，我们在研究ＪＭＸ－１型精密激光测距仪中，采用数字集成电路，做成了数字式混频器，并取得高的测量精度。     

脉冲式混频器概述

在红外激光测距中，一般是通过测量发射连续激光脉冲和被测目标回波信号的相位差而求得被测距离的．为了得到高测距精度，常把2个信号分别同基准信号混频得到2个低频信号再进行检相．传统的频率变换方法是利用晶体管的非线性来实现的，我们在研究JMX-1型精密激光测距仪中，采用数字集成电路，做成了脉冲式混频嚣，并取得了高的测量精度．     

用于相位法激光测距的电路系统设计

本文论述了相位法激光测距的原理和引起误差的原因,提出了电路系统设计方案,着重对频率电路和精神检相电路进行了较为深入的分析与讨论。针对大小角度、零点漂移和信号幅度等原因引起的测量误差,本文提出了具体的解决措施,提高了数字检相电路的测相精度和稳定性,最后给出了测试方法和测试结果。     

Ku波段海表波高／潮位探测系统的研究

本文提出的Ｋｕ波段海表波高／潮位探测系统在测量精度和使用方便上优于沿用至今的波高计和浪潮仪。该探测系统为一机两用,使１４．５ＧＨｚ微波信号通过两只检相管比较Ｄｏｐｐｌｅｒ回波相位,而精确测得波高,使１１ＧＺｚ微波信号通过三角波调频的相干差频可精确测得海表潮位。基于两路信号共用一部天线,采用正交极化工作且各插入带通滤波器,使隔离度在８０ｄＢ以上,相互串扰抑制到很微弱,确保了测量精度在ｃｍ级,使实测值     

基于数字高频检相式的激光测距光学系统设计

为了改善相位差法激光测距测量精度低的现状,采用高频检相法代替模拟测相法,即数字高频检相式的激光测距光学系统来提高测距精度。实现了10MHz的激光调制频率,设计了准直透镜,给出了设计指标,利用ZEMAX软件对光束准直前后进行了对比分析,并通过实验验证了光学系统设计的可行性。结果表明,标准差最大为0.12°,重复距离精度可约达1mm,误差最大为0.09°,最小为0.011°,说明测量的重复性比较好、稳定度高,满足了精度要求,达到了提高精度的目的。     

光纤激光阵列相干组束中位相检测方法的研究

针对光纤激光阵列相干组束中各路光束位相的检测,提出了一种基于快速傅里叶变换的位相检测方法.该方法不需对参考光进行频移,利用各路光束与参考光束间位相变化引起的条纹图移动实现位相检测.同时,为了减小傅里叶变换过程中由于能量泄漏引入的检相误差,提出了条纹图整周期裁剪的方法,用于克服能量泄漏的影响,可有效提高傅里叶变换法的检相精度.文中详述了位相检测的基本原理,分析了能量泄漏对傅里叶变换的影响,数值计算结果表明该方法的检相误差优于光波长的1/1000,从而为光纤激光阵列的高精度位相调节奠定了基础.     

甚高频晶体振荡器相位噪声测量

本文主要讨论正交检相法晶体振荡器相位噪声测量中的一些问题,其中包括诸如检相器的偏移电压,相位正交条件不满足,锁相环路的影响,注入锁相以及干扰等问题。最后给出测试结果、     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.