不同线型的圆光栅副对光电信号的影响

在轴角编码器的应用中 ,由于其基准元件的圆光栅副的工艺制作、参数 (尺寸、每周线数等 )及使用情况的不同 ,将对光电信号产生较大的影响。通过对三类线型的圆光栅副的理论计算和数据分析 ,图示了各类线型的圆光栅副在每个位置处的 (内径处、中径处和外径处 )透光强度 (即光电信号 )的相对变化 ,列表计算了等宽线条的圆光栅副在不同的每周线数值及中径处占空比不同时的各处光强的相对值 ,并由此推出了光电信号图形形状发生的变化。这些结论将对圆光栅副线型的设计、加工、调试和使用具有较大的参考价值     

铂电极对铜和银非电对离子瞬时响应信号的研究

用活度阶梯变化法测量了铂电极对Ｃｕ＾２＋、Ａｇ＾＋的瞬时响应信号为单峰类型，并且在一定浓度范围呈Ｎｅｒｎｓｔ关系。进一步证实了平衡时间子交换产物的摩尔分数Ｓｅｑ值对瞬时响应信号类型的影响。     

DDS芯片AD9854的噪声分析与应用

通过离散傅立叶变换和傅立叶变换得到了直接数字合成(DDS)的相位截断杂散、背景噪声和非线性杂散分布规律，并且用AD9854设计了高频地波雷达频率综合器。设计中根据DDS噪声分布特点从电路布局和控制字设定两个方面进行了改进，减小了DDS的主要杂散。实验证明，该方法提高了高频地波雷达发射信号的无杂散动态范围(SFDR)约10dB，增大了高频地波雷达的探测距离。     

On the origin of time-resolved pump–probe differential signal from excitons in quantum wells

We investigate the origin and nature of femtosecond time-resolved (TR) pump–probe differential (PPD) signal from the exciton resonance in semiconductor quantum wells (QWs) in the coherent regime. The excitonic PPD signal is expressed as a sum of interferences of the excitonic nonlinear polarization with the incident probe field and the linear polarization induced by the probe. A nonzero excitonic TR-PPD signal from QWs can occur for time t larger than the pulse width (t_p) when the exciton dephasing time is longer than t_p, and this signal can originate only from the second interference term for both the negative and positive pump–probe delays, the contribution from the first interference term being zero for t>t_p. This is in contrast with the case of PPD signal in the spectral domain where the first interference term plays a major role. We discuss the effects of many body interactions on the TR-PPD signal. It is shown that excitation-induced dephasing can cause a significant increase in the rise time of the TR-PPD signal.     

Three-photon contributions in optically pumped lasers

A signal flow graph representation of the density matrix equations appropriate to a serial three-wave interaction is introduced, from which perturbation theory and AC Stark shift information may be extracted. The conditions for a large interaction cross section for the three-photon transition are deduced and applied to selected experimental situations with the main conclusion being that the effect may be present in a large number of CW and pulsed experiments.Work supported by the Army Research Office, National Science Foundation, and the Joint Services Electronics Program.Also with the Coordinated Science Laboratory.     

大型设备中金属跌落零件的声学定位问题研究

针对金属跌落零碰金属板产生的冲击信号，比较了时域初始过零点法和能量比法两种时间延心估计方法。     

扫描电压仪设计

本文介绍了一种输出电压随时间线性递增的扫描电压仪，其输出电压幅度和扫描周期可在一定范围内调节。     

Pulse Signal Distortion Characteristic in Erbium-doped Fiber Power Amplifier

1.Intr0ducti0nTheerbium-d0pedfibcrp0x`eran1[7lificrhasrecentlybcenal)I>IiedinmanyappIicd1,iclds.F0rasmallsignalinput,the0utputsignalclist0rti0nisalwaysnegligible.H0wever,ins0meapp1iedfie1dssuchasCATV,submarincc0mmunicati0nandl0calnetw0rk,itisneccssaryt0c0nsiderthepuIsesignaldist0rti0nbccausc0fthehighsignalinputp0wer(~UW).F0rthetw0kinds0fpu1sesignaI(T,XT,TpXT)x`'ithdifferentpulsex`idth,we0btainac10sed-f0rms01uti0nt0theph0t0ntransp0rtequati0nsandtherateequati0ns,andanalyzetheirnumericalca…     

在抑制强溶剂峰的条件下测量T_1值

当所测样品含有强溶剂信号时,由于主要谱线的动态范围受到严重限制,用常规的方法例如IR方法)测量T_1其精度将受到很大影响,而现有的脉冲抑制溶剂峰技术在用于T_1测量时都有一定的困难.本文提出了一种新的改进型IR方法,通过两次结果相加实现溶剂信号抑制后测量T_1,从而解决了上述困难.文中给出了该方法的理论说明,计算和主要实验结果,且与常规反转恢复法(IR)所获得的结果作了比较.