声光调QYAG激光修整超硬磨料砂轮数字测控系统

设计了一套以MSP430F1611芯片为微处理器的在线检测、控制激光烧蚀超硬磨料砂轮的闲环控制电路系统。该装置以连续激光作为测量光源，以采用激光三角测量法探测到的待修整砂轮的形貌信号作为控制输入信号，通过MSP430F1611芯片进行数据处理，输出脉冲控制声光调QYAG激光巨脉冲的发射，以便达到较理想的修整精度。     

Precisely tunable continuous-wave terahertz source with interferometric frequency control

We realized a tunable continuous-wave terahertz source with megahertz frequency resolution. The system is based on optical heterodyning of two near-infrared distributed feedback diode lasers, each laser being stabilized by electronic feedback from a low-finesse quadrature interferometer. The control loop permits precisely linear laser frequency scans over >1200 GHz, and a beat signal linewidth of 1 MHz at 80 ms time scale. Using GaAs photomixers and log-periodic antennae, we achieve a signal-to-noise ratio of the terahertz power of >70 dB at 100 GHz and 100 ms integration time, and still approximately 30 dB at 1 THz. As an example for high-resolution terahertz spectroscopy, we characterize the transmission properties of a subwavelength metal grating.     

Development of a wavelength-stabilized distributed bragg reflector laser diode to the Cs-D2 line for field use in accurate geophysical measurements

We have developed a wavelength-stabilized laser diode (LD) for geophysical measurement devices, which benefit from the uniformity of laser light. Regarding this purpose, a system that has such characteristics as low power consumption, sturdiness against mechanical disturbances, and a long life with long-term frequency stability is especially required. Therefore, we adopt as the light source a distributed Bragg reflector (DBR) LD because it has various advantages concerning such properties. This paper describes the durable and compact wavelength-stabilized laser system. Since our DBR-LD oscillates at 852 nm, we selected the Cs-D2 line (6 2S1/2-6 2P3/2 transition) as a frequency reference to obtain a long-term stability in wavelength. Stabilization is performed by a feedback system using a modulation transfer (MT) method, which is a kind of Doppler-free saturated absorption spectroscopy, to acquire a saturated absorption signal with a high signal-to-noise ratio. Using this system, we could continuously lock the laser frequency to the hyperfine component of the Cs-D2 line for more than one week. By an Allan standard deviation measurement, the uncertainty of the stabilized laser frequency was found to be better than 1 x 10(-10) (<40 kHz) in a Gatetime region longer than 100 s.     

Frequency stabilization of an external-cavity diode laser to metastable argon atoms in a discharge

A laser stabilization scheme using magnetic dichroism in a RF plasma discharge is presented. This method has been used to provide a frequency stable external-cavity diode laser that is locked to the 4s[3/2](2) → 4p[5/2](3) argon laser cooling transition at 811.53 nm. Using saturated absorption spectroscopy, we lock the laser to a Doppler free peak which gave a locking range of 20 MHz when the slope of the error signal was maximized. The stability of the laser was characterized by determining the square root Allan variance of laser frequency fluctuations when the laser was locked. A stability of 129 kHz was measured at 1 s averaging time for data acquired over 6000 s.     

Creation of arbitrary spectra with an acousto-optic modulator and an injection-locked diode laser

We use a double-passed acousto-optic modulator (AOM), driven by an arbitrary waveform generator to produce multiple frequency components for a laser with arbitrary frequency spacings. A programmed sequence containing various sections of radio-frequency sinusoidal signal at different frequency is applied to drive the AOM. The diffracted light is used to injection-lock a diode laser. The combined techniques allow us to generate the multi-line spectra for the diode laser with arbitrary frequency spacings in the range of 100 MHz at a relatively high output power of 80 mW and a small power variation of 2%. Such a light source can be used in the application for laser cooling of molecules.     

直流伺服电机驱动的自动离合器控制

采用直流伺服电机驱动的自动离合器执行机构，与高速开关阀控制液压缸的执行机构相比，可使电控机械自动变速系统的结构大大简化，同时可提高离合器结合速度的控制精度。设计了基于模糊控制和PI控制双闭环控制的伺服电机驱动离合器执行机构，建立了数学模型，并进行了系统仿真。结果表明：直流伺服电机驱动离合器，能很好地控制离合器的结合速度，提高车辆起步品质。     

Model Based Tuning of a Non Linear Spherical Tank Process with Time Delay

Abstract

A 40 liter spherical tank with varying time delay was subjected to open loop analysis using a step response technique with sodium chloride solution as tracer. The experimental data was adequately represented by a first order plus dead time (FOPDT) model with an error of less than five percent. These model parameters were used to generate Smith Predictor controller, IMC controller, and IMC PID controller using MATLAB. For closed loop control of the process based on rise time, settling time, overshoot, peaktime, decay ratio, and ISE, it was found that the IMCPID controller is better suited for this process.     

基于模糊控制的快速自动安平激光扫平仪

研制了一套全新的自动安平机构,以解决传统激光扫平仪无法同时兼顾安平精度、范围和速度的问题。首先,改进了传统自动安平仪器中的倾角传感器,设计了一种带有补偿环节的电子水泡以满足仪器的精度要求;其次,基于PID控制方法设计了用于实现仪器自动安平的闭环控制系统,同时引入模糊控制思想,使其达到了仪器自动安平的速度要求;最后,优化了仪器机械结构,有效增大了仪器的安平范围。实验测试结果表明,该扫平仪在-10°～+10°的安平精度达到10″,且自动安平时间小于10s。传统的激光扫平仪相比,设计的安平仪具有安平精度高、扫描范围大和安平速度快等特点。     

基于DAVLL技术的半导体激光器稳频装置设计

分析了二向色性原子蒸气激光频率锁定(dichroic atomic vapor laser lock,DAVLL)技术稳定激光器频率的原理,并采用DFB894.6nm半导体激光器和Cs原子气室搭建稳频实验装置。实验测量了不同磁场条件下的DAVLL光谱,发现Cs原子D1线的DAVLL光谱零值点处的斜率随磁场强度增加而增大,但谱线零点斜率不随磁场变化。根据半导体激光器锁频原理设计制作了驱动电路,测试结果表明,该稳频装置的短时频率稳定度达16 MHz。     

超磁致伸缩致动器的输出位移与其控制研究

根据自动控制原理，结合磁致伸缩致动器的结构建立了致动器传递函数模型，在此基础上设计了以TMS320C31为核心的致动器位移闭环控制系统。该控制系统主要由硬件和软件两部分组成。进行了致动器位移控制系统的开环实验和闭环实验，实验结果表明，该系统稳定性可靠、精度高，为致动器在实际精密位移控制中的应用打下了基础。     

一种新型的宽带压控振荡器的设计

分析了变容二极管直接调频原理,采用对称的电路结构设计,构建了一种高性能压控振荡器。利用Advance Design System对电路进行仿真和优化,在0-30V的调谐电压范围内输出频率为800MHz-2200MHz,相位噪声为-88．06dBc／Hz@10kHz。实现了一种利用变容二极管直接调频,具有低相位噪声,低成本,易根据需求优化参数的宽带压控振荡器。     

基于改进H∞算法的线控转向系统仿真研究

针对汽车线控转向系统的鲁棒性问题,对汽车线控转向的原理和结构方面进行了研究;对汽车线控转向的动力学模型进行了建立以及简化;对汽车线控转向控制系统进行了分析与设计.以H∞运算为基础,利用反求法,避开了加权函数的选择,通过观察H∞运算中S/T奇异值曲线,运用符合线控转向鲁棒性能要求的预期S/T曲线逆转了该闭环系统,构建出了闭环传递函数,提出了一种基于改进H∞算法的线控转向系统.通过对线控转向系统的时间域和频率域的分析,以及线控转向系统模型干涉和参数扰动下的仿真结果分析,验证了改进H∞算法的控制策略的准确性.研究结果表明,基于改进H∞算法的线控转向系统在保证了鲁棒稳定性的前提下,具有更好的响应性能;并且改进的控制器比传统的控制器具有更好的鲁棒性.     

Self-detection characteristics of the Sagnac frequency shift in a mechanically rotated semiconductor ring laser

Self-detection of the frequency difference between the two counter propagating oscillation frequencies in a mechanically rotated semiconductor ring laser (SRL) was successfully demonstrated. An SRL used for experiments consisted of a pig-tailed laser diode amplifier module. Detection characteristics of an SRL as an optical gyroscope were investigated and discussed. Beat frequency, which was detected by the terminal voltage change of an SRL without branching the circulating optical power, was measured as a function of the rotation rate, changing the loop radius for investigating the loop radius dependence on the detection sensitivity. The measured detection sensitivity characteristics coincided well with the theoretical prediction based on the Sagnac effect, and it was found that SRLs could be operated as optical gyroscopes. Furthermore, we verified that lock-in phenomenon was one of the most dominant noise sources in the S-RLG.     

Mode-locking optimization with a real-time feedback system in a Nd:yttrium lithium fluoride laser cavity

We present a control system, which allows an automatic optimization of the pulse train stability in a mode-locked laser cavity. In order to obtain real-time corrections, we chose a closed loop approach. The control variable is the cavity length, mechanically adjusted by gear system acting on the rear cavity mirror, and the controlled variable is the envelope modulation of the mode-locked pulse train. Such automatic control system maintains the amplitude of the mode-locking pulse train stable within a few percent rms during the working time of the laser. Full implementation of the system on an Nd:yttrium lithium fluoride actively mode-locked laser is presented.     

Linewidth reduction of a distributed-feedback diode laser using an all-fiber interferometer with short path imbalance

The linewidth of a distributed-feedback (DFB) diode laser at 1156 nm, of which free-running linewidth was 3 MHz, was reduced to 15 kHz using an all-fiber interferometer with 5-m-long path imbalance. Optical power loss and bandwidth limitation were negligible with this short optical fiber patch cord. This result was achieved without acoustic and vibration isolations, and the frequency lock could be maintained over weeks. In addition to its simplicity, compactness, robustness, and cost-effectiveness, this technique can be applied at any wavelength owing to the availability of DFB diode lasers and fiber-optic components.     

Generation of control signals for adaptive systems using laser atmospheric backscatter

A method for controlling an adaptive optical system by using the intensity of laser atmospheric backscatter is studied. Mathematical modeling is used to study the generation of a control signal in a monostatic loop and, as a consequence, the range of beam focus with the closed loop. It is shown that this method of generation does not lead to beam collimation even for beams of diffraction quality.     

超硬磨料砂轮激光修整试验系统的研究

设计了一套以声光调QYAG激光的连续输出光作为测量光源 ,采用光学三角测量在线检测的三维激光烧蚀精密加工系统 ,并以该系统进行超硬磨料砂轮修整试验 ,从而找到了超硬磨料砂轮激光精密修整的新方法     

基于线径反馈的模糊PID控制在拉丝机械上的应用

介绍在拉丝机上采用激光CCD实时测径,讨论并设计基于线径、速度反馈的采用模糊PID控制方法的双闭环拉丝控制系统.     

电线电缆外径测控仪的研究

BZH电线电缆外径测控仪是一种能够进行连续性、非接触在线测量电缆外径的仪器,并且具有闭环控制功能。本文介绍了测控仪的设计原理,闭环控制方法,主要技术数据和它的现场使用情况。     

高测速双纵模双频激光干涉仪系统的研究

以合适频率的高稳定度电子振荡器信号分别与双纵模热稳频双频激光干涉仪输出的频率过高的测量和参考信号混频,将信号载波频率降至计数器允许频率范围内,得到全交流的高测速双纵模双频激光干涉仪系统。本文给出了高测速双纵模双频激光干涉仪系统光路框图和信号处理框图,并给出了振荡器频率选择的基本公式。所研制系统纵模间隔约728MHz,计数器选用最大允许计数频率10MHz的82c54,振荡器为频率为723MHz的JE0723型介质振荡器。在3m激光测长机上的实验证实:系统分辨率为0.32μm时,最大允许测量速度可达1300mm/s,能满足各种高速运动设备的检测及标定需求。