Small-dynamic-angle measurement using tangent relationship and phase-modulating technique

A method using two prisms for measurement of small dynamic angles is proposed in which the measurement is based on a simple tangent equation and a phase-modulating interferometer with a laser diode to measure dynamic optical path differences with higher accuracy. Owing to the simple tangent equation, the symmetry requirement on the two prisms in the optical configuration is eliminated, and easy measurement of the separations between two parallel beams with a position-sensitive detector is achieved. Small-dynamic-angle measurements are experimentally demonstrated with high accuracy. (C) 2007 Society of Photo-Optical Instrumentation Engineers.

Parallel plate interferometer with a reflecting mirror for measuring angular displacement

A parallel plate interferometer with a reflecting mirror for measuring angular displacement is proposed. A deflection angle of a beam caused by an angular displacement is amplified by use of a reflecting mirror to increase the optical path difference (OPD) in the plane-parallel plate, which provides high sensitivity of the phase measurement. Detection of light transmitted through the plane-parallel plate with a position sensitive detector (PSD) enables high accurate measurement of the initial angle of incidence to the plane-parallel plate with insensitivity to stray light. The improved parallel plate interferometer achieves a measurement repeatability of 10(-8) rad. (C) 2007 The Optical Society of Japan.

物体表面形貌的正弦相位调制实时干涉测量技术研究

表面形貌干涉测量技术是一种高精度的非接触式测量技术,在工业生产和科学研究中具有广泛的应用。提出一种实时测量表面形貌的正弦相位调制干涉测量新技术。该技术用激光二极管作光源,用自制的高速图像传感器探测干涉信号,通过信号处理电路实时解相得到被测表面所对应的相位分布,实时分析相位获得物体表面形貌。该技术消除了光强和部分外界干扰的影响,提高了系统的测量精度。楔形光学平板表面形貌的测量结果表明,测量点为60×60个的情况下,测量时间小于8.2 ms,重复测量精度(RMS)为4.3 nm。

实时测量表面形貌的正弦相位调制半导体干涉仪

提出一种实时测量表面形貌的正弦相位调制半导体激光干涉仪。利用实时相位检测电路，从正弦相位调制干涉信号中解出被测量物体表面形貌的相位。在实验中，测量了楔形光学平板的表面形貌，对表面形貌上的60

一种使用双棱镜的动态小角度测量方法

提出一种基于正切关系和相位调制技术的动态小角度测量方法。使用双棱镜组成干涉测量臂引导两束平行光至分束棱镜处干涉,通过提取携带被测信息的干涉信号的相位实现动态的小角度测量。由于采用位置探测器(PSD)对测量臂中两平行光束的间距进行测量,简化了测量方程,消除了装置中双棱镜必须对称放置的要求。通过正弦地改变半导体激光器的注入电流在时域内实现对干涉信号的相位调制,形成准外差干涉测量模式,提高了光程差的测量精度。实验验证了该方法的可行性,并讨论了影响小角度测量精度的误差因素。研究结果表明,基于该方法的动态小角度的重

消除正弦相位调制干涉仪中光强调制影响的全光纤干涉仪

在激光二极管(LD)正弦相位调制(LD-SPM)干涉仪中,通过注入电流调制激光二极管波长的同时,光源输出的光强也被调制,成为测量误差的主要来源之一。提出一种新的消除激光二极管正弦相位调制干涉仪中光强调制影响的干涉仪,给出了具体的理论分析。该干涉仪采用全光纤结构,有效减小外界干扰对干涉测量的影响;采用容易实现的前置信号处理电路和实时相位检测器对干涉信号进行处理,消除了激光二极管光强调制产生的测量误差;同时实现了物体微小位移的高精度实时测量,测量的重复精度达到1 nm。实验结果与其他消除光强调制影响的方法测得

Designing a coupler for the intersatellite optical communication system

Coupling a single-mode laser diode with 200 mW to a single-mode fiber (SMF) through an orthonormal aspherical cylindrical lens and a GRIN lens for the intersatellite optical communication system is proposed and demonstrated. We experimentally studied how the coupling efficiency changes with the SMF's position displacement and axial angle variation, and obtained 80 mW output power at the end of the SMF, which shows that the coupling units have satisfied the designed request. (c) 2007 Elsevier GmbH. All rights reserved.

Accuracy analysis of parallel plate interferometer for angular displacement measurement

The measurement accuracy of a parallel-plate interferometer for angular displacement measurement is analyzed. The measurement accuracy of angular displacement is not only related to the accuracy of phase extraction, but also related to initial incident angle, refraction index and thickness of plane-parallel plate as well as wavelength's stability of laser diode, etc. Theoretical analysis and computer simulation show that the measurement error of the angular displacement bears a minimum value when choosing an optimal initial incident angle in a large range. These analytical results serve as a guide in practical measurement. In this interferometer, reducing the refraction index or increasing the thickness of the parallel plate can improve the measurement accuracy; and the relative error of the phase measurement is 3.0 x 10(-4) corresponding to 1 degrees C temperature variation. Based on these theoretical and experimental results, the measurement accuracy of the parallel-plate interferometer is up to an order of 10(-8) rad. (c) 2007 Elsevier Ltd. All rights reserved.

Real-time micro-vibration measurement in sinusoidal phase-modulating interferometry

As there exist some problems with the previous laser diode (LD) real-time microvibration measurement interferometers, such as low accuracy, correction before every use, etc., in this paper, we propose a new technique to realize the real-time microvibration measurement by using the LD sinusoidal phase-modulating interferometer, analyze the measurement theory and error, and simulate the measurement accuracy. This interferometer utilizes a circuit to process the interference signal in order to obtain the vibration frequency and amplitude of the detective signal, and a computer is not necessary in it. The influence of the varying light intensity and light path difference on the measurement result can be eliminated. This technique is real-time, convenient, fast, and can enhance the measurement accuracy too. Experiments show that the repeatable measurement accuracy is less than 3.37 nm, and this interferometer can be applied to real-time microvibration measurement of the MEMS. (C) 2007 Elsevier GmbH. All rights reserved.

Stable single frequency and single polarization DFB fiber lasers operated at 1053 nm

Stable single-frequency and single-polarization distributed-feedback (DFB) fiber laser was realized by giving a pressure on the phase shift region of the fiber grating. The output wavelength of the DFB fiber laser is 1053 nm. When the pump power of 980 nm laser diode is 100 and 254 mW, the output power can reach 8.3 and 37.1 mW and the polarization extinction ratio was 26 and 20 dB, respectively. After chopped by Acousto-optic modulator (0.3 Hz), the pulse peak value variance is 4.65%(peak to peak) and 1.098% (RMS) for 31 min. (C) 2006 Elsevier Ltd. All rights reserved.

梯度补偿法控温晶体的高功率绿光激光器

研究了平均功率超过30 W的稳定高效全固态绿光激光器,分析得出影响全固态腔内倍频激光器倍频效率和输出稳定性的主要因素是倍频晶体局部温升造成的相位失配和热透镜效应,采用温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,降低激光器工作中倍频晶体内外温度梯度从而有效地克服因晶体局部温升造成的倍频相位匹配角失配和热透镜效应。采用三条60 W的半导体激光二极管阵列板条侧面抽运Nd:YAG激光增益介质棒,采用声光调Q,平凹直腔和腔内倍频结构配合温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,得到了稳定高效的532 nm

板条热容激光器的二维热特性

固体热容激光器（SSHCL）作为高功率固体激光器的一个重要发展方向,引起人们广泛关注。数值模拟激光介质板条在热容方式下工作的温度和应力分布是了解该类激光器工作特性的一种有效手段,采用平面应力近似法导出了半导体激光器抽运热容激光介质板的二维温度和应力分布公式,同时也对二维抽运光吸收密度、介质板温度分布和折射率变化进行了分析与讨论。数值计算的结果表明二维效应的温度分布和应力分布要比一维效应给出的分布更均匀。

激光二极管端面抽运Nd∶YVO4固体激光器热致光束畸变非对称的平衡

由于a轴切割Nd∶YVO4晶体的非对称性,使得激光二极管(LD)端面抽运Nd∶YVO4固体激光器不同于Nd∶YAG激光器,输出的激光经常产生非对称结果。用有限元法分析激光二极管端面抽运a轴切割Nd∶YVO4固体激光器的晶体热效应,包括温度分布、内部应力和产生的形变。分析结果表明端面抽运a轴切割Nd∶YVO4晶体产生了椭球热透镜效应。从结构方面和抽运方面提出了热透镜非对称性的平衡方法,实验验证了方法的可行性。

高稳定激光二极管抽运Nd∶YLF再生放大器

设计并实现了一种放大纳秒激光脉冲的高稳定的激光二极管(LD)抽运Nd∶YLF再生放大器。为了获得高稳定的输出,再生放大器工作在饱和状态。此时,再生放大器输出稳定性最好,而且注入激光脉冲能量波动引起的输出激光脉冲波动被抑制。由于增益饱和效应,再生放大器输出脉冲出现时域波形失真,附加后缀脉冲能够减弱时域波形失真。放大器工作波长1053nm,工作频率1Hz。输入240pJ的3ns方波激光脉冲,输出激光脉冲能量4.2mJ,总增益大于107,不稳定度小于1%(均方根),方波扭曲1.33。为3ns方波激光脉冲引入其本身幅度0.75倍的后缀脉冲,输出激光脉冲方波扭曲由1.33降至1.17。

超大功率二维半导体激光列阵并路自适应稳模技术

半导体列阵量子效率高,输出波长范围涵盖570～1600nm,工作寿命可达数百万小时,叠层列阵可提供超高功率激光输出,在工业、医学等很多领域具有非常广阔的应用前景。但列阵在自由运行时,各发光单元发出的光是不相干的,输出质量差,采用1/4Talbot外腔镜耦合技术,列阵实现了空间锁相最高阶超模,然而唯有基超模远场分布是中心单瓣结构,输出接近衍射极限。为得到最小谱宽、最小发散角、最大功率密度输出,必须将外腔镜倾斜β=λ/2d(λ为工作波长,d为列阵周期),这使得仅有基超模光能成像于发光单元内而被允许振荡。应用此