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基于RC电路模型的激光诱导生物组织光热效应 总被引:1,自引:0,他引:1
针对激光诱导生物组织温升预测问题提出了一种新的RC电路理论模型。根据基尔霍夫电压定律(KVL)推导了RC电路的系统函数和单位冲激响应,根据单位冲激响应和矩形输入信号的卷积得到RC电路的零状态响应模型,由激光照射下生物组织温度实验结果确定模型中的两个固定参数,提出了两种模型参数计算方法并进行模拟计算。理论计算与实验结果显示温度响应曲线一致,肝脏和肌肉组织峰值温度相对误差范围分别为-0.0557℃~-0.0025℃和0.0139℃~0.0641℃,温度曲线平均相对误差范围分别为0.55%~2.39%和0.38%~0.99%,这种方法较经典的Pennes生物热传输方程模型所需参数少,精度更高,为激光与生物组织光热效应研究提供了一种新方法。 相似文献
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通过分析垂直腔面发射激光器的速率方程,并结合电子电路的特点,建立了等效电路模型。采用数值计算和电路模拟两种方法给出了垂直腔面发射激光器的频率响应特性。通过分析,证明了电路模型的正确性。通过电路模拟得出了脉冲调制的响应特性,验证了激光器固有的电光延迟和张驰振荡现象。 相似文献
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为了实现高频率的调制激光输出,设计了一种驱动系统由信号放大、电流调制、过流保护和具有慢启动功能的直流偏置电路高度集成的半导体激光高频调制系统。此系统采用了结构简单的直接调制方式,运用线性调频的高频信号去控制半导体激光器发射激光的强度,从而实现高频调制。在运用OrCAD/PSpice对高频调制驱动系统进行模拟仿真的基础上,最终研制出的半导体激光高频调制系统实现了频率为40.02 MHz、直流偏置为493.326 mA、正弦波调制电流峰峰值为850 mA的高频调制输出,调制激光平均功率为300 mW。 相似文献
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通过引入Langevin噪音项的噪音等效电路研究了半导体激光器的热噪音特性.研究表明,在激光器的工作过程中,由于自加热效应所引来的热噪音是不能够被忽略的.本文基于半导体激光器的噪音等效电路,仿真分析不同频带宽度、不同注入电流情况下,工作温度的变化对激光器结电压噪音谱的影响. 相似文献
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Cr,Tm,Ho∶YAG激光器的理论模拟 总被引:1,自引:1,他引:1
为了使CTH∶YAG激光器的设计得到更好的优化,从晶体光谱吸收特性、离子间能量转移过程及准三能级运转方式对CTH∶YAG激光器的工作特性进行了理论分析;依据速率方程理论建立了CTH∶YAG激光器运转的理论模型.模拟能量输出与试验结果较好的吻合,验证了此理论模型描述CTH∶YAG激光器运转规律的合理性.模拟结果表明:CTH∶YAG激光器的激光脉冲输出与泵浦有较长的时间延迟且伴随较强的驰豫振荡,冷却温度对激光输出产生较大的影响. 相似文献
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由于外腔半导体激光器系统中的核心部分——激光器受外界环境影响较大,在装配或工作中极易受到电压、电流和静电荷的影响而损坏.为减少由于电路不稳定产生的激光器损坏,在借鉴各种传统的恒流源电路实现方式的基础上,运用反馈恒流原理,慢启动慢关闭原理,利用场效应管特性,给出一种高准确度恒流电路实现方式.将此电路直接运用于中心波长1550 nm激光器作为驱动电路,工作稳定、输出电流受负载影响很小且输出准确度达到同行业先进水平.电流稳定达到0.01%以上.此电路实现方式简单,实用性较强,对整个电路做出了实验仿真和测试,很好地解决了由于驱动电流不稳造成的激光器损坏的问题. 相似文献
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从半导体激光直接调制理论出发,对直接调制过程中影响半导体激光器高频调制性能的因素进行了研究;运用PSpice建立半导体激光器等效电路模型,仿真研究了电学寄生参数对半导体激光器调制特性的影响且提出了相应的提高其调制性能的方法。在研究半导体激光器调制特性的基础上,设计了一种半导体激光直接调制系统。运用OrCAD/PSpice对直接调制驱动系统进行仿真。研制的半导体激光调制系统实现了频率为1 MHz、平均功率为1.1 W的调制激光输出。 相似文献
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The design of the acoustic resonator is critical for the optimization of the sensitivity of laser photoacoustic spectroscopy (LPAS) in trace gas detection applications. In this paper, an LC circuit model is used for the simulation of a 1D acoustic resonator. This acoustic resonator is designed for CO photoacoustic spectroscopy. The effects of the structural parameters, quality factor and resonant frequency on the performance of the device are theoretically analyzed. The role of the buffer volume as an acoustic filter is investigated and optimized dimensions of the buffer volume, to achieve minimum noise transmission coefficient, are calculated. The effects of the ambient temperature, variety of pressure and gas flow velocity on the resonant frequency of photoacoustic resonator and PA signal are simulated. The temperature dependence of the microphone sensitivity is also introduced. 相似文献
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建立了一种适用于多量子阱和多有源区的多层速率方程模型. 通过小信号分析,得到了光子密度、载流子俘获、逃逸和隧穿时间等关键参数对单有源区和隧道再生双有源区垂直腔面发射激光器频率响应特性的影响,并分析了在相同驱动电流下隧道再生双有源区器件调制带宽大于单有源区器件的原因. 进一步研究了隧道再生双有源区内腔接触氧化限制型垂直腔面发射激光器的寄生电参数及其寄生电路,对其频率响应进行了模拟分析.
关键词:
垂直腔面发射激光器
速率方程
调制特性
隧道再生 相似文献
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H.K. Hisham A.F. Abas G.A. Mahdiraji M.A. Mahdi A.S. Muhammad Noor 《Optics & Laser Technology》2012,44(6):1698-1705
A unified and comprehensive study on the small-signal intensity and frequency modulation characteristics of a fiber Bragg grating Fabry–Perot (FBG–FP) laser are numerically investigated. The effect of injection current, temperature, external optical feedback (OFB), nonlinear gain compression factor, fiber grating (FG) parameters and spontaneous emission factor on modulation response characteristics are presented. The rate equations of the laser model are presented in the form that the effect of temperature (T) and external optical feedback (OFB) are included. The temperature dependence (TD) of laser response is calculated according to the TD of laser cavity parameters instead of directly using the well-known Parkove equation. It is shown that the optimum external fiber length (Lext) is 3.1 cm and the optimum range of working temperature for FGFP laser is within ±2 °C from the FBG reference temperature (To). Also, the antireflection (AR) coating reflectivity and the linewidth enhancement factor have no significant effect on the modulation spectra. It is also show that modulation response is extremely sensitive to the OFB level, high injection current and gain compression factor. The study indicates clearly that good dynamic characteristic can be obtained by system parameters optimization. 相似文献
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An improved electrical equivalent model for multimode laser diode incorporating thermal effects and spectral behavior is developed from the multi mode rate equations. The temperature dependent optical power, wavelength shift, spectral widths are determined in the dc sweep simulations. The output power, frequency chirp and temperature rise are evaluated under pulse modulation conditions. Further, the laser diode bandwidth dependence on temperature is also evaluated. Analysis is carried out in the temperature range of 283–343 K, by simulating the equivalent circuit, using PSpice circuit simulator. 相似文献
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This paper presents an analytical model using equivalent circuit method to design an earbud earphone. The electroacoustic parameters of a miniature loudspeaker are measured through a laser triangulation method. Design configurations are analyzed in accordance with the open and closed states of vent and sound holes of earphone. The equivalent circuit model is validated by the head and torso simulator measurements in an anechoic chamber. The effects of vent and sound holes on frequency response are examined and elucidated. The vent and sound holes found to affect the fundamental resonance frequency, low, and medium frequency response. The effect of sponge cover over the earphone’s front side is also investigated. Finally, it is concluded that the sponge can elevate the sound pressure level to 120 dBSPL and above, raising the possibility of permanent and incurable hearing loss. The major contribution of this work leads to successful development of earbud earphone. 相似文献
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正交四元探测器是第3代红外导引头的核心传感器,为了对该型导引头实施有效干扰,探讨了其探测工作机理,有针对性地提出影响其自动增益控制(AGC)电路工作的干扰策略,对干扰实施过程进行了仿真分析。采用蒙特卡洛方法模拟了在干扰存在频差,干扰占空比改变,干扰相位变化条件下的平均有效干扰率。仿真结果表明:以同频或倍频、0.25占空比、较高功率激光可影响导引头AGC电路正常工作,适时通过调整干扰相位可以影响干扰效果,最终破坏其信号提取逻辑,实现欺骗干扰。分析结果对于激光定向红外对抗系统的研制具有一定理论指导意义。 相似文献
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激光器的打标速度、频率、填充间隔、电流、离焦量等工艺参数直接影响空气开关的打标效果。实验根据5因素4水平正交表L16(45)改变激光工艺参数,利用分光测色计和二维码扫描器对激光标记分别进行色差和读码率的测量,通过正交分析法和极差法研究激光工艺参数对打标效果的影响。研究表明:色差与读码率的数据趋于正比关系,并且存在一个阈值色差;当激光参数的速度为1 000 mm/s、频率为20~30 kHz、填充间隔为0.04 mm、电流为28 A、离焦量为-1 mm时,在空气开关上打标出点密度合适、色差对比度高、易于读取的二维码。 相似文献