共查询到17条相似文献，搜索用时 62 毫秒
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研究了音叉式石英晶振的个体尺寸、安放角度、探测部位以及外部污染对整个石英增强光声光谱系统(QEPAS)的探测灵敏度影响。测试了国内外十种不同音,结果表明顶端为楔形构造的音叉式石英晶振比规则的长方体构造的音叉拥有更高的品质因数(Q值)。在相同的测试条件下探测水的吸收线(7 306 cm-1)时获得更高的灵敏度,探测信号的强度相差高达50%。在研究音叉安放角度对探测信号影响的实验中,发现音叉的旋转角度与俯仰角度对探测信号的强度几乎没有影响,但是当光束以角度φ斜入射时,更多的噪声被带入到测量中。在正入射的情况下音叉的最佳响应位置在距离音叉底部约3.1 mm。定性研究了外部杂物污染对音叉频率的影响,发现随着污染物的附着,石英音叉的频率会呈现降低的趋势,提供了一种改变音叉式石英晶振的共振频率的方法,为石英音叉用于较低调制频率的探测提供了一种理论可能,这对于石英增强光声光谱技术用于V-T弛豫率较慢的痕量气体检测有重要的意义。 相似文献
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何林峰;刘炜壕;黄逸飞;段李福;叶玮琳;郑传涛 《光学学报》2024,(12):412-419
为提高探测性能,可通过在石英音叉周围设计声学谐振管以增强光声信号。然而,不同形状、尺寸和结构的谐振管会对音叉谐振信号产生不同程度的增强效果。旨在探究谐振管参数对石英增强光声光谱（QEPAS）探测性能的影响,通过理论建模和COMSOL Multiphysics软件仿真,研究不同参数下共轴对称和非对称结构谐振管对系统的增益性能,并进行多组对照实验。仿真及实验结果均表明,在共轴对称结构谐振管系统中,随着谐振管内径的减小,对应的最佳长度增加,相对于裸音叉系统可获得更显著的增益效果。在相同内径的谐振管条件下,相较于非对称结构,对称结构显示出更优的增益性能。仿真及实验获得的谐振管最优参数：内径为0.5 mm、长度为5.04 mm,将该谐振管作用于QEPAS探测系统,相较于裸音叉系统,该系统增益性能提高了15倍。采用该系统对体积分数为5×10-3的甲烷标准气体进行长时间测量,结果显示当积分时间为72 s时,系统的探测下限为2.07×10-6。 相似文献
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对石英音叉增强型光声光谱(QEPAS)系统中常用的石英音叉进行了有限元模态计算，获得石英音叉前6阶振型与模态频率，认知了第4阶对称摆动振型为有效振动，利用单因素法分析了石英音叉的音臂长度l1、音臂宽度w1、音臂厚度t、音臂切角θ、音臂圆孔直径d及音臂圆孔高度h对低阶有效共振频率(Fre)的影响，敏感度依次为： l1> w1>d>θ>t>h，考虑实际设计情形，筛选出了l1，w1，d与h四个石英音叉设计变量，采用Box-Behnken实验设计方案与RSM(response surface methodology)方法，以Fre为函数目标，建立l1，w1，d与h的二次回归响应面模型，得到了参数之间的交互作用，利用Design-Expert软件对响应面模型进行设计参数反求，结果表明，在15 000 Hz≤Fre≤25 000 Hz计算区域内误差较小，基本满足QEPAS系统的计算需求，所提出的研究与设计方法具有一定通用性，可为QEPAS系统中石英音叉结构参数设计提供参考。 相似文献
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基于石英增强光声光谱(quartz-enhanced photoacoustic spectroscopy,QEPAS)的气体传感技术具有系统体积小、成本低、环境适应性强等优点,是目前一种重要的光谱式痕量气体检测方法.探测灵敏度是传感器系统的重要指标,关系到能否满足实际应用,因此,本文从提高QEPAS传感系统灵敏度的角... 相似文献
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采用块状光学准直聚焦透镜组的传统石英增强光声光谱(QEPAS)技术存在体积难以缩减,结构稳定性不佳,无法适应空间狭小、振动复杂的特殊环境等缺点.基于此,将光纤倏逝波技术与QEPAS技术相结合,提出了一种新型微纳结构光纤QEPAS痕量气体检测技术.实验中,为了提高QEPAS系统信号幅值,优化了石英音叉与激光束的空间位置、激光波长调制深度,同时对比了两种不同共振频率的石英音叉,最终采用共振频率较低的30.720 kHz石英音叉作为声波探测元件,获得的检测极限为6.25×10~(-4)(体积分数),归一化噪声等效吸收系数为4.18×10~(-7)cm~(-1).W·Hz~(-1/2). 相似文献
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为了进一步提高基于泛频振动的石英增强光声光谱测声器探测灵敏度,在一次泛频振动模式下采用一个比商用标准音叉外形尺寸大5倍的定制大音叉,并对其性能进行优化.通过理论和实验研究得出了音叉与激光的最佳作用位置,发现音叉的一次泛频振动有两个波腹点,且在距离音叉根部8mm处,音叉振臂的振动幅度最大.微型声音谐振腔由三种不同内径的不锈钢毛细管加工而成,与音叉组成共轴配置石英增强光声光谱光谱测声器,用来进一步增强信号幅值.在最佳微型声音谐振腔配置下,获得了30倍的信号增益因子,有效提高了石英增强光声光谱光谱测声器的探测灵敏度. 相似文献
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为了提高全光式石英增强型光声光谱(QEPAS)珐珀解调系统的微弱信号检测能力,设计了一种基于MAX274的有源带通滤波电路和基于AD620的前置放大电路对信号进行预处理,同时利用LabVIEW设计了正交矢量型数字锁相技术的信号处理模块。实验结果表明,该方法能从强背景噪声中获得比较微弱的光声信号,在常温常压下对空气中的水汽含量进行探测,得到其归一化噪声等效吸收系数为1.37×10-6 cm-1 W/Hz1/2。该方法具有结构简单、价格低廉、便于操作和控制、实用性强等特点。 相似文献
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Shinya Ohkubo Shohei Yamazaki Atsuo Takayanagi Yukitoshi Otani Norihiro Umeda 《Optical Review》2003,10(2):128-130
Many studies have reported on the use of quartz tuning forks (a type of crystal oscillator used in wristwatches) in the detection of shear force, employed to control the distance between the probe and the sample in a scanning near-field optical microscope. This study focuses on a newly-devised shear force detection method capable of simultaneous non-external oscillation and detection, which also allows for subsequent reuse of a tuning fork. The optimum configuration and tip length for inserting a probe into the slit of a tuning fork have been elucidated. The shear force was detectable in about 5 nm decay length using such conditions. 相似文献
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CHEN Zheng;SUN Bo;DONG Lei;WU Hongpeng 《光子学报》2023,52(3):268-277
Quartz-enhanced photoacoustic spectroscopy technology has the characteristics of zero-background, excitation wavelength independence, compact structure and cost-effectiveness. Compared with conventional photoacoustic spectroscopy, the innovation of the quartz-enhanced photoacoustic spectroscopy is that a quartz tuning fork is employed as an acoustic transducer instead of the wideband microphone. However, the narrow gap size and the high resonant frequency of the commercially available quartz tuning fork prongs limit the abroad application of quartz-enhanced photoacoustic spectroscopy in many fields. To overcome the disadvantage mentioned above, a custom quartz tuning fork which can reduce the resonance frequency while keeping high quality factor was designed. The finite element software COMSOL Multiphysics was used to estimate the stress field distribution along the quartz tuning fork prongs when the quartz tuning fork was designed. The calculation method of resonant frequency is analyzed by combining thr Euler-Bernoulli equation. For a traditional tuning fork quartz, to reduce the resonant frequency of the tuning fork, the length of the prongs should be increased while the width of the prongs should be reduced. At the same time, to obtain a higher quality factor, the width of the prongs must be increased, which results a higher resonant frequency of a tuning fork. Hence, the high quality factor and the low resonance frequency cannot be taken into account at the same time for the traditional shape of tuning fork quartz. From the results of theoretical analysis, the hammer-shaped prongs can optimize the strain field between the prongs and their support effectively. Hence, a quartz tuning fork with hammer-shaped prongs was designed. The homemade quartz tuning fork has the larger gap size ~800 μm between two prongs, which is nearly three times larger than the prongs' gap size of the standard quartz tuning fork. In the meantime, the quality factor and the resonant frequency of the homemade quartz tuning fork were optimized by 14% and 62% respectively, and the compact quartz-enhanced photoacoustic spectroscopy sensor for C2H2 detection was demonstrated by using hammer-shaped quartz tuning fork to verify the performance characteristics of the novel custom quartz tuning fork. A near-infrared distributed feedback diode laser with a center wavelength of 6 523.88 cm-1 and an output power of ∼12 mW was served as the C2H2 quartz-enhanced photoacoustic spectroscopy sensor excitation source. A so-called acoustic micro-resonator was employed in addition to the hammer-shaped quartz tuning fork for increasing the C2H2 quartz-enhanced photoacoustic spectroscopy signal amplitude via the acoustic resonance effect. The acoustic micro-resonator was assembled in an “on-beam” quartz-enhanced photoacoustic spectroscopy configuration, in which the acoustic micro-resonator was formed by two metallic thin tubes and was coupled to the homemade quartz tuning fork via the excited sound wave in gas contained inside the acoustic micro-resonator tubes. Both the length and assembly position of the acoustic micro-resonator were optimized in terms of signal amplitude and signal-to-noise ratio. And the two parameters mentioned above were selected to be 9 mm and 1.5 mm by experiment respectively. The second-harmonic detection technique was employed to reduce the sensor background noise and simplify the data process. The wavelength modulation depth was optimized at room temperature and atmospheric pressure. The hammer-shaped quartz tuning fork based C2H2 sensor achieved a minimum detection limit of 282×10-9 for a 300 ms averaging time and 12 dB/oct filter slope, which corresponds to a normalized noise equivalent absorption coefficient of 3.84×10-9 ![]()
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设计并演示了一种全光型石英增强光声光谱技术, 该技术在传统的石英增强光声光谱系统中增加了另一束探测光束, 把与气体浓度成正比的石英晶振振臂的振动幅值转化为探测光束的强度变化, 实现了探测气体处无电子元件的全光学系统. 如此的设计使该系统具有较强的抗电磁干扰能力和非常小的传感头体积, 能够用于探测空间受限或探测环境恶劣的情况下, 并实现远距离探测. 在这种配置下, 探测大气压下的水汽, 获得的噪声等效吸收系数为1.13×10-6 cm-1W/√Hz. 进一步讨论了优化系统和提升其探测灵敏度的途径.
关键词：
石英增强光声光谱
音叉式石英晶振
气体传感 相似文献
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文中对自制对称正型音叉与自制非对称异型音叉受力F后音叉产生的振动的现象进行了研究,用DIS声传感数字化信息系统采集振动频率,研究频率与音叉叉股长度的关系,从而对音叉叉股对称与非对称的情况进行研究。 相似文献
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实验中设计了一种基于微型非共振腔的石英增强光声光谱痕量气体传感器, 用来检测非纯氦气中的痕量氨气浓度. 该传感器采用的微型非共振腔只在空间上限制声波扩散以达到增强信号目的, 而不是像传统微型共振腔一样依靠共振效应. 如此的设计使探测小分子无机气体的光谱测声器尺寸远远小于共振腔的配置而有利于准直. 不同气压下的信号和噪声也被研究, 用来优化传感器性能. 在这种配置下和27.7 kPa的最优气压下, 获得的最佳氨气探测灵敏度为463 ppb (1σ , 1 s积分时间), 相应的归一化噪声等效吸收系数为4.3×10-9cm-1W/√Hz.
关键词：
气体传感器
石英增强光声光谱
音叉式石英晶振
类氢气体纯度分析 相似文献