SNR Improvement of QEPAS System by Preamplifier Circuit Optimization and Frequency Locked Technique

Zhang, Qinduan; Chang, Jun; Wang, Zongliang; Wang, Fupeng; Jiang, Fengting; Wang, Mengyao

doi:10.1007/s13320-018-0468-y

Cited by 7 publications

(7 citation statements)

References 11 publications

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“…In the wavelength stabilization scheme, the power incident into the gas cell is 5.6 mW, the lock-in amplifier bandwidth is 0.08 Hz, and the gas concentration is 800 ppm. Hence, the system normalized noise equivalent absorption coefficient (NNEA) of 1σ should be 7 1 1 / 2 6.08 10 W cm Hz…”

Section: System Performance With Wavelength Stabilization Schemementioning

confidence: 99%

“…The SNR of 135.01 in the wavelength stabilization scheme is also 10.1 times higher than that of the conventional WMS, and the MDL is estimated to be 11.85 ppm. Because the power incident into the gas cell is 7.6 mW, the lock-in amplifier bandwidth is 0.08 Hz, and the gas concentration is 1600 ppm, the NNEA of 1σ should be 7…”

Section: System Performance With Wavelength Stabilization Schemementioning

confidence: 99%

“…Over the last few decades, tunable diode laser absorption spectroscopy (TDLAS) has been widely used in the trace gas detection in various fields, such as industrial production control [1], mine safety monitoring [2,3], combustion processes [4,5], Zongliang WANG et al: Multi-Component and Multi-Point Trace Gas Sensing in Wavelength Modulation Spectroscopy Based on Wavelength Stabilization 377 environmental monitoring [6,7], and explosive analysis. Moreover, owing to the well-known advantages of resistance to electromagnetic interference, low cost, and portability, TDLAS has been widely studied [8,9].…”

Section: Introductionmentioning

confidence: 99%

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Multi-Component and Multi-Point Trace Gas Sensing in Wavelength Modulation Spectroscopy Based on Wavelength Stabilization

Wang

Chang

et al. 2019

Photonic Sens

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Multi-component and multi-point trace gas sensing in the wavelength modulation spectroscopy is demonstrated based on the frequency-division multiplexing and time-division multiplexing technology. A reference photodetector is connected in series with a reference gas cell with the constant concentration to measure the second-harmonics peak of the components for wavelength stabilization in real time. The central wavelengths of the distributed feedback lasers are locked to the target gas absorption centers by the reference second-harmonics signal using a digital proportional-integral-derivative controller. The distributed feedback lasers with different wavelengths and modulation frequencies are injected into the gas cell to achieve multi-components gas measurement by the frequency-division multiplexing technology. In addition, multi-point trace gas sensing is achieved by the time-division multiplexing technology using a photoswitch and a relay unit. We use this scheme to detect methane (CH 4 ) at 1650.9 nm and water vapor (H 2 O) at 1368.597 nm as a proof of principle with the gas cell path length of 10 cm. The minimum detection limits achieved for H 2 O and CH 4 are 1.13 ppm and 11.85 ppm respectively, with three-point gas cell measurement; thus 10.5-fold and 10.1-fold improvements are achieved in comparison with the traditional wavelength modulation spectroscopy. Meanwhile, their excellent R-square values reach 0.9983 and 0.99564 for the concentration ranges of 500 ppm to 2000 ppm and 800 ppm to 2700 ppm, respectively.

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Section: System Performance With Wavelength Stabilization Schemementioning

confidence: 99%

Section: System Performance With Wavelength Stabilization Schemementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-Component and Multi-Point Trace Gas Sensing in Wavelength Modulation Spectroscopy Based on Wavelength Stabilization

Wang

Chang

et al. 2019

Photonic Sens

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“…For example, a stabilization technique with lock-in amplification can be used to This work was supported by Military University of Technology grant no. UGB 22-871. extract a signal from the noise, but the modulation frequency and phase must be known [7,8]. Moreover, the lock-in instrumentation is complex and expensive [9].…”

Section: Introductionmentioning

confidence: 99%

IR detection module with integrated real-time FIR filter implemented in FPGA

Achtenberg,

Mikołajczyk,

Bielecki

2024

International Journal of Electronics and Telecommunications

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Infrared detectors are usually characterized by 1/f noise when operating with biasing. This type of noise significantly reduces detection capabilities for low-level and slow signals. There are a few methods to reduce the influence of 1/f noise, like filtering or chopper stabilization with lock-in. Using the first one, a simple 1st-order analog low-pass filter built-in amplifier usually cuts off 1/f noise fluctuations at low frequencies. In comparison, the stabilization technique modulates the signal transposing to a higher frequency with no 1/f noise and then demodulates it back (lock-in amplifiers). However, the flexible tuned device, which can work precisely at low frequencies, is especially desirable in some applications, e.g., optical spectroscopy or interferometry. The paper describes a proof-of-concept of an IR detection module with an adjustable digital filter taking advantage of finite impulse response type. It is based on the high-resolution analog-to-digital converter, field-programmable gate array, and digital-to-analog converter. A microcontroller with an implemented user interface ensures control of such a prepared filtering path. The module is a separate component with the possibility of customization and can be used in experiments or applications in which the reduction of noises and unexpected interferences is needed.

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“…Although voltage-mode front-end preamplifiers for the QTF have been proposed in the literature [10][11][12][13], the most common circuit configuration for interfacing the QTF is still the classic transimpedance preamplifier (TIA), schematically represented in Figure 3 [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Gain–Bandwidth of the Front-End Amplifier on the Performance of a QEPAS Sensor

Lombardi,

Matarrese,

Marzocca

2024

Acoustics

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The quartz tuning fork used as an acoustic sensor in quartz-enhanced photo-acoustic spectroscopy gas detection systems is usually read out by means of a transimpedance preamplifier based on a low-noise operational amplifier closed in a feedback loop. The gain–bandwidth product of the operational amplifier used in the circuit is a key parameter which must be properly chosen to guarantee that the circuit works as expected. Here, we demonstrate that if the value of this parameter is not sufficiently large, the response of the preamplifier exhibits a peak at a frequency which does not coincide with the series resonant frequency of the quartz tuning fork. If this peak frequency is selected for modulating the laser bias current and is also used as the reference frequency of the lock-in amplifier, a penalty results in terms of signal-to-noise ratio at the output of the QEPAS sensor. This worsens the performance of the gas sensing system in terms of ultimate detection limits. We show that this happens when the front-end preamplifier of the quartz tuning fork is based on some amplifier models that are typically used for such application, both when the integration time of the lock-in amplifier filter is long, to boost noise rejection, and when it is short, in order to comply with a relevant measurement rate.

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SNR Improvement of QEPAS System by Preamplifier Circuit Optimization and Frequency Locked Technique

Cited by 7 publications

References 11 publications

Multi-Component and Multi-Point Trace Gas Sensing in Wavelength Modulation Spectroscopy Based on Wavelength Stabilization

Multi-Component and Multi-Point Trace Gas Sensing in Wavelength Modulation Spectroscopy Based on Wavelength Stabilization

IR detection module with integrated real-time FIR filter implemented in FPGA

Influence of the Gain–Bandwidth of the Front-End Amplifier on the Performance of a QEPAS Sensor

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