共查询到20条相似文献,搜索用时 31 毫秒
1.
Tingdong Cai Guangzhen Gao Xiaoming Gao Weidong Chen Gang Liu 《Molecular physics》2013,111(5):539-545
Spectral measurements of two line pairs of CO2 and CO in the temperature range 300–1000 K at 1.573 µm were performed using a fiber-coupled distributed feedback (DFB) diode laser. The two line pairs can be used in a tunable diode laser (TDL) absorption sensor for simultaneously detecting CO2 and CO gas in a single scan of the diode laser. The spectral parameters (line strengths, air-broadening coefficients and the temperature exponent n) of the two pairs are presented. The measured data agree well with existing databases (HITRAN 2004 and HITRAN 2008), the discrepancies being less than 5% for most of the probed transitions. Although the HITRAN database is a useful tool for sensor design, we found that laboratory measurements of the spectroscopic data for the line pair selected for high-temperature sensors are necessary for establishing the uncertainty for accurate measurements. 相似文献
2.
A sensor using a single DFB diode laser at 1.4 μm based on wavelength modulation spectroscopy for the measurements of the gas temperature and the H2O concentration in combustion gases is developed. A line pair of H2O absorption transitions located at 7085.251 and 7085.876 cm?1 is selected based on some design rules. The 1f normalized 2f method is used to remove the need for the calibration and to correct for the transmission variation due to beam steering, mechanical misalignments, soot, and window fouling. The precision for the temperature and H2O concentration measurements are 1.05 and 2.10% in a controlled static cell, respectively. Burner experiments demonstrate the ability of the system for in situ measurements. 相似文献
3.
A fiber-optic instrument for temperature measurement is presented. The sensing element consists of an optical dielectric multilayer system acting as a micro-interferometer which is deposited on a single-mode fiber tip. The sensitivity of the implemented system is theoretically derived and experimentally determined by a calibration measurement. The small size of the probe makes the system well-suited, for instance, for endoscopic in vitro and in vivo measurements in medical applications, especially in small samples. The sensor is used for the investigation of the transient thermal behavior of vitreous during Er:YAG laser irradiation in order to study the local thermal effects that are important to minimize the potential for unintentional injury in laser vitrectomy and laser vitreoretinal surgery. 相似文献
4.
We have developed a specially designed sensor with its associated instrumentation using a so called acoustical near-field technique based on small resonating horns. Contrary to the conventional measuring devices used in the rheology industry, this sensor enables wide-range and continuous viscosity measurements, including liquid to solid material transition. The sensor is composed of a small piezoelectric element which enables the horn to resonate. Shear waves are generated by means of the thinner part of the sensor (dipped into the material) confining the acoustic field to the tip to ensure local measurements. The frequency is scanned across the resonating frequencies in order to perform these measurements with the maximum of speed and efficiency. The shear moduli G' and G' of the material is deduced from the electrical impedance measurement at the resonance frequencies. In case of rapidly changing materials, such as quick setting cements or polyesters, we have developed a specific fast instrumentation based on the impulse response of the sensor, which realizes very fast measurements, typically 30 measurements per second. Modelization and experiments are reported. 相似文献
5.
A methane sensor based on quartz-enhanced photoacoustic spectroscopy was developed. An antimonide quantum-well diode laser
was used as an excitation source. The GaInAsSb/AlGaAsSb laser was fabricated by molecular beam epitaxy on GaSb substrate.
This diode laser emits in the 2.35 μm range at room temperature in the continuous wave regime. A spectrophone constituted
of a quartz tuning fork and two steel microresonators was used. The analysis of the sensor response with one, two or without
microresonators is presented. Second derivative wavelength modulation detection was used to perform low concentrations measurements,
thus we obtained a CH4 detection limit of 1 ppmv. 相似文献
6.
The self-mixing sensor based on Er3+–Yb3+ co-doped Distributed Bragg reflector fiber laser (EYDBR) has been demonstrated for detecting the effect of external objects scattering property on self-mixing signal. Results show that self-mixing interference inside fiber laser with short cavity length especially EYDBR fiber laser can keep high SNR with different types of scattering surfaces even the white print paper. Meanwhile, we have obtained a high and stable SNR at least 29.9 dB in measurements at incident angles smaller than 20°. In this way, the sensing system we demonstrate is suitable for vibration and displacement measurements, particularly for high-precision industrial measurements. 相似文献
7.
A new sensor has been developed for measuring atomic mercury using absorption spectroscopy with 254-nm radiation generated
from two sum-frequency-mixed diode lasers. Beams from a 375-nm external-cavity diode laser and a 784-nm distributed feedback
diode laser are mixed in a beta-barium-borate crystal to generate approximately 4 nW of ultraviolet radiation. The development
of the sensor is described along with extensive characterization experiments in a mercury vapor cell in the laboratory. An
accuracy of ±6% in the absolute concentration of atomic mercury has been demonstrated by comparison with equilibrium vapor
pressure calculations. The detection limit is approximately 0.1 parts per billion of atomic mercury in a meter path length
for 300-K gas and a 10-s integration time. The insensitivity of the sensor to broadband attenuation is demonstrated. Measurements
of collision-broadening coefficients for air, N2, Ar, and CO2 are reported, and implementation of wavelength-modulation spectroscopy with the sensor is demonstrated. Finally, results
are presented from measurements with the sensor in situ in the exhaust stream of an actual coal-fired combustor.
PACS 07.07.Df; 42.62.Fi; 42.65.Ky; 42.72.Bj 相似文献
8.
9.
Mid-infrared laser absorption sensors based on quantum cascade laser (QCL) technology offer the potential for high-sensitivity, selective, and high-speed measurements of temperature and concentration for species of interest in high-temperature environments, such as those found in combustion devices. A new mid-infrared QCL absorption sensor for carbon monoxide and temperature measurements has been developed near the intensity peak of the CO fundamental band at 4.6 μm, providing orders-of-magnitude greater sensitivity than the overtone bands accessible with telecommunications lasers. The sensor is capable of probing the R(9), R(10), R(17), and R(18) transitions of the CO fundamental ro-vibrational band which are located at frequencies where H2O and CO2 spectral interference is minimal. Temperature measurements are made via scanned-wavelength two-line ratio techniques using either the R(9) and R(17) or the R(10) and R(18) line pairs. The high-speed (1–2 kHz) scanned-wavelength sensor is demonstrated in room-temperature gas cell measurements of CO and, to demonstrate the potential of the sensor for high-temperature thermometry, in shock-heated gases containing CO for a very wide range of temperature (950–3500 K) near 1 atm. To our knowledge, these measurements represent the first use of QCL-based absorption sensor for thermometry at elevated combustion-like temperatures. The high-temperature measurements of CO mole fraction and temperature agree with the post-reflected-shock conditions within ±1.5% and ±1.2% (1σ deviation), respectively. 相似文献
10.
We establish a single diode laser sensor system to obtain temperature and water concentration in CH4/air premixed flame.Line-of-sight properties are analyzed,but line-of-sight results are not path average values for temperature measurements.The measurements are performed on a flat burner based on scannedwavelength direct absorption spectroscopy using two adjacent water lines at 7153.75 and 7154.35 cm 1.Real-time results are acquired using a data acquisition card with a Labview data processing program.The standard uncertainties of the temperature and water concentration measurements are 2.3% and 5.1%,respectively. 相似文献
11.
提出一种由157 nm激光制造的新型微型光纤法布里-珀罗折射率传感器的制作方法,传感头由靠近单模光纤端的具有光纤顶端微通道的法布里-珀罗空气腔组成,将单模光纤顶端的微通道作为检测介质的入口.分别在珐珀腔的反射界面镀以薄膜作为反射镜面来确保高的光对比度.试验中获得了1 130.887 nm/refractive-index的分辨率.和其他的光纤传感器相比,这种传感器具有体积小,结构坚固,高分辨率,线性良好,测量范围宽等优点,能够满足实际应用的要求,特别是对需要小型传感器的场合. 相似文献
12.
This paper describes a technique in which a laser light vibration sensor based on a Michelson interferometer is used. With a 5 mW laser the instrument will make measurements on a moving target at ranges greater than 200 m without using retro-reflective materials. Careful optimization of the electro-optic design reduces the effects of environmental disturbances and allows vibration amplitude resolution of 0·2 μm with a flat response in the bandwidth 0·1–150 Hz. Field tests and actual measurements of the radial and tangential displacements of an arch dam are shown. 相似文献
13.
M. Köhring S. Huang M. Jahjah W. Jiang W. Ren U. Willer C. Caneba L. Yang D. Nagrath W. Schade F. K. Tittel 《Applied physics. B, Lasers and optics》2014,117(1):445-451
The development of a sensitive sensor for detecting nitric oxide (NO) emissions from biological samples is reported. The sensor is based on tunable diode laser absorption spectroscopy (TDLAS) using a continuous wave, thermoelectrically cooled quantum cascade laser (QCL) and a 100-m astigmatic Herriot cell. A 2f-wavelength modulation spectroscopy technique was used to obtain QCL-based TDLAS NO emission measurements with an optimum signal-to-noise ratio. An absorption line at 1,900.076 cm?1 was targeted to measure NO with a minimum detection limit of 124 ppt. Positive control measurements with the NO donor DETA NONOate were performed to determine and optimize the sensor performance for measurements of biological samples. Our measurements with NO donor show the potential suitability of the sensor for monitoring NO emission from cancer cells for biological investigations. 相似文献
14.
A four-wavelength near-infrared (NIR) tunable diode laser sensor has been developed for the simultaneous measurement of liquid
water film thickness, liquid-phase temperature and vapor-phase temperature above the film. This work is an important improvement
of a three-wavelength concept previously introduced by Yang et al. (Appl. Phys. B 99:385, 2010), which measured the film thickness in environments with known temperature only. In the new sensor, an optimized combination
of four wavelengths is chosen based on a sensitivity analysis with regard to the temperature dependence of the liquid water
absorption cross section around 1.4 μm. The temperature of liquid water and the film thickness are calculated from absorbance
ratios taken at three wavelength positions assessing the broad-band spectral signature of liquid water. The vapor-phase temperature
is determined from the absorbance ratio of two lasers rapidly tuned across two narrow-band gas-phase water absorption transitions.
The performance of the sensor was demonstrated in a calibration cell providing liquid layers of variable thickness and temperature
with uncertainties smaller than 5% for thickness measurements and 1.5% for liquid-phase temperatures, respectively. Experiments
are also presented for time-resolved thickness and temperature measurements of evaporating water films on a quartz plate. 相似文献
15.
Johannes K. Schaller Christo G. Stojanoff 《Particle & Particle Systems Characterization》1996,13(3):196-204
A Diesel spray injected into a high-pressure test chamber was investigated with two different holographic techniques. The usual off-axis recording geometry was used to investigate the very early beginning of the injection. Double pulsing of the recording laser facilitated velocity measurements. By using two different reference angles for the two recording the two images can be separated upon reconstruction of the holograms. Thus superior image quality could be achieved. Processes leading to jet formation could be identified: the spray tip is periodically axially decelerated and radially accelerated. Consequently, liquid moves at the tip off axis. The spray consists of fast central region surrounded by a slower outer jet region. The outer jet region exhibits periodic droplet concentration fluctuations which are interpreted as a result of the periodic processes at the spray tip. Some high concentration regions in the outer jet region were investigated using a dark-field holographic technique. This technique permits single droplet velocity measurements and local droplet concentration determination at extremely high droplet concentrations. The most important result of these investigations is that no correlation between the local droplet concentration and the droplet velocity could be found. 相似文献
16.
A novel fiber-optic curvature sensor, which can measure curvature directly, has been developed in recent years. The electric current measurements system based on fiber-optic curvature sensor and electromagnetic principle is developed. A fiber-optic curvature sensor is bonded to a thin-walled cantilever and two circular magnet targets with the same parameters are configured at the tip of the cantilever symmetrically. In this case, the throughput of the sensor will be changed due to the bending deformation of cantilever, which is proportional to the electromagnetic force caused by measured electric current. Direct and alternate characteristics of the proposed measurement system are studied experimentally. The results show that the measurement errors are within the range of ±5.5 mA and the corresponding accuracy is within 1% at the current measurement range from −300 mA to 300 mA, which indicate the feasibility of the proposed measurement system. 相似文献
17.
A simple fiber tip sensor for refractive index(RI) measurement based on Fabry-Perot(FP) interference modulated by Fresnel reflection is proposed and demonstrated.The sensor head consists of an etchinginduced micro air gap near the tip of a single-mode fiber.The microgap and the fiber tip function as two reflectors to form a FP cavity.The external RI can be unambiguously measured by monitoring the fringe contrast of the interference pattern from the reflection spectrum.The experimental results show that the proposed sensor achieves temperature-independent RI measurement with good linear response.The proposed sensor achieves a high RI resolution of up to 3.4×10 5 and has advantages of low cost and easy fabrication. 相似文献
18.
A study on fiber Bragg grating (FBG) strain sensor, based on erbium-doped fiber (EDF) laser, is presented. A strain-sensing element, FBG, also acts as the lasing wavelength selecting component. When strain is applied on the FBG, the laser cavity loss changes, leading to a modification of the laser transient. Strain measurements are obtained in the time domain by simply measuring the EDF laser build-up time. Relative variation in the build-up time of up to 190%, for a strain range from 0 με to 2350 με, is achieved with a resolution corresponding to a strain of better than 2.35 με. This study demonstrates a novel fiber sensor concept and the technical feasibility to develop fiber strain measurement. 相似文献
19.
We propose a novel Fabry-Perot optical fiber tip sensor for high temperature measurement. The sensor consists of a short section of a special all-silica photonic crystal fiber spliced at one end to a silica single-mode fiber. Because of its all-silica structure, the sensor allows linear and stable measurements of temperature up to 1200 °C with a high sensitivity. The sensor is easy and inexpensive to fabricate and could find wide applications in mechanics, aeronautics, and metallurgy. 相似文献
20.
M. Gentile M. Hentschel R. Taubert H. Guo H. Giessen M. Fiebig 《Applied physics. B, Lasers and optics》2011,102(1):149-162
The development of a laser absorption spectroscopy sensor system has been described for measurement of two-dimensional (2D)
integrated absorbance linear density and temperature distributions. The system incorporates a tunable distributed feedback
(DFB) diode laser at 1391.67 nm and a scanning mirror mounted on a moveable carriage, whilst a photodetector and a second
scanning mirror are mounted on another moveable carriage. Both carriages move independently along a circular rail with a diameter
of 97 cm. The positions of the carriages and the scanning mirrors are controlled by a program via four servomotors. The laser
wavelength is scanned over H2O absorption transitions for 11 fan beam projections from five equally spaced points around the circle. 2D images of the integrated
absorbance linear density due to water molecules influenced by two heaters were obtained using the algebraic reconstruction
technique (the Kaczmarz method). The derived temperature distribution compared well with thermocouple measurements. The experimental
results demonstrate that the system based upon a tunable laser absorption sensor can be used for monitoring the 2D distribution
of chemical species and temperature in various reactive flow applications. 相似文献