A Tandem Spectrometer to Detect Laser-Excited Raman Radiation

Landon, D. O.; Porto, S. P. S.

doi:10.1364/ao.4.000762

Cited by 45 publications

(6 citation statements)

References 2 publications

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“…Landon and Porto [1965] report the stray light rejection ratio for a double spectrograph with a narrow exit slit to be of the order of 10 -8, this value is expected to be much larger for systems with a diode array. The system used in this study has a measured spectrograph scattered light contribution with a 25 mm long diode array of =10 -5.…”

Section: Spectrograph and Detectormentioning

confidence: 95%

“…The double spectrometer configuration provides a large reduction in the ratio of scattered light to the main signal within the spectrograph; this is important because it tends to "fill in" the absorption features, thereby generating a systematic error in absorption measurements. Landon and Porto [1965] report the stray light rejection ratio for a double spectrograph with a narrow exit slit to be of the order of 10 -8, this value is expected to be much larger for systems with a diode array. The system used in this study has a measured spectrograph scattered light contribution with a 25 mm long diode array of =10 -5.…”

Section: Spectrograph and Detectormentioning

confidence: 95%

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Measurement of tropospheric trace gases by long‐path differential absorption spectroscopy during the 1993 OH Photochemistry Experiment

Harder¹,

Jakoubek²,

Mount³

1997

J. Geophys. Res.

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Abstract. In August and September 1993 a comparative study of tropospheric long-path absorption techniques with in situ methods was performed for both the hydroxyl radical and the other important trace species. Long-path measurements were made over the 10.3 km path between Fritz Peak Observatory and Caribou Mine in the mountains 17 km west of Boulder, Colorado. At Caribou Mine, a 121 element, 1 m2 retroreflector array folds the optical path to give a total path of 20.6 km. The in situ instruments were located at Idaho Hill 0.5 km northwest of Caribou Mine. The optical design and analysis techniques used to obtain the pathintegrated concentrations of 03, CH20, SO2, and NO2 will be presented. The spectrograph used in this study is a 1/4 rn double, crossed Czerny-Turner that employs a diode array detector allowing the acquisition of 40 nm spectral bands in the near UV and visible spectral regions. This system also utilizes automatic alignment and self-adjusting time integration so the system will acquire data in an unattended mode. The spectral bands selected for this study permit the simultaneous measurement of 03, NO2, CH20, and SO2; NO2 and H20; and NO3 and H20. The data analysis uses a nonlinear least squares regression procedure to deduce the concentration of each of the species present in the atmosphere and also provides an effective method for removing the influence of scattered solar light for daytime measurements. An estimate of the measurement precision can be found by comparing atmospheric spectra analyzed with two different I o spectra; one measured through the atmosphere and the other a direct arc lamp spectrum.

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Section: Spectrograph and Detectormentioning

confidence: 95%

Section: Spectrograph and Detectormentioning

confidence: 95%

Measurement of tropospheric trace gases by long‐path differential absorption spectroscopy during the 1993 OH Photochemistry Experiment

Harder¹,

Jakoubek²,

Mount³

1997

J. Geophys. Res.

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“…17 On the other hand, sharp spectral filters can be used to suppress elastic scattered laser light since the Raman peaks are spectrally shifted from the fundamental laser wavelength. In case of performing Raman scattering in harsh conditions, it might be necessary to suppress the scattering even further by using tandem spectrographs 75 or by employing spatial tagging of the laser light at the spectrometer slit, allowing frequency analysis to remove strong laser-light components that are scattered in the spectrometer. 76 Further, the polarization properties of the Raman signal are different from long-lived LIF interferences (which essentially are depolarized).…”

Section: Spontaneous Molecular Scattering Techniquesmentioning

confidence: 99%

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering

Ehn

Zhu

et al. 2017

Appl Spectrosc

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Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

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“…The construction of the Raman spectrometer was the same as that of Landon and Porto [21]. The output of a He-Ne laser (Spectra Physics Model 125), after passing through an interference filter, was focused on the sample with a microscope objective.…”

Section: Experimental Arrangementmentioning

confidence: 99%