18 research outputs found
Optical Frequency Comb Fourier Transform Spectroscopy of NO at 7.8 {\mu}m
We use a Fourier transform spectrometer based on a compact mid-infrared
difference frequency generation comb source to perform broadband
high-resolution measurements of nitrous oxide, NO, and
retrieve line center frequencies of the fundamental band and the
+ - hot band. The spectrum spans 90 cm
around 1285 cm with a sample point spacing of 3 10
cm (9 MHz). We report line positions of 67 lines in the
fundamental band between P(37) and R(39), and 78 lines in the +
- hot band (split into two components with e/f rotationless
parity) between P(34) and R(33), with uncertainties in the range of 90-600 kHz.
We derive upper state constants of both bands from a fit of the effective
ro-vibrational Hamiltonian to the line center positions. For the fundamental
band, we observe excellent agreement in the retrieved line positions and upper
state constants with those reported in a recent study by AlSaif et al. using a
comb-referenced quantum cascade laser [J Quant Spectrosc Radiat Transf,
2018;211:172-178]. We determine the origin of the hot band with precision one
order of magnitude better than previous work based on FTIR measurements by Toth
[http://mark4sun.jpl.nasa.gov/n2o.html], which is the source of the HITRAN2016
data for these bands
Spectroscopie de temps de déclin en cavité par peigne de fréquences optiques
National audienceNous présentons les résultats préliminaires de spectroscopie de temps de déclin large bande, obtenus avec un dispositif reposant sur un peigne de fréquences optiques dans le proche infrarouge coupléà une cavité dont la transmission est analysée avec un spectromètreà transformée de Fourier résolu en temps
Optical frequency comb cavity ring-down spectroscopy using a time-resolved Fourier transform spectrometer
International audienc
Cavity ring-down Fourier transform spectroscopy based on a near infrared optical frequency comb
International audienc
Technique to Investigate Pulverizing and Abrasive Performance of Coals in Mineral Processing Systems
The operating costs of breaking coal particles into fine powder, to achieve optimum combustion for the boilers in a power plant, are made up of power input to carry on an energy intensive comminution mechanism and to overcome friction losses within pulverising machines. The operating costs also include the cost of the replacement of the processing system’s components due to wear. This study presents the development and application of an attrition test machine that enables an investigation of the factors that influence pulverizing efficiency. The attrition tester simulates grinding conditions in real vertical spindle mills. In this kind of mill, as with the tester, the size reduction process results from a shearing action during the redistribution of the coal particles. The redistribution and attrition within the coal bed are forced by movement of the rollers (or by a disc rotation, in the case of the tester). The testing method was oriented toward mechanical properties, i.e., internal friction shear strength, abrasiveness and grindability. This method enables facilitated testing procedures and a more exact simulation of grinding in vertical spindle coal mills. Ball-race mills and Loesche roller mills were used
Demonstration of supercontinuum and frequency shifted solitons pumped at 1.56 µm as seed sources for Tm-doped fiber amplifiers
Demonstration of supercontinuum and frequency shifted solitons pumped at 1.56 µm as seed sources for Tm-doped fiber amplifiers
Robust, fast and sensitive near-infrared continuous-filtering Vernier spectrometer
We present a new design of a robust cavity-enhanced frequency comb-based spectrometer operating under the continuous-filtering Vernier principle. The spectrometer is based on a compact femtosecond Er-doped fiber laser, a medium finesse cavity, a diffraction grating, a custom-made moving aperture, and two photodetectors. The new design removes the requirement for high-bandwidth active stabilization present in the previous implementations of the technique, and allows scan rates up to 100 Hz. We demonstrate the spectrometer performance over a wide spectral range by detecting CO2 around 1575 nm (1.7 THz bandwidth and 6 GHz resolution) and CH4 around 1650 nm (2.7 THz bandwidth and 13 GHz resolution). We achieve absorption sensitivity of 5 × 10−9 cm-1 Hz-1/2 at 1575 nm, and 1 × 10−7 cm-1 Hz-1/2 cm-1 at 1650 nm. We discuss the influence of the scanning speed above the adiabatic limit on the amplitude of the absorption signal