Remote Raman Microimaging Using an AOTF and a Spatially Coherent Microfiber Optical Probe

1996 ◽  
Vol 50 (8) ◽  
pp. 1007-1014 ◽  
Author(s):  
H. Trey Skinner ◽  
Thomas F. Cooney ◽  
S. K. Sharma ◽  
S. M. Angel
Keyword(s):  
High Power ◽  
Near Infrared ◽  
Fiber Optic ◽  
High Spatial Resolution ◽  
Optical Probe ◽  
Tunable Filter ◽  
Line Of Sight ◽  
Phase Boundaries ◽  
Optical Fiber Bundle ◽  
Clear Line

A fiber-optic Raman microimaging probe is described that is suitable for acquiring high-spatial-resolution Raman images in sampling situations with no clear line of sight. A high-power near-infrared diode laser combined with an acousto-optic tunable filter and a spatially coherent optical fiber bundle allow fluorescence-free Raman images of remotely located samples to be acquired at distances up to several meters. The feasibility of this technique is demonstrated with Raman images of (1) a pellet containing a mixture of a highly scattering sample, bis-methylstyrylbenzene (BMSB), KCl, and graphite, and (2) a partially graphitized diamond. These images clearly show phase boundaries over an area of approximately 0.1 mm2 with ∼4-μm resolution.

Dryer Effluent Monitoring in a Chemical Pilot Plant via Fiber-Optic Near-Infrared Spectroscopy

1998 ◽  
Vol 52 (5) ◽  
pp. 717-724 ◽  
Author(s):  
Charity Coffey ◽  
Alex Predoehl ◽  
Dwight S. Walker
Keyword(s):  
Real Time ◽  
Pilot Plant ◽  
Near Infrared ◽  
Fiber Optic ◽  
Tunable Filter ◽  
Calibration Model ◽  
Gas Cell ◽  
Rotary Dryer ◽  
Vapor Stream ◽  
Effluent Stream

The monitoring of the effluent of a rotary dryer has been developed and implemented. The vapor stream between the dryer and the vacuum is monitored in real time by a process fiber-optic coupled near-infrared (NIR) spectrometer. A partial least-squares (PLS) calibration model was developed on the basis of solvents typically used in a chemical pilot plant and uploaded to an acousto-optic tunable filter NIR (AOTF-NIR). The AOTF-NIR is well suited to process monitoring as it electrically scans a crystal and hence has no moving parts. The AOTF-NIR continuously fits the PLS model to the currently collected spectrum. The returned values can be used to follow the drying process and determine when the material can be unloaded from the dryer. The effluent stream was monitored by placing a gas cell in-line with the vapor stream. The gas cell is fiber-optic coupled to a NIR instrument located 20 m away. The results indicate that the percent vapor in the effluent stream can be monitored in real time and thus be used to determine when the product is free of solvent.

scholarly journals A Radiometric Technique for Monitoring the Desulfurization Process of Blister Copper

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 842
Author(s):  
Alejandro Vásquez ◽  
Francisco Pérez ◽  
Maximiliano Roa ◽  
Ignacio Sanhueza ◽  
Hugo Rojas ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Emissivity ◽  
Optical Probe ◽  
Blister Copper ◽  
Optical Absorption Spectroscopy ◽  
Total Irradiance ◽  
Desulfurization Process ◽  
Radiometric Technique ◽  
Collimating Lens ◽  
Total Emissivity

In this paper, a novel optical technique for following the progress of the blister copper desulfurization process is presented. The technique is based on the changes observed in the continuous spectrum of the visible–near-infrared (VIS–NIR) radiation that the blister melt emits while the chemical reactions of the sulfur elimination process are taking place. Specifically, the proposed technique uses an optical probe composed of an optical fiber, a collimating lens, and a quartz tube, which is immersed in the melt. This optical probe provides a field of view of the blowing zone where the desulfurization reaction occurs. The experimental results show that the melt VIS–NIR total irradiance evolves inversely to the SO2 concentration reported by a gas analyzer based on differential optical absorption spectroscopy. Furthermore, the blister copper spectral emissivity as well as the total emissivity observed throughout the process show strong correlation with the sulfur content during desulfurization reaction.

Multipoint Fiber-Optic Hot-Spot Sensing Network Integrated Into High Power Transformer for Continuous Monitoring

2008 ◽  
Vol 8 (7) ◽  
pp. 1264-1267 ◽  
Author(s):  
A. B. Lobo Ribeiro ◽  
N. F. Eira ◽  
J. M. Sousa ◽  
P. T. Guerreiro ◽  
J. R. Salcedo
Keyword(s):  
High Power ◽  
Continuous Monitoring ◽  
Fiber Optic ◽  
Power Transformer ◽  
Hot Spot

Effect of Sample Heterogeneity on near Infrared Meat Analysis: The Use of the RMS Statistic

1998 ◽  
Vol 6 (A) ◽  
pp. A313-A320 ◽  
Author(s):  
M.L. Martínez ◽  
Ana Garrido-Varo ◽  
E. De Pedro ◽  
L. Sánchez
Keyword(s):  
Near Infrared ◽  
Fiber Optic ◽  
Iberian Pig ◽  
Set Up ◽  
Sample Heterogeneity ◽  
Meat Analysis

Ground and emulsified samples from Iberian pig hams were analysed by reflectance and interactance reflectance mode. Spectral errors due to intra-sample variations were calculated for both analysis modes. The spectral errors were calculated by means of the STD RMS statistic included on the ISI software. The results obtained show that a mean STD RMS value as low as 4200, could be obtained for paired subsamples of the same sample and that an STD limit of 4374 could be fixed at the instrument set-up program in order to ensure that a representative spectrum has been obtained from two subsamples readings of the same sample. That procedure avoids the need to take numerous subsamples, as is traditional in NIR/NIT meat analysis. The results also show that the spectral repeatability using fiber optic is worse than for spinning cups and it has been concluded that effort should be made to avoid moisture variations during scanning in order to improve spectral repeatability.

High-power, continuous-wave, single-frequency, all-periodically-poled, near-infrared source

2012 ◽  
Vol 37 (24) ◽  
pp. 5049 ◽  
Author(s):  
Kavita Devi ◽  
S. Chaitanya Kumar ◽  
M. Ebrahim-Zadeh
Keyword(s):  
High Power ◽  
Near Infrared ◽  
Continuous Wave ◽  
Single Frequency ◽  
Periodically Poled ◽  
Infrared Source

Efficient miniature fiber-optic tunable filter based on intracore Bragg grating and electrically resistive coating

1998 ◽  
Vol 10 (3) ◽  
pp. 361-363 ◽  
Author(s):  
H.G. Limberger ◽  
Nguyen Hong Ky ◽  
D.M. Costantini ◽  
R.P. Salathe ◽  
C.A.P. Muller ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Tunable Filter ◽  
Bragg Grating ◽  
Resistive Coating
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