Optics: measuring and testing – For light transmission or absorption – Of fluent material
Patent
1995-04-18
1996-08-27
Rosenberger, Richard A.
Optics: measuring and testing
For light transmission or absorption
Of fluent material
G01N 2100
Patent
active
055506364
ABSTRACT:
The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable.
According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer's law.
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Reid et al "High Sensitivity Pollution Detection Employing Tunable Diode Lasers" Applied Optics vol. 17, No. 2 (15 Jan. 1978).
Paper, Lawrence Livermore National Laboratory, Joe Galkowski & Karla Hagans, "Laser Absorption Spectroscopy System for Vaporization Process Characterization and Control" Sep. 1993.
Paper, Lawrence Livermore National Laboratory, Karla Hagans & Joe Galkowski, "The Use of Laser Diodes for Control of Uranium Vaporization Rates" Sep. 1993.
Paper, Lawrence Livermore National Lboratory, Leon V. Bervins, "Using Laser Absorption Spectroscopy to Monitor Composition and Physical Properties of Metal Vapors" Sep. 1993.
Berzins Leon
Galkowski Joseph
Hagans Karla
Seng Rita
Daubenspeck William C.
Moser William R.
Rosenberger Richard A.
The United States of America as represented by the United States
Valdes Miguel A.
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