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Arnold F. Theisen

Publications and source records attributed to Arnold F. Theisen.

8 recordsLinked to original sources
USGS1981

Digital processing techniques for small digital arrays (FLD data set)

The purpose of the Workshop on Luminescence Techniques was threefold: (1) to review the state-of-the-art capabilities of luminescence methods, (2) to consider a variety of concepts for the development of future luminescence sensor systems, and (3) to discuss appropriate research and development strategies for advancing the current state-of-the-art.

Conference Paper↗
USGS1980

Plant stress detection by remote measurement of fluorescence

Chlorophyll fluorescence of mature lemon trees was measured with a Fraunhofer line discriminator (FLD). An increase in fluorescence was correlated with plant water stress as measured by stomatal resistance and twig water potential.

Applied Optics↗
USGS1980

Airborne Fraunhofer line discriminator (FLD) luminescence imaging systems and its application to exploration problems

Experiments with an imaging airborne Fraunhofer line discriminator (FLD) are being conducted to establish the feasibility of delineating the areal extent of luminescent materials on the earth's surface from aircraft and spacecraft. All luminescence measurements are related to a standard set of conditions with rhodamine wt dye used as a reference standard. The FLD has a minimum detectable rhodamine wt concentration of 0.1 parts per billion (ppb) at a signal-to-noise ratio of 5.0. Luminescence, when expressed in a signal-to-noise ratio (R) is related to equivalent ppb rhodamine wt through the relationship ppb=(0.1R-0.4). Luminescent materials imaged from an aircraft altitude of approximately 2400 m above terrain include fluorite in association with molybdenum, Pinenut Mountains, Nevada (R=62.0); mineralized playas, Claunch, New Mexico (R=960.0); uranium and vanadium-bearing outcrops, Big Indian Valley, Utah (R=105.0); uranophane sandstones, Sandia Mountains, New Mexico (R=60.0); phosphate outcrops, Pine Mountain, California (R=76.0); and marine oil slicks, Santa Barbara Channel, California (R=24.0). Correlation between the amount of fluorite in the rocks and soils of the Pinenut Mountains and luminescence, measured by the FLD, is as high as 0.88 at the 95 percent confidence level.

Sixth Annual Pecora Symposium and Exposition↗
USGS1977

Luminescence properties of selected radioactive rocks and minerals

This study is a continuation of the work reported in "Use of an Airborne Fraunhofer Line Discriminator (FLD) for the detection of solar stimulated luminescence", U.S. Geological Survey open file report 76-202, January 1976, in which luminescence data were obtained on a variety of natural materials, both in the laboratory and in the field. The objectives of this study are to update the catalogue of natural material to include radioactive rocks and minerals and to determine 1) if significant luminescence exists which may be used for detection and/or identification purposes in remote sensing applications and 2) optimum wavelength(s) for the detection of a particular rock/mineral type. Measurements were made on 8 different types of materials both in the laboratory, using a laboratory Fluorescence Spectrometer and outdoors, using the Fraunhofer Line Discriminator.

Open-File Report↗