An overview of vis-nir-swir field spectroscopy - Spectral International

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The utilization of this range (350 to 2500nm) of the Electromagnetic Spectrum for
mineral exploration comes out of remote sensing needs as does the invention
and subsequent refinements of the field spectrometers, which have become the
prime vehicles for this methodology. Initial field units from the GER Mark series
(Geophysical Environmental Resources of Millbrook New York) to the ASD
classics and FieldSpec Pros were developed using solar illumination to
correspond to the satellite and airborne sensors for which they provided ground
truth or verification.
With the addition of an internal light source to eliminate the effects of
atmospheric water spectra, users quickly discovered that the portable
spectrometers had so many more applications then just ground truthing remotely
sensed data and the technology came into its own.
Although there are numerous companies offering instruments in the Visible and
short wave infrared for applications ranging from vegetation, water, forestry,
wood products, paint, carpets, wheat protein content, pharmaceuticals, forensics,
plastics, oil, among others, most are not portable to the field nor general enough
for geologic applications. GER was the company with the Mark series of field
spectrometers, who has always been more involved in the general remote
sensing side of the application rather then specifically targeting the mining
industry. Alex Goetz, at that time of Jet Propulsion Laboratory, Ron Lyon of
Stanford University, Larry Rowan of the U.S. Geological Survey, Robert Agar of
AGARS, Australia, Jon Huntington, CSIRO, Australia, Fred Kruse of AIG, Floyd
Sabins of Chevron, Jim Taranik of the University of Nevada-Reno, and the
present author, among hundreds of others, have all used this instrument for
mostly geologic, but some exploration and mining, applications. At issue has
always been the solar illumination and the corresponding atmospheric water
interference bands that mask out vital components and absorption features in the
mineral spectra. This interference made the application less attractive for
alteration characterization. Even 15 years ago, the solar illumination-based
technology was the best available.
With the introduction of the internal light source, the PIMA-II field spectrometer by
Integrated Spectronics of Sydney, Australia, in the early 1990s, the concept of
portability and field characterization of alteration took on a new perspective and
many new applications. Over 200 PIMAs, the majority of which are still
operational, were pioneering devices for developing new methods of alteration
mapping, core logging, drill well targeting, and field reconnaissance. Most of the
major mining companies worldwide adopted this new technology and utilized it
well for new discoveries and in-depth knowledge of their alteration systems.
In the late 1990s, ASD Inc. (formerly Analytical Spectral Devices, Inc.)
introduced their FieldSpec Pro. This instrument did have an internal light
source probe on it. It was upgraded in 2005 to the “FR3”, which had a refined
probe. Neither of these instruments were designed for the minerals industry, but
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