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Nanotechnology advances over the past
decade have enabled these laboratory
systems to be turned into powerful and
compact portable instruments. The first
truly self-contained handheld LIBS in-
strument was introduced in 2013. The
miniaturization of electronic compo-
nents as well as two key advances made
this possible: First, a laser source of a
practical size became powerful and sta-
ble enough for use in the smaller design
footprint; and second, a mobile power
source in the form of a nonexplosive
lithium iron phosphate (LiFeP) battery
was developed to provide enough
power to operate the laser and electron-
ics for up to 1000 analyses.
LIBS vs. XRF and OES
The primary objective of LIBS,
OES, and XRF instruments is to either
qualitatively or quantitatively analyze a
material. Portable versions of these in-
struments simplify the operation of
complex spectrometers into point-and-
shoot tools that can be used with mini-
mal training or understanding of the
instrument’s inner workings.
OES and LIBS share similarities on
the detection side as both are atomic
emission techniques. Where LIBS uses
a laser to create the plasma in which the
elements are excited, OES uses an arc
or spark between an electrode and the
sample. Because of this, OES requires a
conductive sample and is constrained to
metal analysis only. LIBS is considered a
virtually nondestructive technique be-
cause only one nanogram of material is
consumed during a typical measure-
ment. OES is considered destructive be-
cause it removes far more material
(approximately one microgram). Nev-
ertheless, within industrial sectors and
for many applications, the burn mark is
recognized as a quality seal and serves
as confirmation of sample analysis.
XRF uses a radiation source, either
an x-ray tube or radioactive isotope, to
excite atoms and a detector to interpret
the spectrum, typically at wavelengths
>1 nm. Because no material is con-
sumed during analysis, XRF is also con-
sidered nondestructive. Unlike the rela-
tively complex LIBS or OES spectrum,
which may contain dozens of character-
istic lines for each element present in
the sample, an XRF spectrum is rela-
tively simple, containing two to five
characteristic lines per element.
In all three techniques, a portion of
the electromagnetic spectrum is moni-
tored and the number of incidents at
each discrete wavelength is counted
over a period of time to determine the
amount of each element in the analyzed
sample. Where LIBS and OES require a
means to disperse the emitted light to
separate it into different wavelength
bands, XRF, more specifically energy-
dispersive XRF, does not require any ad-
ditional hardware between the sample
and detector.
The LIBS laser is very powerful,
but is focused to a microscopic point
on the sample and causes virtually no
sample heating around the test area.
Outside of the focal point, the laser is
virtually harmless, provided the beam
is not aimed directly into the retina
from a short distance. The laser will
not penetrate the human body and is
non-ionizing. Further, laser light is
considered noncarcinogenic.
Metal analysis
Thousands of portable metal ana-
lyzers are sold annually for a variety of
purposes including quality control at
production facilities, inspection of
petrochemical process equipment,
and rapid sorting at scrap recycling fa-
cilities. These analyzers are typically
based on either XRF or OES. XRF is
more common for alloy sorting and
materials identification purposes be-
cause it is self-contained, accurately
measures a wide range of elements,
and is easy to transport and operate.
XRF is safe, but because it uses a radi-
ation generating device—either an x-
ray tube or radioactive isotope
source—some regions require licens-
ing and certification to use it.
OES instruments can measure ele-
ments critical to the metal industry that