Newport’s Delay Line Linear Stages offer high performance at a very affordable price. Linear motor driven stages
with an integrated motion controller and optimized for repeatable positioning and fast traverse speeds, make the
DLS Linear Stage the ideal solution in your lab for spectroscopy applications that require delay lines.
For more information about our Newport
Brand visit www.newport.com or
nerves, resulting in severe pain and facial
deformity. “Due to limited imaging capabilities combined with rough cutting and
nonspecific cautery tools, a conventional
surgical approach to acoustic neuroma
can result in a damaged nerve and a distorted facial appearance,” Milner says.
For several critical reasons, Milner’s
team has identified a Q-switched Tm3+
laser as an ideal tool in this application. First, efficient absorption of the
laser wavelength by soft tissues (which
are full of water) leads to highly localized
ablation at high removal rates, together
with minimized peripheral tissue damage.
This is further enhanced by using short
Q-switched pulses with high peak power.
In addition, the near-IR wavelength can
be fiber-delivered, enabling use at inaccessible body locations as well as supporting
many laparoscopic surgical applications.
The Milner team and Coherent
(formerly Nufern) engineers worked
together to define target laser parameters
for this application. “While it is chal-
lenging to efficiently obtain stable, high-
power output from thulium-doped fiber
lasers, we achieved success through opti-
mized Tm3+ doping in the fiber, resonant
pumping at 793 nm, the use of fiber with
a pedestal cross-section, optimization of
the oscillator fiber length, and optimized
splice recipes,” says Coherent compo-
nents and defense sales manager Jeff
Wojtkiewicz. “This resulted in a laser with
a 120 ns pulse width, > 15 W average
power, and > 4 k W peak power—param-
eters believed to be a good match for
these types of microsurgery applications.”
Milner’s group used this custom
laser to investigate precision ablation
of tissue phantoms made with 70%
water and 30% gelatin mix. Specifi-
cally, the tissue phantoms contained
500-µm-diameter cylindrical polymer
conduits embedded into the gel to
mimic blood vessels in tissues. Prelim-
inary results showed that they could
indeed ablate the gel without damage
to these conduits, solving the non-
laser surgical problem wherein bleeding
impairs tissue visibility during surgery.
Another common surgical application
of cutting close to, but sparing, sensi-
tive tissue structures (such as nerves) was
also explored. For this study, a vessel was
embedded deeper in the tissue phantom.
Again, the laser was able to cut pre-
cisely and cleanly close to the vessel with
minimal thermal damage.
“The applications for fiber lasers are still
growing rapidly,” Wojtkiewicz says. “We
believe that our ability to develop custom
gain and passive fibers at new wavelengths should broaden this market even
further, and enable many other medical,
industrial, and scientific applications in
the future.”—Gail Overton
1. P. Ahmadi et al., “1940 nm all-fiber Q
-switched fiber laser,” Proc. SPIE, 10083, 100830G
(Feb. 22, 2017).