NASA Team Investigates Ultrafast Laser Machining For Multiple Spaceflight Applications
A Goddard team is using an ultrafast laser to bond
dissimilar materials, with the goal of ultimately eliminating epoxies that
outgas and contaminate sensitive spacecraft components. Shown here are a few
samples (from left to right): silica welded to copper; silica welded to Invar;
and sapphire welded to Invar.
An ultrafast laser that fires pulses of light just 100
millionths of a nanosecond in duration could potentially revolutionize the way
that NASA technicians manufacture and ultimately assemble instrument components
made of dissimilar materials.
A team of optical physicists at NASA's Goddard Space Flight
Center in Greenbelt, Maryland, is experimenting with a femtosecond laser and
has already shown that it can effectively weld glass to copper, glass to glass,
and drill hair-sized pinholes in different materials.
Now the group, led by optical physicist Robert Lafon, is
expanding its research into more exotic glass, such as sapphire and Zerodur,
and metals, such as titanium, Invar, Kovar, and aluminum — materials often used
in spaceflight instruments. The goal is to weld larger pieces of these
materials and show that the laser technology is effective at adhering windows
onto laser housings and optics to metal mounts, among other applications.
With support from the Space Technology Mission Directorate's
Center Innovation Fund program, the group is also exploring the technology's
use in fabricating and packaging photonic integrated circuits, an emerging
technology that could benefit everything from communications and data centers
to optical sensors. Though they are similar to electronic integrated circuits,
photonic integrated circuits are fabricated on a mixture of materials,
including silica and silicon, and use visible or infrared light, instead of
electrons, to transfer information.
“This started as pure research, but now we hope to start
applying what we have learned to the fabrication of instruments here at
Goddard,” Lafon said, referring to the work he and his team, including Frankie
Micalizzi and Steve Li, are using to experiment with different materials and
techniques that could benefit spaceflight applications. “We already see what
the applications could be. In this case, research for research's sake is in our
best interests,” Lafon said.
The Technology's Virtues
Steve Li (left), Frankie Micalizzi (middle), and Robert
Lafon (right) are using an ultrafast laser to bond dissimilar materials and
etch microscopic channels or waveguides through which light could travel in
photonic integrated circuits and laser transmitters. (Photo Credit: Bill
Hrybyk/NASA) Credits: NASA/W. Hrybyk
Central to advancing these applications is the laser itself.
By virtue of its short pulses — measured at one quadrillionth of a second — an
ultrafast laser interacts with materials in a unique way, Lafon said. The laser
energy doesn't melt the targeted material. It vaporizes it without heating the
As a result, technicians can precisely target the laser and
bond dissimilar materials that otherwise couldn't be attached without epoxies.
“It's not possible to bond glass to metal directly,” Lafon said. “You have to
use epoxy, which outgases and deposits contaminants on mirrors and other
sensitive instrument components. This could be a serious application. We want
to get rid of epoxies. We have already begun reaching out to other groups and
missions to see how these new capabilities might benefit their projects.”
Another important application is in the area of
micromachining. “The ability to remove small volumes of material without
damaging the surrounding matter allows us to machine microscopic features,”
Microscopic features include everything from drilled,
hair-sized pinholes in metals — an application the team already demonstrated —
to etching microscopic channels or waveguides through which light could travel
in photonic integrated circuits and laser transmitters. The same waveguides
could allow liquids to flow through microfluidic devices and chips needed for
chemical analyses and instrument cooling.
Widespread Applicability to NASA Projects
“Ultrafast lasers offer fundamental changes in how we can
microprocess materials,” said Ted Swanson, senior technologist for strategic
integration at Goddard. “The team's work on this research effort will allow
Goddard to adapt this emerging technology to a wide variety of flight
To that end, the team — between working on several of NASA's
high-profile laser communications projects, including the Laser Communications
Relay Demonstration — plans to compile a library of micromachining and welding
capabilities. “Once we are able to demonstrate this capability reliably, we
will attempt to apply it to existing challenges here at Goddard. Our initial
research is showing that this technology could be applied to a large number of
projects across NASA,” Lafon said.