development and applications. On average, the Fraunhofer ILT files one patent each month. Its core expertise is in developing new laser radiation sources and components, laser measuring and testing technology as well as laser manufacturing. Overall, we are engaged in laser plant engineering, process control and regulation, model- ing as well as system engineer- ing. The services range from
feasibility studies to process qualification
to customer-tailored integration of laser
processes in a production line.
We maintain close contact with industrial partners. For example, we offer our
long-term partners the chance to locate in
our application center as guest companies
and to use our technical infrastructure.
There they can implement their ideas
in their own separate laboratories. Our
research emphasis is on the development
of radiation sources and creating new
applications. The following are some
recent examples of our work.
guided through drill holes with a
diameter of a human hair to the
rear side of the cell. It is necessary
to produce up to 100 drill holes in
less than a second.
To reach these goals, we rely
on the 400-W fs laser to process
the silicon cells. We have devel-
oped a contact-free procedure
that can drill more than 3,000
holes per second at a diameter of
40 µm in silicon cells. This pro-
cedure enables new cell designs
and, thus, higher efficiency. With new
optical systems and improved radiation
concepts, we are aiming to reach drill-
ing speeds of up to 10,000 drill holes
per second.
Researchers at the
Fraunhofer ILT have
now developed an ultra-short pulsed laser with
pulse durations of less
than a picosecond.
400 W femtosecond laser
developed by
the Fraunhofer
ILT for ultra-precise materials processing.
Fraunhofer ILT
The 400-W femtosecond laser
Femtosecond (fs) lasers are key to ultra-precise processing. Unlike longer nanosecond pulses or continuous wave lasers,
with fs lasers there is no direct interaction between the light and the dispersing material. This enables an extremely
precise amount of material to be ablated.
Up until now, however, the use of these
lasers has been limited by their relatively
low median output power. Researchers at
the Fraunhofer ILT have now developed
an ultra-short pulsed laser with pulse
durations of less than a picosecond.
These pulses—which are less than
a quadrillionth of a second—allow the
material to evaporate before it becomes
too warm and deforms. With a median
output of more than 400 W, this new
radiation source achieves an output
power eight times higher than commer-
cial femtosecond lasers. By simplifying
fs laser systems and the costs bound up
with them, we have created an essential
prerequisite to their extensive applica-
tion in the industrial environment. In
medical technology, electronics, solar
technology and the aerospace industry,
the innovative radiation source can
be used to ablate, drill and structure
surfaces. We are working on scaling the
laser to outputs greater than 1,000 W.
Higher efficiency in photovoltaics
In the middle of the next decade, the
cost of solar electricity will likely even
out with the price of conventionally produced electricity in Germany. In order for
this to happen, however, the production
costs of solar cells must fall, their efficiency must improve, and the throughput
rate production must increase. These are
the goals of the 6 million euro research
and development project called the Next
Generation Solar Cell and Module Laser
Processing Systems (SOLASYS) supported by the European Union. Led by the
Fraunhofer ILT, ten companies are working out the economic feasibility of laser
applications in the photovoltaic sector.
Currently lasers are only used sporadically to manufacture solar cells. Now,
researchers have shown that, using laser
drilling, SOLASYS can reduce production costs for silicon solar cells. In the
“metal-wrap-through” concept, the metallic contacts of the front side of the cell are
Guided cell growth
Our employees are very active in biotechnology and medical technology. Among
other things, we are working on possible applications for laser processes to
produce medical-technical products.
With brilliant fiber lasers, we join plastic
medical products such as catheters and
microfluidics under sterile conditions
without influencing their functionality.
In the field of surface functionalization,
our researchers have developed procedures to favor the guided development
of biological cells into tissue.
Networked knowledge
The Fraunhofer Society works closely
with international partners. Our institute
cooperates, for example, with the University of Michigan and the University
of Central Florida in the United States.
We are also represented by the Center
for Laser Technology CLP in Plymouth,
Michigan, U.S.A., and we are a member
of the Laser Institute of America. Since
1979, we have participated in the Coo-pération Laser Franco-Allemande in Paris
with leading French research facilities.
We hope that the Fraunhofer Society’s
innovative projects and applied focus
would make our namesake proud. t
Reinhart Poprawe ( poprawe@ilt.fraunhofer.de) is
the director of the Fraunhofer Institute for Laser
Technology and Chair of Laser Technology at the
RWTH Aachen University in Germany.
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