FUSION Issue 3-2026 DIGITAL - Flipbook - Page 34
COMPOSITES
Non-contact inspection is transforming
how composite parts are checked
LOOKING
INSIDE,
WITHOUT
TOUCHING
The hardest part of a composite part is the part you
cannot see. A new inspection method uses light and
sound, and nothing else, to find the flaws hidden inside.
A finished composite component can look flawless and still be
hiding a problem. The trapped void, the missed bond, the whisper
of a delamination deep between the plies: none of these announce
themselves on the surface. Finding them is the job of non-destructive
testing, the quiet discipline that checks a part is sound without cutting it
open to prove it.
For decades, the workhorse of that discipline has been ultrasound. It
works well, but it comes with a catch that anyone who has run it will
recognise. Traditional ultrasonic inspection needs the sound to travel
from the probe into the part, and sound does not cross an air gap easily.
So the part must be coated in gel, sprayed with water, or lowered into a
tank, so the ultrasound has something to travel through. That coupling
step slows everything down, complicates automation, and is simply not
an option for parts that must never get wet.
Light in, sound out
A technology now reaching the production floor removes the contact
entirely. Developed by the Austrian firm Xarion and shown at a major
2026 composites exhibition, it is called laser excited acoustics, and it
inspects a composite part without gel, without water, and without
anything ever touching the surface.
The principle is elegant. A pulse of laser light is aimed at the surface of
the part. Where it lands, it deposits a tiny burst of energy that makes the
material expand and contract for an instant, and that flicker generates an
ultrasonic wave inside the part, exactly the kind of wave a conventional
probe would have injected through gel. The light, in effect, becomes the
sound source. No coupling required, because nothing has to bridge the
gap but the beam itself.
Listening for the result is just as clever. Instead of a traditional transducer
pressed against the part, the system uses an optical microphone: a sensor
with no moving parts that detects the faint sound in the air using light.
33
“ The light becomes the sound source. Nothing
touches the part but a beam, and nothing
listens but a microphone made of light. ”
Because nothing mechanical has to vibrate, it responds cleanly across
an enormous range of frequencies, and it can sit to one side of the part
rather than on it. The whole inspection happens at arm's length.
Why it matters on a real production line
The appeal is not just technical neatness. As composite manufacturing
scales towards higher production rates, inspection has become one
of the bottlenecks. Every part that has to be gelled, scanned, cleaned,
and dried is a part moving slowly through the line, and every change of
part shape can mean reconfiguring the whole coupling setup. Speed of
inspection increasingly limits how fast parts can be made at all.
A method that needs no contact and no preparation changes that
equation. Mounted on a robot arm, it can scan a component fully
automatically from a single side, moving straight from one part geometry
to the next without the fuss of tanks and probes. For moisture-sensitive
parts, where water-based inspection was never allowed in the first place,
it opens a door that was previously shut.
Why catching it early matters
There is a bigger principle underneath the clever engineering. Every
defect this kind of technology catches is a failure prevented before it
reaches a customer, an aircraft, a hull, or a vehicle. The cost of finding a
flaw at the inspection stage is trivial compared with the cost of finding
it in service. Faster, cleaner, more automated inspection does not just
speed up production. It raises the odds that nothing slips through.
Composite manufacturing has spent years perfecting how parts are
made. Tools like this reflect a maturing industry turning the same
rigour on how parts are checked, because a part is only as good as
our confidence that it is sound. Being able to look inside without ever
touching the surface is a genuinely useful step towards that confidence.
