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 | |  |  |  | | From StarWars to fine art | | Laser physicist John Asmus won a Rolex Award in 1990 to support his pioneering work to restore one of the world’s cultural treasures. Since then his discoveries have created a new branch of science, inspired hundreds of scientists and helped return numerous masterpieces to their original glory. |
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In an extraordinary adventure of
modern science, an erstwhile
weapon of war is unveiling the
wellsprings of human creativity in
some of the world’s most venerated
and ancient works of art.
From the Mona Lisa and Parthenon
of Athens to the entombed warriors of
the Qin dynasty, the medieval glories
of Venice and Florence, the cathedrals
of Spain and Austria and the early
churches of Egypt and Romania, the
laser – once envisaged by governments
as a weapon – is performing
marvels of renewal, shedding its
unique light on aspects of the human
genius long lost.
A pioneer in the use of laser light
for cleaning and renovating works of
art, Dr John Asmus, of the University
of California, stumbled into the field
serendipitously in the 1970s, a time
when lasers were seen chiefly as
applying to medicine, defence and
industry. What unfolded was a remarkable
new branch of science, today
pursued by more than 500 researchers
and conservators worldwide in their
efforts to rescue history’s most celebrated
artworks and monuments.
“In 1971, with the first inklings of
sea level rise, there was concern about
Venice being drowned,” Dr Asmus
recalls. “I was asked to go to Italy and
use lasers to make holograms of the
city, so people could see what it had
once been like, when it was gone.” |
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While there he soon learned of
another problem: the grimy, acidic
encrustation of centuries was devouring
the city’s glorious statuary and
buildings.
Removing a black deposit from a
white marble object seemed to him
like a task tailor-made for lasers,
which could “cook” it off, leaving the
surface unharmed. It worked perfectly:
“We zapped the black stones with a
laser and white spots appeared immediately.
We’d rediscovered Nobel
laureate Arthur Schawlow’s famous
‘laser eraser’, which he developed to
correct typing errors,” Asmus recounts.
The black layer absorbs the massive
heat of the laser, causing it to vaporise,
while the cooler white beneath
reflects the heat and is left undamaged.
“It is a beautiful, self-limiting
process, so precise you can actually
do it with your eyes closed, by listening
to the sound of the laser.”
Since that day he has used it to pare
away the grime of centuries from
bronze, iron and stone, from oil
paintings and other treasures, though
nowadays computers control the oncemanual
operation with elegant precision.
In those early pioneering days,
however, the initial response was
scepticism. So implanted was the
notion of lasers as tools of destruction
– encouraged by their role in the US
Strategic Defense Initiative (“Star
Wars”) where they were intended to shoot down nuclear missiles – that
people found it hard to see them in
the delicate field of art restoration.
And leading curators of the day were
firmly attached to chemical methods.
“I published actively about the laser
technique – but the conservators
mostly laughed,” Asmus ruefully
recalls. “Although, unlike other methods,
lasers leave no chemical residues
to worry about in future.”
He confided his disappointment to
the University of California’s Jim
Arnold, one of the originators of radiocarbon
dating, who reassured him:
“When we discovered radiocarbon
dating, there was one big worldwide
yawn for about ten years. Then,
suddenly, everyone wanted it. Lasers
will have their day. Just wait.” |
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Professor Arnold was proved
right. The 1980s were a quiet
period for laser art restoration,
though Asmus’s techniques continued
to advance. The breakthrough came
in 1990, with an invitation from the
People’s Republic of China to help
restore the 2,200-year-old entombed
warriors of Emperor Qin Shi Huang.
About that time Asmus’s wife,
Barbara, noticed an advertisement for
the Rolex Awards for Enterprise and
encouraged him to apply. His selection
as a Laureate in 1990, and the
attendant publicity and funding,
helped loft laser art conservation into
the serious category.
In the Chinese city of Xian, Asmus
found himself working with Chinese
scientists who, like him, had spent
their careers investigating defence uses
for lasers but had lately turned them
to the peaceful goal of preserving
human heritage. The work was scientifically
demanding – not only was
there a tough deposit coating the
surface of the warriors from their
centuries in the soil, but it also masked the bold colours in which
they had originally been painted.
“Real-time computer processing was
just coming in, and I got hold of one
of the earliest systems to study the
spectra of materials being vaporised
by the laser off the surface of the
artwork, so I could determine its
composition,” he explains. The work
was vital. Asmus wanted the laser to
cut deep enough to remove the coating,
but not harm the colours beneath.
Detecting metal atoms from the paint
as the laser cut through, they could
control its depth perfectly.
Centuries of burial had oxidised the
warriors’ glowing colours to an
earthen tint. Asmus believed he could
use lasers to burn off the oxygen and
restore the pigments’ former brilliance.
Five different attempts failed, but then
Meg Abraham, a former student,
suggested enclosing the artwork in an
activated atmosphere of argon and
methane while applying the laser.
It worked – and the ancient colours
sprang back to vivid life.
By the mid-1990s the project seemed
poised to unveil an army of warriors
resplendent in their original uniforms,
but politics inhibited contact between the US and Chinese scientists. Progress
since then has been limited because
Asmus’s Chinese colleagues were
assigned to industrial laser projects
in other parts of China.
However, delays in the Terracotta
Warriors project did not deter Asmus,
who was soon advising the Greek
government on ways to regenerate the
hues that once adorned the work of
the 5th-century BC sculptor Pheidias
on the Athenian Parthenon. This has
proved the greatest triumph for laser
art restoration to date, removing the
patina of air pollution and revealing
many figures in their pristine colours,
in time for the 2004 Athens Olympics. |
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As Jim Arnold had predicted, by
the mid-1990s teams in several
countries, including Greece,
Italy, Germany and Spain, were using
lasers to restore ancient art and architecture,
leading to the formation of
LACONA, the international Association
for Lasers in the Conservation of
Artworks, on whose technical committee
John Asmus still sits.
The flowering of laser conservation
saw St Stephen’s vast cathedral in
Vienna and the Florentine Duomo
stripped of the grime of antiquity.
Asmus himself used lasers to explore
the Mona Lisa, revealing her to be
secretly wearing an ornate necklace,
later painted out by Leonardo da
Vinci.
From Argentina came work more
poignant. Memories of the numerous
murders inflicted under the former
fascist regime are raw, and thousands
of citizens make pilgrimages to the
dank cells and torture chambers where
so many suffered and died. After the
regime ended, the legacy of its bloody
handiwork on the walls of these cells
was quickly concealed under heavy
coats of institutional paint. Lost with
the bloodstains were the messages of prisoners, scrawled or incised in
despair, terror or farewell on the walls
– and it is these that the laser is now
restoring to view. Not only is it bringing
to life the cries of the “vanished”,
but also forensic evidence in the
pursuit of the perpetrators.
Asmus is uplifted by a current project,
to restore to freshness the sublime
frescoes in many of the unique Orthodox
churches along the Moldau River
in Romania. He is a member of the
committee planning the conservation
of this World Heritage site, which has
identified laser techniques suitable for
conserving each church. A parallel
project in Egypt aims to renovate the
ancient Coptic churches of Alexandria
starting with laser analysis, crystal by
crystal, to understand the composition
of their murals before they are
cleaned.
Preserving 20th-century art is just as
vital, Dr Asmus says – and has helped
clean San Diego’s famous and delicate
sand sculptures and to recover Jay de
Feo’s classic beat generation sculpture,
The Rose, for display at New York’s
Metropolitan Museum of Art.
Though he came to art from a career
in science, never having studied it
academically, John Asmus says that as
he works on historic masterpieces, he
often grows to a deep wonder at both
these works and their creators through
the atomic intimacies his lasers reveal.
“If I’d designed my life from the start,
it wouldn’t have been half as exciting
as it has turned out to be,” the grandfather
of laser conservation reflects.
JULIAN CRIBB |
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Mr John Fredrich Asmus
Research Physicist University of California, San Diego
Institute for Pure and Applied Physical Sciences, 0360
9500 Gilman Drive La Jolla, CA 92093-0360
United States
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