The sweet sound of X-ray CT scanning
Nikon Metrology was contracted to perform a CT scan on a treasured 18th-century Venetian violin from the Oberlin Violin Makers Foundation. With Nikon’s advanced non-destructive technology, the violin was able to be imaged from all angles, helping today’s music makers understand how these magnificent instruments were created hundreds of years ago.
“What’s past,” as William Shakespeare wrote in The Tempest, “is prologue.” Which means that the people, the events, and even the musical instruments of yesteryear form the prism through which we view the world of today.
That’s an assessment of history with which the board members of the Oberlin Violin Makers Foundation would certainly agree. Their mission is to promote and preserve the rich lineage of violin making, an art (as well as a science) that stretches back to Italy in the late Renaissance. One way they accomplish this goal is through the careful modeling and reconstruction of extremely rare antique violins.
Given the value of the instruments with which they work, destructive means of precision analysis for the purposes of replicating a violin such as the 1739 Montagnana is obviously out of the question. Thus, X-ray computed tomography (CT) became the technology of choice for the members of the Oberlin Violin Makers Foundation in their mission to reverse-engineer and thereby discover how past masters created their instruments.
Art meets science
When the Oberlin Violin Makers Foundation first decided to scan their violins a few years ago, they used medical CT technology. However, there were issues with this approach.When the Oberlin Violin Makers Foundation first decided to scan their violins a few years ago, they used medical CT technology. However, there were issues with this approach.
“Medical CT scanning is great because you have not just outside info, but inside info, too,” says Schryer. “But the thickness of the slices of information was only about 0.3 mm. You need better resolution than that to 3D print a really accurate model from an STL file,” which is a triangulated surface file showing both inner and outer surfaces.
Schryer and five other members of the Oberlin Violin Makers Foundation traveled to Nikon Metrology’s facility in Brighton, Michigan, to analyze the violin. It was scanned by Nikon Metrology’s M2 high-precision X-ray/CT inspection system, using a 225kV microfocus source. This powerful scanner provided almost three times the resolution that the Oberlin Violin Makers Foundation had been receiving from their medical scanners, translating to 5,453 slices of information vs. 1,829. That level of detail is imperative when you are attempting to replicate an object in which every micron of material makes a difference in the performance.