Images for the Blind
SLS System® Replicates Precious Image

This story is not about how a 3D Systems SLS® system saved anyone weeks of valuable development time and trimmed thousands of dollars from the budget. It’s about one woman’s determination to capture a priceless and fleeting image — and hold on to it forever.

Yuen Har Tse is a telecommunications network architect who studied engineering at The University of Exeter. She is the proud mother of a 13-month old son, Christopher. She’s also blind.

Earlier this year, this amazing individual developed astonishing energy in her determination to challenge the confinements imposed on her by her inability to see. Most parents simply use photo technology to capture their child’s every phase and mood. In contrast, Yuen had no way to record these precious moments and memories in a "readable" format.

"When I realized the amazing speed at which my baby’s appearance was changing, I wanted to be able to capture the memory of his early looks for the future," recalls Yuen.

Many technologies exist that could potentially solve this challenge. Unfortunately, no one had yet combined them in a way that would safely convert a baby’s expression into a three-dimensional touch-and-feel-object, the only representation that a blind person can "see."

In a situation that others might have accepted, she began searching for new ways to use the latest in engineering equipment to help her overcome her problem.

"During the past few years, a number of technologies suited to scan, compute, and reproduce three-dimensional objects have become available, mainly for product development applications," says Yuen.

Basically, the technologies she needed were available somehow and someplace, but it seemed nobody had ever thought of linking them together to reproduce a small child’s face.

"I wanted to be able to recapture the memory of my son’s early looks for the future."
                                             - Yuen Har Tse,
                                              Telecommunications Network Architect

It was at this stage that Yuen contacted her old admissions tutor at The University of Exeter’s School of Engineering and Computer Science. He then put her in touch with a group of engineers within the department. "

The task we had to perform was rather different from our normal work, which is helping local companies with design, manufacturing, and materials problems," says Mike Felstead, Industrial Design Engineer at Exeter Advanced Technologies (X-AT).

Undaunted, the engineers took up the challenge and pushed ahead with the project as a demonstration of what is possible using their equipment and that of their partner companies.

The centerpiece of their advanced systems is a SLS system from 3D Systems. This system builds three-dimensional objects by selectively melting together powder particles in thin, superimposed layers using the energy of a CO2 laser beam guided by a computer. The computer system within the SLS system accepts data files in a common format output by most modern 3-D CAD systems.

SLS systems are commonly employed in automotive and consumer product manufacturing to produce prototypes of new products for evaluation and testing purposes. It also has been useful in applications in medical and scientific applications.

"Our SLS system, together with the CAD software we run here, covered two of the three major stepping stones of this task," says Felstead. The missing stepping stone was finding a suitable scanning system to safely capture the dimensions and contours of the infant’s face.

Unfortunately, most scanning systems are designed for robust objects that tend not to crawl away or get tired, bored, or scared. Laser scanning systems, though convenient and fast, were ruled out completely since the child’s eyes could not be exposed to such a hazard.

Finally, the project team located a solution, an optical 3D metrology camera system initially developed by German company Breuckmann GmbH. This device is typically used for reverse engineering applications in the automotive industry. It detects the topology of an object by projecting a variety of fringe patterns onto it and scans the resulting distortion with a fast stereoscopic camera system. Best of all, the light used in the process does not harm the eyes, and the camera is very fast.

"To avoid stressing the child, we made arrangements to perform the scanning at his home," explains David Rogerson, Managing Director of Burleigh Instruments, the company that supplies the scanning system in the United Kingdom.

Baby Christopher didn’t feel or see anything since the team patiently waited until his mother had convinced him to take a short nap. The actual scanning took only a few seconds. The "cloud" of thousands of individual three-dimensional points was transformed into a surface model then converted in to a solid model file.

"Once the file of Christopher was sent to us, we carried out a series of trimming and adjustment operations in order to prepare the file for the SLS system," says Felstead. The computer system of the SLS system slices the geometrical model into superimposed layers, which are then built sequentially by the laser beam. The whole process took about 15 hours.

In an unusual step for the team, the technical staff within the Engineering Department carefully hand-finished the model and coated it with a gold lacquer. It was mounted on a presentation base fitted with a special Braille plaque commemorating the event. This plaque was completed with the help of The West of England School for the Blind. The model was officially presented to Yuen and her family this year in a special ceremony that attracted a flock of journalists and several TV crews.

"I am absolutely delighted about the outcome," Yuen said, smiling as she explored the model of her baby’s face with her fingertips. It was only after she received this amazing reproduction that she discovered details she had never noticed before.

Since a baby is not a statue, its facial muscles contract in response to tactile communication from his mother, even in his sleep. With a 3-D replica of Christopher’s face in hand, Yuen could explore his face without it moving. This happy mother can now, or at any time in the future, explore the tiny grooves she never noticed before in her son’s lips and trace the shape of his closed eyes.

Felstead and his colleagues are sure the project will trigger similar initiatives all around the globe and prompt a number of interesting spin-offs, even within their own school.