A laser camera system that can detect half-millimeter cracks in the Space Shuttle's heat-resistant tiles makes use of ultra-rugged, high-accuracy laser scanning galvanometers from General Scanning.

Inventor of the optical scanner, General Scanning (a member of GSI Group) provides critical laser scanning and beam positioning technology to Neptec of Ottawa, ON, developer of a laser camera system (LCS) that played a vital role in the safe return of NASA's Space Shuttle Discovery last August. By providing detailed 3-dimensional images of the spacecraft's heat shield tiles from a distance of up to 4 m over the entire surface of the craft, the system allows any defects to be spotted prior to shuttle reentry.

The Neptec LCS uses a pair of ultra-rugged, high-accuracy laser scanning galvanometers from General Scanning. Successful operation of the system required that the galvanometers survive the severe vibration of the shuttle's ascent. Following the stress of liftoff, the galvanometers then had to drive large mirrors with sufficient accuracy for an image resolution of 350-500 microns.

"Not only did the General Scanning M2 galvo meet NASA's vibration specification, the M2 ended up being pretty much indestructible," according to Iain Christie, from Neptec's business development and R & D. "We shook it as hard as we could and we couldn't destroy one."

In addition, General Scanning's galvanometers had to operate in the vacuum of space without their bearing lubricant out-gassing and contaminating the mirror surfaces. It was here that General Scanning's applications engineering team played a critical role.

"Our director of engineering worked directly with the people at General Scanning to qualify an alternative dry lubricant that would solve this problem," stated Christie. He added, "The Scanner flew and it worked."