August 4, 2005 - When the space shuttle Discovery took off for space last week, a piece of insulating foam on the fuel tank broke off and struck tiles designed to protect the shuttle from extreme heat on reentry to the earth’s atmosphere. What was initially thought to be a dangerous situation was later revealed as a minor problem thanks to the Laser Camera System (LCS), a new piece of imaging equipment developed by the Canadian company Neptec.
The Laser Camera System is a high speed, wide angle imaging system that uses a series of lasers to scan the exterior of the shuttle and render highly-detailed 3D models accurate to a few millimeters, with the camera suspended up to 10 meters away.
“Our scanner was able to measure the size of the hole caused by the insulating foam,” said Iain Christie, Neptec’s director of research and development. “NASA was then able to determine that the whole was not a serious threat.”
Suspended on a boom that extends from the shuttle’s cargo bay, the camera, which is about the size of a breadbox, was passed over the surface of the Discovery to create a 3D image of the shuttle’s exterior. Engineers at NASA mission control were then able to use the rendering to find out the exact depth and width of the hole, information that would be difficult to determine from a 2D photograph.
By design, the camera is superior to existing video and still imaging systems. Regardless of lighting conditions, the LCS is able to render 3D images that can be zoomed and tilted to reveal even the tiniest defects. This imperviousness to difficult lighting conditions is particularly crucial in space; when the shuttle is orbiting the earth, the sun typically rises and sets 18 times in the course of a 24 hour period.
The camera uses a synchronized scanning technique, developed and patented by the National Research Council of Canada, to produce three dimensional data. Laser light is projected onto the shuttle and the reflected light is picked up by a linear detector that is essentially a one line tall CCD.
“For every point the scanner measures x, y and z positions and intensity,” said Christie. “The computer is then able to render a 3D model.”
The system uses information from triangulated laser beams to determine the exact location of any point. It’s not just laser beams and electronics that enable the system to work, “there is a fair bit of optical design,” said Christie, indicating how the sensor is able to make measurements to within a few millimeters.
Neptec has also developed additional applications for the scanner technology. The company is currently developing a highly sensitive LCS, called TriDar, that will help guide an unmanned vehicle to the Hubble space telescope, where it will perform repairs. The company also hopes to adapt the technology to defense needs as well as industrial assembly line automation.
