Wireless Sensor Images in 3-D

A cordless, lightweight sensor device the size of a shoebox can take 3-D images virtually anywhere, including crime scenes, doctors' offices, and manufacturing production lines.

The sensor was developed at the Fraunhofer Institute for Applied Optics and Precision Engineering (Fraunhofer IOF) in Jena. "It consists of two cameras with a projector in the center," said IOF Optical Systems department head Gunther Notni, PhD. "The two cameras provide a three-dimensional view, rather like two eyes. The projector casts a pattern of stripes on the objects. The geometry of the measured object can be deduced from the deformation of the stripes."

The Kolibri Cordless sensor developed at the Fraunhofer Institute for Applied Optics and Precision Engineering is lightweight, about the size of a shoebox, and quickly takes 3-D images. (Photo copyright ©Fraunhofer IOF)

Stripe projection technology isn't new. What is new about the measuring device, called the Kolibri Cordless, is its measuring speed, size, weight (about 2 lbs), and cordless operation, the researchers said. Conventional 3-D imaging devices typically weigh four or five times as much and are more than twice the size.

"The reason it can be so much smaller is because of the projector, which produces light with light-emitting diodes instead of the usual halogen lamps," Notni said. The challenge in using LEDs is that the light they provide shines in all directions. To make sure the resulting image is bright enough, the light has to be collected with special micro-optics so that it hits the lens.

Fans of crime shows such as "CSI" know that forensic experts often make plaster casts of tire tracks left in soft surfaces for later comparison with the tracks made by suspects' vehicles. But the Fraunhofer researchers said their method offers a much faster, easier way of creating an image: The battery-powered sensor can be aimed at the tracks in question, its button pressed, and a few seconds later police officers can see a 3-D image of the track on their laptop computer, sent wirelessly by the sensor.

The device also has medical applications, such as providing a 3-D scan of a patient's face prior to plastic surgery or other procedures.

"Patients who snore often need a breathing mask when they sleep. To ensure that the mask is not too tight, it has to be specially made for each patient. Our system enables the doctor to scan the patient's face in just a few seconds and have the breathing mask made to match these data," Notni said.

He said he considers quality assurance in production processes he most important application for the device. The device's small size also makes it possible to measure installed components and zones that are difficult to access, such as the position of foot pedals inside a car, Notni said.

The researchers will showcase the sensor at the Control trade fair in Stuttgart, Germany, April 21-25 (Hall 1, Stand 1520).

For more information, visit: www.iof.fhg.de/index_e.html