1 June 2011

Osram laser used in 3D camera for precise range finding

Osram Opto Semiconductors GmbH of Regensburg, Germany says that a fast laser diode that it has developed specially for 3D cameras is providing light for the new C70 camera made by Fotonic of Stockholm, Sweden, which facilitates range finding for moving object with good depth resolution at video rate.

The new infrared laser diode provides high optical power of about 0.5W, even when in continuous wave (cw) operation. With a wavelength of about 845nm the light is hardly visible to the human eye, yet it is well within the sensing range of the camera chip.

Picture: The Fotonic C70 3D camera, which produces relief images that yield the distance between object and camera for each pixel.

Three-dimensional cameras superimpose a two-dimensional picture with information on the range and surface profile of an object. Industrial applications for such systems include the gauging of fluid levels or the grading of objects according to size or shape. Three-dimensional sensors also provide reliable stereoscopic information, e.g. for the control of robot arms.

The Fotonic C70 is based on a CMOS sensor and makes use of the principle of time-of-flight measurement. A laser diode, which is integrated into the camera, transmits a light pulse that the target reflects back. Each of the 120x160 pixels of the camera chip records the distance to the object by measuring a respective phase shift compared to the emitted light pulse.

The precision of this distance measurement and the range of the sensor increases with the modulating frequency of the light source. Due to their fast switching times of just a few nanoseconds, laser diodes are particularly well suited for this application, says Osram Opto. Developed for this kind of 3D camera, the laser diode is modulated at 44MHz. Within a range of 0.1–7m, the camera measures distance with an accuracy of 3–30mm.

For Osram Opto this is the first application of a laser diode in a 3D sensor of this type. “Together with Osram we’ve managed to increase the performance of our Fotonic C70 Camera,” comments Fotonic’s Rickard Åström. “We plan to use this component in future generations of our camera,” he adds.

“In industry, three-dimensional sensor technology is on the advance,” says Dr Jörg Heerlein (marketing manager for pulsed laser diodes at Osram Opto) who predicts a growing market for such applications. “This technology is becoming interesting for the consumer market and the automobile sector too,” he adds. “To name a few applications, it is used for touch screens, or in sensors for accident avoidance systems in automobiles. We therefore designed this new laser diode specially for 3D sensor technology.” The sturdy metal package of the component also meets the demands for industrial applications.

Osram Opto is presenting the laser (together with the Fotonic C70 3D camera) at the Measurement Fair Sensor+Test 2011 in Nuremberg, Germany (7–9 June).

Tags: Osram Laser diode

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