A laser sensor that is making music

Micro-Epsilon: The optoNCDT laser triangulation sensors from Micro-Epsilon are typically used in industrial plants for non-contact distance, displacement and position measurements. Bremen's Arts University, Hochschule für Künste, is now using a sensor for a musical instrument.

This instrument consists of a rotation mechanism and a laser displacement sensor. Everyday objects are clamped into the device and revolve around their axis. The displacement sensor scans their shape. The distance information is then translated into acoustic frequencies and presented via loudspeakers. This instrument can “play” a great variety of everyday things, with their silhouettes determining melody and rhythm. “Playing this instrument requires a mixture of practice, intuition and coincidence,” explains the inventor, Professor Dennis Paul.

Laser triangulation is based on a geometric triangular relationship: A laser diode transmits the laser beam onto the measurement object. A lens focuses the reflected rays onto a CCD array within the sensor. This forms a triangle between laser diode, measuring point on the object surface, and the CCD array. A trigonometric calculation uses the lengths, angles and the length of the triangle transversal to determine other variables. This is how the distance from sensor to measurement object is calculated.

Typical industrial applications for laser triangulation displacement sensors include critical object measurements (e.g. hot metal) at long distances, and fast processes with high precision requirements.