Optical measurement of loudspeaker cone vibration (scanning vibrometry) can also be accomplished by using Laser triangulation technique which is a cost effective alternative to Doppler interferometry. Since triangulation sensors provide primarily displacement advanced signal processing is required to measure the break-up modes up to 20 kHz at sufficient signal to noise ratio. In addition to stroboscopic animation of the radiation pattern a new decomposition technique is presented for the visualization of the measured data. Radial and circular modes can be separated and the total vibration can be split into radiating and non-radiating vibration components. This kind of post-processing reveals critical vibration modes, simplifies the interpretation and gives indications for further improvements.
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