Range finding
Range finding equipment with pulsed laser sources are based on the time-of-flight (TOF) principle. The distance between the laser emitter and a remote object is determined by measuring the time delay between an emitted optical pulse and the detection of the reflected pulse. Normally, each optical pulse is emitted, reflected and detected before next pulse is emitted. Especially for reflection against a diffuse object, which provide very low level of reflected light, it is important to match very well the detector optics and electronics to the emitter properties.
The emitter beam size should be as small as possible at the target, and the field of view of the detector optics must overlap the emitter beam at the target. The pulse length of the emitter source limits the resolution in the measurement, but this must be traded-off against signal-to noise ratio since the large bandwidth electronics required for very short pulse detection will increase the level of electronic noise in the signal. Integration over large number of pulses increases the maximum measurable distance, but this has in turn to be traded-off against required detection speed. Finally, spectral filtering of the detected light to avoid background light and synchronization with the emitter pulse repetition rate contribute strongly to a larger measurement range.
The Cobolt Tango™ has, thanks to its high peak power and suitable pulse
length of 3-5 ns, proven to enable measurement of distances up to >10 km
against highly diffuse objects.
