Using a Mach-Zehnder interferometer (MZ) as an edge filter, we read the frequency modulation (FM) of a laser diode (LD) self-mixing interferometer (SMI), and obtain much better performance respect to the normally used amplitude modulation (AM) signal. The MZ filter has a conversion factor of 19 (GHz)-1and is tuned at half-fringe on the laser wavelength with a feedback loop acting on the laser bias current. On small amplitude vibrations measured with the converted- FM signal, we attain a noise-equivalent-displacement (NED) of 1.3-pm/vHz, a factor 130 better than AM channel or a normal SMI.
Self-mixing vibrometer has picometer sensitivity by exploiting the FM channel
Norgia, Michele
2018-01-01
Abstract
Using a Mach-Zehnder interferometer (MZ) as an edge filter, we read the frequency modulation (FM) of a laser diode (LD) self-mixing interferometer (SMI), and obtain much better performance respect to the normally used amplitude modulation (AM) signal. The MZ filter has a conversion factor of 19 (GHz)-1and is tuned at half-fringe on the laser wavelength with a feedback loop acting on the laser bias current. On small amplitude vibrations measured with the converted- FM signal, we attain a noise-equivalent-displacement (NED) of 1.3-pm/vHz, a factor 130 better than AM channel or a normal SMI.File in questo prodotto:
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