A system comprising: a laser device; an optical circulator optically coupled to said laser device; a telescope optically coupled to said optical circulator; a tunable interferometer optically coupled to said optical circulator; a photodetector optically coupled to said tunable interferometer; and a signal processor electrically coupled to said photodetector, wherein said tunable interferometer is a scanning Fabry-Perot interferometer comprising a plurality of piezoelectric transducers, and said signal processor is electrically coupled to said piezoelectric transducers, and wherein said signal processor is configured to supply scanning voltages to said piezoelectric transducers which have the effect of adjusting a wavelength of said tunable interferometer so that the wavelength varies within a range of wavelengths that includes a wavelength of light emitted by said laser device and a wavelength of light which was first emitted by said laser device and then Doppler shifted by a target, wherein said signal processor is configured to perform the following operations: (a) monitoring a detection voltage produced by said photodetector as a function of the scanning voltages supplied to said piezoelectric transducers; (b) identifying scanning voltages where peak detection voltages occur; (c) comparing differences in scanning voltages where the peaks occur to reference voltages in a calibration table to determine the relative speed of the target as well as the resonant vibration frequency of the target; and (d) identifying the target based on the resonant vibration frequency determined in operation (c). a laser device; an optical circulator optically coupled to said laser device; a telescope optically coupled to said optical circulator; a tunable interferometer optically coupled to said optical circulator; a photodetector optically coupled to said tunable interferometer; and a signal processor electrically coupled to said photodetector, wherein said tunable interferometer is a scanning Fabry-Perot interferometer comprising a plurality of piezoelectric transducers, and said signal processor is electrically coupled to said piezoelectric transducers, and wherein said signal processor is configured to supply scanning voltages to said piezoelectric transducers which have the effect of adjusting a wavelength of said tunable interferometer so that the wavelength varies within a range of wavelengths that includes a wavelength of light emitted by said laser device and a wavelength of light which was first emitted by said laser device and then Doppler shifted by a target, wherein said signal processor is configured to perform the following operations: (a) monitoring a detection voltage produced by said photodetector as a function of the scanning voltages supplied to said piezoelectric transducers; (b) identifying scanning voltages where peak detection voltages occur; (c) comparing differences in scanning voltages where the peaks occur to reference voltages in a calibration table to determine the relative speed of the target as well as the resonant vibration frequency of the target; and (d) identifying the target based on the resonant vibration frequency determined in operation (c). (a) monitoring a detection voltage produced by said photodetector as a function of the scanning voltages supplied to said piezoelectric transducers; (b) identifying scanning voltages where peak detection voltages occur; (c) comparing differences in scanning voltages where the peaks occur to reference voltages in a calibration table to determine the relative speed of the target as well as the resonant vibration frequency of the target; and (d) identifying the target based on the resonant vibration frequency determined in operation (c).