Theoretical analysis of the impact of local oscillator frequency noise on a laser vibration sensor

Abstract

The sensitivity of a mDoppler sensor is proportional to the velocity noise PSD (Power Spectral Density (m/s)2/Hz). In long-range applications, LO (Local Oscillator) laser frequency noise can be the dominant velocity noise source. In this paper we develop the relationship between the LO laser frequency PSD (Hz2/Hz) and the measured velocity noise PSD. The integrated velocity PSD or velocity variance is shown to depend upon the LO noise PSD shape and amplitude, the target round-trip time, and the measurement. The performance of a frequency stabilized and unstabilized LO laser, which exhibit a white and 1/f2 frequency noise spectrum respectively, is then predicted from this transfer function theory.