  We propose a novel scheme for laser phase noise measurements with minimized
sensitivity to external fluctuations including interferometer vibration,
temperature instability, other low-frequency noise, and relative intensity
noise. In order to minimize the effect of these external fluctuations, we
employ simultaneous measurement of two spectrally separated channels in the
scheme. We present an algorithm for selection of the desired signal to extract
the phase noise. Experimental results demonstrate potential of the suggested
scheme for a wide range of technological applications.
