Dynamic range extension of heterodyne fiber-optic interferometers via instantaneous carrier measurement

A method of extending the dynamic range in a heterodyne fiber-optic interferometer via an instantaneous carrier measurement, the method comprising:

• providing a heterodyne fiber-optic interferometer having a demodulator and an associated carrier frequency;
• determining demodulator excessions;
• determining a correction factor based on the detected demodulator excession, wherein each of the detecting of the demodulator excessions and the determining of a correction factor is based on information from an instantaneous carrier frequency;
• and
• introducing the correction factor to the demodulator to mitigate errors, thereby extending the dynamic range of the heterodyne fiber-optic interferometer,
• wherein the determining of demodulator excessions comprises:
• using the instantaneous carrier frequency to determine the instantaneous direction of phase rotation;
• and
• using the instantaneous carrier frequency to determine the instantaneous angular velocity, wherein each of the determined instantaneous direction of phase rotation, and the determined instantaneous angular velocity are used to determine the demodulator excessions, and
• wherein the determining of demodulator excessions comprises:
• measuring the instantaneous carrier frequency;
• and
• from the measured instantaneous carrier frequency, deriving the angular velocity of an incoming signal associated with the instantaneous carrier frequency, by utilizing a sample rate times π (±πfsamp), wherein said sample rate times π (±πfsamp) occur when said angular velocity is greater than that of the demodulator,
• wherein the determining of a correction factor based on the detected demodulator excession comprises establishing initial correction factors from:
• fe(m)=fc+m/2(fsamp) for m=±1,±2, . . . ,
• wherein fc is the instantaneous carrier frequency, fe is the instantaneous carrier frequency at the excession crossing, and fsamp is the sample frequency.