METHOD FOR PHASE-OPTICAL SENSOR SIGNAL DEMODULATION Russian patent published in 2019 - IPC G01B9/02 G02F1/01 

FIELD: measuring equipment.

SUBSTANCE: invention relates to optical methods of measuring physical values using phase optical sensors (interferometers), including for measuring mechanical and acoustic oscillations, as well as data collection lines based thereon. Disclosed method of phase optical sensor signal demodulation includes additional modulation of phase difference in phase optical sensor by saw-tooth signal, conversion of the signal of the phase optical sensor is carried out at a frequency four times greater than the frequency of modulating the phase difference in the phase optical sensor, generating triplets and quadruples of readings from samples of the signal of the phase optical sensor of each period of additional modulation of the phase difference, after which calculation of the unknown phase difference is carried out for each triplet using formulas:

where: φ_c – unknown phase difference,

,

b=(1-2cosβ)∙u⁽⁰⁾+2cosβ∙u⁽¹⁾-u⁽²⁾, where: u⁽⁰⁾, u⁽¹⁾, u⁽²⁾ are values of counts in triple, measured at values of additional saw-tooth modulation of phase difference φ⁽⁰⁾=0, φ⁽¹⁾=β and φ⁽²⁾=2β, β=φ_m/4 is increment of phase difference between adjacent readings under action of additional saw-tooth modulation of phase difference, φ_m is amplitude of additional saw-tooth modulation of phase difference, φ_m<4π. At that, in order to obtain accurate values of the unknown phase difference in case of deviation of the real amplitude of additional saw-tooth modulation of the phase difference from the given value, the increment of phase difference between adjacent readings is calculated using four counts with formula

,

where: u⁽⁰⁾, u⁽¹⁾, u⁽²⁾, u⁽³⁾ are values of counts of phase optical sensor signal in four, measured at additional saw-tooth modulation of phase difference φ⁽⁰⁾=0, φ⁽¹⁾=β, φ⁽²⁾=2β and φ⁽³⁾=3β. To maintain optimum value of amplitude of additional saw-tooth modulation of phase difference φ_m, equal to 2π, error signal is used, calculated by formula S=φ_m-2π, where: S is the error signal supplied to the amplitude difference of the additional saw-tooth modulation of the phase difference, φ_m is the amplitude of the additional saw-tooth modulation of the phase difference, calculated from the formula φ_m=4β, where β is the value of increment of phase difference between adjacent readings under the action of additional saw-tooth modulation of phase difference, calculated using four samples based on the above formula.

EFFECT: elimination of errors occurring during demodulation of a signal of a phase optical sensor in case of deviation of modulation amplitude from a given value.

1 cl, 1 tbl