METHOD OF DETERMINING THE SYMMETRICAL OPTICAL STRUCTURE (VERSIONS) CENTRAL FREQUENCY AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2017 - IPC G01M11/00 

FIELD: measuring equipment.

SUBSTANCE: when implementing the methods of determining the symmetrical optical structure central frequency, single-frequency probing radiation is generated, converted into the two-frequency one, fed it to the input and received from the symmetrical optical structure output. Further, the probing radiation frequency in the measurement range is tuned, lying in the band area passing the symmetric optical structure, its parameters changes are recorded, according to which the symmetrical optical structure central frequency is calculated. At that, when implementing the method of the first embodiment, the difference frequency is selected not exceeding the half-width of the symmetrical optical structure slopes. During the single-frequency optical radiation frequency tuning, memorize the first value of the beat envelope modulation coefficient between the double-frequency probing radiation components m=m₁ and fix the corresponding value of the double-frequency probing radiation average frequency f_CP=f_CP1. Further during the single-frequency optical radiation frequency tuning, memorize the second value of the beat envelope modulation coefficient between the double-frequency probing radiation components m=m₂=m₁ and fix the corresponding value of the double-frequency probing radiation average frequency radiation f_CP=f_CP2. Then the symmetrical optical structure central frequency is calculated according to the formula f_C=(f_CP1+f_CP2)/2. While implementing the method according to the second embodiment, during the single-frequency optical radiation frequency tuning, two adjacent measurements are recorded, in the first of which there is the modulation coefficient of the beat envelope between the double-frequency probing radiation components m=m₃<1, while in the second m=m₄=1, and memorize the double-frequency probing radiation average frequency value f_CP=f_CP4 for the second of them. Further during the tuning, the data of two other adjacent measurements is recorded, in the first of which the modulation coefficient of the beat envelope between the double-frequency probing radiation components m=m₅=1, and in the second m=m₆<1, and memorize the double-frequency probing radiation average frequency value f_CP=f_CP5 for the first of them, according to which the symmetrical optical structure central frequency is calculated as f_C=(f_CP4+f_CP5)/2. The device for determining the symmetrical optical structure central frequency consists of series-connected the single-frequency optical radiation frequency tunable source, the single-frequency optical radiation converter into the double-frequency one, the circulator, the first fiber optic cable, one end of which is connected to the first circulator output, and the other end to the symmetrical optical structure input of the second fiber optic cable, one end of which is connected to the symmetrical optical structure output and the second end with the second circulator input, the detector, the tuned filter of the difference frequency, and the symmetric optical structures central frequency control and measuring controller. Moreover the frequency tunable source of the single-frequency optical radiation, the single-frequency optical radiation converter into the double-frequency one, the tunable difference frequency filter, and the control and measuring controller of the central frequency have the control inputs / outputs combined in the control bus.

EFFECT: determination accuracy increase of the central frequency both as narrowband and broadband of the symmetric optical structure.

3 cl, 4 dwg