Demodulation method and device for a distributed optical fiber Raman temperature system
A technology of distributed optical fiber and demodulation method, which is applied to thermometers, measuring devices, thermometers with physical/chemical changes, etc., can solve the problems of poor matching of optical fiber loss factor and inability to reduce the same temperature flatness, and eliminate Effects of transmission loss, elimination of unstable and coupled random noise, and reduction of temperature flatness
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Embodiment 1
[0044] This embodiment provides a distributed optical fiber Raman temperature system demodulation method, including the following steps:
[0045] Step 1: Inject laser light into the reentrant sensing fiber to obtain backscattered anti-Stokes light information, backscattered Rayleigh light information and temperature information at the incident end of the sensing fiber;
[0046] Step 2: According to the backscattered anti-Stokes light information and the backscattered Rayleigh light information, the two quantities at the same measurement point are multiplied and then square rooted to obtain the processed backscattered anti-Stokes Light information and backscattered Rayleigh light information;
[0047] Step 3, obtain the physical structure of the sensing fiber according to the processed backscattered Rayleigh light information; judge whether the sensing fiber has received external intrusion, and if so, send an alarm signal, otherwise enter step 4;
[0048] Step 4, using the tem...
Embodiment 2
[0054] The distributed optical fiber Raman temperature system demodulation device provided by this embodiment is as follows: figure 1 As shown (the thick line in the connecting line represents the cable, and the thin line represents the optical cable), the device includes a laser driver 11, and the laser driver 11 periodically drives the laser 12 to emit laser light according to the start signal sent by the computer 17, and the laser light passes through the optical fiber circulator 13 Inject into the reentrant sensing fiber 14, the backscattered light generated by the sensing fiber 14 is directed to the wavelength division multiplexer 15 through the optical fiber circulator 13, and the wavelength division multiplexer 15 filters out Rayleigh light and anti-Stokes light, The digital signal is received and processed by the detector assembly 16 and sent to the computer 17; the starting point of the sensing fiber 14 is provided with an electronic thermometer 18; the electronic the...
experiment example
[0061] Assume that the sensing fiber with a one-dimensional length of L meters is actually measured, and the length of the measuring point from the processing system end (incidence end of the sensing fiber) is x meters, and the distributed optical fiber Raman temperature system demodulation device is set to obtain the digitally averaged value for many times. The forward point backscattered Rayleigh light power is:
[0062] S x = η 0 P i exp(-2α 0 x) (3)
[0063] The backscattered Rayleigh optical power of the back point is:
[0064] S 2L-x = η 0 P i exp(-2α 0 (2L-x)) (4)
[0065] The forward point backscattered anti-Stokes light power is:
[0066] P x = η as P iR(T)exp(-(α 0 +α as )x) (5)
[0067] The backscattered anti-Stokes optical power is:
[0068] P 2L-x = η as P i R(T)exp(-(α 0 +α as )(2L-x)) (6)
[0069] R(T)=[exp(hΔν / κT)-1] -1 is the anti-Stokes backscattering factor, h is the Plank coefficient, κ is the Boltmann coefficient, Δν=1.32×10 13 Hz,...
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