Fizeau interference-based ultra-weak grating perimeter security and protection system

Abstract

The invention discloses a Fizeau interference-based ultra-weak grating perimeter security and protection system. The system comprises a detection optical cable, a query unit and a control unit; the detection optical cable is an optical fiber-armored micro-vibration optical cable which is provided with a large number of ultra-weak broad-spectrum gratings; the query unit is connected with the detection optical cable and is used for generating and splitting the reflection signals of target gratings in an array; and the control unit is connected with the query unit and is used for generating pulse control signals, synchronously carrying out phase demodulation, judging an intrusion behavior through signal processing and pattern recognition, and positioning the intrusion behavior. According to the Fizeau interference-based ultra-weak grating perimeter security and protection system of the invention, a characteristic that ultra-weak grating pairs can generate Fizeau interference is utilized, a long-distance optical fiber perimeter is divided into a plurality of micro protection regions, whether intrusion behaviors exist in the protection regions is judged through detecting Michelson interference phenomena of the reflection light of the grating pairs in the micro protection regions, a quick protection region scanning query method is used in combination, and therefore, all-optical fiber distributed sensing can be realized. With the Fizeau interference-based ultra-weak grating perimeter security and protection system adopted, problems such as low sensitivity, short sensing distance, poor positioning performance and false alarm of a traditional distributed perimeter security and protection system can be solved. The Fizeau interference-based ultra-weak grating perimeter security and protection system has a bright application prospect in the perimeter security and protection field.

Description

technical field [0001] The invention relates to the technical field of optical fiber perimeter security, in particular to an ultra-weak grating perimeter security system based on Fizeau interference. Background technique [0002] Optical fiber perimeter security uses optical fiber as the sensing medium and signal transmission channel, which has the advantages of passive, anti-electromagnetic interference, and high sensitivity, and is convenient for long-distance deployment. The perimeter security field has a wide range of needs, [0003] In the mid-1990s, developed countries took the lead in applying optical fiber sensing technology to the perimeter security field. At present, the world that can master this technology and put it into use is mainly concentrated in a few countries such as Europe and the United States, such as the United Kingdom, the United States, Israel, Australia, etc., and most of them use distributed sensing technology based on the principle of Mach-Zehnd...

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Problems solved by technology

The patent (publication number: 105180977A, "a single-fiber Michelson interference sensor and sensing system") proposes a distributed vibration sensing method for a single span using two ultra-weak gratings, but the single-span sensing The length is limited by the coherence of the light source, and it lacks the function of accurately locating event points. It is difficult to meet the needs of multi-point detection and large-scale perimeter security, and there are huge obstacles in engineering applications.

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