System for detecting temperature and depth of sea water by fiber bragg grating

Abstract

The invention discloses a system for detecting the temperature and depth of sea water by a fiber bragg grating. The system comprises a data processing device and an underwater fiber sensor chain which are connected through a transmission optical cable, wherein the data processing device comprises an optical fiber coupler connected with a light source and a wavelength detection module connected with the optical fiber coupler; the wavelength detection module is connected with a data processing module; and the optical fibber sensor chain is formed by connecting more than two temperature and depth sensing probes with the same structure in series through the transmission optical fiber and an optical fiber connector along the vertical direction. The optical fiber sensor chain generally comprises 4 to 8 temperature and depth sensing probes which are arranged at an interval of between 2 and 10m. The system has a simple structure, is safe and reliable, is convenient to use and can easily perform expandable measurement on depth and layer number; the detection signal is an optical signal; the technical problems such as water tightness, pressure resistance and the like of the conventional electric signal detection equipment are solved; and the measurement signal is stable and the system has obvious effect. The temperature and depth sensing probes have small volume and light weight, are connected through connectors and are convenient to transport, mount, debug and maintain.

Description

technical field [0001] The invention relates to the fields of fiber grating sensing and marine environment monitoring, in particular to a fiber grating seawater temperature and depth detection system. Background technique [0002] Traditional seawater temperature and depth detection, especially profile detection systems, are mainly based on ship-borne CTD profile measurement, disposable CTD and combined temperature and salt sensor chain measurement methods. The ship-borne launch method requires the survey ship to drive to the designated location, and the CTD sensor is hoisted into the water by a marine winch at a constant speed to complete the profile measurement. This method requires a survey ship, which requires a high cost, limited data volume, and the sensor is watertight. Disposable The cost of CTD is high and the risk is relatively high; the combined temperature and salt sensor chain uses CTD sensors to be set at intervals along the main cable and a data recorder is ar...

AI Technical Summary

Problems solved by technology

The ship-borne launch method requires the survey ship to drive to the designated location, and the CTD sensor is hoisted into the water by a marine winch at a constant speed to complete the profile measurement. This method requires a survey ship, which requires a high cost, limited data volume, and the sensor is watertight. Disposable The cost of CTD is high and the risk is relatively high; the combined temperature and salt sensor chain uses CTD sensors to be set at intervals along the main cable and a data recorder is arranged at the bottom to realize the detection of different depth profiles and the recording of detection data. In this way, the main cable and the suspended multiple The group CTD is connected through a branch watertight cable interface formed by a special mold, the cost is high, and the sensor detection signals are all electrical signals, which makes it difficult for underwater pressure resistance and watertight treatment

More importantly, due to the harsh working environment of marine measurement equipment, the damage rate of underwater optical fiber sensor chains is high. The cost of traditional CTD detection equipment is almost all on CTD sensors. To increase the number of underwater measurement layers, CTD sensors must be added. Quantity, the cost of the system will increase multiples, the price of each CTD sensor is around tens of thousands, if it is damaged, the loss will be heavy

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