Seawater salinity and temperature detection device based on double-bend long-period fiber bragg grating and use method

Abstract

The invention discloses a seawater salinity and temperature detection device based on double-bend long-period fiber gratings and a use method. A measurement sensing part of the seawater salinity and temperature detection device comprises three LPFGs, a traction rope, three pulleys, a weight, a floating substance, a seawater solution and a seawater container; the LPFG signal demodulation part comprises an ASE broadband light source, an F-P filter, an optical splitter, a photoelectric detector, a signal conditioning circuit, an ADC acquisition module, an FPGA and the like. According to the principle that floating substances have different draught depths in seawater with different salinity, original contact type refractive index measurement is changed into non-contact type bending measurement, so that the sensitivity of seawater salinity measurement is improved; on the basis of double LPFGs, a temperature compensation sensor is provided while the bending variation is detected; a temperature sensor based on LPFG is added to realize simultaneous measurement of seawater salinity and temperature; the FPGA and the F-P filter are utilized to complete demodulation of an LPFG signal, and the problem that a spectrometer is inconvenient to carry is solved. The device is simple in structure and convenient to carry, and can effectively improve the seawater salinity, the temperature sensitivity and the measurement precision.

Description

technical field [0001] The invention belongs to the field of optical fiber sensing and optical communication passive devices, and in particular relates to a seawater salinity and temperature detection device based on a double-curved long-period optical fiber grating and a use method. Background technique [0002] The ocean accounts for about 71% of the earth's surface area, and is an important part of the earth's environment, affecting the survival and development of human beings. Among them, seawater salinity and temperature are important basic parameters for human exploration and research of the ocean, and are crucial to ocean research. Optical fiber sensors have been widely used in seawater salinity and temperature measurement due to their small size, light weight, anti-electromagnetic interference, high insulation, corrosion resistance, high sensitivity, and fast response. Among them, the long-period fiber grating has a narrow bandwidth and is sensitive to the refractiv...

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Problems solved by technology

The optical fiber sensor corroded by hydrofluoric acid has a fragile structure and is easily damaged; the steps of coating a high refractive index film are cumb

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