CN204086135U - A kind of volatile organic matter Fibre Optical Sensor of interfering based on fiber end face F-P - Google Patents

Abstract

The utility model is bright discloses a kind of volatile organic matter Fibre Optical Sensor of interfering based on fiber end face F-P, one section of hollow-core fiber is connected at single-mode fiber end, the end of hollow-core fiber is closed with certain polymeric material, between polymeric material and single-mode fiber end face, form F-P interference cavity, form volatile organic matter sensing head thus; Light beam enters the F-P interference cavity in the middle of hollow-core fiber by single-mode fiber, and when fibre-optical probe contact volatile organic matter, the thickness of polymeric material will change, thus change the length of interference cavity; The frequency spectrum of interference light is subject to the modulation of interference cavity length, by spectrometer, interference light is analyzed to the measurement that just can realize volatile organic matter.The utility model comprises wideband light source, three-dB coupler, sensor fibre, sensing probe and spectrometer.This sensor construction is simple, and compact, signal to noise ratio (S/N ratio) is high, can realize monitoring the real-time continuous of escaping gas in the system such as production run, disaster monitoring.

Description

A kind of volatile organic matter Fibre Optical Sensor of interfering based on fiber end face F-P

Technical field

The utility model belongs to sensory field of optic fibre, is specifically related to a kind of volatile organic matter Fibre Optical Sensor of interfering based on fiber end face F-P.This sensor construction is simple, and compact, signal to noise ratio (S/N ratio) is high, can realize monitoring the real-time continuous of volatile organic matter in the system such as production run, disaster monitoring.

Background technology

Volatile organic matter (volatile organic compounds, VOCs) be modal class air pollutants, typically refer to boiling point at 50 ~ 250 DEG C, the organism of steam can be formed at normal temperatures and pressures, mainly comprise benzene homologues, organic chloride, Freon series, organic ketone, alcohols, amine, ether and lipid etc.VOCs has toxicity, pungency and carcinogenicity, can havoc environmental and human health impacts.Therefore the method developing VOCs content in sensitive, quick, Accurate Determining air is very important.

In existing detection method, due to the particular advantages of optical fiber, such as volume is little, and loss is low, is suitable for remote detection etc., and the volatile organic matter based on optical fiber detects and is more and more subject to people's attention.Simple, Practical Determination Method of VOCs kind based on optical fiber is a lot, and modal is method based on spectral analysis, carries out detection analysis obtain gas concentration to be measured to the characteristic absorpting spectruming line of gas to be measured.This detection method is highly sensitive, and response is fast, but the normal absorption spectra scope needing special light source to mate variety classes gas to be measured, and therefore cost is high, limits its range of application.Volatile organic matter based on fiber grating detects also to be reported to some extent, and gas to be measured acts on fiber grating outside, by the drift affecting the fibre core of fiber grating, cladding-effective-index causes resonance wavelength.But the inscription of grating can cause damage to optical fiber, is difficult to Long-Time Service.

For the problems referred to above, we have proposed a kind of volatile organic matter Fibre Optical Sensor of interfering based on fiber end face F-P.This sensor construction is compact, can duplicate measurements for a long time, is convenient to trace monitoring, highly sensitive, has the characteristic of optical fiber resisting temperature interference simultaneously, can well realize the detection of variety classes volatile organic matter.

Utility model content

The purpose of this utility model there is provided a kind of more flexible simple, degree of accuracy is high, the gas pressure intensity Fibre Optical Sensor of interfering based on fiber end face F-P of good reliability.

Technical solution of the present utility model is as follows:

Based on the volatile organic matter Fibre Optical Sensor that fiber end face F-P interferes, comprise wideband light source (1), three-dB coupler (2), Transmission Fibers (3), sensing probe (4) and spectrometer (5); Above-mentioned three-dB coupler comprises four ports, wideband light source (1) and spectrometer (5) input and are connected with two ports of three-dB coupler side respectively, the port in one end of Transmission Fibers (3) and the opposite side of three-dB coupler is connected, and the other end of Transmission Fibers (3) is connected with sensing probe (4);

Above-mentioned sensing probe (4), it is characterized in that forming F-P interference cavity by one section of hollow-core fiber and the welding of single-mode fiber phase, hollow-core fiber length is between 1-3cm, and the outer face of hollow-core fiber is closed by polymeric material; Described polymeric material has the effect absorbing volumetric expansion after volatile matter.

The beneficial effects of the utility model are:

Based on the volatile organic matter Fibre Optical Sensor that fiber end face F-P interferes, connect an optical fiber volatile organic matter sensing probe in single mode sensor fibre optical cable one end, the other end is connected with spectrometer with wideband light source respectively via three-dB coupler.

After wideband light source sends light beam, be coupled into sensor fibre by three-dB coupler, light beam enters sensing probe by sensor fibre.Light beam enters the F-P interference cavity in the middle of hollow-core fiber by single-mode fiber, and two reflectings surface of interference cavity are made up of polymeric material and single-mode fiber end face.The interference light formed in interference cavity is passed back via single-mode fiber, is coupled into spectrometer by three-dB coupler.

When volatile organic matter and described polymer material contact, polymeric material will expand, and the chamber changing F-P interference cavity is thus long.Frequency spectrum due to interference light is subject to the modulation of interference cavity length, by spectrometer, interference light is analyzed to the measurement that just can realize volatile organic matter.

By spectrometer, interference light wave is analyzed, the change of volatile organic content can be obtained.This invention flexibly simple, degree of accuracy is high, good reliability, being applicable to multiplely needs to carry out the real-time monitoring of volatile organic matter and the occasion of measurement.

Accompanying drawing explanation

Fig. 1 is a kind of structural representation of the volatile organic matter Fibre Optical Sensor based on fiber end face F-P interference.

Fig. 2 is a kind of structural representation of the volatile organic matter Fibre Optical Sensor sensing probe based on fiber end face F-P interference.

In figure: single-mode fiber 1 hollow-core fiber 2 polymeric material 3

Embodiment

Below in conjunction with accompanying drawing and embodiment, the invention will be further described:

As Fig. 1 shows, based on the volatile organic matter Fibre Optical Sensor that fiber end face F-P interferes, comprise wideband light source (1), three-dB coupler (2), Transmission Fibers (3), sensing probe (4) and spectrometer (5); Above-mentioned three-dB coupler comprises four ports, wideband light source (1) and spectrometer (5) input and are connected with two ports of three-dB coupler side respectively, the port in one end of Transmission Fibers (3) and the opposite side of three-dB coupler is connected, and the other end of Transmission Fibers (3) is connected with sensing probe (4).

As shown in Figure 2, above-mentioned sensing probe (4), it is characterized in that forming F-P interference cavity by one section of hollow-core fiber and the welding of single-mode fiber phase, hollow-core fiber length is between 1-3cm, and the outer face of hollow-core fiber is closed by polymeric material; Described polymeric material has the effect absorbing volumetric expansion after volatile matter.

The utility model is based on following principle:

It is I that wideband light source sends energy ₀light beam, three-dB coupler is coupled into sensor fibre, then is conducted in the F-P interference cavity that hollow optic fibre forms by sensor fibre.Interfering beam enters spectrometer via single-mode fiber by three-dB coupler.The interference light that spectrometer receives can be expressed as:

Wherein for phasing degree, λ is optical wavelength, n _efffor effective refractive index, Δ L is the length variations amount of interference cavity.Utilize phase demodulating can realize solving the length L in chamber.In central wavelength pair carry out Taylor expansion:

When have

$\mathrm{\Δ\λ}=\frac{{\mathrm{\λ}}_0^2}{n_{\mathrm{eff}}\·\mathrm{\ΔL}}---\left(3\right)$

Obtain the length variations Δ L of interference cavity and the relation of interfering wavelength changes delta λ thus.

Interfere the changes delta λ of wavelength just can obtain the length variations Δ L of the inner F-P interference cavity of hollow-core fiber caused due to volatile organic content change by spectrometer measurement.

The working method of present embodiment is:

The light that wideband light source is sent out incides in three-dB coupler, and light, by coupling mechanism, arrives sensing probe through Transmission Fibers; Owing to absorbing extraneous volatile organic matter, the polymeric material of sensing probe end expands, and F-P cavity length in sensing probe is changed; Interference light wavelength in F-P cavity is subject to the long modulation in chamber; Light wave is interfered to enter into spectrometer by Transmission Fibers via three-dB coupler; The interference wave length shift that volatile organic matter causes can be observed by spectrometer; This sensor can realize the sensing to volatile organic matter thus.

The technology of putting into that this device can realize volatile organic matter sensing is:

1. the end face of sensing probe is coated with a kind of polymeric material, and when this polymeric material contacts with volatile organic matter, polymeric material will expand, and its length in hollow-core fiber will increase.With the increase of volatile organic matter concentration, polymer volume also will constantly increase.

2., in hollow-core fiber, there are polymeric material and single-mode fiber end face to form F-P interference cavity.Along with the change of polymeric material length, the length of the F-P interference cavity in hollow-core fiber will change.Frequency spectrum due to interference light is subject to the modulation of interference cavity length, by spectrometer, interference light is analyzed to the measurement that just can realize volatile organic matter.

Claims (1)

1., based on the volatile organic matter Fibre Optical Sensor that fiber end face F-P interferes, comprise wideband light source (1), three-dB coupler (2), Transmission Fibers (3), sensing probe (4) and spectrometer (5); Above-mentioned three-dB coupler comprises four ports, wideband light source (1) and spectrometer (5) input and are connected with two ports of three-dB coupler side respectively, the port in one end of Transmission Fibers (3) and the opposite side of three-dB coupler is connected, and the other end of Transmission Fibers (3) is connected with sensing probe (4);

Above-mentioned sensing probe (4), it is characterized in that forming F-P interference cavity by one section of hollow-core fiber and the welding of single-mode fiber phase, hollow-core fiber length is between 1-3cm, and the outer face of hollow-core fiber is closed by polymeric material; Described polymeric material has the effect absorbing volumetric expansion after volatile matter.