CN106226559A - A kind of scaling method of chirp grating - Google Patents

Abstract

Invention describes the scaling method of a kind of chirp grating, belong to field of sensor calibration.Contacting grating grid region with thermal probe, the position on reflectance spectrum that contact site is corresponding can produce depression, and after thermal probe removes, depression disappears and restores to the original state.On the contact position of record probe and corresponding spectrogrph, these data are carried out linear fit, i.e. can get the linear relationship of chirped grating length and wavelength, thus obtain chirped grating length, chirp rate, reflection spectrum width by the wavelength data of recess under reflectance spectrum.The present invention is with low cost, simple to operate, and to grating without damaging.

Description

A kind of scaling method of chirp grating

Technical field

The invention belongs to the technical field of transducer calibration, be specifically related to the scaling method of a kind of chirp grating.

Background technology

Optical fiber sensing technology is the newcomer in sensing family, and it is just with the tradition incomparable unique advantage of electric transducer Develop rapidly, refresh people's traditional view at sensory field.Fiber grating developed the most rapid optical fiber as nearest 20 years One of passive device, is widely used in sensor field, as strain, temperature, pressure, ultrasound wave, acceleration, The measurement of magnetic field and speed etc..

Detonation wave be a kind of with high-speed chemical reaction zone, in explosive propagate a kind of strong shock wave, detonation wave Speed is called for short explosion velocity, typically up to several thousand metres/second, propagates the impact being little affected by external condition, and detonation wave speed is explosive weight One of characterisitic parameter wanted, significant to research detonation propagation, energy transmission etc..

The measurement of explosion velocity can use chirp grating method, chirp grating (CFBG) to belong to the one of Fibre Optical Sensor.Utilize When chirp grating surveys detonation wave speed, detonation wave acts on chirp grating, makes the length of grating reduce, and return signal light intensity subtracts Weak, utilize this phenomenon can measure the continuous velocity of detonation wave.

For solving speed, need the length of chirp grating is demarcated, obtain the length value of chirp grating.And it is long The whether accurate precision directly influencing the speed finally tried to achieve of degree.

The scaling method of chirp grating is usually patterning method at present, takes and cuts with in a collection of grating, passes through Record the light intensity magnitude of each cutting position and return, obtain the length of chirp grating.But this method exists one Fatal defect, that is, this demarcation is destructive, has demarcated rear grating and has also damaged, it is impossible to has been continuing with, it addition, this side Method is regarding as just the same with batch of grating, but although being actually with a collection of grating, it is poor to yet suffer between individuality Different.Thermoprobe method in the present invention, can demarcate it in the case of not damaging chirp grating.

Summary of the invention

The technical problem to be solved in the present invention is: overcome the deficiencies in the prior art, proposes a kind of heat demarcating chirp grating Sonde method, the method has simple to operate, with low cost, under conditions of not destroying grating, it can be carried out demarcation etc. excellent Point.

The present invention solves the technical scheme of above-mentioned technical problem employing: the scaling method of a kind of chirp grating, the method Step is as follows:

Step 1: be pasted onto on plane steel plate by chirp grating, fixes a rule on grating limit；

Step 2: with certain position of thermal probe contact chirp grating, record length L on rule now, and at light Wavelength value λ that under spectrum, recess is corresponding is read on spectrometer；

Step 3: repeat step 2, obtain a series of length-wavelength data；

Step 4: read the reflection spectral width Δ λ of chirp grating, length-number of wavelengths that step 3 is obtained on spectrogrph According to carrying out linear fit, obtain the relation of length and wavelength, and calculated the grid region length of chirp grating by reflection spectral width Δ λ Δ L, by grid region length Δ L and reflection spectral width Δ λ, also can get the chirp rate of chirp grating.

Further, described rule minimum resolution 0.02mm.

Further, described thermal probe temperature is higher than 100 degrees Celsius, and needle point spot diameter is less than 0.1mm.

Further, described reflection spectral width Δ λ is read by spectrogrph.

Present invention advantage compared with prior art is:

(1), the present invention propose scaling method, with low cost, simple to operate.

(2), the present invention under conditions of not destroying grating, it can be demarcated, still can use after having demarcated, Thus the speed finally tried to achieve is more accurate.

Accompanying drawing explanation

Fig. 1 is the schematic diagram that thermoprobe method demarcates chirp grating, in figure: 1, plane steel plate, 2, rule, 3, thermal probe, 4, chirp grating.

Fig. 2 is the reflection spectral line schematic diagram before and after thermal probe contact chirp grating.

Detailed description of the invention

Below in conjunction with the accompanying drawings the detailed description of the invention of the present invention is described, in order to be more fully understood that the present invention.Should It is emphasized that it is that the description below is merely exemplary rather than in order to limit the scope of the present invention and application thereof.

The scaling method of a kind of chirp grating of the present invention, by chirp grating by optical circulator and wideband light source and spectrogrph Being connected, the laser that wideband light source sends enters into chirp grating through optical circulator, and the light that chirp grating returns is again by annular Device enters spectrogrph.Observe the reflectance spectrum of chirp grating with spectrogrph, when contacting grating grid region with thermal probe, contact site is corresponding Reflectance spectrum on position can produce depression, after thermal probe removes, depression disappear, restore to the original state, as shown in Figure 2.Record is visited On a series of contact positions of pin and corresponding spectrogrph, these data are carried out by the wavelength data of chirped grating reflection spectrum recessed location Linear fit, i.e. can get the linear relationship of chirped grating length and wavelength, and total length.As it is shown in figure 1, concrete steps are such as Under:

Step 1: be pasted onto on plane steel plate 1 by chirp grating 4, fixes a rule 2 on grating limit；

Step 2: contact certain position of chirp grating with thermal probe 3, length L on record rule 2 now, and Wavelength value λ that under spectrum, recess is corresponding is read on spectrogrph；

Step 3: repeat step 2, obtain a series of length-wavelength data；

Step 4: read the reflection spectral width Δ λ of chirp grating, length-number of wavelengths that step 3 is obtained on spectrogrph According to carrying out linear fit, obtain the relation of length and wavelength:

L=a λ+b (1)

Wherein, a, b are the coefficient of linear fit.

And the grid region length of chirp grating is calculated by reflection spectral width Δ λ:

Δ L=a Δ λ (2)

By grid region length Δ L and reflection spectral width Δ λ, also can get the chirp rate of chirp grating:

$C=\frac{\mathrm{\Δ}\mathrm{\λ}}{\mathrm{\Δ}L}---\left(3\right)$

Although detailed description of the invention illustrative to the present invention is described above, in order to the technology people of this technology neck Member understands the present invention, it should be apparent that the invention is not restricted to the scope of detailed description of the invention, and the ordinary skill to the art From the point of view of personnel, as long as various change limits and in the spirit and scope of the present invention that determine, these become in appended claim Change is apparent from, and all utilize the innovation and creation of present inventive concept all at the row of protection.

Claims (4)

1. the scaling method of a chirp grating, it is characterised in that the method step is as follows:

Step 1: be pasted onto on plane steel plate (1) by chirp grating (4), fixes a rule (2) on grating limit；

Step 2: certain position of use thermal probe (3) contact chirp grating, length L on record rule (2) now, and Wavelength value λ that under spectrum, recess is corresponding is read on spectrogrph；

Step 3: repeat step 2, obtain a series of length-wavelength data；

Step 4: read the reflection spectral width Δ λ of chirp grating on spectrogrph, the length-wavelength data obtaining step 3 enters Line linearity matching, obtains the relation of length and wavelength, and is calculated the grid region length Δ L of chirp grating by reflection spectral width Δ λ, By grid region length Δ L and reflection spectral width Δ λ, also can get the chirp rate of chirp grating.

The scaling method of a kind of chirp grating the most according to claim 1, is characterized in that: minimum point of described rule (2) Resolution 0.02mm.

The scaling method of a kind of chirp grating the most according to claim 1, is characterized in that: described thermal probe (3) temperature is high In 100 degrees Celsius, needle point spot diameter is less than 0.1mm.

The scaling method of a kind of chirp grating the most according to claim 1, is characterized in that: described reflection spectral width Δ λ by Spectrogrph reads.