CN101226082A - Photoelectric temperature sensing device based on interference - Google Patents

Abstract

The invention relates to a transmission type or reflective type photoelectric optical fiber temperature sensor based on interference principle, comprising a photoelectric processing unit, transmission optical fiber and a passive temperature sensing unit. The photoelectric optical fiber temperature sensor, based on film or crystal interference principle, adopting mature narrow-band wavelength light source in optical communications industry, measures the temperature according to the measurement of the intensity of the signal light passing the front or back of the temperature sensing unit made of film or crystal or other structures; the upper limit of the temperature measurement can reach above 2000 DEG C according to the selections of various films or crystals and the measuring accuracy is within one DEG C. The transmission type or reflective type photoelectric optical fiber temperature sensor based on interference principle has the advantages that the temperature sensing unit has no movable components, belonging to pure passive structure; the photoelectric optical fiber temperature sensor is not sensible for outside environment and can be applied in harsh environment, such as high-voltage, high temperature, high-humidity and high dust conditions.

Description

A kind of based on the photoelectric temperature sensing device of interfering

Technical field

The present invention relates to a kind of temperature sensing device, in particular, is a kind of based on the photo-electric optical fiber sensing temperature monitor of interfering.

Background technology

Utilize optical fiber sensing technology to carry out temperature survey and monitoring, in commercial production and daily life, have and important meaning.The main at present contact electric transducer technology that adopts is carried out monitoring temperature, as thermopair, thermal resistance or the like, uses but these technology are difficult in fields such as EHV transmission equipment, inflammable and explosive occasion, hot and humid environment, high corrosion environment.In the UHV (ultra-high voltage) occasion, there is electromagnetic interference (EMI), and, will causes serious personnel casualty accidents if insulation is not carried out.In inflammable and explosive occasion, fax temperature-sensitive degree monitor mode is easy to cause electric spark and causes fire and blast.At hot and humid or high corrosion environment, fax sense itself can be worn out rapidly and be damaged, and causes can't measuring at all.

In petroleum industry, the darkest oil, the gas drilled hole degree of depth are above 6000 meters, it is most important to oil or gas extraction constantly to survey downhole temperature, but existing contact fax temperature-sensitive degree probe at all can't be in the existence of the down-hole of High Temperature High Pressure because of the restriction of the heat resistance of electron device own.Equally, in the high temperature of steel industry, many wet, environment that vaporific steam is boundless and indistinct, also there is not a kind of effective method can measure the temperature of casting billet surface accurately so far

Utilize optical fiber to carry out the method for temperature sensing, can well solve electromagnetic interference (EMI) and electrical isolation problem in the high voltage environment, simultaneously because the temperature range height of its measurement, corrosion-resistant and obtain people's high praise, thereby develop various optical fiber temperature sensing devices, as Brillouin scattering temperature sensor, Raman scattering temperature sensor, fiber-optical grating temperature sensor, microbend fiber temperature sensor or the like.

Fiber-optical grating temperature sensor research is at most, and is widest in area, but because fiber grating is subjected to the influence of temperature and strain simultaneously, also relatively harsher to the application condition, can't use on a large scale.

Chinese patent " photoelectric temperature sensing device " (publication number CN 1548932A, open day on November 24th, 2004) in, disclose and a kind ofly utilized length or two different cylinder top differences in height of thermal expansivity to vary with temperature and different characteristics is made the temperature sensor of optical attenuation formula, though this scheme has avoided the light grating to be subjected to the influence of temperature and strain simultaneously, but it is very big that this scheme is influenced by vibration, the stability of light source of external environment.

4598996 of U.S. Patent No.s adopt birefringece crystal, utilize the temperature variant characteristic of double refractive inde of crystal, mode detecting temperature by strength investigation, this scheme adopts full fixed part, not influenced by extraneous vibration, measurement temperature range height, have nothing to do or the like with strain, have broad application prospects, but, this scheme must be selected specific birefringece crystal for use, the phase differential that birefringence causes in the time of can't fundamentally eliminating temperature variation is to the influence of different wave length, thereby makes temperature detection accuracy variation, simultaneously, the mode of strength investigation makes result of detection be subjected to light source stability, detector sensitivity, polarization scrambling, the influence of factors such as detector is aging makes that long-term detection stability is not enough.In order to address this problem, world patent WO93/11412 adopts the method for measuring interference fringe, and the La that utilizes high-temperature to put mutually ₂Be ₂O ₅Crystal has realized in 1000 ℃ ± measurement of 1 ℃ of precision that still, this scheme needs complicated interference fringe analysis device, and cost is high.

In addition, above-mentioned U.S. Patent No. 4598996 and world patent WO93/11412 also do not consider the variation of the phase differential that the thermal expansion of crystal causes, and cause the temperature detecting error big.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, the fibre optic temperature sensor of a kind of interference of based thin film cheaply or birefringece crystal principle of interference is provided.Principal feature of the present invention is: (one) utilizes the narrow-band light source that adopts the industry maturation, utilizes measurement to measure temperature by the mode of the intensity contrast of flashlight before and after the responsive to temperature unit, need not use complicated interference fringe analysis device; (2) can adopt film to replace birefringece crystal, realize surveying, overcome the influence that polarization disturbs based on the responsive to temperature unit that interferes; (3) birefringece crystal is not had special requirement, it is different and different with temperature to allow different wave length to pass through behind the birefringece crystal pairwise orthogonal polarized light phase differential; (4) use the narrow-band light source of optical communication industry maturation, be convenient to the cost degradation and the practicability of sensor.

Photoelectric temperature sensing device of the present invention is made up of passive temperature-sensitive probe, Transmission Fibers and Photoelectric Signal Processing unit.Described passive temperature-sensitive probe comprises transmission-type and reflective two kinds.

The passive temperature-sensitive probe of transmission-type is to be connected in sequence by collimating apparatus (4), responsive to temperature unit (5) and collimating apparatus (6); Described responsive to temperature unit (5) can be enamel-Po (F-P) interference thin film, also can constitute by the polarizer (11), birefringece crystal (12) and analyzer (13), wherein, the polarizer (11) rise folk prescription to the analyzing direction of analyzer (13) must not be parallel or vertical with the optical axis direction of birefringece crystal (12), and rise folk prescription to and the analyzing angular separation between 0 °～90 °; The wavelength that the light source of photoelectricity processing unit (1) sends is after the flashlight of λ passes through Transmission Fibers (2), enter collimating apparatus (4), light behind the collimation incides responsive to temperature unit (5), here, flashlight is subjected to the modulation of temperature signal, flashlight after the modulation enters the photo-detector (8) of photoelectricity processing unit by collimating apparatus (6), Transmission Fibers (7), utilizes the mode of measuring the intensity contrast by responsive to temperature unit (5) front and back flashlight to separate and reads temperature information;

Here, if responsive to temperature unit (5) adopts interference thin film, then described Transmission Fibers (2) and (7) can be non-polarization maintaining optical fibres, also can be polarization maintaining optical fibres; If when responsive to temperature unit (5) adopted birefringece crystal, described Transmission Fibers (2) and (7) were polarization maintaining optical fibre, disturb with the polarization of eliminating circuit.

Reflective passive responsive to temperature unit is to be connected in sequence by collimating apparatus (4), responsive to temperature unit (5) and reverberator (10); Described responsive to temperature unit can be enamel-Po (F-P) interference thin film, also can constitute by the polarizer (11) and birefringece crystal (12), wherein, the polarizer (11) play folk prescription to must not be parallel or vertical with the optical axis direction of birefringece crystal (12); The wavelength that the light source of photoelectricity processing unit (1) sends is that the flashlight of λ passes through light directional transmissions device (9), after passing to Transmission Fibers (2), enter collimating apparatus (4), light behind the collimation incides responsive to temperature unit (5), here, flashlight is subjected to the modulation of temperature signal, flashlight after the modulation is by reverberator (10) reflection, once more by responsive to temperature unit (5), collimating apparatus (4) and Transmission Fibers (2), enter light directional transmissions device (9), arrive the photo-detector (8) of photoelectricity processing unit, utilize measurement to separate and read temperature information by the mode of the intensity contrast of flashlight before and after the responsive to temperature unit (5);

Here, when if responsive to temperature unit (5) adopts interference thin film or adopts birefringece crystal the polarizer (11) for light rises inclined to one side beam splitter, described Transmission Fibers (2) can be non-polarization maintaining optical fibre, it also can be polarization maintaining optical fibre, if responsive to temperature unit (5) adopts birefringece crystal, and when the polarizer (11) was light polarization plate, described Transmission Fibers (2) was a polarization maintaining optical fibre, disturbed with the polarization of eliminating circuit.

The temperature modulation of responsive to temperature of the present invention unit is achieved by following technical proposals.

When responsive to temperature unit adopts film,, cause light can change with variation of temperature, thereby make interference fringe receive the modulation of temperature in the optical path difference of the two-beam of two surperficial outgoing of film because film can expand with heat and contract with cold with temperature.Here, be the narrow-band light source of λ because light source is a wavelength, show as to vary with temperature and change by the signal light intensity behind the film, therefore, by measuring the Temperature numerical that the signal light intensity that sees through behind the film just can calculate reality.

Unit adopts the polarizer when responsive to temperature, when birefringece crystal and analyzer combine, light source is by the light of remaining particular polarization behind the polarizer, pass through birefringece crystal then, with the photolysis of particular polarization is the light of two bundle cross polarizations, this two-beam during by birefringece crystal because different refractive indexes produces certain optical path difference, once more by behind the analyzer, only remaining have the two-beam of the identical polarization direction of having of specific light path difference component and produce interference, here, the refractive index of birefringece crystal varies with temperature and changes, simultaneously, birefringece crystal has certain thermal expansivity, its length variations also varies with temperature and changes, thereby make the optical path difference of two-beam be subjected to the modulation of temperature variation, cause by behind the analyzer, the interference fringe of the two-beam of identical polarized component is received the modulation of temperature, when light source is that wavelength is when being the narrow-band light source of λ, show as to vary with temperature and change by the signal light intensity after the responsive to temperature unit, therefore, just can calculate actual Temperature numerical by measuring through the signal light intensity after the responsive to temperature unit.

Because the present invention uses the narrow-band light source of wavelength as λ, see through responsive to temperature unit front and back intensity variations as the reference signal of measuring temperature by measuring, can realize the measurement of temperature very easily, in addition, by the reasonable disposition to responsive to temperature unit and transmission fibre type, the influence that can peel off polarization noise.Responsive to temperature of the present invention unit does not have movable part, belongs to pure passive structures, and environment is insensitive to external world, can use in rugged environments such as high voltage, high temperature, high humidity, high dust.

Description of drawings

Accompanying drawing 1: the structure principle chart of transmission-type photoelectric temperature sensing device

Accompanying drawing 2: the structure principle chart of reflection-type photoelectricity formula temperature sensing device

Accompanying drawing 3: transmission-type adopts the responsive to temperature meta structure figure of birefringece crystal

Accompanying drawing 4: reflection-type adopts the responsive to temperature meta structure figure of birefringece crystal

Accompanying drawing 5: light polarization direction is by the evolution diagram of the polarizer, birefringece crystal and analyzer in the transmission-type photoelectric temperature sensing device

Accompanying drawing 6: light polarization direction is by the polarizer, birefringece crystal and the evolution diagram by the polarizer once more in reflection-type photoelectricity formula temperature sensing device

Among accompanying drawing 7: the embodiment 1, wavelength X ₀During for 1600nm, contrast η and temperature variation graph of a relation

Pass through the temperature variant deflection graph of transmission peak value wavelength of sapphire crystal among accompanying drawing 8: the embodiment 1

Among accompanying drawing 9: the embodiment 2 under the normal temperature flashlight by the light intensity contrast ratio η before and after the sapphire crystal and the relation of wavelength

Among accompanying drawing 10: the embodiment 2, wavelength X ₀During for 1560nm, contrast η and temperature variation graph of a relation

Embodiment

Below, in conjunction with the accompanying drawings, be example with the responsive to temperature unit that adopts birefringece crystal, the invention will be further described.

Embodiments of the invention 1 are the transmission-type photoelectric temperature sensing device, and relevant drawings is 1,3 and 5, and the light intensity of sending from light source 1 is I ₀Wavelength is the flashlight of λ, by entering the polarizer 11 formation polarization directions after polarization maintaining optical fibre 2 and the collimating apparatus 4 is P1, amplitude is the linearly polarized light of A1, vertical by birefringece crystal 12, it is orthogonal to be decomposed into two bundle polarization directions, but ordinary light that light path is identical (amplitude is Ao) and extraordinary ray (amplitude is Ae), suppose this moment the optical axis direction C of birefringece crystal and the angle of the polarization direction P1 of the polarizer 11 be α, two bundle ordinary lights and extraordinary ray are by behind the analyzer 13, the polarized component of two-beam realizes interfering on the P2 of the polarization direction of analyzer 13, in order to allow interference effect reach best, the angle that makes P1 and P2 is 90 °, at this moment, the polarisation of light direction develops as shown in Figure 5:

The amplitude of ordinary light:

Ao＝A1sinα (1)

The amplitude of extraordinary ray:

Ae＝A1cosα (2)

By the ordinary light components of analyzer 13 back on the P2 of polarization direction:

A2o＝A1sinαcosα (3)

By the extraordinary ray components of analyzer 13 back on the P2 of polarization direction:

A2e＝A1sinαcosα (4)

Ordinary light and the extraordinary ray phase differential after by birefringece crystal is:

$\mathrm{\Δ\φ}=\frac{2\mathrm{\πd}}{\mathrm{\λ}}\mathrm{\Δn}+\mathrm{\π}---\left(5\right)$

Here, d is the length of birefringece crystal, and Δ n is the refringence of extraordinary ray and ordinary light in the birefringece crystal, and λ is the incident light wavelength, has also added in the phase differential because the additional phase error π that A2o and A2e projection produce.

Usually, the temperature linearity characteristic for the birefringence rate variance of birefringece crystal has:

Δ(Δn)＝kΔT (6)

Wherein, k is a specific constant, corresponding different birefringece crystals, and Δ T is the temperature variation of birefringece crystal.

In addition, the thermal expansivity of birefringece crystal is β, and then the birefringece crystal length d with the variation of temperature rate is:

Δd＝dβΔT (7)

Can get according to formula (5), (6) and (7), behind the temperature variation Δ T, the phase differential of crystal is:

$\mathrm{\Δ\φ}=\frac{2\mathrm{\πd}}{\mathrm{\λ}}(1+\mathrm{\β\ΔT})(\mathrm{\Δn}+\mathrm{k\ΔT})+\mathrm{\π}---\left(8\right)$

Consider that k and β are very little, formula (8) can be approximately:

$\mathrm{\Δ\φ}=\frac{2\mathrm{\πd}}{\mathrm{\λ}}[\mathrm{\Δn}+(k+\mathrm{\β\Δn})\mathrm{\ΔT}]+\mathrm{\π}---\left(9\right)$

Unite with following formula (1) and can get the output intensity I behind the analyzer 13 to formula (9) ₁For:

$I_1=\frac{I_0}{4}(1-\cos \{\frac{2\mathrm{\πd}}{\mathrm{\λ}}[\mathrm{\Δn}+(k+\mathrm{\β\Δn})\mathrm{\ΔT}]\left\}\right){\sin }^{2}2\mathrm{\α}---\left(10\right)$

In order to strengthen the brilliant intensity of interfering of birefringence, allow the optical axis direction of crystal and the polarizer polarization direction angle α be 45 °, then formula (11) becomes:

${\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="A20071005129600132.png,A20071005129600152.png"\; state="\{\{state\}\}">I</figure-callout>}}_1=\frac{I_0}{4}(1-\cos \{\frac{2\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]\left\}\right)---\left(11\right)$

Then the contrast η by flashlight light intensity before and after the responsive to temperature unit is:

$\mathrm{\&eta;}=\frac{1}{4}(1-\cos \{\frac{2\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]\left\}\right)---\left(12\right)$

By formula (12) as can be seen, when light intensity contrast ratio η was maximum, phase difference φ satisfied:

$\frac{2\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]=(2m+1)\mathrm{\&pi;}---\left(13\right)$

And light intensity contrast ratio η is hour, and phase difference φ satisfies:

$\frac{2\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]=\left(2m\right)\mathrm{\&pi;}---\left(14\right)$

Wherein, m is an integer.

According to formula (13) and (14), can draw measurable range of temperature Δ T in a monotony interval ¹For:

${\mathrm{\&Delta;<figure-callout\; id="1"\; label="T"\; filenames="A20071005129600132.png,A20071005129600152.png"\; state="\{\{state\}\}">T</figure-callout>}}^1=\frac{\mathrm{\&lambda;}}{2d(k+\mathrm{\&beta;\&Delta;n})}---\left(15\right)$

Therefore, for selected crystal, d, k, β, Δ n etc. are constants, so we can measure temperature by measuring the light intensity contrast ratio η that sees through responsive to temperature unit front and back very easily.

If birefringece crystal is selected the long sapphire crystal of d=2mm for use, according to the characteristic of sapphire crystal: k=5.8*10 ^-7/ K, β=5*10 ^-6Δ n=0.008 under/K and the room temperature can calculate the relation by light intensity contrast ratio η before and after the responsive to temperature unit and wavelength of flashlight under the normal temperature, and as shown in Figure 7, wherein horizontal ordinate is a wavelength, and the nm of unit, ordinate are normalized light intensity contrast ratio η, and peak value is 1.

Choose the wavelength X of a contrast minimum among Fig. 7 ₀Be 1600nm, according to formula (15), then observable maximum temperature variation range is Δ T=645.16 ℃, and Fig. 8 is a wavelength X ₀During for 1600nm, contrast η and temperature variation relation, the temperature of horizontal ordinate wherein for changing, unit be ℃, ordinate is for by the front and back flashlight light intensity contrast ratio η of responsive to temperature unit.If light intensity detection accuracy 0.001mw, then the detection accuracy of temperature can reach 1 ℃.The length d of suitable selection sapphire crystal and peak wavelength λ ₀, detectable maximum temperature surpasses 2000 ℃, and wherein detection accuracy is in 1 ℃.

Embodiments of the invention 2 are reflection-type photoelectricity formula temperature sensing device, and relevant drawings is 2,4 and 6.The light intensity of sending from light source 1 is I ₀Wavelength is the flashlight of λ, by light directional transmissions device 9, entering the polarizer 11 formation polarization directions after Transmission Fibers 2 and the collimating apparatus 4 is P1, amplitude is the linearly polarized light of A1, vertical by birefringece crystal 12, it is orthogonal to be decomposed into two bundle polarization directions, but ordinary light that light path is identical (amplitude is Ao) and extraordinary ray (amplitude is Ae), suppose this moment the optical axis direction C of birefringece crystal and the angle of the polarization direction P1 of the polarizer 11 be α, two bundle ordinary lights and extraordinary ray are by reverberator 10 reflected back birefringece crystals 12, once more by the polarizer 11, the polarized component of two-beam realizes interfering on the P1 of the polarization direction of the polarizer 11, at this moment, the polarisation of light direction develops as shown in Figure 8:

By the ordinary light components of analyzer 13 back on the P2 of polarization direction:

A2o＝A1sin ²α (16)

By the extraordinary ray components of analyzer 13 back on the P2 of polarization direction:

A2e＝A1cos ²α (17)

Ordinary light and the extraordinary ray phase differential after by birefringece crystal is:

$\mathrm{\&Delta;\&phi;}=\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}\mathrm{\&Delta;n}---\left(18\right)$

The phase differential that association type (6), (7) and (18) can get behind the temperature variation Δ T is:

$\mathrm{\&Delta;\&phi;}=\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]---\left(19\right)$

Can get the output intensity I behind the polarizer 11 by formula (15), (16) and (18) ₂For:

$I_2=\frac{I_0}{2}-\frac{{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="A20071005129600152.png,A20071005129600161.png"\; state="\{\{state\}\}">I</figure-callout>}}_0}{4}(1-\cos \{\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]\left\}\right){\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A20071005129600131.png,A20071005129600132.png"\; state="\{\{state\}\}">sin</figure-callout>}}^{2}2\mathrm{\&alpha;}---\left(20\right)$

In order to strengthen the brilliant intensity of interfering of birefringence, allow the optical axis direction of crystal and the polarizer polarization direction angle α be 45 °, then formula (20) becomes:

$I_2=\frac{I_0}{4}(1+\cos \{\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]\left\}\right)---\left(21\right)$

Then the contrast η by flashlight light intensity before and after the responsive to temperature unit is:

$\mathrm{\&eta;}=\frac{1}{4}(1+\cos \{\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]\left\}\right)---\left(22\right)$

By formula (22) as can be seen, when light intensity contrast ratio η was maximum, phase difference φ satisfied:

$\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]=\left(2m\right)\mathrm{\&pi;}---\left(23\right)$

And light intensity contrast ratio η is hour, and phase difference φ satisfies:

$\frac{4\mathrm{\&pi;d}}{\mathrm{\&lambda;}}[\mathrm{\&Delta;n}+(k+\mathrm{\&beta;\&Delta;n})\mathrm{\&Delta;T}]=(2m+1)\mathrm{\&pi;}---\left(24\right)$

Wherein, m is an integer.

According to formula (23) and (24), can draw measurable range of temperature Δ T in a monotony interval ¹For:

${\mathrm{\&Delta;<figure-callout\; id="1"\; label="T"\; filenames="A20071005129600132.png,A20071005129600152.png"\; state="\{\{state\}\}">T</figure-callout>}}^1=\frac{\mathrm{\&lambda;}}{4d(k+\mathrm{\&beta;\&Delta;n})}---\left(25\right)$

Therefore, for selected crystal, d, k, β, Δ n etc. are constants, so we can measure temperature by measuring the light intensity contrast ratio η that sees through responsive to temperature unit front and back very easily.

If birefringece crystal is selected the long sapphire crystal of d=2mm for use, according to the characteristic of sapphire crystal: k=5.8*10 ^-7/ K, β=5*10 ^-6Δ n=0.008 under/K and the room temperature can calculate the relation by light intensity contrast ratio η before and after the responsive to temperature unit and wavelength of flashlight under the normal temperature, and as shown in Figure 9, wherein horizontal ordinate is a wavelength, and the nm of unit, ordinate are normalized light intensity contrast ratio η, and peak value is 1.

Choose the wavelength X of a contrast minimum among Fig. 9 ₀Be 1560nm, according to formula (25), then observable maximum temperature variation range is Δ T=314.52 ℃, and Figure 10 is a wavelength X ₀During for 1560nm, contrast η and temperature variation relation, the temperature of horizontal ordinate wherein for changing, unit be ℃ that ordinate is the light intensity contrast ratio η by responsive to temperature unit front and back flashlight.If light intensity detection accuracy 0.001mw, then the detection accuracy of temperature can reach 1 ℃.The length d of suitable selection sapphire crystal and peak wavelength λ ₀, detectable maximum temperature surpasses 2000 ℃, and wherein detection accuracy is in 1 ℃.

Principle of interference based on birefringece crystal, mode detecting temperature with strength investigation, the temperature investigative range depends on the dissimilar crystal and the thickness of crystal, the detection accuracy of temperature depends on the detection accuracy of signal light power, shown in above-mentioned embodiment 1 and embodiment 2, temperature is surveyed and can be reached more than 2000 ℃, and the temperature detection accuracy is about 1 ℃.

Claims (10)

1. the photoelectric temperature sensing device based on interference comprises passive temperature-sensitive probe, Transmission Fibers and Photoelectric Signal Processing unit, it is characterized in that:

Described passive temperature-sensitive probe comprises transmission-type and reflective two kinds: the passive temperature-sensitive probe of transmission-type is to be connected in sequence by collimating apparatus (4), responsive to temperature unit (5) and collimating apparatus (6); Described responsive to temperature unit (5) can be enamel-Po (F-P) interference thin film, also can constitute by the polarizer (11), birefringece crystal (12) and analyzer (13), wherein, the polarizer (11) rise folk prescription to the analyzing direction of analyzer (13) must not be parallel or vertical with the optical axis direction of birefringece crystal (1 2), and rise folk prescription to and the analyzing angular separation between 0 °～90 °; The wavelength that the light source of Photoelectric Signal Processing unit (1) sends is after the flashlight of λ passes through Transmission Fibers (2), enter collimating apparatus (4), flashlight behind the collimation incides responsive to temperature unit (5), here, be subjected to the modulation of temperature by the flashlight light intensity after the responsive to temperature unit (5), flashlight after the modulation enters the photo-detector (8) of photoelectricity processing unit by collimating apparatus (6), Transmission Fibers (7), measures temperature according to the intensity contrast of measuring by responsive to temperature unit (5) front and back flashlight;

Reflective passive responsive to temperature unit is to be connected in sequence by collimating apparatus (4), responsive to temperature unit (5) and reverberator (10); Described responsive to temperature unit can be enamel-Po (F-P) interference thin film, also can constitute by the polarizer (11) and birefringece crystal (12), wherein, the polarizer (11) play folk prescription to must not be parallel or vertical with the optical axis direction of birefringece crystal (12); The wavelength that the light source of Photoelectric Signal Processing unit (1) sends is that the flashlight of λ passes through light directional transmissions device (9), after passing to Transmission Fibers (2), enter collimating apparatus (4), light behind the collimation incides responsive to temperature unit (5), here, be subjected to the modulation of temperature by the flashlight light intensity after the responsive to temperature unit (5), flashlight after the modulation is by reverberator (10) reflection, once more by responsive to temperature unit (5), collimating apparatus (4) and Transmission Fibers (2), enter light directional transmissions device (9), arrive the photo-detector (8) of photoelectricity processing unit, measure temperature according to the intensity contrast of measuring by flashlight before and after the responsive to temperature unit (5).

2. photoelectric temperature sensing device according to claim 1 is characterized in that, described temperature detection method is to measure temperature according to the intensity contrast of measuring by flashlight before and after the responsive to temperature unit (5).

3. photoelectric temperature sensing device according to claim 1 is characterized in that, the light source (1) of described Photoelectric Signal Processing unit is a narrow-band light source, and the 3dB live width is in 0.1nm.

4. photoelectric temperature sensing device according to claim 1 is characterized in that, described responsive to temperature unit (5) can be enamel-Po (F-P) interference thin film.

5. photoelectric temperature sensing device according to claim 1 is characterized in that, described responsive to temperature unit (5) can be that the polarizer, birefringece crystal and analyzer constitute.

6. responsive to temperature unit according to claim 5 (5) is characterized in that, described birefringece crystal can be that one or more identical birefringece crystal constitutes, and also can be that the different birefringece crystal of polylith constitutes.

7. according to claim 1,5 and 6 described photoelectric temperature sensing devices, it is characterized in that, the optical axis direction angle at 45 of polarization direction behind the light transmission polarizer (11) and birefringece crystal (12), and play folk prescription to become 0 ° or 90 ° of angles with the analyzing direction.

8. according to claim 1,5,6 and 7 described photoelectric temperature sensing devices, it is characterized in that the described polarizer (11) or analyzer (13) can be light polarization plates, also can be that light plays inclined to one side beam splitter.

9. photoelectric temperature sensing device according to claim 1, it is characterized in that, when adopting the passive temperature-sensitive probe of transmission-type, if responsive to temperature unit (5) adopts interference thin film, then described Transmission Fibers (2) and (7) can be non-polarization maintaining optical fibres, also can be polarization maintaining optical fibres; If when responsive to temperature unit (5) adopted birefringece crystal, described Transmission Fibers (2) and (7) were polarization maintaining optical fibre.

10. photoelectric temperature sensing device according to claim 1, it is characterized in that, when adopting reflective passive temperature-sensitive probe, when if responsive to temperature unit (5) adopts interference thin film or adopts birefringece crystal the polarizer (11) for light rises inclined to one side beam splitter, described Transmission Fibers (2) can be non-polarization maintaining optical fibre, also can be polarization maintaining optical fibre, if responsive to temperature unit (5) adopts birefringece crystal, and when the polarizer (11) was light polarization plate, described Transmission Fibers (2) was a polarization maintaining optical fibre.

Images