CN107560738B - A kind of laser beam deviation means for correcting based on dichroic light splitting - Google Patents
A kind of laser beam deviation means for correcting based on dichroic light splitting Download PDFInfo
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Abstract
The present invention proposes a kind of laser beam deviation means for correcting based on dichroic light splitting, this method mainly comprises the steps that infrared laser light source and near-infrared laser light source launch amplitude phase triangular signal all the same, infrared laser is a branch of to be used as reference signal I by being divided into two beams after fiber optic splitter1, another beam after fiber coupler through collimator with near-infrared laser by being emitted, and emergent light is irradiated to dichroic light splitting piece after passing through tested flame, and infrared laser reaches infrared laser detecting device 401 with 45 degree of angle of reflection and obtains laser signal I2, and near-infrared laser obtains laser signal I by the detection of near-infrared laser detector 402 through light splitting piece3, utilize the influence of absorption and deviation relationship elimination laser deviation between three laser signals.It is the configuration of the present invention is simple, easy to operate, there is important broad application prospect in combustion diagnosis with laser field.
Description
(1) technical field
The present invention relates to a kind of laser beam deviation means for correctings based on dichroic light splitting, and in particular to uses dichroic
The test light on same path and calibration light are realized while being detected to light splitting piece, corrects test light using calibration light, to solve to swash
The deflection of light problem as caused by refraction when light passes through flame.
(2) background technique
The efficient diagnosis of burning suffers from very the various aspects such as industry security production, energy-saving and emission-reduction, scientific research
Important role not only may be used for example, effectively being monitored on-line to aeroengine combustor buring indoor temperature field and Gas Components
Effective reference frame is provided with the design for aeroengine combustor buring room, also can use gained measurement data to aeroplane engine
The theoretical model of machine combustion chamber is verified and is corrected.Contact can be mainly divided into the measurement method of combustion parameter and non-connect
Two class of touch, common contact have thermocouple thermometry, gas alloying apparatus etc., and contactless mainly includes acoustic method, spectroscopic methodology
Deng.Contact measurement method low-response, meeting stream field impacts, in addition, with the development of combustion technology, flame temperature is more next
The higher demand for making contact measurement method be no longer satisfied real process；Acoustic method is by combustion field endoparticle, air-flow
Disturbing factor is affected, and anti-interference ability is poor；In contrast, laser-diagnose technology due to not contacted with measured medium, ring
The advantages that answering speed fast and be widely used.In recent years, laser inductive fluorescence method (LIF, Laser Induced
Fluorescence), coherent anti-stokes raman scattering spectroscopic methodology (CARS, Coherent Anti-stokes Raman
Spectroscopy), the optical diagnostic methods such as Laser absorption spectroscopy (LAS, Laser Absorption Spectroscopy)
It is widely applied to the measurement of the parameters such as combustion flame temperature, Gas Components.Wherein, Laser absorption spectroscopy has structure letter
List, measuring speed is fast, measurement accuracy is high, high reliability, is with a wide range of applications in combustion diagnosis field.
Laser absorption spectroscopy measurement temperature principle is: being exported and is swashed using sawtooth signal modulation tunable laser diodes
Light, is allowed to inswept entire absorption line shape, and laser absorbs then arrival detector photosurface by specific molecular first by flame and obtains
To intensity signal.When data processing, integral absorptivity is obtained by integrating entire absorption line shape, and then calculate temperature and gas
Concentration.Therefore, can the intensity signal that accurately obtain after flame be the key that Laser absorption spectroscopy.Flame reaction area
For high-temperature region, internal composition and its density are constantly changing, therefore irregular variation occurs at any time for refractive index, makes
When measuring flame inside parameter with Laser absorption spectroscopy, deflection of light effect can occur for laser, cause arrival detector photosensitive
The laser spot in face constantly shakes, and irregular variation occurs at any time for the light intensity signal that detector detects, and ties to measurement
Fruit causes serious influence.When the strong flame of the pulsation such as measurement aero-engine swirl flame, flame inside density of fraction
Variation is more violent, causes light intensity signal variation serious, or even cause measurement that can not carry out.
Diffraction dispersion occurs when in order to overcome laser to pass through flame, some researchers propose to make laser through over-firing both at home and abroad
Method (Almodovar C A, Spearrin R M, the Hanson R that integrating sphere is received by a detector again is introduced into after flame
K.Two-color laser absorption near 5μm for temperature and nitric oxide
sensing in high-temperature gases[J].Journal of Quantitative Spectroscopy and
Radiative Transfer,2017；H Yang.Tunable diode-laser absorption-based sensors
for the detection of water vapor concentration,film thickness and temperature
[D].Duisburg-Essen,2012；Yang Huinan, Guo Xiaolong, Su Mingxu, Cai little Shu are based on TDLAS technology and exist
Line measures liquid film dynamic thickness [J] Chinese laser in flow channel, 2014,41 (12): 211-216.).Integrating sphere is an inner wall
The hollow spheres of diffusive white reflective material are coated with, the laser into integrating sphere passes through inner wall multiple reflections, finally on inner wall
Even distribution, it can be ensured that remained unchanged by the laser intensity that integrating sphere reaches detector photosurface.However, due to by integrating
Laser is evenly distributed on entire ball inner wall after ball, and the laser signal that detector detects can become very weak, it is difficult to effectively be visited
It surveys, in addition, the multiple reflections in integrating sphere, which are equivalent to, increases laser light path, and laser may also have suction in integrating sphere
It receives, this can impact measurement result.Stanford University professor Hansen etc. designs the non-sensitive ray-collecting system of deflection of light
System solves the problems, such as deflection of light (Strand C L.Scanned Wavelength-Modulation Absorption
Spectroscopy with Application to Hypersonic Impulse Flow Facilities[D]
.Stanford University,2014；Goldenstein C S,Schultz I A,Strand C L,et
al.Hypersonic scramjet testing via TDLAS measurements of temperature and
column density in a reflected shock tunnel[C].Aerospace Sciences
Meeting.Maryland,2014).Basic skills is that laser is made to converge to optical fiber by being focused lens first after flame
In, laser reaches detector by optical fiber, however the system difficult design, experimental debugging difficulty is big, in addition, ray-collecting process
Middle intensity loss is larger, is not suitable for industry spot application.Stanford University Ritobrata Sur proposes to increase beam diameter to subtract
Influence (Sur R, Sun K, Jeffries J B, the et al.Scanned-wavelength- of decreased light deviation
modulation-spectroscopy sensor for CO,CO 2,CH 4 and H 2 O in a high-pressure
engineering-scale transport-reactor coal gasifier[J].Fuel,2015,150:102-111.)。
However laser still can be detected by detector after increase beam diameter can only ensure deflection of light, but due to beam cross section
Face laser intensity distribution is uneven, and the light intensity shake that laser deviation still can be such that detector detects, practical there is no solve light
Line segregation problem.Therefore, existing method cannot all efficiently solve deflection of light problem, in order to carry out to flame inside parameter
Effectively measurement, meets industrial development demand, needs a kind of new method that can fundamentally solve the problems, such as deflection of light.
The present invention calibrates test light using calibration light, exports triangular signal to sharp using signal generator first
Optical controller, laser controller make Near-infrared Tunable laser and infrared laser launch amplitude phase triangle all the same
Wave signal, infrared laser is divided into two beams by fiber optic splitter, a branch of directly to be detected by photodetector 403 without flame
To reference signal I1；Another beam and near-infrared laser are emitted after fiber coupler through collimator, emergent light by flame it
Afterwards, it is irradiated to dichroic beamsplitter surface with 45 degree, infrared laser reaches infrared detector 401 with 45 degree of angle of reflection and obtains
Laser signal I2, and near-infrared laser reaches near infrared detector 402 through dichroic light splitting piece and obtains laser signal I3, thus
It realizes while detecting near-infrared laser and infrared laser on same path and separate.The near-infrared laser as used in LAS can be fired
Product is burnt to absorb, and the infrared laser selected will not be then absorbed, therefore infrared laser is only influenced by deflection of light, it can be with
Utilize the influence of absorption and deviation relationship elimination laser deviation between three laser signals.
(3) summary of the invention
The present invention proposes a kind of laser beam deviation means for correcting based on dichroic light splitting, is made using dichroic light splitting piece
Different wave length laser on same path separates, to detect the infrared laser and near-infrared for passing through flame along same path simultaneously
Laser is modified near-infrared laser signal using infrared laser signal, realizes that eliminating deflection of light effect causes measurement
Influence.
Element used includes: signal generator, near-infrared laser controller, infrared laser controller, Near-infrared Tunable
Laser light source, infrared laser light source, fiber coupler, fiber optic splitter, collimator, dichroic light splitting piece and photodetector.
The technical solution adopted by the present invention is that: infrared laser and near-infrared laser under identical laser control signal,
With the output of identical triangular wave light intensity signal, infrared laser is a branch of without flame by being divided into two beams after fiber optic splitter
Reference signal is directly used as by detector detection；Another way is incident with 45 degree by flame after coupling with near-infrared laser signal
Dichroic light splitting piece surface is incident at angle, and infrared laser is reached on infrared laser detecting device with 45 degree of angle of reflection, and close red
Outer laser light light splitting piece is detected by near-infrared laser detector, to detect the infrared laser light after flame simultaneously
Strong signal and near-infrared laser light intensity signal.Infrared laser will not be burned product absorption, therefore can be from by after flame
Infrared laser signal and reference signal obtain the influence of deflection of light effect, and then near-infrared laser signal is modified,
Eliminate the influence of deflection of light.
The present invention has the advantages that 1. present invention are realized using light splitting piece detects the sharp of different wave length on same path simultaneously
Optical signal will not make the laser intensity reached on detector photosurface die down, facilitate detection；2. laser signal is by dichroic point
It is detected after mating plate by detector, laser path is not obviously prolonged, and avoids traditional quadrature ball method multiple reflection inside band
The laser absorption come is influenced caused by measurement result.
(4) Detailed description of the invention
The present invention will be further described with reference to the accompanying drawings and detailed description.
Fig. 1 is light path principle figure of the invention；
Fig. 2 is by the infrared laser signal before flame；
Fig. 3 is by near-infrared laser signal before flame；
Fig. 4 is by the infrared laser signal after flame；
Fig. 5 is by the near-infrared laser signal after flame；
Fig. 6 is the near-infrared laser signal after amendment.
Attached drawing mark
101: Near-infrared Tunable laser, 102: infrared laser, 201,202: collimator, 301: dichroic light splitting
Piece, 402: near-infrared laser detector, 401,402: infrared laser detecting device.
(5) specific embodiment
In Fig. 1, near-infrared laser and infrared laser after overcoupling by collimator 201 through being projected, with 45 degree of incidence angle
It is incident on 301 surface of dichroic light splitting piece, reflection light is vertical with incident ray and is received by infrared laser detecting device 401, closely
Infrared laser detecting device is located at after dichroic light splitting piece, for detecting the near-infrared laser of transmission, is projected by collimator 202
Infrared laser is directly received by detector 403 without flame, as reference light intensity signal.
Step 1: signal generator exports identical triangular signal and controls to near-infrared laser controller and infrared laser
Device makes near infrared laser and infrared laser launch amplitude phase triangular signal all the same；
Step 2: infrared laser is divided into two beams by fiber optic splitter, a branch of to pass through fiber coupler with near-infrared laser
It is emitted by collimator 201, the direct outgoing of collimator 202 of another way reaches detector 403, obtains without the infrared of flame
Laser signal (see Fig. 2) is denoted as I as light intensity signal is referred to1；
Step 3: the laser emitted by collimator 201 is by flame with 45 degree of incident angles to dichroic light splitting piece table
On face, infrared laser is reached on infrared laser detecting device 401 with 45 degree of angle of reflection, and near-infrared laser is then arrived across light splitting piece
Up on near-infrared laser detector 402, infrared laser light intensity signal (see Fig. 4) and close is just obtained after flame simultaneously in this way
Infrared laser light intensity signal (see Fig. 5), is denoted as I respectively2With I3；
Step 4: reference optical signal, the infrared laser signal after flame, near-infrared laser signal are utilized respectively
Formula (1) is normalized:
Wherein, Ii(i=1,2 or 3) are original laser signal, Iimin、IimaxRespectively the minimum value of original laser signal with
Maximum value, Ii1For the laser signal after normalization.
Step 5: the Diffraction dispersion of laser light-intensity variation Δ I caused by signal can be obtained by formula (2):
Δ=I21-I11 (2)
Wherein, I11、I21Without flame and by the infrared laser signal of flame after respectively normalizing.
Step 6: the near-infrared laser signal I after correcting can be obtained by following formula:
I=I31-ΔI (2)
Fig. 6 be it is corrected after near-infrared laser signal, show that the present invention can overcome flame Diffraction dispersion to bring
Influence, and then utilize LAS principle carry out flame parameters accurate measurement.
Claims (3)
1. a kind of laser beam deviation means for correcting based on dichroic light splitting, including the control of signal generator, near-infrared laser
Device, infrared laser controller, Near-infrared Tunable laser light source, infrared laser light source, fiber coupler, fiber optic splitter, standard
Straight device, dichroic light splitting piece and photodetector, which is characterized in that infrared laser is divided into two beams by fiber optic splitter, a branch of
As reference, another beam after fiber coupler through collimator with near-infrared laser by being emitted, and emergent light is after tested flame
It is irradiated to dichroic light splitting piece, infrared laser detecting device is placed on reflection light path, and near-infrared laser detector is placed in
On transmitted ray path, the influence of absorption and deviation relationship elimination laser deviation between three laser signals is utilized.
2. a kind of laser beam deviation means for correcting based on dichroic light splitting according to claim 1, which is characterized in that red
Outer laser light source and Near-infrared Tunable laser light source launch amplitude phase triangular signal all the same, and infrared laser passes through
Fiber optic splitter is divided into two beams, a branch of directly to obtain reference signal I by photodetector (403) detection without flame1；It is another
Beam coupled with near-infrared laser after by flame, be then irradiated on dichroic light splitting piece with 45 degree of incidence angles, infrared laser with
45 degree of angle of reflection reach infrared detector (401) and obtain laser signal I2, near-infrared laser reaches close red through light splitting piece
External detector (402) obtains laser signal I3。
3. a kind of laser beam deviation means for correcting based on dichroic light splitting according to claim 2, which is characterized in that institute
It states infrared laser not to be absorbed across flame, light intensity signal is only influenced by deflection of light effect, therefore produced by flame
Diffraction dispersion light-intensity variation Δ I caused by signal be formula (1):
Δ I=I21-I11 (1)
Wherein, I11、I21Without flame and by the infrared laser signal of flame, normalized laser after respectively normalizing
Signal is obtained by formula (2):
Wherein, Ii(i=1,2 or 3) are original laser signal, Iimin、IimaxThe respectively minimum value of original laser signal and maximum
Value, Ii1For the laser signal after normalization, revised near-infrared laser signal I can be obtained by formula (3):
I=I31-ΔI (3)
Wherein, I31For the near-infrared laser signal after normalization, laser is overcome by revised near-infrared laser signal
Diffraction dispersion, and then can use the accurate measurement that laser absorption method principle carries out flame parameters.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103884663A (en) * | 2014-03-19 | 2014-06-25 | 中国人民解放军装备学院 | Two-dimensional reconstruction light distribution optimization method based on laser absorption spectrum technology |
| CN103954588A (en) * | 2014-05-15 | 2014-07-30 | 北京龙源欣盛科技有限公司 | Distributed TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas detection system and method |
| CN103969203A (en) * | 2014-05-15 | 2014-08-06 | 北京龙源欣盛科技有限公司 | Self-calibration method of TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas detection system |
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2017
- 2017-07-12 CN CN201710567248.XA patent/CN107560738B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103884663A (en) * | 2014-03-19 | 2014-06-25 | 中国人民解放军装备学院 | Two-dimensional reconstruction light distribution optimization method based on laser absorption spectrum technology |
| CN103954588A (en) * | 2014-05-15 | 2014-07-30 | 北京龙源欣盛科技有限公司 | Distributed TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas detection system and method |
| CN103969203A (en) * | 2014-05-15 | 2014-08-06 | 北京龙源欣盛科技有限公司 | Self-calibration method of TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas detection system |
Non-Patent Citations (2)
| Title |
|---|
| "Scanned-wavelength-modulation-spectroscopy sensor for CO, CO 2 , CH 4 and H 2 O in a high-pressure engineering-scale transport-reactor coal gasifier";Ritobrata Sur 等;《Fuel》;20150217;102-111页 * |
| "基于TDLAS技术在线测量气流道内液膜动态厚度";杨荟楠 等;《中国激光》;20141231;1208010-1-6页 * |
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