CN204359686U - A kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference - Google Patents
A kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference Download PDFInfo
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- CN204359686U CN204359686U CN201420796280.7U CN201420796280U CN204359686U CN 204359686 U CN204359686 U CN 204359686U CN 201420796280 U CN201420796280 U CN 201420796280U CN 204359686 U CN204359686 U CN 204359686U
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Abstract
The utility model belongs to optical technical field, is specifically related to a kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference.A kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference, by optical fibre Michelson interferometer, precision three-dimensional displacement platform and signal processing unit, be made up of wideband white light source and driver thereof, 3dB fiber coupler, optical fiber collimator, reflective scan mirror, the detection optical fiber with collimating apparatus, photo-detector, signal processing unit, testing fiber prefabricated rods, precision three-dimensional displacement platform.The optical fiber precast rod refractivity profile survey device that the utility model proposes has the advantages such as structure is simple, measurement is convenient, operation adjustment is simple.
Description
Technical field
The utility model belongs to optical technical field, is specifically related to a kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference.
Background technology
Refractive index is a basic parameter of crystal, is the basis of other optical property of research crystal.For same crystal, the refractive index that different wave length is corresponding different, its measured value is most important to device layout.
Optical fiber is as novel light wave transmissions medium, owing to having the performances such as excellent physics, chemistry, machinery, in Modern optical communication and the development of light sensing, there is very important status, and be widely applied in fields such as industrial and agricultural production, scientific research, national defense safety, space technologies.
When manufacturing optical fiber, first will produce preform, the diameter of preform is generally from several millimeters to tens millimeters (being commonly called as optical wand).The inner structure of optical fiber is formed in prefabricated rods, and thus, the performance of prefabricated rods is most important part in optical fiber fabrication technology.Many times, we tentatively will understand the refractive index of preform before drawing optical fiber, and then understood other optical property.Therefore, significant to the research of optical fiber precast rod refractivity measurement mechanism.
As far back as nineteen eighty-two, once someone pointed out to adopt light beam deflectometry to survey the index distribution (optical technology, 1982,01 phase 11-15) of preform, and its measuring method is divided into two parts.Part I is the refractive index value measuring prefabricated rods foreskin, Part II measures the prefabricated rods not having foreskin (prefabricated rods being put into the immersion oil with foreskin index matching), in this step, first need equally to measure light intensity, peak value according to light intensity calculates deflection angle, and then calculates refractive index.As can be seen here, the method measuring process is loaded down with trivial details.First, the immersion oil with index matching be configured, but immersion oil is volatile, so that its refractive index can be changed.And the factor that can have an impact to measurement result is also a lot, such as, very high to the requirement of light beam when measuring light intensity value, require light beam superfine otherwise can error etc. be brought.Publication number is propose a kind of measuring method and the device that adopt fine light beam scanning polymer optical fiber precast rod refractivity in the patent document of CN1776411A.Its measuring method is that light source irradiation is on the side of preform, arrive on the test surface of ccd video camera after the diametric(al) transmission of prefabricated rods, and by related data transmission to computing machine, after utilizing index distribution test procedure to carry out simulating and process, finally demonstrate the refractive index distribution curve of preform on computers.In measuring process, the thin cylinder layer regarded as by preform by a lot of refractive index is different forms, and the problem that therefore has occurs, if hierarchy number very little, because the theory calculate related to is many, error will be larger; If hierarchy number is too many, computer capacity may can be exceeded again.Therefore this kind of precision of method is not very high, and control errors is more complicated also.Consider, the utility model provides a kind of optical fiber precast rod refractivity profile survey device based on the absolute light path relative method of white light interference, and gives its concrete measuring method.
Utility model content
The purpose of this utility model is to provide a kind of easy, stable, reliable optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference.
The purpose of this utility model is achieved in that
A kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference, comprise optical fibre Michelson interferometer, precision three-dimensional displacement platform and signal processing unit, by wideband white light source and driver thereof, 3dB fiber coupler, optical fiber collimator, reflective scan mirror, with the detection optical fiber of collimating apparatus, photo-detector, signal processing unit, testing fiber prefabricated rods, precision three-dimensional displacement platform forms, the a end of 3dB fiber coupler is connected with wideband white light source, b end is connected with optical fiber collimator, reflective scan mirror is placed at the exit end of optical fiber collimator, the c end of fiber coupler is connected with detection optical fiber, the d end of fiber coupler is connected with the receiving end of photo-detector, the output terminal of photo-detector is connected with signal processing unit, the right-hand member of detection optical fiber faces testing fiber prefabricated rods, testing fiber prefabricated rods is fixed on precision three-dimensional displacement platform, the wide spectrum optical that white light source sends is via after the beam splitting of 3dB fiber coupler, light beam is coupled to optical fiber collimator via end, be irradiated to reflective scanning mode mirror, surface is reflected, reflected light gets back to 3dB fiber coupler, another light beam is coupled to detection optical fiber via end, first the reflection end face being irradiated to testing fiber prefabricated rods reflects, reflected light gets back to 3dB fiber coupler equally, after two bundle reflection combiners, received by photo-detector via d end, can obtain after signal processing unit processes signal with reference to interference signal P
1(x, y), reflective scan mirror is distally moved until the light path corresponding to back end reflective signal that reflects light path and prefabricated rods complete equal time, obtain the position P measuring interference signal peak value
2(x, y).
Based on the optical fiber precast rod refractivity profile measuring method of the absolute light path relative method of white light interference, the wide spectrum optical that white light source sends is via after the beam splitting of 3dB fiber coupler, light beam is coupled to optical fiber collimator via b end, be irradiated to reflective scanning mode mirror, reflect on surface, reflected light gets back to 3dB fiber coupler, another light beam is coupled to detection optical fiber via c end, first the reflection end face being irradiated to testing fiber prefabricated rods reflects, reflected light gets back to 3dB fiber coupler equally, after two bundle reflection combiners, received by photo-detector via d end, can obtain after signal processing unit processes signal with reference to interference signal P
1(x, y), reflective scan mirror is distally moved until the light path corresponding to back end reflective signal that reflects light path and prefabricated rods complete equal time, obtain the position P measuring interference signal peak value
2(x, y), in measuring process, the scanning mirror position corresponding to reflected signal of any locus point is all P all mutually
1(0), preform is placed on three-D displacement platform, and the two-dimentional point by point scanning of having been moved preform section by three-D displacement platform in x-y plane is measured, by measuring before and after reflective scanning mode mirror difference DELTA P (x, the y)=P of the locus movement of scanning mirror corresponding to twice interference peak signal
2(x, y)-P
1(0), obtaining and pass this some transmission length in preform is L
0the light path refractive index value that is located at this point on preform transversal section be n (x, y), light path is n (x, y) L
0, by optical path difference P
2(x, y)-P
1(0)=n (x, y) L
0measurement realize the measurement of refractive index, both
refractive index n
cl, corresponding light path is n
cll
0, record index distribution n (x, the y)=n of preform
cl+ [P
2(x, y)-P
2(x
0, y
0)]/L
0, P
2(x
0, y
0) representing the position of the reflective scan mirror corresponding to covering place prefabricated rods far-end reflected signal interference peak of known refractive index, preform length is L
0, the refractive index of optical fiber prefabricating stick cladding is n
cl.
Wide spectrum light source is ASE light source or SLD light source or LED light source.
The beneficial effects of the utility model are:
The optical fiber precast rod refractivity profile survey device that the utility model proposes has the advantages such as structure is simple, measurement is convenient, operation adjustment is simple.
Accompanying drawing explanation
Fig. 1 is the optical fiber precast rod refractivity profile survey device schematic diagram based on the absolute light path relative method of white light interference;
Fig. 2 is testing fiber prefabricated rods and index distribution schematic diagram to be measured thereof;
Fig. 3 glass sheet to be measured and index distribution schematic diagram thereof.
Embodiment
Below in conjunction with accompanying drawing, the utility model is described in more detail:
The optical fiber precast rod refractivity profile survey device based on the absolute light path relative method of white light interference that the utility model proposes comprises optical fibre Michelson interferometer, measurement mechanism and signal processing unit.Wherein a end of 3dB fiber coupler is connected with the driver 1 of wide-spectrum white-light light source (such as: ASE or SLD); B end is connected with optical fiber collimator 3, and the other end of optical fiber collimator 3 places a reflective scanning mode mirror 4; C end is connected with detection optical fiber, and the right-hand member of detection optical fiber is placed testing fiber prefabricated rods 8 and placed the three-D displacement platform 9 of preform; D end is connected with the receiving end of photo-detector 6, and the other end of photo-detector is connected with signal processing unit 7.Adopt this measurement mechanism and suitable signal processing method, the measurement of optical fiber precast rod refractivity section can be realized.
The optical fiber precast rod refractivity profile measuring method based on the absolute light path relative method of white light interference that the utility model proposes, it is characterized in that: the wide spectrum optical that white light source sends is via after 3dB fiber coupler 2 beam splitting, light beam is coupled to optical fiber collimator 3 via b end, then reflective scanning mode mirror 4 is irradiated to, reflect on its surface, reflected light gets back to 3dB fiber coupler 2.Another light beam is coupled to detection optical fiber 5 via c end, and first the reflection end face being then irradiated to testing fiber prefabricated rods 8 reflects, and reflected light gets back to 3dB fiber coupler 2 equally.After two bundle reflection combiners, received by photo-detector 6 via d end.Can obtain after signal processing unit 7 pairs of signals process with reference to interference signal P
1(x, y), now reflective scan mirror 4 is distally moved until the light path corresponding to back end reflective signal that reflects light path and prefabricated rods 8 complete equal time, obtain the position P measuring interference signal peak value
2(x, y).In measuring process, because the index distribution of near-end reflected signal and reflecting surface has nothing to do, the scanning mirror position corresponding to reflected signal of any locus point is all identical, and we are unified is designated as P
1(0).Preform is placed on three-D displacement platform, and the two-dimentional point by point scanning of having been moved preform section by three-D displacement platform in x-y plane is measured.By difference DELTA P (x, the y)=P of the locus movement of scanning mirror corresponding to twice, the front and back interference peak signal measuring reflective scanning mode mirror 4
2(x, y)-P
1(0), can obtain and pass this some transmission length in preform is L
0light path, suppose that the refractive index value of this point on preform transversal section is n (x, y), so this light path is n (x, y) L
0, this shows can by optical path difference P
2(x, y)-P
1(0)=n (x, y) L
0measurement realize
The measurement of refractive index, both
for preform, if known
The refractive index of certain point, the such as refractive index n at covering place
cl, corresponding light path is n
cll
0so, by the method for xsect last some light path pointwise comparison, index distribution n (x, the y)=n of the preform that can survey
cl+ [P
2(x, y)-P
2(x
0, y
0)]/L
0, P here
2(x
0, y
0) representing the position of the reflective scan mirror corresponding to covering place prefabricated rods far-end reflected signal interference peak of known refractive index, preform length is L
0, the refractive index of optical fiber prefabricating stick cladding is n
cl.
Composition graphs 1, embodiment of the present utility model is: light source ASE sends the wide spectrum light source of power stability by driver drives, injects three-dB coupler 2, be divided into uniform two bundles from a end, a branch of end by b enters optical fiber collimator 3, reflects on reflective scanning mode mirror 4 surface; Another bundle enters detection optical fiber collimating apparatus 5 by c end, and this light beam is L in length
0, radius is r
0the end face of testing fiber prefabricated rods 8 reflect, two bundle reflected light get back to three-dB coupler 2 respectively by the b end of three-dB coupler 2 and c end, close Shu Houjing, by d end, interference signal are delivered to photo-detector 6, process finally by signal processing unit 7.In measuring process, preform is placed on three-D displacement platform, has been moved the two-dimensional scan of preform section by three-D displacement platform in x-y plane.According to white light interference theory, when only having optical path difference to be less than the coherent length of light source, just interference fringe can be produced.Wherein, when two-way optical path difference is zero, that is two light paths absolute equal time, two-way light path exact matching, there is central fringe in interferogram at this moment, the position of scan bits moving stage corresponding to this central fringe we be designated as P.
Embodiment 1: for testing fiber prefabricated rods as those given in figure 2, provides following method of testing by proving installation of the present utility model shown in Fig. 1.First, a little selected at preform near-end, the refractive index of this point is designated as n
i(x
i, y
i), by mobile reflective scanning mode mirror record respectively successively there is two white light interference figure peak values time scanning mirror position P value, near-end is designated as P
1(0), far-end is designated as P
2(x
i, y
i).In measuring process, assuming that on each transversal section of preform, refractive index radially distributes is all identical, the length thus for measuring is L
0the index distribution of the point corresponding to this section of former and later two end faces of preform is also identical.According to white light interference condition, when two light path absolute equal time corresponding be the peak value maximum value of interferogram just, at this moment just have
P
2(x
i,y
i)-P
1(0)＝n(x
i,y
i)L
0(1)
Preform xsect is selected the some P (x corresponding to covering
0, y
0), according to white light interference condition, when two light path absolute equal time, similar has
P
2(x
0,y
0)-P
1(0)＝n
clL
0(2)
Above-mentioned two formulas subtract each other the refractive index obtaining any point on prefabricated rods xsect
n
i(x
i,y
i)＝n
cl+[P
2(x
i,y
i)-P
2(x
0,y
0)]/L
0(3)
From formula (3), use the method that the utility model proposes, can obtain the refractive index of arbitrfary point on preform section, its distribution schematic diagram as shown in Figure 2.For graded index fiber, because the refractive index of preform is maximum at the central point of prefabricated rods section, reduce along with the increase of radius, therefore, its refractive index curve distributes axisymmetricly.
Shown by above-mentioned refractometry principle, the method that the utility model proposes is not by the restriction of preform xsect index distribution, not only can measure the optical fiber precast rod refractivity section of symmetrical refraction rate distribution, and any asymmetric index distribution can be measured, overcome the existing limitation only measuring symmetrical refraction rate profile fiber precast rod refractivity section in first technology.
The utility model can not only overcome the symmetrical limitation of optical fiber precast rod refractivity, and can measure non-circuit symmetric fiber index preform.In order to illustrate advantage of the present utility model further, second embodiment that shown below is as shown in Figure 3 is illustrated.
Embodiment 2: the optical fiber precast rod refractivity profile survey device based on the absolute light path relative method of white light interference that the utility model proposes not only can the cylindrical refractive index such as measuring optical fiber prefabricated rods, also can measure the index distribution of the unsymmetric structure prefabricated rods such as glass, specific implementation method is as follows simultaneously:
As shown in Figure 3, two panels thickness is M
1glass sheet in the middle of place thickness be M
2glass sheet, three sheet glass hold tightly together, and the length of two kinds of glass sheet is all L
0, index distribution to be measured is n (x).Principle and method of measurement is identical with embodiment 1, and in measuring process, glass sheet is placed on three-D displacement platform, has been moved the scanning of glass sheet by three-D displacement platform along x-axis.Finally can show that refractive index is
n(x
i)＝n
1+[P
2(x
i)-P
2(x
0)]/L
0(4)
Its refractive index curve is (what provide in figure is the situation that glass refractive index is 2. greater than glass refractive index 1.) as shown in Figure 3.
Claims (2)
1. the optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference, comprise optical fibre Michelson interferometer, precision three-dimensional displacement platform and signal processing unit, by wideband white light source and driver (1) thereof, 3dB fiber coupler (2), optical fiber collimator (3), reflective scan mirror (4), with the detection optical fiber (5) of collimating apparatus, photo-detector (6), signal processing unit (7), testing fiber prefabricated rods (8), precision three-dimensional displacement platform (9) forms, it is characterized in that: a end of 3dB fiber coupler (2) is connected with wideband white light source (1), b end is connected with optical fiber collimator (3), reflective scan mirror (4) is placed at the exit end of optical fiber collimator (3), the c end of fiber coupler is connected with detection optical fiber (5), the d end of fiber coupler is connected with the receiving end of photo-detector (6), the output terminal of photo-detector (6) is connected with signal processing unit (7), the right-hand member of detection optical fiber (5) faces testing fiber prefabricated rods (8), testing fiber prefabricated rods (8) is fixed on precision three-dimensional displacement platform (9), the wide spectrum optical that white light source sends is via after 3dB fiber coupler (2) beam splitting, light beam is coupled to optical fiber collimator (3) via b end, be irradiated to reflective scan mirror (4), surface is reflected, reflected light gets back to 3dB fiber coupler (2), another light beam is coupled to detection optical fiber (5) via c end, first the reflection end face being irradiated to testing fiber prefabricated rods (8) reflects, reflected light gets back to 3dB fiber coupler (2) equally, after two bundle reflection combiners, received by photo-detector (6) via d end, can obtain after signal processing unit (7) processes signal with reference to interference signal P
1(x, y), reflective scan mirror (4) is distally moved until the light path corresponding to back end reflective signal that reflects light path and prefabricated rods (8) complete equal time, obtain the position P measuring interference signal peak value
2(x, y).
2. a kind of optical fiber precast rod refractivity profile measurement mechanism based on the absolute light path relative method of white light interference according to claim 1, is characterized in that: described wideband white light source is ASE light source or SLD light source or LED light source.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104535534A (en) * | 2014-12-15 | 2015-04-22 | 哈尔滨工程大学 | Device and method for measuring refractive index distribution profile of optical fiber preform rod based on white light interferometry absolute optical path comparison method |
| CN105372206A (en) * | 2015-11-05 | 2016-03-02 | 沃派物联网科技(天津)有限公司 | Parallel remote optical fiber sensing system for detecting various gas refractive indexes |
| CN105866071A (en) * | 2016-06-02 | 2016-08-17 | 吉林大学 | Device for measuring refractive index through optical fiber interferometry |
-
2014
- 2014-12-15 CN CN201420796280.7U patent/CN204359686U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104535534A (en) * | 2014-12-15 | 2015-04-22 | 哈尔滨工程大学 | Device and method for measuring refractive index distribution profile of optical fiber preform rod based on white light interferometry absolute optical path comparison method |
| CN104535534B (en) * | 2014-12-15 | 2017-08-04 | 哈尔滨工程大学 | A kind of optical fiber precast rod refractivity profile measurement apparatus and measuring method based on the absolute light path comparison method of white light interference |
| CN105372206A (en) * | 2015-11-05 | 2016-03-02 | 沃派物联网科技(天津)有限公司 | Parallel remote optical fiber sensing system for detecting various gas refractive indexes |
| CN105372206B (en) * | 2015-11-05 | 2018-10-30 | 沃派物联网科技(天津)有限公司 | Parallel remote optical fiber sensing system for the detection of multiple gases refractive index |
| CN105866071A (en) * | 2016-06-02 | 2016-08-17 | 吉林大学 | Device for measuring refractive index through optical fiber interferometry |
| CN105866071B (en) * | 2016-06-02 | 2019-04-26 | 吉林大学 | A kind of fiber optic interferometric method surveys the device of refractive index |
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