CN101375191B - Optical fiber position determination - Google Patents

Abstract

In positioning or aligning ends of optical fibers (13) in relation to each other an offset distance between the fiber ends, the offset distance e.g. being the distance between predetermined reference positions in the fiber ends, is stepwise adjusted using a cascade technique. The method can be executed accurately and fast and be used e.g. in a procedure for core alignment, the predetermined reference positions then being the positions of the cores (14') of the fiber ends such as the positions of the center lines or axes of the cores. Also, the method can be used in a procedure in which the self-focusing effect of optical fibers is used for finding the reference positions, which in this case are the positions of the center lines or axes of the total fiber ends, i.e. center lines or axes of the surfaces of the claddings (14) of the optical fiber ends.; Finally, the method can be used for the longitudinal positioning of the fiber ends in which the gap between end surfaces of the fiber ends is set to a desired value.

Description

The position of optical fiber is confirmed

Related application

The application requires to have the right of priority of the Swedish patent application 0502951-7 that proposed on Dec 30th, 2005 and to benefit from this application, and whole teachings of this application by reference and incorporated herein.

Technical field

The position that the present invention relates to optical fiber is confirmed, specifically, relates to the method that is used for optical fiber end is moved on to said position, and also relates to the method and apparatus of welding optic fibre.

Background technology

In recent years, fiber laser has been regarded as solid-state and CO ₂The important substitute of laser instrument is applied to fields such as military affairs, space flight, medical treatment and industrial materials processing.Fiber laser is mainly due to its high-output power and splendid beam quality and laser design dirigibility and very attractive.Big mode field area doubly clad optical fiber (LMA-DCF) is one of vitals in the fiber laser.For efficiently pumping energy being coupled among this type of LMA-DCF, and also allow high-output power, the LMA-DCF blanket design becomes to have the xsect of high-NA and different shape, like circle, octagon, square etc.Look output power levels and decide, the cladding diameter of LMA-DCF is generally in the 300-1000 mu m range.The fibre core of LMA-DCF often is doped with the high concentration rare earth element, and like ytterbium, and its size can be greatly to 50 μ m, and has low numerical aperture to reduce nonlinear effect.

One of subject matter that hinders use LMA-DCF is to use traditional joining technique to realize that the high-quality of this type optical fiber engages extremely difficult.Owing to the aggregate demand reason in the fiber laser design, dissimilar optical fiber will be bonded with each other, for example; Joint between difform LMA-DCF joins octagon LMA-DCF to like circular LMA-DCF, and the LMA-DCF that contains rare-earth dopant joins the not LMA-DCF of doped with rare earth thing to; And LMA-DCF joins traditional single-mode fiber (SMF) to; Latter two fibre cladding diameter has very big difference each other, for example, differs three times or more times.The main difficulty that engages among the LMA-DCF is traditional fibre core centering operation of in traditional welding, using.Can be observed two subject matters.At first, the information at the covering edge that relevant traditional centering operation requires can't realize that this is that the imaging system of using in traditional contact maker can't be handled because the LMA-DCF size is too big.Secondly, be difficult to observe simultaneously the fibre core image that its cladding diameter and its structure have two optical fiber of big difference.Therefore, in practice, measure auxiliary manual centering operation through being usually used in engaging LMA-DCF through power delivery, this since engage often have too low-quality former thereby cause manufacturing process inefficiency and output low.

The exploitation of traditional fibre core centering operation of using today can be traced back to the initiative work before 20 years, sees also people such as T.Katekuri 1984 in the said content of IEEE J.Lightwave Technol. the 2nd volume 277-283 page or leaf.The basis of these fibre core centering operations is the analyses to the fibre core image of taking from the fiber light level profile that will engage.In this type of technology, illuminate the fibre core image that optical fiber obtains the optical fiber of investigating from optical fiber side through using external light source.Theoretical and experiment shows, places light to leave the optical fiber edge of optical fiber the object plane of high-resolution imaging system, when imaging system is seen, just can resolve the fibre core image of optical fiber.Through using the information of extracting from the fibre core image, various automatic fibre core centering operations have been developed.

Disclose one of fibre core centering operation based on graphical analysis in the various Jap.P.s, for example, seen also the Jap.P. 11194227 of authorizing Fujikura.Through using these technology, in the optical fiber photo of taking that will engage, be the vertical range of each optical fiber measurement between the position at for example covering upper limb and fibre core image approximate center, optical fiber is positioned at horizontal level by traditional being assumed to be in photo.Subsequently through two optical fiber are shifted each other, make said two measuring distance differences of two optical fiber become and equal two vertical difference between the fibre cladding upper limb position.Because the method relies on from the information of fibre core image and the extraction of covering edge image, therefore, is difficult to carry out accurate fibre core centering.Because sizable difference aspect refractive index, only the light through covering is different with comparing its behavior through the light of covering and fibre core.Therefore, the object plane optimum position that obtains high-quality fibre core image is not equal to the optimum position that obtains having high-quality covering edge image.This situation means possibly can't realize the while with high-acruracy survey fiber core and covering marginal position, and this causes the centering degree of accuracy based on this type of photo the time, to reduce again.Needs to relevant covering marginal position information in the centering operation have also caused the needs to special imaging system, and these imaging systems comprise extremely expensive large-scale sensor, and therefore maybe be not cost-effective in contact maker is made.

Authorize that to disclose a kind of in the United States Patent (USP) 5570446 of Ericsson be the distinct methods that fibre core centering uses so-called warm optical fiber image to analyze.In the method, actual optical fiber end is in contact with one another before, do not use exterior light to illuminate optical fiber, and the optical fiber end that is to use generation will engage than the glow discharge of low melting glass heating.Because concentration of dopant is higher than the concentration in covering in fiber core, therefore, the thermoluminescence of fibre core is better than the thermoluminescence of covering far away, and this has produced the photo that heat or warm fiber core image are arranged.Through anatomizing the light intensity profile that derives from this type of warm optical fiber photo, the information that can extract relevant fiber core position is to use in fibre core centering operation.Because the method does not need the information of relevant covering marginal position, therefore, can high precision carry out fibre core centering operation.But, in the preheating step technology of in the method, using, find the extremely difficult fibre core image in the LMA-DCF photo of observing.This is that this situation has produced and made traditional saturated thermoluminescence of fusion splicer imaging system usually because the desired energy of heating LMA-DCF fiber core is higher than the energy that traditional optical fiber is used for signal post's expectation far away.Another problem is the fibre core dopant that in preheating step, takes place.This diffusion can make optics mode field diameter (MFD) significantly expand, and causes two MFDs of optical fiber at the abutment not match, and this has produced high optical loss in the joint.

Therefore, in technical field, need a kind of method of exploitation, the defective that can avoid prior art is to carry out high-precision fibre core centering operation to all types optical fiber, particularly LMA-DCF.

Be entitled as and disclose the method for feeling relieved again in a kind of wherein captive plane of photo in the open International Patent Application WO 01/86331 of " arc is felt relieved again " (Arc Recentering), wherein capture plane moves according to arc center.

Summary of the invention

An object of the present invention is to provide a kind of with the method for optical fiber end with desired mutual geometric relationship location, as with the mutual centering of optical fiber end.

Another object of the present invention provides and is used for method and apparatus that optical fiber end is bonded with each other.

Being used to carry out the optical fiber end location, make in the method that offset distance is arranged between the optical fiber end, use concatenation technology progressively to adjust the for example offset distance of distance between the optical fiber end predetermined reference position.This method can be used in the process of fibre core centering, so predetermined reference position becomes the position of optical fiber end fibre core, like the position of the center line or the axis of fibre core.In addition, this method can be used for searching the process of reference position at the self-focusing effect of optical fiber to be used, and in this case, the reference position is the position of the center line or the axis of total optical fiber end, the i.e. center line of optical fiber end cladding surface or axis.At last, this method can be used for the longitudinal register of optical fiber end, and wherein the interval between the end face of optical fiber end is made as expectation value.

Other purposes of the present invention and advantage be describing in the explanation below, and partly will be obvious from explanation, perhaps can understand through the present invention's practice.Objects and advantages of the present invention can realize through method, technology, instrument and the combination of in the claims of enclosing, specifically noting and obtain.

Description of drawings

Though in the claims of enclosing, specifically described novel characteristics of the present invention; But through considering the following detailed description of the unrestricted embodiment that hereinafter illustrates and describes; Can obtain aspect tissue and content to above-mentioned and other characteristic of the present invention better, more complete understanding, wherein:

-Fig. 1 is the synoptic diagram that is used for catching some critical pieces of imaging system that are included in optical fiber coupler optical fiber photo;

-Fig. 2 is the SMF typical case photo of taking with the optical fiber coupler imaging system;

-Fig. 3 is the light intensity profile figure that extracts from Fig. 2;

-Fig. 4 is the ray trace simulation drawing that light passes through SMF;

-Fig. 5 a, 5b are respectively the photo that circle and octagon 400 μ mLMA-DCF take on the self-focusing plane with the optical fiber coupler imaging system;

-Fig. 6 is the light intensity profile figure that extracts from Fig. 5 a;

-Fig. 7 is the first order derivative figure of the truncation gaussian profile curve of Fig. 6;

-Fig. 8 is to be the light intensity profile figure that 400 μ m octagon LMA-DCF confirm;

-Fig. 9 explains the synoptic diagram of the principle that the fibre core skew is confirmed;

-Figure 10 a is based on self-focusing effect, is used for the process flow diagram of optical fiber end centering operation;

-Figure 10 b is the process chart that is used for confirming at the optical fiber end photo that uses self-focusing effect to take position of center line;

-Figure 10 c is the process flow diagram of employing based on the optical fiber end centering operation of the Cascading Methods of self-focusing effect;

-Figure 10 d is based on the process flow diagram of the optical fiber end centering operation of the photo that the end fibre core is shown;

-Figure 11 a is a synoptic diagram of having drawn the optical fiber coupler of imaging system critical piece;

-Figure 11 b is a synoptic diagram of having drawn the optical fiber coupler of the main electric component of imaging system equally;

-Figure 12 a is to use the block diagram of the centralising device of centre focus method;

-Figure 12 b is to use the block diagram of the centralising device of Cascading Methods;

-Figure 12 c is to use the block diagram of the centralising device of fibre core centering method;

-Figure 13 a is to use left optical fiber end implementation center is focused on the best imaging system setting of centering operation, the photo or the photo of two optical fiber ends that be bonded with each other of being caught by the optical fiber coupler imaging system;

-Figure 13 b is to use left optical fiber end is carried out the best imaging system setting of fibre core centering operation, the photo or the photo of two optical fiber ends that be bonded with each other of being caught by the optical fiber coupler imaging system;

-Figure 14 a is to use the best imaging system setting of fibre core centering operation is carried out than the thin optic fibre end in the left side, the photo or the photo of two ends that be bonded with each other, that have different-diameter of being caught by the optical fiber coupler imaging system;

-Figure 14 b is to use best photo or the photo imaging system setting, that be similar to Figure 14 a of fibre core centering operation is carried out in thicker end, right side;

-Figure 15 a is to use and uses the centre focus method to carry out the best imaging system setting of centering operation to the left side than the thin optic fibre end, will be bonded with each other by what the optical fiber coupler imaging system was caught, has the photo or the photo of two ends of different-diameter; And

-Figure 15 b is to use and uses the centre focus method to carry out best photo or the photo imaging system setting, that be similar to Figure 15 a of centering operation to thicker end, right side.

Embodiment

The method of for example in optical fiber couplers such as automatic optical fiber contact maker, carrying out, two optical fiber ends are bonded with each other will be described among this paper.Particularly, use description to carry out the rapid shifting function of multistep, the method that optical fiber end is placed with desired mutual geometric relationship, wherein, the method is mainly as the process part of the mutual centering of optical fiber end is described.

As shown in Figure 1; Be used for that traditional automatic fusion splicer that optical fiber is bonded with each other is had at least one image capture system basically; This system generally comprises: source of parallel light 1; Like light emitting diode 3 (LED) and collimating apparatus 5, send parallel beam to the imaging system that comprises optical system 76, and optical system 7 comprises for example poly-lens assembly; Image capture apparatus 9, for example, charge-coupled device (CCD) (CCD) type plates; And electronic image processing and analytic unit 11, be also referred to as elementary area.Source of parallel light, imaging system and parts thereof are positioned as has common optical axis 12.For extracting the detailed structure information about the object that will form images, imaging system 6 is designed to make that the object plane 15 of optical system can be with respect to the movement of objects that will form images.In fusion splicer, thing is actually the optical fiber 13 of two adjacent end portions that comprise two optical fiber that will engage each other as a rule.Optical fiber has covering 14, and great majority often also have fibre core 14 '.Optical system is only to the thing imaging at object plane, so that image capture apparatus in the clear picture of catching as the plane, is the front surface of image capture apparatus 9 as the plane herein.In fact, the displacement of object plane generally is to realize through optical system 7 is moved forward and backward with respect to optical fiber 13, and optical fiber can be assumed to be and has clear and definite reference position.Therefore, in the imaging capture systems, the position of light source 1 and image capture apparatus 9 is fixed, and optical system 7 is movably.In addition, thing 13 is removable, but will realize centering, and this moves and only in the plane perpendicular to optical axis 12, (is also referred to as the current direction of checking) and takes place.When observing such as things such as optical fiber, object plane 15 also can be considered viewing plane, and therefore term object plane and viewing plane refer to same plane, and are used alternatingly each other in the text.

Be positioned at through object plane 15 near the leading edge or near region of the thing (this thing that is envisioned for optical fiber 13 thereafter is optical fiber end or rather) that for example will observe, can obtain comprising the photo of the image of optical fiber 13 optical system 7.Fig. 2 is the typical photo of the single-mode fiber (SMF) of catching for this type of position of object plane, and it also can be considered the image that is included in closing line 18 single-mode fiber (SMF) ends that separate, same kind.For optical fiber and each optical fiber end; Observe or captured pictures comprises and has different light intensity degree or brightness respectively; Distinct horizontal direction is extended field or longitudinal field; Be also referred to as longitudinal region, vertical district, vertical image area etc., latter two term is used alternatingly the information with the indication identical type in the text each other.The brightness of catching in the photo is generally measured with gray level.Particularly, through in catching photo, searching light intensity profile, the position shown in Fig. 2 center line 17, can obtain to be used for carrying out the fibre core that will describe such as literary composition in the desired information of centering operation such as centre focus centering operation.Light intensity profile is also referred to as transverse intensity distribution; Be the brightness of in catching photo, measuring along the line that is approximately perpendicular to the optical fiber image longitudinal axis; Be also referred to as light intensity as stated; It changes with position along the line, changes with the traditional upright position of catching in the photo that has horizontal orientation as shown in Figure 2 at optical fiber or optical fiber end the most often.Extract about information such as optical fiber end positions such as fibre core 14 ' position and covering 14 marginal positions; Can be through examine and analyze position and brightness, the especially light intensity profile of observing/catching different fields in the photo such as Flame Image Process and analytic unit 11.

Drawn the light intensity profile of measuring at Fig. 2 line 17 in the figure of Fig. 3, in Fig. 3, can be observed profile and comprise five peak structures clearly, five peaks corresponding among Fig. 2 by the field with littler brightness/light intensity around five distinct fields.Two outside peaks p _Ol, p _OrThe expression as from imaging system 6 or by its covering of seeing 14 upper and lower outer rims.Distance W 2 in the photo between the edge image of covering upper and lower is directly proportional with the physics cladding diameter of imaging fibre 13, and wherein proportionality constant is mainly confirmed through the enlargement factor of optical system 7.For understanding and quantification explanation center three peak structure p _3c, carried out the simulation of the ray trace of SMF, referring to the figure of Fig. 4, among the figure covering 14 be assumed to be have be different from fibre core 14 ' the constant or unified refractive index of constant refractive index.It is that parallel beam illuminates that optical fiber end 13 is assumed to be by directional light as shown in Figure 1.Simulation realizes through the snell law that repeated application is known.

The light of hitting optical fiber 13 is refracted in the air on the border of optical fiber, and it also reflects at inside of optical fibre when having different or the refractive index that changes regional.Optical fiber can be considered as the such work of column optical lens usually, and this situation is called " lens effect ".Checked on the direction what investigate; Promptly in the vertical outermost part of optical fiber, observe, when the optical axis 12 of imaging system 6 is assumed to be level with direction of observation therefore, on optical fiber and the border that is shown " d " in the air; At the light of optical fiber 13 internal refraction and the bias light edge of indexed optical fiber together; This has produced the image at edge, covering 14 upper and lower, that is, and and two most external peak p shown in Figure 3 _Ol, p _OrThese two peaks have above black or closely two horizontal bar strip region r of the brightness of black region on every side corresponding to shown in Figure 2 _Ol, r _OuThe strong refraction of light also causes dull thread in two zones in the optical fiber.These two zones are corresponding to referring to inner " black region " r of optical fiber 13 images of Fig. 2 _Bl, r _BuWith the regional b in Fig. 3 intensity profile _l, b _r

The careful investigation through the converging light of 14 ' boundary vicinity zone to covering 14 can find that light through 14 ' time of fibre core other refraction is taking place.Therefore, light is divided into three parts, for some interior at interval object plane 15 between Fig. 4 " a " and " c " position, can be observed this effect.For through during this time at a distance from the object plane image of catching, can be observed the banded recombination region r of central bars _3c, this zone has considerably beyond black region r on every side _BlAnd r _BuThe brightness of brightness, and form, i.e. bottom and top bright areas r by three distinct zones _Cl, r _CuWith central bright zone r _c, these zones are by two with littler a little brightness narrow regional r _Sl, r _SuSeparate each other.The Central Composite zone is corresponding to characteristic three peak center structure p _3c, this structure can be observed the light intensity profile that obtains from corresponding photo, central bright zone r _cCorresponding to central peak p _c, and bottom and central upper portion bright areas r _Cl, r _CuCorresponding to side peak p _Cl, p _CrClearly, corresponding division center p _3cIn central bright zone r _cWith central peak r _cBe attributable to have carried out the effect of birefracting refract light, and bottom and central upper portion bright areas r _Cl, r _CuAnd two corresponding side peak p _Cl, p _CrLight by only passing through covering 14 forms.Investigate Fig. 3 and Fig. 4, can understand, central bright zone r _cWith central peak p _cThe information that comprises relevant fibre core, central peak are called " fibre core image peak ".In division center, be also referred to as two side peak p of satellite peak _Cl, p _CrDifferent with " fibre core image peak ", be called " covering image peak ".

Between three center light fields and correspondingly fibre core image peak and the peak-to-peak separation degree of covering image mainly by fibre core 14 ' the refractive index of refractive index and covering 14 between difference confirm, and should poor design definite by type dopant and concentration of dopant in fibre core and the covering and optical system 7.Also can directly see the width W 1 of Fig. 2 Central Composite light field and changing along with the change of optical system 7 object planes 15 positions referring to the width W 1 in the profile center three peak structures of Fig. 3 accordingly from Fig. 4.Usually, fibre core 14 ' and object plane between distance more little, width W 1 is just big more.

For simplicity, fibre core centering operation has below been introduced at two parameters " H1 " and " H2 " shown in Fig. 3 in describing.First Parameter H 1 expression center light field r _cTotal contrast, that is, and the high-high brightness in central field with such as black field r among Fig. 2 _Bl, r _BuDeng the difference between the zone leveling brightness of wherein seeing spuious or " noise " light only.For light intensity profile, first Parameter H 1 is with respect to the parasitic light rank, that is, and and above-mentioned " black region " b _l, b _rIn other fibre core image of light intensity level peak p _cMaximal value.The size of the position influence Parameter H 1 of optical system 7 object planes 15.Second Parameter H 2 expression center light field r _cLocal contrast, that is, and high-high brightness and Central Composite light field r in the central field _3cIn the narrow more details in a play not acted out on stage, but told through dialogues r that separate around two _Sl, r _SuDifference between the minimum brightness average.For light intensity profile, second Parameter H 2 is the contrasts at fibre core image peak, and may be defined as fibre core image peak p _cTwo the minimum value ms adjacent with fibre core image peak _l, m _rAverage between difference.

Clearly, be in the object plane 15 diverse location captured pictures, the photo with second Parameter H, 2 mxm.s is a best photo of observing the fibre core image, and therefore corresponding object plane position is the optimum position of observing the fibre core image.The value of two Parameter H 1 and H2 can be used as the criterion in the centering operation, as hereinafter with in the fibre core centering operation of describing.

For carrying out the accurate centering of optical fiber (particularly LMA-DCF), and do not comprise the defective of prior art, developed centering method such as fiber cores such as LMA-DCF.The method comprises four critical process or four committed steps, comprising:

-utilize the lens effect of optical fiber, carry out centre focus centering operation-this technology and also can use separately, and also be used to not have the optical fiber of fibre core.

-utilize first Parameter H 1 to search for the object plane band of position, search the fibre core image.

-utilize second Parameter H 2 confirm to be used to observe fibre core 14 ' best object plane position.

-with cascade process (cascade process) skew of different directions is reduced to predetermined value fast, particularly reduce the fibre core skew to adopt predetermined value.

These processes can various array modes each other be used or use with the combination of other method, perhaps like above-mentioned first method, as the unique centering operation before engaging.

From Fig. 4, can draw; Viewing plane for right-angle view axis 12; Can the fibre core 14 of light through optical fiber 13 ' the residing viewing plane in position in observe the Central Composite light field that in optical fiber image, has three distinct light fields and three peak structures in the respective light intensities profile, and increase along with the increase of the propagation distance of electrical distance light source with corresponding fibre core image peak by the center light field intensity of first Parameter H, 1 value representation.Be reduced to the central field of no distinct fields inside at the Central Composite light field, and three peak structures in the light intensity profile are reduced to unimodal structure, in the position by " c " indication, the value of total contrast H1 reaches the mxm. of its viewing plane.This position of object plane or viewing plane is so-called " the self-focusing position of optical fiber ".Fig. 5 a and Fig. 5 b are that object plane 15 is respectively the circular LMA-DCF of 400 μ m and 400 μ m octagons when being positioned at the self-focusing position and mixes the photo that the LMA-DCF of Yb takes.Can see, with regard to the corresponding photo central area that " white area " promptly has big brightness/highlight strength, find very similarly image of these two optical fiber.

Be the lens effect and the self-focusing effect of understanding optical fiber in depth, extracted the light intensity distributions in " white area " from Fig. 5 a, and with line 19 indication extracting positions.Fig. 6 has drawn light intensity distributions.What can remember is, for self-focusing effect, fibre core 14 ' in anaclasis unimportant, and therefore for the optical fiber of no fibre core, this effect also can occur.

Can be observed, in the light intensity profile of Fig. 6, central peak c _pWith truncation gaussian profile curve similarity is arranged.This and following situation adapt: referring to the central bright in the optical fiber image of Fig. 5 a zone r _cAlong its center line the field in have high and the most constant brightness.It is very good that detail analysis has showed that said center line and truncation profile center and the match of fibre cladding center get, and the high symmetry of covering xsect is made explanations in enough all the commercial optical fiber of this ability.Therefore, the lens effect of optical fiber self-focusing can be used for developing and need not relevant " like covering centering " technology of catching covering marginal position information in the image.This centering operation is so-called " centre focus centering ".

The notion of " centre focus " is introduced in Ericsson FSU975PM-A contact maker, referring to FSU975PM-A user manual 94ST005R1D, and 1998, the 39 pages.The exploitation of this technology has been the reference position for the establishment imaging system, obtains the profile that polarization is observed with scioptics effect trace, and promptly the POL profile sees also said United States Patent (USP) 5572313.In this article, the notion of " centre focus " further develops and is used for centre focus centering process.

Be to implement " centre focus centering " technology, must find the self-focusing position of the optical fiber of being investigated 13.This can particularly carry out through anatomize truncation center profile for this type of change through the center light field that respectively changes the position of assessment object plane 15, for example, supposes it is the truncation Gaussian curve.Because the truncation of central peak has clearly been indicated the saturated of imaging system 6, especially light-sensitive unit 9 is saturated, and therefore, identification is through the jag part of saturation effect removal, the light intensity profile of truncation structure easily.Light intensity of observing or brightness truncation or saturated obviously is equal to following situation: light intensity in some zones or brightness is greater than predetermined value, for example with the contrast value H1 that wherein observes the relative bright field of Central Composite, H2 or the respective light intensities profile of top discussion in three peak structures compare higher relatively.

A kind of mode of searching the position that can obtain saturated and truncation structure is to measure the maximal value of high-high brightness HM or light intensity profile; And the saturation threshold SAT of it and imaging system 6 compared; For example; At the gray-scale value 255 of the exemplary device that is used for studying this effect, therefore saturation threshold is above-mentioned higher predetermined value.Can recognize saturated can near the wider range the self-focusing position of the optical fiber of being investigated " c ", the appearance.In catching the optical fiber end image of photo, only obtain single central bright longitudinal field and search search self-focusing plane more accurately under the situation of scope or the object plane position of position, clearly also can use total contrast value H1 or corresponding average H1 _AvObtain the saturated condition in central bright zone and be equal to condition H1＞SAT subsequently, wherein, SAT is the saturation degree of image capture apparatus 9.SAT obviously is a scheduled volume, and is equal to predetermined threshold.But also service condition H1 _Av＞SAT or use HM＞H1 usually _High(H1＞H1 _HighOr H1 _Av＞H1 _High, wherein, H1 _HighBe the higher thresholds of suitably selecting, and H1 _AvIt is the average relative brightness of central field.

Subsequently, usually suitable H1 is being set _HighAfter the value, can start the pre-service of the initial object plane of quick search position.This search can begin from the reference position that clearly defines of object plane, and the small distance of side is perhaps got in certain position of the optical fiber end side of this desirable object optical system in position, and said distance is little, for example for the diameter of the optical fiber end of being investigated 13.Subsequently, the object plane 15 of optical system 7 moves apart optical fiber end, and photo is taken continuously, corresponding HM value (H1 value or H1 _ThValue) draws and and H1 through for example analyzing the intensity profile that obtains from photo _High(SAT) compare.If find to satisfy condition HM＞H1 _High, then pre-service stops, and the current location of object plane is the reference position of subsequent processing.Can uncertain single position, but the scope of confirming will start or search for the object plane position of next process that is used for definite self-focusing position, above-mentioned condition is all satisfied in the interior object plane position of this scope.If confirmed for example this type of scope, the reference position (being also referred to as primary importance) that then is used for next process can be in the somewhere in this scope, as therebetween.

Subsequently,, can use an additional process for obtaining definite self-focusing position " c ", wherein, the central bright district r in some images _cWidth W 1 or the central peak c in the respective light intensities profile that is equal to _pWidth W 1 be minimized, it is the true picture plane that is regarded as the optical fiber of optical lens that this type of minimum value is obviously indicated corresponding viewing plane/object plane.For the input directional light, this viewing plane/object plane is the focal plane of cylindric optical fiber lens.

Finding such object plane zone or at least one position first, wherein can obtain saturated and the therefore center profile of truncation, perhaps wherein be observed usually light intensity or brightness greater than said higher predetermined value after, can start this additional process.Subsequently, can be through near the position of having found truncation center profile, moving forward and backward the object plane 15 of imaging system 6, continuously shot images during moving, and measure the width W 1 of truncation center profile in real time, search minimum widith W1 _MinTerm " continuously " can be used in the text as traditional expression through with the short period at interval or through less predetermined steps distance, the step pitch that promptly has an a certain predetermined length repeats shooting and analysis image when moving object plane.(the W1-W1 if the position of object plane 15 satisfies condition _Min)＜δ 1, then search procedure stops, and wherein, δ 1 is also referred to as threshold value, can be made as the predetermined value or the predetermined constant that generally equal 0.1 μ m.Usually, the W1 of given type fiber _MinValue is definition clearly.As stated, center light field r _cWith truncation center profile p _cThe obvious approximate representation in center or the center of indexed optical fiber covering 14, this center can be used for carrying out " like covering centering " by two optical fiber of actual imaging.

For accurately confirming the width W 1 and center C 1 of bright central field/truncation center profile, the method that can use some to be fit to for light intensity profile, for example can be used to relate to the method that the contour curve derivative is analyzed.For example, in Fig. 7, drawn first derivative of the truncation center profile of Fig. 6.Can see, be positioned at two strong peak P at center _Cp, p _CnBe superimposed upon on the noise.Positive and negative peak-to-peak distance in the curve of Fig. 7 has obviously provided the accurate measurement of profile width W1.Suppose corresponding to two peak P _Cp, P _CnPeaked coordinate is x1 and x2, and W1=x2-x1 is then arranged, and the center of profile can be derived as C1=(x1+x2)/2 simply.

" centre focus centering " technology comprises the step of in two optical fiber ends, confirming the center of covering 14 earlier in the end view picture of each, desirable center, this position light field T _cCenter line or the value C1 that confirms from the respective light intensities profile, and comprise last use center really allocation with the step of two optical fiber end centerings.This technology in many aspects of great use.Because the maturation of manufacturing process, most of fiber manufacturers of today can be produced high-quality optical fiber, for example, have non-circularity less than 1% with the SMF optical fiber of degree of eccentricity less than 0.2 μ m.Degree of eccentricity refers to the limited allowance that fiber core is not accurately felt relieved with respect to fibre cladding (or more precisely with respect to covering outside surface) in the optic fibre manufacture process.Experimental data shows, for the optical fiber with little non-circularity and little degree of eccentricity, uses the technology that is called the technology of " centre focus centering " or is called " fibre core centering " difference not for splice-losses.Therefore, " centre focus centering " alternative true fibre core centering operation is carried out the centering of high quality optical fiber on the technological principle.

In addition, except for example standard single-mode fiber is used the centre focus centering operation, this technology also can be used for carrying out the centering of large-diameter fibre-optical (LDF).Compare with the SMF with standard 125 μ m diameters, term LDF refers to have greater than 300 μ m, the optical fiber of general cladding diameter in the 300-1000 mu m range.When using the standard imaging system in traditional optical fiber coupler, because the restriction of the size of image capture apparatus or light sensor 9, limitation in height particularly can't be observed the edge of many LDF optical fiber.On the other hand; Referring to Fig. 5 a and Fig. 5 b; Can notice that the width W 1 of truncation peak, center or center light field in the self-focusing zone is general than catching in the photo the little 5-10 of cladding diameter width times; This means that the advanced picturing system that need on short transverse, not have the large-size imageing sensor especially obtains traditional orientation of optical fiber and optical fiber photo, and/or has the optical system of zoom function when using the centre focus centering method to carry out centering.Therefore, centre focus centering is with the cost-benefit solution of having of LDF centering in fusion splicer.

But,,, still be difficult to make high-quality LMA-DCF owing to making major technology reason and quite complicated technology among the LMA-DCF as observing.For example, the usually about 1-2 μ m of the typical degree of eccentricity of LMA-DCF, this degree of eccentricity than traditional SMF is big 5 times.For the optical fiber of large eccentricity degree like this, when the method for using based on covering centering, the quality of joint is inconsistent.This is because according to the optical fiber azimuthal orientation that will engage, fibre core skew random variation causes.For example, suppose that two fibre claddings with identical degree of eccentricity 2 μ m have splendid centering, the final fibre core skew in the joint can change between 0 to 4 μ m.The splice-losses that the variation of initial fibre core skew causes a joint to engage with another has corresponding marked change.

Therefore, fibre core centering can be improved the joint of LMA-DCF, and also can improve the joint of other optical fiber with large eccentricity degree.But well-known, for common or traditional SMF, fibre core centering can not guarantee that the optical fiber with large eccentricity degree has low splice-losses.Because eccentricity effect when the mutual accurate centering of fibre core of two optical fiber, journal offset or laterally offset can occur between the fibre cladding surface that will engage, be also referred to as lateral excursion.During melting process, because the viscosity self-centering effect of molten material (being typically some glass), i.e. the reason of so-called surface tension effect, optical fiber is attempted journal offset is reduced to minimum.Therefore, at last before actual melting process, the fibre core of centering will become after melting process is accomplished and misalign in advance, and the fibre core of fiber optic splicing even can be crooked at the abutment, and this has caused high splice-losses again.

SMF is different with standard, and experiment shows, at the joint between most of LDF and/or for engaging between LDF and other type fiber group, surface tension effect can be ignored.Be combined as example with 600 μ m LDF and 125 traditional μ m SMF, viscosity self-centering effect can be because surface tension averaging out and almost be cancelled on the position angle.For two LDF are bonded with each other, also find to compare with for example standard SMF, because big relatively quality or the volume of LDF, its surface tension effect is much smaller than the surface tension effect of two SMF.The bending of the fiber core that quality that in addition, LDF is big relatively or volume have prevented to be bonded with each other.Therefore, fibre core centering can be improved the joint result of the LDF with large eccentricity degree greatly.

Through above-mentioned discussion, though centre focus centering operation possibly not be suitable for the LMA-DCF with large eccentricity degree, it can be used as the preceding technology of centering of the senior LMA-DCF fibre core centering operation of exploitation at least.Aforesaid centre focus centering operation can be located LMA-DCF approx, makes it have less fibre core skew each other.This means to significantly reduce, need not to know the position at covering edge in taking pictures to searching the scope that the fibre core image is analyzed.Below will describe and be specially adapted to LMA-DCF in view of the situation, but also be applicable to fibre core centering skill other type fiber, that need not use complicacy and advanced picturing system.

Therefore, at first use description to search fast the process of the fiber core image of being investigated.In Fig. 8, drawn the light intensity profile that object plane 15 extracts for the photo of taking when position " a ", " b " and " c " shown in the Fig. 4 that is used for 400 μ m octagon LMA-DCF.Corresponding image is through with the octagon fiber orientation, so that the optical axis 12 " coupling " of the axis of symmetry of optical fiber and imaging system 6 and obtaining.This means one of octagonal flat surface of directional light vertical irradiation.

From Fig. 8, profile c is characterised in that at central peak p _c" saturated ", and can identify immediately, this profile is obtained when being used for the position " c " of " optical fiber self-focusing " at object plane.Profile b takes from the thing of in the position " b ", and wherein, the fibre core image is resolved well, can be observed center three peak structure p _3cThough, covering peak p _S1, p _SrReceive the influence of height " noise ".Profile a obtains when object plane is positioned at position " a ", and in this position, the profile center is quite smooth.But, fibre core image p _cStill resolved well, and two inverted peaks p that it is characterized in that having " minimum intensity " _I1, p _IrObserve; The contact maker device that is being used for testing; The upper and lower bound that obtains center three peak structures is respectively the gray level of about H1=120 and H1=60; Promptly, clear and definite central peak intensity upper and lower bound is arranged, between bound, can clearly distinguish and so analytic centre three peak shape p for each optical fiber and device _3cDetailed research shows, is provided with for the optical fiber of given type and clear and definite imaging system 6, and corresponding upper and lower bound almost is identical.Therefore, can set up threshold value H1 _ThTo search three peak structures fast.Should remember that center three peak structures are equivalent in optical fiber image, to have one and comprise and the center light field of fiber core 14 ' related and the Central Composite light field of light field on every side.

Threshold value H1 _ThFit value may be defined as can fine parsing three peak structures range limit and lower limit mean value, and it usually will less than or preferably significantly less than saturation degree SAT, perhaps be analogous to the H1 of the image capture system 9 of use equivalently _HighOctagon LMA-DCF with 400 μ m is an example, and as stated, upper and lower bound is respectively 60 and 120 gray levels.Therefore, the threshold value that is fit to can be made as H1 _Th=90 gray levels.The threshold value of dissimilar optical fiber can be confirmed and/or confirm through valid conjecture through experiment.For example, according to the fundamental mechanism that the fibre core image forms, referring to Fig. 4, the object plane 15 that imaging system 6 is set is to obtain H1 _ThRational position, leave the side or the surface of the covering 14 of optical fiber 13 near light.

Next problem is how to confirm that intensity profile has the situation of three peak structures that can fine parsing.Through the noise level (desirable for example about 2 gray levels in being actually used in the equipment of test) that counts imaging system, three peak structures that can fine parsing usually can be by the minimum acceptance value H2 of local fibre core peak contrast H2 _MinConfirm.Value H2 _MinGenerally can be made as higher 2 times than noise level, that is, and H2 _MinIn given example, can be made as 4 gray levels, and common H2 _MinValue should not be worth less than this.

At definite H1 _ThFit value after, can begin to search for fast pre-service, search provides the object plane position of three peak structures in catching photo.Search can begin from the clear and definite reference position of object plane, and this position is the self-focusing plane of the desirable optical fiber end of investigating 13 for example, perhaps gets usually away from the position of the optical fiber end side of object optical system or in the big distance of this side.Finding this type of initial position, behind the self-focusing plane, the object plane 15 of optical system 7 is to the fibre core 14 of optical fiber 13 ' move, and photo is taken continuously, and corresponding H1 value is extracted also and H1 through the real-time analysis intensity profile _ThCompare.If find to satisfy condition H1＞H1 _Th, then pre-service stops, and the current location of object plane is the reference position of subsequent processing.

Clearly, in search, do not use as above total contrast H1 of definition, but can use average total contrast H1 _Av, average total contrast is defined as at Central Composite light field r _3cIn mean flow rate with catch the adjacent black region r of photo _B1, r _BrDifference between the middle brightness, or be defined as three peak structure p equivalently at the center _3cIn average luminous intensity with from catching the adjacent black region b of intensity profile that photo draws ₁, b _rDifference between the middle light intensity.Equally obviously, can not use the condition of definition, and type of service | H1-H1 _Th|≤δ 6 or (H1 _Th-H1)≤general condition of δ 6, wherein, δ 6 is less predetermined values of suitably selecting, is used to object plane chosen position or scope, in this position or scope will start or search for next process that is used for definite optimum position.For example,, then be used for the somewhere that the reference position of next process can be in scope, as therebetween if confirmed this type of scope.

Subsequently, with the optimum position of the fibre core 14 ' position of confirming to be used for to confirm to take pictures.The best object plane position of the photo that clearly, imaging system 6 is provided therefrom can confirm fibre core 14 ' position is that local fibre core contrast H2 has its mxm. H2 _MaxThe position, this is because at H2 _MaxThe object plane position, can obtain the best analytic structure at fibre core image peak.Find the value of providing H2 _MaxThe object plane position, can approximate H1 greatly through total fibre core peak contrast in take pictures _ThThe position object plane 15 that moves around, make the value of local fibre core contrast H2 can become maximal value.If satisfy the condition (H2 of object plane position _Max-H2)＜and δ 2, then this process stops, and wherein, constant δ 2 is predetermined value or predetermined constant, is generally the 1-2 gray level at the equipment that is used for method of testing.H2 _MaxValue can draw through experiment.

Through using local fibre core contrast H2 to search in taking pictures, to be used for the best object plane position of confirming fibre core 14 ' picture position, can obtain many advantages.At first, use art methods,, fix the position that is used to observe given fiber core like disclosed method in said open Japanese patent application 11194227 and open Japanese patent application 1114853.Because the limited franchise of parts such as optical lens for example in making imaging system, the optimum focusing of a system and another system or object plane position can great changes have taken place, causes the picture quality variation of a contact maker and another contact maker.Overcome this problem, must carry out strict optics franchise inspection, this has increased manufacturing cost greatly.Use technology described herein, be used for the dynamically definite and optimization of optimum position quilt that each imaging system 6 is observed fiber core.Therefore, can reduce the requirement of making optical lens.Secondly, obtaining H2 _MaxThe object plane position, can be from two sides " covering peak " separation/parsing fibre core image well.Therefore, the covering peak reduces to minimum to the negative effect at fibre core peak in this position, and this type of negative effect for example comprises because the intensity p at fibre core peak and covering image peak _Sl, p _SrMutual superposition and the fibre core peak p that causes _cLittle skew.At last, this technology provides and has carried out the possibility of fibre core centering, and need not the information about covering marginal position in taking pictures.

Can remember equally, be equivalent to therefrom to obtain the brightness value of the corresponding fields in the photo of light intensity profile like the light intensity that writes down in the light intensity profile.Particularly, maximum optical intensity is equivalent to maximum brightness value, and minimum light intensity is equivalent to minimum luminance value.

The existing direct centering method of using cascade process of describing.

As stated, after confirming as the one or more suitable position of optical fiber end imaging,, can confirm in the corresponding views lateral excursion between two optical fiber ends as after having found best object plane position or focal position.Subsequently, imaging system 6 is set earlier, to catch the suitable photo of one of two optical fiber ends wanting first centering and be bonded with each other subsequently (for example left optical fiber end).In this type of photo, can see the image of two optical fiber ends usually.Specifically, can be observed fiber core 14 in the photo ' image, or the image of the center line that is produced by the refraction in the covering 14 is referring to following explanation.Subsequently, the setting of change imaging system 6 is caught the photo of the other end in two optical fiber ends so that it gets suitable position when needing.In the suitable photo of observing another optical fiber end, observe the fibre core of another optical fiber end or the image of center line.From these are observed, confirm lateral excursion.

Therefore, usually, lateral excursion for example can particularly be confirmed according to the core centre position according to two fiber core positions in the photo, perhaps confirms according to the position of above-mentioned center line.Fibre core 14 in the photo ' or the position of center line can from fibre core or center line image, obtain by a single point such a single point position and suitable small distance is arranged again from the fiber end face image.Difference between the position that the observed skew of imaging system obtains from is laterally at last confirmed.

Perhaps; For realizing higher degree of accuracy; The position of fibre core or center line can be from fibre core or center line image institute's a plurality of points of getting really allocation obtain; It is more and more far away from the end view drawing picture that this type of puts the constant space and the position that for example have suitable selection, leaves the nearest some position of end view drawing picture thereby also from the fiber end face image suitable small distance is arranged.Can pass through suitable method subsequently by fitting a straight line in the some position of laterally confirming, for example, through certain standard method like " linear regression fit " method.

Be that two straight lines extended to the abutment after two optical fiber ends were confirmed this type of straight line always, perhaps more precisely, extend to the plane that will engage always, this plane is the expection closing line in the photo.From the intersecting of straight line and closing line, the horizontal fibre core skew in can confirming to take pictures is as confirming through the distance or the difference that form between the point of crossing.

Show to each optical fiber end uses a plurality of definite points with the synoptic diagram mode among Fig. 9 and search the skew or the technology of distance.

Particularly, fibre core 14 ' or the position of center line can obtain from the single intensity profile that is positioned at the small distance that is fit to from the fiber end face image.But, with identical as stated mode higher degree of accuracy can be provided, to confirm fibre core or position of center line according to being positioned at a plurality of intensity profiles of on end view drawing picture line more and more far away, being got.Therefore, can obtain the many intensity profile samples along optical fiber end, for example, the end view drawing picture that is also referred to as exploded end from the optical fiber of being investigated is got 20 samples at interval with 5 μ m.Subsequently, confirm the center of fibre core peak or central peak for each sample intensity profile.The method that below argumentation is used for the center of definite fibre core peak or common central peak.Suitable method is passed through as stated by fitting a straight line in these centers, for example, and through certain standard method like " linear regression fit " method.

In fusion splicer, check at two usually and watch two optical fiber in the plane or for its imaging, these two planes are taken as perpendicular to X and Y and check direction among this paper that in most cases they are vertical each other but in some install, another angle possibly arranged each other.Under arbitrary situation, check direction perpendicular to and check plane parallel in location in device and the parallel optical fiber end that clamps vertically, this vertically be taken as Z to.According to the shifted by delta X, the Δ Y that confirm in taking pictures, can calculate true from the enlargement factor of optical system 7 or actual physical skew DX, DY.Skew DX is the skew of seeing on the direction X checking, and skew DY is the skew of seeing on the direction Y checking.

Be the reliable or enough good value of distance B Z between two fiber end faces that obtain to engage, in the suitable photo of taking pictures, through using for example linear regression method, the image of end face can be fit to two straight lines similarly.Subsequently, confirm or calculate two mean distances between the straight line, the distance during this distance is taken as and takes pictures between the end face.Among this distance, delta Z that from photo, confirms, can use the enlargement factor of optical system 6 to calculate the true or actual shifts DZ between Z direction upper surface as stated.

The centering operation is easily understood.The parallel longitudinal of adjustment earlier and clamped optical fiber end extends, and the vertical misalignment DZ between two fiber end faces on the Z direction obtains clear and definite spacing distance DG in the predetermined threshold δ 3 with approximate.Subsequently; Can be parallel to this motor 33 of checking the corresponding fiber clamp 31 on plane and reduce to minimum through correspondingly starting to be used for moving like the skew DX that in laterally checking first direction of direction, sees or DY; Referring to the detailed description of following Figure 11 a and Figure 11 b, and therefore the optical fiber end that anchor clamps keep moves in same plane.This moves and can should be minimum constant step pitch through its value and carry out, that is, the corresponding offset minus that a step back captured pictures is shown in a small amount should should be very little or very little with respect to the lateral dimension of catching optical fiber image in the photo.

Accelerate the centering operation, can use the specific process that is called " concatenation technology ".Concatenation technology refers to use particular algorithm to be reduced in the skew on the Z direction, on X, Y direction, observes equally.The method is included in corresponding anchor clamps 31 and optical fiber end, when the institute that on same direction, takes is used for that in steps skew is reduced to minimum possible value, uses the step pitch of more and more littler value.This type of more and more littler value in one example can be according to the decaying exponential function value, but can use other attenuation function, and the actual function of use for example depends on the desired speed before the smallest offset that reaches.In fact, found that the algorithm that uses half step cascade to reduce skew is a good selection in some cases.

Therefore, in the method, confirm the skew in the back photo of per step; Subsequently; If it is enough little that skew between the optical fiber end or corresponding physical skew have dropped to, that is, and less than predetermined threshold δ 4 that is respectively applied for shifted by delta X or Δ Y or δ 5; And subsequently anchor clamps 31 are moved the new step pitch with the value of calculating, with the skew of confirming now be reduced to its value half.Skew terminates in the operation of being investigated of checking centering on the direction during less than predetermined value.Afterwards, check direction for another and carry out identical technology.At last, when needed, can first check catch on the direction photo with inspection wherein as the skew of confirming whether still enough little.If it is not littler, then check that at this operation that is used for centering on direction can continue to obtain desired centering quality.After all were to the executed of neutron operation, optical fiber can be bonded with each other.Constant δ 4 and δ 5 are confirmed by the degree of accuracy of mechanical system.The respective value of calculations of offset is 0.1 μ m to the representative value of these two constants in the photo for physical deflection or for catching, and according to the enlargement factor acquisition of optical system 7, for digital imagery, then is the picture element density of catching in the photo.Similarly method also may be used on vertical misalignment DZ and is set to desired value DG.

On a view or direction, be used for centering or location process may further comprise the steps according to Cascading Methods:

1. one of two optical fiber ends are moved on to the initial position with respect to another optical fiber end that for example can think to fix; Gap with mechanical system in the moving of this initial position is absorbed; And optical fiber end must move on same moving direction to absorb the gap; So that offset minus is extremely minimum, perhaps making skew get predetermined value.

2. catch the optical fiber end photo in this position and confirm skew of being investigated or the distance, delta in the photo ₁

3. if whether the departure of confirming to confirm skew or distance and expectation value is also referred to as predetermined quality value, littler then stop this process less than predetermined value.

4. calculate corresponding to skew in the photo of confirming than a last step 2 or apart from the littler skew or the displacement steps distance of distance.

5. at the moving direction identical, optical fiber is moved corresponding to the distance that calculates the displacement steps distance with step 1.

6. catch the optical fiber end photo in this position and confirm skew of being investigated or the distance, delta in the photo ₂

7. whether the departure of confirming to confirm skew or distance and expectation value is less than the predetermined quality value, if littler this process that then stops.

8. calculate corresponding to skew in the photo of confirming than a last step 6 or apart from the littler skew or the new displacement steps distance of distance.

9. repeating step 5-8 is until in step 7, stopping.

In step 4 and 8, displacement steps is apart from s ₁, s ₂... According to s _j=a _jΔ _j, j=1,2 ... Calculate, wherein, constant a ₁, a ₂... Be on the occasion of, all less than 1, for example, aj=3/4, j=1,2 ...If the precision of mechanical motion system is very low, then all constants are made as a little value, for example, less than 1/4; This possibly be a good selection usually, and in other cases, all constants can be made as bigger value; For example, greater than 1/3, and being worth 1/2, to tend to be good selection.Constant a ₁, a ₂... In alternatives, can be depending on the actual or true skew of being investigated between the optical fiber end on the direction of checking, for big actual shifts, constant has bigger value with for example; But for less actual shifts; They have less value, and this provides accurately and rapidly centering in some cases and has not had that optical fiber is actual to be moved with " overshoot ", promptly; Optical fiber moves oversize distance, makes them have to displacement in the opposite direction so that skew is reduced to predetermined value.Constant a ₁, a ₂... In this case can with the actual shifts correlation of indices, this skew is reduced to the smaller value that is used for less offset from the higher value that is used for bigger skew.Perhaps, constant a ₁, a ₂... Can have big fixed value for skew greater than threshold value, for example, 3/4, and have less fixed value for the skew that is less than or equal to threshold value, for example, 1/2.

Be the position C2 of fibre core image peak center in accurately definite light intensity profile, and also confirm the position of single central peak in the centre focus method when needed, can use so-called card side (χ ²) the curve fitting technology of match, see also above-mentioned International Patent Application WO 01/86331.In the method, suppose that the selected interior at interval profile of measuring can come modeling through the stack of analytic function plus noise background.The quality of curve fitting can be through the card side (χ that simplifies ²) function evaluation.(the χ that simplifies ²) function can be expressed as:

${\mathrm{\χ}}^2=\frac{1}{N-\mathrm{\μ}}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left(\frac{F_i\left(x_i\right)-\underset{j=1}{\overset{n}{\mathrm{\Σ}}}G(x_{i,j};a_{i,j})-C}{\mathrm{\Δ}{F}_i}\right)}^2---\left(1\right)$

Wherein, G (x _{I, y}a _{I, j}Be to have fitting parameter a _{I, j}J analytic function, F _i(x _i) be x in the position _iWith measuring error rod Δ F _iZ intensity in fibre core image peak of measuring.Here, error bar Δ F _iEstimate through standard deviation, promptly $\mathrm{\Δ}{F}_i\≈\sqrt{F_i\left(x_i\right)}.$ N is at x _iMeasurement point sum.C is the noise background of picture system, and is assumed to be the change constant, and μ is the fitting parameter quantity that during fit procedure, changes.Integer n is the independent analysis function numbers of using in the fit procedure.

In profile analysis, Gaussian function can be the suitable analytic function that will be used to the residing profile modeling in fibre core image peak.Therefore, equality (1) can be reduced to:

${\mathrm{\χ}}^2=\frac{1}{N-\mathrm{\μ}}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left(\frac{F_i\left(x_i\right)-G(x_i;a_1;a_2)-C}{\mathrm{\Δ}{F}_i}\right)}^2---\left(2\right)$

In the formula, G (x _ia ₁a ₂) be to have fitting parameter a ₁And a ₂Gaussian function.Parameter a ₁And a ₂Be illustrated respectively in the halfwidth (FWHHM) at expection center He this peak at top in the profile.Best fit parameters collection { a _{1, best}a _{2, best}C} is maximized those parameters of probability with the expression measurement data.In fact, search is to produce χ ²≈ 1 result's fitting parameter.Through changing fitting parameter, and calculate χ with clear and definite match ring ²Respective value, draw { a that is used to represent fibre core image peak _{1, best}a _{2, best}The value χ of the best-fit values of C} ²≈ 1.Therefore, the position at fibre core image peak is by a _{1, best}Provide.Initial value { a that is used for fitting parameter _1,0a _2,0C} confirms through the preanalysis of image, and for example can use following value: a _1,0=x _i{ Max (F _i), a _2,0=2{a _1,0-x _k[Max (F _i)/2] }, C=Min{F (x _i).

Obtain better statistical data, can be each position x _iTake a plurality of images (m).If supposing the respective intensities of each independent image is h _{I, l}(x _i), l=1,2 ..., m, then be worth F _i(x _i) will confirm through the measured intensity that obtains from image being asked average, that is:

$F_i\left(x_i\right)=\frac{1}{m}\underset{l=1}{\overset{m}{\mathrm{\Σ}}}{h}_{i,l}\left(x_i\right)---\left(3\right)$

But be stressed that according to basic mathematical, light intensity profile can be represented through one group of basic function, like quadratic function, polynomial function, logarithmic function, exponential function etc. on principle.The selection of the analytic function that uses depends primarily on centering degree of accuracy and the time that execution model calculates.Therefore, for the optical fiber of given type, any function that satisfies about clear and definite centering degree of accuracy and time requirement should be regarded as suitable Model Calculation function.Typical example is the quadratic function that in fact successfully is used for express-analysis and definite fibre core peak center.

For two optical fiber ends that identical cladding diameter is arranged that will engage with for having of will engaging is less difference or than two optical fiber ends of the cladding diameter of big difference, the centering operation can be carried out to accomplish some operations quickly or to simplify working process in a different manner each other.Usually, be apparent that, in relevant technology be " the best " centering position of as above defining of two optical fiber each other enough near the time, the centering process possibly used single object plane position and object plane position captured pictures for this reason.Subsequently, this single object plane position can certain mode from confirming that the centering position draws, for example be its average, perhaps or even the centering position of one of two optical fiber ends, this situation thereby only require to be that an optical fiber end is searched for the centering position.Otherwise, catch independent photo and assess for each centering position possibly.

Below three kinds of situation can consider to be used for the fibre core centering method, but identical situation possibly also be applicable to the centre focus method:

(a) if the fibre cladding diameter that engages is identical,, also possibly obtain two fiber core images of equal in quality even then have only an optical fiber to be used to search for the fibre core image.In fact, can be through accomplishing this operation in the object plane position of the fibre core image optimum quality of being investigated of checking the optical fiber end that the News Search generation is moved on the direction, this optical fiber end moves in perpendicular to the plane of being investigated of checking direction at that time.In the photo of Figure 13 a and Figure 13 b, this type of optimum position is respectively applied for the left optical fiber end of centre focus situation and fibre core focus situation.As if the object plane position of using provide carrying out the enough good photo of respective type centering.

(b) if the difference between the cladding diameter of fiber optic splicing is less, for example, than the 10%-50% of the diameter of thin optic fibre or even in 10% to 100% scope, then when carrying out centering, use the object plane optimum position that only limits to than thin optic fibre maybe be just enough.For fibre core centering and Yan Yingzhi; Than the image of jumbo fiber thereby possibly not have best in quality, but in most of the cases, this quality possibly be acceptable for carrying out accurate centering; Referring to the photo of Figure 14 a, wherein the difference between the cladding diameter is actually than 150% of thin optic fibre diameter.But, can not use best object plane position than jumbo fiber, this is because play a leading role than the lens effect of jumbo fiber, if use this object plane, then can not observe fibre core 14 than thin optic fibre ', referring to the photo of Figure 14 b.The advantage of only using the image of an optical fiber end to carry out centering is that obviously the centering operation can become rapider, and is shorter to the T.T. that fibre core centering operation requires in this situation.This obviously is suitable for for centre focus centering operation is same.

(c) if the difference between two fibre cladding diameters that engage is bigger; For example; Respectively greater than than 50% or 100% of the diameter of thin optic fibre; When then only using an object plane position to carry out centering, the situation that basis (a) described method possibly occur or all can not successfully use according to (b) described method.In this case; Can transfer the optimum position of using in two optical fiber object plane 12 separately to; This means that the optimum position of using earlier one of optical fiber end confirms the reference position of this optical fiber end in its image, as its fibre core 14 ' the position, subsequently; Use the optimum position of another optical fiber end to confirm its reference position in its image; The skew of calculating afterwards as in X and Y direction, seeing on the current direction, and at last through checking that perpendicular to current the displacement that is fit in the plane of direction reorientates optical fiber end, with the offset minus that calculates to minimum.Therefore, the method (c) is a method in common, is applicable to all situations, but it possibly need the quite a long time.In fact, the centre focus centering that shows in the photo for for example Figure 15 a and Figure 15 b, it possibly be desirable using the method, wherein, best object plane position is respectively applied for thin and than jumbo fiber (left and right optical fiber end).

If two fibre cladding diameters that engage can confirm through imaging system 6,11 automatically, then can be according between the cladding diameter poor, carry out automatically like (a) and (b) and (c) selection of described appropriate methodology.Otherwise the user can import certain order, confirms the method that will use, and at needs or where applicable, and the image of confirming to be used for the centering operation is that a left side is or/and the image of right optical fiber end.

The more details of the automatic optical fiber contact maker that can carry out said method have been shown among Figure 11 a.Optical fiber 13,13 ' let its end regions between eletrode tip 21 discharges 23 for the heating optical fiber end betwixt, and the intensity of discharge is controlled by the strength of current between the electrode 21.Optical system by lens 7 representative also is similar to Fig. 1, and the optical fiber end zone in the photosensitive area 9 of two cameras is shown on two vertical direction, and the photosensitive area for example is the plate that carries the CCD element.Digital imagery disposal system 11 is used for handling the electric signal from photosensitive area 9, thus the optical fiber 13,13 that keep watch on to use ', and accomplish engaging process through the position determining means and the electrode current magnitude of control optical fiber.This image processing system is connected to monitor or display unit 29, with display photos, and one of two photos of for example being caught.As shown in the figure, according to the particular type photo that forms by image processing system 11 also can illustrate as see on two vertical direction, bonding station between the optical fiber end respect to one another.

In the synoptic diagram of Figure 11 b, show the more details of automatic type fiber bonding device on electrical structure.Coupling device has anchor clamps or fixator 31, optical fiber 13,13 between location and joint aging time ' the end place and firmly remain on wherein.Anchor clamps can move on three normal coordinates directions, two anchor clamps all be parallel to the vertical Z of optical fiber to, and be on X and the Y direction at both direction perpendicular to this direction.Anchor clamps 31 are by the 33 unshowned suitable mechanical guide rail displacements in edge of control motor.Electric wire to electrode 21 and light source 1, motor 33 and camera 6 extends from circuit module 35, from driving circuit 39 and 41 extensions and 43 extensions of the video interface from electronic circuit module 35, a circuit only is shown among the figure respectively.Be used for optical system object plane displacement that respective camera is comprised to the control line of camera.The picture signal that is fit to is transported to Flame Image Process and image analyzing unit 11 from video interface 43.Various process steps are by the control circuit unit that for example comprises one or more suitable electronic microprocessors 45 controls.Control circuit 45 is carried out the said process step; And therefore through on the sense of displacement that is fit to, controlling optical fiber end displacement respect to one another for motor 33 power supplies; And provide a signal to Flame Image Process and image analyzing unit 11, to start the analysis operation of different types of acquisition photo.In addition, control circuit 45 control fusion current time that will begin to be provided to electrode 21 and this electric current to fail repeatedly during and strength of current.

Therefore; In bonding operation; Elder generation grip optical fibers 13,13 ' end in anchor clamps 31; Through use as by light source 1, camera 6 and the motor 33 of electronic circuit cell 35 controls with optical fiber end centering, and at last through for electrode 21 power supplies form discharge, the heating optical fiber end also makes its fusion thus and is bonded with each other.

For being chosen in the centering operation is will use an object plane position only or will be used for the object plane position that two optical fiber ends are confirmed, a unit 193 can be set in control circuit unit 45.This element can comprise subelement 194 in addition, is used for the diameter of two optical fiber ends of access, and for example manually input receives the value of expression diameter, and perhaps it can be used for order imaging system 6 and catches photo, confirms this type of value by elementary area 11 from the image of catching.In addition, unit 193 can comprise subelement 195 that is used for the comparison diameter value and the subelement 196 that is used to make correct decision or selection.

Control circuit unit 45 also can comprise the GU Generic Unit 197 that carries out centering with some definite optics settings, and this subelement can comprise the subelement 198 that is used for positioning optical waveguides end on it is vertical again.Below description is included in other unit in the electronic circuit cell 35, and in example embodiment, clearly describe, for example be included in other unit in control circuit unit 45 and the elementary area 11.

The corresponding unit that comprises in now will simplify procedures process flow diagram and electronic circuit module 35 with reference to Figure 10 a, 10b, 10c and 10d, concise and to the point describe to be used to search be fit to object plane position and the position that is used for above-mentioned optical fiber and confirm the whole bag of tricks with centering.

The process flow diagram of Figure 10 a is depicted as the key step of searching the self-focusing position or realizing self-focusing effect and using this effect that the optical system setting of two optical fiber alignment is used.Process used selected direction, X or the Y direction of checking in steps.In first step 201, its end is kept by anchor clamps 31 and two optical fiber of clamping carry out preparatory centering roughly.In advance the check mark step for example can manually be carried out, perhaps referring to Figure 11 b, and through the preparatory centralising device 51 in the control circuit 45, execution under the help of the suitable unit of Flame Image Process and analytic unit 11.This type of preparatory centering step 51 can be by means of the guiding of the photo of camera 6 automatic shooting and in the analysis like elementary area 11 unshowned suitable unit; Correspondingly with anchor clamps 31 displacements, unit 51 also sends to video interface 43 and elementary area with appropriate command subsequently by control motor 33.

Then, through getting into first subprocess, search and to search for the zone of self-focusing position therein subsequently and start the process of searching required setting.This GU Generic Unit 53 that is used for confirming the self-focusing position through startup carries out with the unit 55 that is used to carry out first subprocess (promptly search the object plane that expection can find the self-focusing position earlier 15 zones are set); Also referring to Figure 12 a, these unit are included in the control circuit unit 45.At first, in step 203, imaging system 6 is located at suitable initial position, is also referred to as reference position in this case, and so that the object plane 15 of optical system 7 is located near the optical fiber side of imaging system, this side is called nearside.It can be carried out by corresponding cells 57, and this unit sends to optical system 7 with appropriate signals through driving circuit 41, and sends to video interface 43 when needed and reached desired proximal most position with elementary area 11 with inspection.In the step 205 that unit 59 is carried out, start setting up procedure subsequently, wherein will take photo about two adjacent fiber ends for first end in the maintenance optical fiber end of seeing at preferential direction.Unit 59 is correspondingly ordered video interface subsequently, and captured pictures is received by Flame Image Process and analytic unit 11.In next step 207; Confirm to catch the height H 1 of the intensity profile central peak structure of the first optical fiber end image in the photo; This highly can be aforesaid relative height or total contrast value, and this operation obtains intensity profile and command unit 65 by the selected optical fiber end image of unit 63 from catch image in the order elementary area 11 and starts from the unit 61 of intensity profile determined value H1.

Subsequently, for fiber type under the optical fiber that from the image of its optical fiber end, has obtained intensity profile and value H1, definite determined value H1 be greater than or equal the effective threshold value H1 of the type _HighAlso referring to Figure 11 b, this is carried out by comparing unit 67 in step 209, for threshold value H1 _High, the value that this step uses the parameter list of the dissimilar optical fiber of 69 storages from memory location storer 71 to get, the required type stores of optical fiber with current optical fiber end are in the memory location 73.If comparative result is " denying ", then execution in step 211, in this step, the object plane 15 of optical system 7 checked on the direction from the predetermined step pitch of fiber optics displacement or had the step pitch of predetermined length selected.Unit 75 sends a command to imaging system 6 subsequently, so that 77 length that obtain are the setting of the step pitch change optical system of s1 from the memory location.Subsequently, execution in step 205,207 and 209 once more, carried out by units corresponding.

If confirm that in step 209 height H 1 satisfies condition, then the unit 79 through comprising in the unit 53 that is enabled in control circuit unit 45 stops first subprocess, and gets into second subprocess.Execution in step 213 subsequently, in this step, confirm the intensity profile central peak width W 1 of the first optical fiber end image, and this operation is by 81 controls of the unit in the unit 79, and the intensity profile of having been confirmed by unit 63 is handled in unit 83 in the unit 81 order elementary areas 11.In step 215, confirm subsequently to have confirmed whether width enough little, that is, and with the value W1 that characterizes fiber type _MinDeparture whether less than target offset value δ 1.Compare operation is carried out by the comparer in the control module 45 85, and this comparer is the table from memory location 69 and be used for the memory location 87 acquisition value W1 of storing predetermined maximum deflection difference value respectively _MinWith δ 1.

If confirmed that width W 1 is inadequately little; Then being arranged on of imaging system is modified predetermined amount in the step 217; Promptly optical system 7 is adjusted so that object plane 15 displacement predetermined steps apart from s2, promptly have the step pitch of predetermined length s2, this displacement is after leave first subprocess; The new reference position of finding in step 209 back when promptly condition satisfies therein of object plane begins, and near displacement back and forth this position.In fact, this is provided with change and can carries out in the following manner:

1. selected optical fiber end is for example left in choice direction.

Preferential direction make object plane 15 with displacement steps apart from the s2 displacement.

3. continue to be implemented as the step that selected optical fiber end is taken pictures and confirmed W1.

4., then return the top new reference position of confirming, and change direction into opposite direction, promptly towards selected optical fiber end if fixed W1 value has the trend of increase.

5. execution in step 2-4 once more.

The change step pitch can be by unit 89 orders, the stride value s2 of 77 acquisition step pitch length from the memory location.Step pitch s2 can be preferably the step pitch s1 that uses less than in last subprocess, even much little.In step 219,, catch photo in the selected direction of checking once more according to the order of unit 91.Subsequently, execution in step 213 once more.

If confirm that in step 215 width W 1 is enough little, then the self-focusing position of object plane 15 reaches, so stop second subprocess.As with memory location 95 that selected optical fiber end is associated in the unit 93 of the value that is provided with of storage representation performed the same, but in step 221 Set For Current of storing optical system 7.Subsequently, in step 223, can confirm the center of central peak structure or intensity profile, or certain equivalent, as in the central peak structure, getting peaked position for it.The execution of this step can be by unit 97 controls, and this unit sends to the necessary unit 99 that calculates of execution in the elementary area 11 with order.For example, can use the method for the derivative of working strength profile as stated.But the method requires in the intensity profile zone at place, central peak side, to have the pixel of sufficient amount.If the side is too steep, then possibly can't confirm derivative with gratifying degree of accuracy.In this case, object plane 15 can on the arbitrary direction in two reverse directions, move apart a little the position of finding with self-focusing, like certain predetermined steps distance of displacement, promptly have the step pitch of certain predetermined length.When needing, can be as above said from taking from the center of confirming central peak perpendicular to a plurality of intensity profiles of the different parallel lines of the optical fiber end of being investigated and/or near object plane 15 a few diverse locations the optimum position of being found with reference to Fig. 9.

Being used for confirming the step of central peak position at one/a plurality of selected optical fiber end images of catching photo, for example can be those steps shown in Figure 10 b process flow diagram.

After in step 223, from the intensity profile that the first optical fiber end image obtains, having confirmed the central peak position, in step 225 for appreciable another optical fiber end in the same photo repeats identical process, i.e. step 203-223.These can be by unit 101 controls, and the memory location 103 of the current optical fiber end designator of its image perhaps will analyzed through using storage in this unit, selects the optical fiber end such as a left side or right optical fiber end.In the end in the step 227; Through starting at least one motor 33 in the plane of checking direction perpendicular to selecting; The optical fiber end that anchor clamps 31 are kept moves step pitch or the distance of confirming according to the central peak center of two optical fiber end photos; With with the mutual centering of central peak, realize desired " centre focus " centering thus, actual produce as check fibre cladding 14 centerings seeing on the direction selecting.Perhaps, optical fiber end can be positioned in the move operation as checking the desired distance B X each other observing on the direction selected _Des, DY _DesMoving step 227 can be by 105 execution of the unit in the control module 45 and control; Control module available cell 106 is again confirmed check the skew between two optical fiber ends seeing in the plane of direction perpendicular to selecting; This unit for example calculates in step 223 poor between the position of confirming, and this position is calculated by unit 99.

Subsequently; Can be other and check the identical process step of direction execution shown in Figure 10 a; This utilizes storage maybe will analyze the current memory location 109 of checking the direction designator of its photo by selecting such as level or checking that vertically direction or leading section or rearward end check that direction etc. checks unit 107 controls of direction.

As above be that step 223 is said; To the intensity profile that obtains from the optical fiber end image of catching photo, confirm the position of central peak; Be its center or certain measurement of getting peaked position, can carry out a process, as relate to " defocusing " operation Figure 10 b shown in process.As above hypothesis checks that direction is selected.In first step 301, selection makes the direction of object plane 15 displacements of optical system 7.This direction can away from or towards the optical fiber end of being investigated.In next step 303, confirm intensity profile along first line in the selected optical fiber end image of former captured pictures.In step 305, confirm the derivative of intensity profile subsequently, and in step 307, confirm posivtive spike and negative peak in the derivative of indication central peak side subsequently, referring to Fig. 7 with above quote this figure description.Above-mentioned confirm to comprise especially confirm pixel quantity in the zone of confirming these peaks, i.e. the point or the discrete variable of intensity profile function in each this type of zone are referring to step 309.Subsequently, whether these quantifications of inquiry enough in step 311, as quantity be greater than or equal predetermined quantity p, in one step of back, to obtain gratifying definite for the position of getting plus or minus step pitch extreme value for it.If lazy weight is enough, then execution in step 313, and whether defocusing in this step on the inquiry preferential direction too far away, that is, the step pitch quantity on the preferential direction be greater than or equal predetermined quantity d.If this is a truth, then in step 315, changes preferential direction, and in step 317, make object plane be displaced to its reference position.After this step, and also after the step 313 under in the selected direction the not many situation of step pitch, in process steps 319, make object plane 15 displacements of optical system 7 have the step pitch of length s3 in the selected direction.This is " defocusing " step.In next step 321, catch photo, afterwards execution in step 303 again.

If confirm that in step 311 pixel quantity is enough, then execution in step 323, in this step, confirm the position of extreme value in the derivative or the center of posivtive spike and negative peak.In step 325,, confirm the center position measurement or the actual maximal value of the central peak in the intensity profile through getting the position average of confirming in the last step.In optional step 327,, then confirm intensity profile along catching in the photo another line if confirm and analyze the intensity profile of sufficient amount as yet.Subsequently, the same as more early carrying out, in step 329, confirm the derivative of this intensity profile, in step 331, locate posivtive spike and negative peak in the derivative, and execution in step 323 more subsequently.If according to confirming in step 327; Analyzed intensity profile along the parallel lines of quantity sufficient; Then in final step 333, confirm the accurate position of the central peak in the up-to-date optical fiber end image of being investigated of catching photo with certain suitable mode, as calculating average or the mean of mean of in step 325, confirming; Perhaps for obtaining to be applicable to more accurately measuring of centering operation; Use above-mentioned linear regression method, with confirming that average is fitted to straight line and the point of composition plane is hit as this straight line in the position at peak, composition plane generally be perpendicular to keep the plane longitudinally of optical fiber end; Pass electrode 21 points, and be regarded as the perpendicular line of catching in the photo.

Process in the step 227 that Figure 10 a describes can " cascade " mode shown in Figure 10 c flow chart step also be carried out with the unit shown in Figure 11 b and Figure 12 b.In the first step 401 of carrying out and controlling by unit 121,, they are fully separated each other optical fiber end being moved certain distance each other perpendicular to selecting in the plane of checking direction.Subsequently, they are being moved to absorb mechanical clearance in the other direction.For example, if mechanical clearance equals P, and select and check that the desired off-set value on the direction equals Δ _Des, then optical fiber end must be removed at least (P+ Δ each other from approximate centering or preparatory centering position _Des+ r) distance, displacement P on opposite direction then, wherein, r is little scheduled volume.

The optical system 7 of imaging system or camera 6 is made as the photo of taking first end in two optical fiber ends in step 403, for example obtain the relevant information that is provided with through one of the storage unit 183 that will describe from storage unit 95 or hereinafter.This step can be carried out by unit 122.In next step 405, such as unit 123 order and taking pictures.In step 407, confirm the reference position, like position of catching the central peak center in the optical fiber end image in the photo or central peak maximal value present position of being investigated or the position of catching end face in the photo, this step is by unit 127 startups and control.The reference position is confirmed in suitable unit in the unit 129 in the unit 127 order elementary areas 11; Start said units 99 to confirm the position of central peak as passing through; Perhaps wait certain other unit to confirm that central peak obtains its peaked position like unit 131, perhaps unit 132 is to confirm the position of end face in the first optical fiber end image.Unit 131 for example can use above-mentioned card side approximating method.In the step 409 below, 411 and 413, be that second optical fiber end repeats first three step 403,405 and 407.This can be carried out by the said same unit that is used for first three step, and by the optical fiber end of unit 133 controls to select its image to handle, unit 133 for example uses storage unit 103.

Behind the reference position in confirmed two optical fiber end images for twice through execution in step 413, confirm in step 415 to have confirmed skew or distance, delta X, Δ Y or the Δ Z between the reference position in the image that this carries out in unit 129.In next step 417, inquiry has confirmed whether skew is enough to equal desired skew or distance value Δ X respectively _Des, Δ Y _DesOr Δ Z _Des, as being at most the amount of δ 4 or δ 5 with its deviation.Desired skew that obtains from photo or distance value are corresponding to desired skew or the distance value DX of real machinery _Des, DY _DesOr DZ _DesThis step can be carried out in comparer 131, uses the maximum deflection difference value δ separately 4 and δ 5 of 87 acquisitions from the memory location.If result relatively be skew or distance fully near expectation value, then stop this process.Otherwise, in step 419, calculate the mechanical each other respective distances that moves of optical fiber end by unit 133 usefulness cameras, 6 times magnification numerical value.In next step 421, this distance that calculates is reduced a multiple, in this step, unit 135 from storage be used for the multiple of different distance memory location 137 (possibly be table) obtain multiple.Subsequently; In step 423; In perpendicular to the selected plane of being investigated of checking direction; On the direction identical with the decline of the step 401 that is used for absorbing the gap with optical fiber end move each other with reduce calculate distance or the displacement steps distance that step pitch equates, this is controlled by unit 139.Subsequently, carry out this process once more, from step 403 beginning and continuation repetitive process, abundant from definite skew of taking pictures for expectation value until in step 417, confirming.

Obviously, for the compare operation of step 417, can not use from catching skew or distance, delta X, Δ Y or Δ Z and corresponding desired skew or the distance value Δ X that photo directly obtains _Des, Δ Y _DesOr Δ Z _Des, but can use corresponding mechanical bias or distance B X, DY or DZ and desired mechanical bias or distance B X _Des, DY _DesOr DZ _Des, this need carry out the calculating like execution in step 419.

Referring now to the process flow diagram of Figure 10 d and the unit shown in Figure 11 b and Figure 12 c, the fibre core centering method is described briefly.The process steps of the method can be by 151 controls of fibre core centralising device.In first step 501, two optical fiber ends carry out preparatory centering, are for example carried out by the unit 141 of unit 51 or implementation center's focus method, and unit 141 for example comprises the above-mentioned various unit that are used to carry out the method.Best object plane position is confirmed by unit 153.

Then; Start a sub-processes, confirming subsequently suitable scope, or confirm a suitable primary importance the best possible position of the object plane 15 of search; To search for the best possible position of object plane 15 subsequently from this position or near this position, this is by unit 155 controls.Check that direction, imaging system 6 are made as and make its object plane 15 promptly, with the end big distance is arranged or at remote location, this is by sending unit 157 execution of appropriate command to imaging system 6 in second step 503 fully away from optical fiber end for selected.In next step 505, catch photo according to the order of unit 159 on the direction selected checking subsequently, and in step 507,, be two selected end determined value H1 that are held in the optical fiber end as above to be the described identical mode of step 207.Unit 161 is used for confirming that from catching the selected optical fiber end image of image the unit 63 of intensity profile confirms unit 65 with H1 through sending control signals to, to value H1 confirm control.Perhaps, unit 161 can with as be used for the identical mode in many other unit described herein, itself comprise unshowned subelement, to carry out the such one or more basic steps of described two steps that comprise in confirming such as H1.In step 509, determined value H1 and threshold value H1 more _Th, this step is by being the corresponding fiber type value of searching H1 in the table of memory location 69 storages _ThComparer 163 carry out.If comparative result is that determined value H1 is greater than threshold value, then execution in step 511, in this step, check on the direction that selected object plane 15 with imaging system 6 moves predetermined steps apart from s4 to optical fiber end, promptly has the step pitch of predetermined length s4.This step is carried out by the corresponding unit 165 of the 77 access s4 values from the memory location.If confirm that in step 509 determined value H1 is less than or equal to predetermined threshold H1 _Th, then stop being used to search the subprocess that is fit to scope or zone or primary importance.

Entering subsequently is used to search best object plane position to obtain another subprocess by the image of fibre core 14 ' generation, and this is carried out by unit 167.For the image of catching photo and selected optical fiber end, determined value H2 in step 513, this is by confirming the unit 169 of intensity profile in order to command unit 63 and being used for controlling from intensity profile determined value H2 unit 171.In next step 515, inquire whether determined value H2 is enough high, promptly with the maximal value H2 that supposes _MaxDeparture is at most δ 2.This table in storage from memory location 69 obtains maximal value H2 _Max, and obtain the comparer 173 of deviate δ 2 from memory location 87 and to carry out.If determined value H2 is not high enough in step 515; Then execution in step 517; In this step,, leaving first subprocess and getting into second subprocess as above to be the identical mode of the said mode of step 217 among Figure 10 a; Near the position that object plane has when promptly getting into step 513, the object plane 15 of the optical system that moves around 7.Move and carry out with the step pitch of predetermined length s5, this length is preferably less, as is far smaller than the predetermined step-length s4 that in for this subprocess search reference position of searching best object plane position, uses, referring to square frame 511.This moves by unit 177 controls, and this unit is 77 retrieval step-length s5 from the memory location, and appropriate command is sent to imaging system 6.Subsequently, in step 519 and by unit 179 controls, take pictures in the selected direction of checking.Once more from step 513 beginning, carry out second subprocess subsequently.If determined value H2 is enough high in step 515, then stop this subprocess.

Now can be in step 521 the actual setting of storing optical system 7, the order of the unit 181 that for example is provided with according to storage in corresponding in two memory locations 183.Subsequently, can in step 523, confirm central peak center or peaked position in the central peak structure, perhaps certain equivalent in the intensity profile.The execution of this step can be by unit 185 control, and this unit sends to order and carries out the necessary benchmark that calculates and confirm certain unit of comprising in the unit 129.When needing, said with reference to Fig. 9 and Figure 10 b, a plurality of intensity profiles that can obtain from the different parallel lines perpendicular to the optical fiber end of being investigated are confirmed the center of central peak.

After in step 523, having confirmed the central peak position in the selected optical fiber end image; It in step 525 another optical fiber end of appreciable two optical fiber ends in same photograph; For the identical selected direction of checking, repeat to comprise the whole process of step 501-523.These can be by unit 187 controls, and the memory location 103 of the current optical fiber end designator of its image perhaps will analyzed through using storage in this unit, selects the optical fiber end such as a left side or right optical fiber end.In final step 527; Through starting at least one motor 33 in the plane of checking direction perpendicular to selecting; The optical fiber end that anchor clamps 31 are kept moves the distance of confirming according to the definite position of the central peak in two optical fiber end images each other; With with the mutual centering of central peak, realize thus as the required fibre core centering seeing on the direction perhaps can fibre core being placed the desired distance in space selected checking.This step can use " Cascading Methods " shown in Figure 10 c to carry out by unit 189.Usually, this unit available cell 191 is confirmed check that perpendicular to selected skew between two optical fiber ends seeing in the plane of direction, this element for example calculate poor between the position of in step 523, confirming of being calculated by unit 99.

Come 10a with the aid of pictures, can be other and check the identical process step shown in the direction execution graph 10d, this uses the current memory location 109 of checking the direction designator of storage by unit 107 controls of selecting to check direction.

In Figure 11 b and Figure 12 a, Figure 12 b and Figure 12 c, provide to be used to carry out like the unit of disclosed process different task of this paper and step and the particular example of subelement particular example and tissue and relation.But; Those skilled in the art understand; The desired unit of implementation can multiple alternative, equivalent mode design, organize with relevant with subelement, can be carried out by individual unit or subelement like in groups task and step, rather than carried out by a plurality of unit and/or subelement; Perhaps carry out by being different from a plurality of unit as herein described and/or subelement; The unit or the subelement that are used for special duty or step can be included in and be different from unit as herein described and/or subelement, and the execution of some tasks and step is divisible between a plurality of unit and the subelement, rather than are carried out by individual unit or subelement.Particularly; Elementary cell shown in the said figure; All unit of promptly in said process, only carrying out little basic step can all be regarded as only being included in the electronic circuit cell 35, and are not included in the various master units of carrying out the technology that comprises a plurality of basic steps.

Though specific embodiment of the present invention illustrates and describes at this paper, can recognize that those skilled in the art will be easy to realize many additional advantages, modification and change.Therefore, its wider aspect, the invention is not restricted to shown in this paper and described specific detail, indication device and example shown.Therefore, under situation about not breaking away from, can carry out various modifications like claims and defined general invention main idea of equivalent or scope.Therefore, be appreciated that the claims of enclosing are intended to be encompassed in all this type of modification and the changes in true spirit of the present invention and the scope.

Claims (19)

1. One kind through the mechanical system using two parallel optical fiber ends are relative to each other moved to two optical fiber ends location in perpendicular to the plane of checking direction, to be had the method for the position of desired skew each other; Said mechanical system has the gap, and said method comprises following consecutive steps:

   -in initial step; In said plane, two optical fiber ends are moved on to remote location relative to each other on first direction; And on opposite second direction, moving on to the starting position subsequently to absorb the gap, said far-end and starting position are chosen to make it possible on said second direction, move said two optical fiber ends to obtain desired skew from said starting position;

   -definite two optical fiber end reference positions separately on said plane and said first, second direction;

   The difference of the said reference position of-calculating;

   -confirm whether institute's difference of calculating departs from desired value to be at most predetermined maximum deflection difference value; And

   If-confirmed that institute's difference of calculating and desired value deviation surpass said predetermined maximum deflection difference value, the consecutive steps 1 below then carrying out)-4):

   1) reduces said difference to form displacement;

   2) on second direction described in the said plane, said two optical fiber ends are relative to each other moved said displacement; And

   3) begin from confirming the step of reference position subsequently, repeat each step for the end separately of said two optical fiber ends;

   4) thus confirm the deviation of the difference of calculating and desired value be at most under the situation of said predetermined maximum deflection difference value, obtain the desired position of said two optical fiber ends.
2. 2. the method for claim 1 is characterized in that, through said difference being multiply by less than 1 and reducing said difference more than or equal to 1/2 the factor.
3. 3. the method for claim 1 is characterized in that, reduces said difference through the factor that said difference multiply by less than 1, is used for the factor than big difference greater than the factor that is used for less difference.
4. 4. the method for claim 1; It is characterized in that; Said difference multiply by the factor that depends on said difference reduce said difference, this factor has from being used for being reduced to than the higher value of big difference the exponential dependence of the difference of the smaller value that is used for less difference.
5. 5. the method for claim 1 is characterized in that, in moving the initial step of two optical fiber ends, the said first direction in the said plane be chosen as perpendicular to said two optical fiber ends common vertically.
6. 6. method as claimed in claim 5 is characterized in that, in the step of confirming two optical fiber end reference positions separately, said reference position is confirmed as the position of the fibre core of a respective end in said two optical fiber ends.
7. 7. method as claimed in claim 5 is characterized in that, in the step of confirming two optical fiber end reference positions separately, said reference position is confirmed as the center line of a respective end in said two optical fiber ends or the position of the longitudinal axis.
8. 8. the method for claim 1 is characterized in that, in moving the initial step of two optical fiber ends, the said first direction in the said plane be chosen as be parallel to said two optical fiber ends common vertically.
9. 9. method as claimed in claim 5 is characterized in that, in the step of confirming two optical fiber end reference positions separately, said reference position is confirmed as the position of the end face of a respective end in said two optical fiber ends.
10. 10. method that two optical fiber ends are bonded with each other may further comprise the steps:

    -locate said two optical fiber ends with the method for claim 1; And

    -afterwards, said two optical fiber ends are interconnected at its end face, heat in the zone of said end face, and the end face of said optical fiber end at them fused each other.
11. 11. the device that two optical fiber ends are bonded with each other comprises:

    -anchor clamps, each anchor clamps is configured to keep one of two optical fiber ends, so that vertically roughly being parallel to each other of said two optical fiber ends;

    -motor moves said optical fiber end thereby be connected to said anchor clamps to move said anchor clamps;

    -electrode is used between eletrode tip, producing electric arc, and said electric arc heats said two optical fiber ends at end region, at said end face the material fusion is formed to engage;

    -imaging system is used for checking that direction catches the photo of said optical fiber end that said imaging system comprises optical system;

    -electronic circuit cell, said electronic circuit cell comprise following assembly 1)-9):

    1) control module is connected to said motor to drive them, is connected to said electrode and thinks said electrode power supply, and be connected to said imaging system to adjust and to order it to catch photo;

    2) elementary area is connected to said imaging system to receive the information of representing the photo of being caught;

    3) be used to control the unit of motor; In order to said two optical fiber ends are relative to each other moved on to remote location at first direction in perpendicular to the said plane of checking direction; And on opposite second direction, move on to the starting position subsequently must be to absorb for these move the gap in the said motor that starts and the mechanical attachment that is associated, said far-end and starting position are chosen to make said two optical fiber ends can be on said second direction to move from said starting position to move with one or many and obtain desired skew;

    4) be used for confirming the unit of reference position, it confirms the reference position on said plane and said first, second direction separately for said two optical fiber ends;

    5) be used to calculate the unit of difference of definite reference position;

    6) be used for confirming whether institute's difference of calculating is at most the comparer of being scheduled to maximum deflection difference value with desired deviation;

    7) deviation that is used for confirming institute's difference of calculating and desired value at said comparer starts the unit of following two unit above under the situation of said predetermined maximum deflection difference value:

    8) be used to reduce the difference of calculating to form the unit of displacement value; And

    9) be used to control the unit that said motor moves anchor clamps, and move said two optical fiber ends thus, displacement equals on second direction described in the said plane formation value of displacement relative to each other;

    -said comparer confirm the deviation of the difference of calculating and desired value be at most under the situation of said predetermined maximum deflection difference value, for said electrode power supply with said two unit that optical fiber end is bonded with each other.
12. 12. device as claimed in claim 11 is characterized in that, the configuration of cells that is used to reduce the difference of calculating becomes through said difference being multiply by less than 1 and reducing said difference more than or equal to 1/2 the factor.
13. 13. device as claimed in claim 11 is characterized in that, the configuration of cells that is used to reduce the difference of calculating becomes and to reduce said difference through the factor that said difference multiply by less than 1, is used for the factor than big difference greater than the factor that is used for less difference.
14. 14. device as claimed in claim 11; It is characterized in that; The configuration of cells that is used to reduce the difference of calculating becomes said difference multiply by the factor that depends on said difference to reduce said difference, and this factor has from being used for being reduced to than the higher value of big difference the exponential dependence of the difference of the smaller value that is used for less difference.
15. 15. device as claimed in claim 11 is characterized in that, the configuration of cells that is used to control said motor becomes as perpendicular to said two optical fiber ends first and second directions longitudinally jointly.
16. 16. device as claimed in claim 15 is characterized in that, is used for confirming that the configuration of cells of reference position becomes the position of the reference position of optical fiber end being confirmed as said optical fiber end fibre core.
17. 17. device as claimed in claim 15 is characterized in that, is used for confirming that the configuration of cells of reference position becomes the center line of a respective end of said two optical fiber ends or the position of the longitudinal axis are confirmed as in the reference position of optical fiber end.
18. 18. device as claimed in claim 11 is characterized in that, the configuration of cells one-tenth that is used to control said motor is as being parallel to said longitudinally jointly first and second directions of two optical fiber ends.
19. 19. device as claimed in claim 18 is characterized in that, is used for confirming that the configuration of cells of reference position becomes the position of the reference position of optical fiber end being confirmed as the end face of said optical fiber end.

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