Background technology
Optical fiber image transmission beam generally is that, diameter certain by make thousands of of glass material or tens thousand of length forms at some microns monofilament (simple optical fiber) boundling.In order directly to transmit image information, require each root monofilament (being each pixel) in the coherent fiber bundle to arrange according to close relation one to one, that is to say that each pixel residing relative position on end face in incident end and the exit end is in full accord in the position at coherent fiber bundle two ends.Like this, every monofilament just can be regarded a taking unit as, i.e. pixel, and image can transfer to exit end respectively through the decomposition of a large amount of pixels, because exit end and incident end have same arrangement mode, become complete image so reconfigure reduction in the exit end image information.The principle of work of Here it is optical fiber image transmission beam.
Coherent fiber bundle generally has two kinds of production technologies: the one, and row's silk method, the 2nd, sour molten method.Row's silk method is the two-dimensional array that directly a large amount of monofilament is become proper alignment at the two ends boundling.Requirement is very high but the difficult point of this method is manufacturing technology, tens thousand of diameters is had only neat the lining up and being not easy of monofilament of micron dimension.Usually in order to reduce manufacture difficulty, filament diameter is generally bigger, and for example tens to hundreds of microns diameter is unfavorable for the raising of resolution like this under the condition of limited of space.In order to improve pixel number, need to increase the diameter of coherent fiber bundle, to reach several millimeters diameter usually, this has directly limited the range of application of coherent fiber bundle.If can do thinner, coherent fiber bundle just can directly insert more tiny biologic-organ, as blood vessel, bile duct etc.And coherent fiber bundle is generally by the brittle glass manufacturing, and therefore the fracture of wire phenomenon is easy to take place in the middle of row's silk method manufacture craft, thereby yield rate is low, the cost height.In use, the monofilament of coherent fiber bundle also is easier to rupture because of factor such as bending, and its pixel of transmitting will disappear so, thereby stain occurs, makes image region the dead space occur, and resolution descends.
The molten method of acid, this method is at first to make three layers of coaxial monofilament (innermost layer is a sandwich layer, the centre is a cortex, outermost layer is the soluble glass layer), arrange bunchy then, hot melt is drawn into composite filaments, at last this is met filament and places the outermost material (except the coherent fiber bundle two ends) of removing monofilament in the acid solution, and then make each monofilament separately, thereby obtain the pliability of coherent fiber bundle.This process technology limit pass the monofilament quantity of pixel, just directly limited the increase of pixel.This is because if the beam diameter that monofilament is formed, and promptly the coherent fiber bundle diameter is too big, and more than 3mm, the soluble glass in the middle of the video beam can can't be corroded because acid solution can't permeate into smoothly, and then is difficult to the flexility that obtains to expect.
CN1828348A has described the manufacture method that the molten legal system of a kind of acid is made the small section flexible optical fiber image transmission beam.The three layers of coaxial monofilament that adopted three cover crucible manufactured are arranged hot melt then again and are become the rigidity multifilament, at last this multifilament are carried out sour molten processing and become flexible optical fiber image transmitting beam.This method can be made the less flexible coherent fiber bundle in cross section, and diameter is at 0.6~2mm, and effectively logical light area mention high to 40~50%, but pixel is less, be generally about 10000 and below, big again words will be brought very big difficulty to production technology.CN101419308A has described a kind of heavy in section optical fiber image transmission beam.The heavy in section here mainly is that high pixel requires to cause.Final design pixel can be up to 140000, but the diameter of coherent fiber bundle reaches about 5.6mm simultaneously, and resolution is only in 40~60lp/mm scope.This causes (more than the 12um) more greatly because of filament diameter.
CN1800892A has introduced a kind of manufacture method of high-resolution optical fiber image transmission bundle.This method representation can be produced filament diameter and be low to moderate about 3 μ m, and resolution reaches the optical fiber image transmission beam of 166lp/mm, and area of section reaches 10 * 10mm.And in fact will the composite filaments of 12~18 μ m be arranged again, this is very difficult in actual production process.Because there is more complete invalid space in the simple arrangement mode that its composite filaments is carried out between the composite filaments, this has reduced the effectively logical light area of coherent fiber bundle, and can have influence on resolution in addition.
High-resolution optical fiber image transmission beam all has a wide range of applications in scientific research, medical treatment, military field etc., in military scouting periscope, antitank missile system, all adopt the long-pending optical fiber image transmission beam in high resolving power heavy in section, more than the resolution requirement 90lp/mm, sectional area is more than 5 * 5mm.Then require coherent fiber bundle pliable and tough in medically application, diameter is little, and pixel is higher, and resolution is very high, for example greater than 100lp/mm.Such optical fiber image transmission beam can be used for deeps such as esophagus, rectum, bladder, uterus, stomach and detect endoscope (gastroscope, angioscope etc.).
Summary of the invention
The defective of purpose of the present invention in order to exist on several optical fiber image transmission beam designing and manufacturing methods that solve above-mentioned prior art and mention: but as pixel on the low side or technical matters such as the high resolution of pixel is not high, the manufacture craft difficulty is big.It is easy that the present invention proposes a kind of technology, and can make the method for high-resolution optical fiber image transmission bundle, use the resolution of the optical fiber image transmission beam that this method makes can reach 249lp/mm, filament diameter is low to moderate 2um, pixel at least greater than 8000, representative value is 20000~100000 flexible optical fiber image transmitting beam.The diameter of coherent fiber bundle is at 0.2mm~2mm, and this method can be made resolution height, higher, the pliable and tough optical fiber image transmission beam of pixel, has output height, characteristics that cost is low simultaneously.
This method is based on plasma chemistry vapor phase deposition (PCVD) technology, and the precast rod refractivity section that is used to draw the coherent fiber bundle monofilament is designed, and utilizes PCVD technology to make prefabricated rods again.Utilize ripe PCVD technology to help bringing into play the advantage of ripe telecommunication optical fiber prefabricated rods manufacturing technology, can effectively reduce optical fiber because the loss that factors such as foreign ion, defective, pollutant are brought.Optical fiber designs based on PCVD technology makes that acquisition monofilament biography optical loss is very little fully, and for example maximum transmission of visible light transmission loss helps improving to greatest extent transmittance less than 0.03dB/m.Loss is compared and above patent, extremely when young an order of magnitude.
When selecting the material of monofilament, require the transmittance height of core material, and clad material requires refractive index low, and require the refractive index of core material and clad material to differ to be the bigger the better.Aspect thermal behavior, require two kinds of material coefficient of thermal expansion coefficients to be close, if differ bigger, then monofilament is inner can form big internal stress, and the transmittance of monofilament waveguide and intensity are reduced.In addition, require the softening point of two kinds of materials and the viscosity under the high temperature all will be close, otherwise, can cause core material and clad material in conjunction with inhomogeneous, will have influence on the leaded light performance of monofilament.The preform that the meteorological chemical deposition of plasma (PCVD) that adopts the telecommunication optical fiber manufacturing process generally to use is made is used to draw the monofilament of the coherent fiber bundle that needs herein.The making of this prefabricated rods fully takes into account the coupling of viscosity under waveguiding structure rationality, material thermal expansion coefficient, softening point and the high temperature.In this prefabricated rods, its core diameter 15~20mm, cladding diameter is 18~24mm, so the core bag is 0.62~0.91 than typical range, much larger than above this value of mentioning in the patent, this will greatly improve the effectively logical light area of coherent fiber bundle.Here this prefabricated rods that is used for the monofilament drawing is two-layer coaxial structure.
The factor that influences the monofilament usability is a lot, and the light collecting light ability of monofilament, light transmission, resolution and contrast are to influence the leading indicator of fibre bundle biography as ability.Numerical aperture is used to represent the size of monofilament light collecting light ability and receives what of light, and the size of numerical aperture is directly relevant with the refractive index of light transmitting fiber core material and clad material, it is big more that the refractive index of core material and clad material differs, and then the light collecting light ability of monofilament is just strong more; The light transmission of monofilament is then relevant with the physical dimension of employed material, numerical aperture and fiber, and descends along with the increase of filament length.The readability of image is by the resolution decision, and resolution and fibre-optic diameter are inversely proportional to, and therefore fibre-optic diameter is thin as much as possible.The factor that influences the light transmitting fiber contrast mainly contains the thickness of the light collecting light ability of fiber, transmittancy, resolution characteristic and covering.The degree of covering thickness is suitable moderate, and the too thick meeting of cladding thickness directly causes effectively logical light area to descend significantly, too thin then can light leak, thereby cause the light of monofilament transmission to be crosstalked mutually making that image thickens unclear.
Technical scheme implementation of the present invention:
A kind of manufacture method of high-resolution optical fiber image transmission bundle, carry out according to the following steps:
(1), adopt PCVD technology to make prefabricated rods, be used for the drawing of monofilament, described prefabricated rods is two-layer coaxial structure, the sandwich layer diameter is 15~20mm, cladding diameter just this prefabricated rods diameter is 18~24mm, the scope of core bag ratio is 0.62~0.91;
(2), prefabricated rods being drawn on the ordinary optic fibre wire-drawer-tower is that diameter is at the identical monofilament of 0.5~3mm scope diameter;
(3), will draw the monofilament that obtains cuts and is processed into equal length, segment length's plurality of sections of 300mm~900mm; It is carried out after cleaning-drying handles, and according to the quantitative requirement of required optical fiber image transmission beam pixel, (1), (2), (3) calculate the quantity of monofilament, multifilament as follows, and the monofilament of requirement is arranged moulding by closely packed mode;
S
N1=(3N
1+3)N
1(1)S
N2=(3N
2+3)N
2(2)PixelCount=S
N1×S
N2(3)
(4), the filament tow that step (3) heap is good puts into a thin-walled outer tube, and gap location filled, packing material is the suitable pure silicon dioxide glass fiber of diameter or forms the consistent still slightly different monofilament of diameter of structure with monofilament material;
(5), filament tow that step (4) is formed places on the common wire-drawer-tower, draw to be the multifilament of diameter at 0.5~3mm; This multifilament is cut into equal length, and in acid solution, the outer tube of this multifilament outsourcing is eroded, cleaning-drying again, and then the multifilament of requirement is arranged as multifilament bundled by closely packed mode;
(6), above multifilament bundled is put into a thin-walled outer tube, and to the gap between the single multifilament, and fill with the suitable pure silicon dioxide glass fiber of diameter in the gap between multifilament bundled and the outer tube;
(7), the multifilament bundled that above step (6) is formed places common wire-drawer-tower to draw optical fiber facsimile beam into diameter 0.2mm~2mm.This optical fiber image transmission beam has certain flexibility, and for the coherent fiber bundle of 0.2mm, minimum bending radius can be low to moderate 15mm, and resolution can reach 249lp/mm.
The used prefabricated rods of described drawing monofilament is two-layer coaxial configuration, and the described core material that is used for drawing the prefabricated rods of monofilament is any of following combination: pure silicon dioxide, pure silicon dioxide are mixed Ge, pure silicon dioxide mixes F, pure silicon dioxide Ge and F mixes altogether.
The described covering layer material that is used for drawing the prefabricated rods of monofilament is any of following combination: pure silicon dioxide, pure silicon dioxide are mixed F.
The sandwich layer of the described prefabricated rods that is used to draw monofilament and the ratio of cladding diameter are 0.62~0.91, and its core diameter is 15-20mm, and cladding diameter is 18~24mm.
For guaranteeing that monofilament possesses good receipts luminous energy power, the described core material refractive index n that is used to draw the prefabricated rods of monofilament
2Refractive index n with clad material
1Satisfy: 1.46<n
2<1.5,1.44<n
1<1.46, and satisfy relation between them:
The described typical index section that is used to draw the prefabricated rods of monofilament is a step change type, perhaps is gradation type, as shown in Figure 2.
The refractive index profile of described monofilament and the refractive index profile of described prefabricated rods are just the same, so the numerical aperture NA of prefabricated rods represented the NA of monofilament, just the NA of the final coherent fiber bundle that obtains.NA is defined as:
Described step (3) monofilament is arranged by closely packed mode, needs the quantity of monofilament to estimate with following formula:
S
N1=(3N
1+3)N
1 (1)
Here S
N1The quantity of the required monofilament of expression step (3), N
1The closely packed number of plies of expression step (3).
In order to obtain higher pixel, typical N
1Span be: 5≤N
1≤ 12.
The multifilament that described step (5) obtains is arranged by closely packed mode, and the quantity that needs can be estimated with following formula:
S
N2=(3N
2+3)N
2 (2)
Here S
N2The quantity of the required multifilament of expression step (5), N
2The closely packed number of plies of expression step (5) multifilament.
In order to obtain higher pixel, usually N
2Span be: 5≤N
2≤ 12.
Optical fiber image transmission beam overall diameter 0.2mm~2mm that described final drawing obtains.The quantity of pixel is roughly determined by following formula:
PixelCount=S
N1×S
N2 (3)
Described optical fiber image transmission beam has certain flexibility, and for the coherent fiber bundle of 0.2mm, minimum bending radius can be low to moderate 15mm; Resolution can reach 249lp/mm.
The present invention adopts PCVD technology to make the prefabricated rods that is used to draw monofilament, has guaranteed the raw-material high-purity of optical fiber image transmission beam, and the accurate refractive index profile of monofilament distributes.Subsequent technique adopts the mode of similar row's silk method, twice arrangement: be that millimeter level monofilament is arranged for the first time, this is to realize easily on technology; Also be that millimetre-sized multifilament is arranged for the second time, this also is to realize easily.This method to the arrangement of millimeter level monofilament or multifilament guaranteed the quality of arranging, thereby guaranteed the accuracy of each pixel location, also avoided the also high problem of wire broken rate of stacked decision silk rate height can't be done filament diameter in the patent as stated in the Background Art very thin shortcoming, sour molten process that sour molten method is carried out simultaneously.The wire broken rate that adopts this method is zero, has effectively guaranteed the pixel quality of coherent fiber bundle.Adopt the method for twice arrangement to improve the quantity of pixel greatly, pixel number determines that by formula (3) as seen will obtain very high pixel is easily.For example work as N
1And N
2All equal 7, then pixel is 28224.Owing to the drawing process of the simple glass silk of using for reference and the heap drawing process (stacking and drawing process) of photonic crystal fiber, the each drawing can reach 530 meters (N by drawing length in addition
1And N
2All equal at 7 o'clock, draw the optical fiber image transmission beam of 860um glass diameter).This makes method of the present invention become a kind of low cost, the optical fiber image transmission beam method for making of high yield.
Specific embodiment
Specific implementation of the present invention is:
(1), employing PCVD technology is made prefabricated rods, and is drawn out monofilament.This prefabricated rods is two-layer coaxial structure, shown in Fig. 1 a, Fig. 1 b, the diameter of sandwich layer 11 is 17mm, the diameter of covering 12 just this prefabricated rods diameter is 20mm, then core bag diameter ratio is 0.85, its refractive index profile also can adopt the prefabricated rods of its refractive index profile shown in Fig. 2 b shown in Fig. 2 a; It is that diameter is at the identical monofilament of 1~2mm scope diameter that this prefabricated rods is drawn on the ordinary optic fibre wire-drawer-tower;
(2), will draw the monofilament that obtains and cut and be processed into equal length, segment length's plurality of sections of every section 900mm carries out getting 270 monofilament after cleaning-drying handles to it, arranges moulding by closely packed mode, as shown in Figure 3;
(3), the filament tow that step (2) heap is good puts into a thin-walled outer tube, thereby and gap location filled form filament tow; Packing material is the suitable pure silicon dioxide glass fiber of diameter, or with the monofilament material composition, but structure is consistent the slightly different monofilament of diameter; Filling is in order to guarantee to draw the circularity of back filament tow, and reduces the deformation of each monofilament in pulling process;
(4), the filament tow that step (3) is formed places on the common wire-drawer-tower, draw and be the multifilament of diameter at 2mm, then this multifilament is cut into the short multifilament that length is 900mm, again behind the sleeve pipe counterpart of all multifilament ragged edge outsourcings of sour eating away, cleaning-drying, and then get 270 short multifilament and be arranged as multifilament bundled by closely packed mode, put into a thin-walled outer tube again, and to the gap between the single multifilament, and the gap between multifilament bundled and the outer tube fills with the suitable pure silicon dioxide glass fiber of diameter, and is shown in Figure 4;
(5), multifilament bundled that above step (4) is formed places common wire-drawer-tower to draw, the final drawing is the optical fiber facsimile beam of diameter 0.86mm.This optical fiber image transmission beam has certain flexibility, and minimum bending radius can be low to moderate 30mm; Resolution reaches 227lp/mm, and pixel number reaches 72900.