CA1290602C - Optical waveguide for illumination and production of the same - Google Patents
Optical waveguide for illumination and production of the sameInfo
- Publication number
- CA1290602C CA1290602C CA000499250A CA499250A CA1290602C CA 1290602 C CA1290602 C CA 1290602C CA 000499250 A CA000499250 A CA 000499250A CA 499250 A CA499250 A CA 499250A CA 1290602 C CA1290602 C CA 1290602C
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- Canada
- Prior art keywords
- core
- methacrylate
- optical waveguide
- waveguide
- optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Abstract
Abstract:
An optical waveguide for illumination use comprises a core made of a transparent polymer having a glass transition temperature no higher than 50C and a cladding made of a polymer having a lower refractive index than that of the core. The waveguide has good light transmission property and flexibility and is useful as an illumination element of an optical sensor.
An optical waveguide for illumination use comprises a core made of a transparent polymer having a glass transition temperature no higher than 50C and a cladding made of a polymer having a lower refractive index than that of the core. The waveguide has good light transmission property and flexibility and is useful as an illumination element of an optical sensor.
Description
0~ 32 Optical Waveguide For Illumination And Production Of The Same The present invention relates to an optical waveguide for illumination and a method for producing the same. More particularly, it relates to a plastic, optical waveguide useful for illumination in, for example, an optical sensor, and to a method for producing an optical waveguide that has an optical image fiber and, optionally, a tube member and/or a continuous bore along the length of the waveguide. Such a waveguide is useful in an optical communication system, an optical information system or an optical measuring instrument.
In addition, it is usable as a fiber scope for medical use.
Optical waveguides may be made of glass or plastic. A
plastic optical waveguide is preferably used for illumination, since the material itself is highly elastic and flexible.
An optical sensor transmits light and/or images, and is composed of an optical waveguide as well as an optical image fiber and, optionally, a tube member and/or a continuous bore which transmit a fluid.
To enable the background to the invention to be explained with the aid of diagrams, the figures of the drawings will first be listed.
Fig. 1 is a cross section of one embodiment of an optical waveguide for illumination, Fig. 2 schematically shows one embodiment of apparatus for producing an optical waveguide containing an image fiber, and Fig. 3 is a cross section of one embodiment of an optical waveguide containing an image fiber.
Fig. 1 shows a cross section of one example of an optical waveguide for illumination to be used as a medical fiber scope.
The waveguide 1 comprises a core 2 and outer and inner claddings 3 and 3'. Bores 4 surrounded by the inner claddings 3' are used for transporting a fluid or inserting an optical image fiber therein. The sizes of the core and cladding vary with the end use of the waveguide. Generally, the diameter of the core is from 0.25 to 1.00 mm, and the wall thickness of the cladding is from lO to 20 ~m (0.01 to 0.02 mm).
The conventional plastic optical fiber predominantly comprises a core made of poly(methyl methacrylate) (hereinafter referred to as "PMMA"), although it may comprise a core made of other transparent plastics such as polystyrene. However, the number of highly transparent plastics is not large. A
commercially available plastic optical fiber comprises a core made of PMMA or polystyrene. Between them, the former is more important, since it has better optical transmission charac-teristics than the latter.
The polymethacrylate type of optical fiber includes the following three types:
A) An optical fiber comprising a core made of PMMA and a cladding made of a fluororesin.
This type of PMMA optical fiber has good light transmission characteristics and low attenuation due to absorption, and is widely commercially available. However, it has the drawback that it shrinks substantially at a temperature higher than 30 100C. For example, at 120C, it shrinks to a length of about 50 % of its original length in several seconds. This is because the PMMA optical fiber is stretched during fabrication to impart flexibility to the fiber, since the unstretched PMMA
optical fiber has poor flexibility. When heated, the stretched PMMA optical fiber recovers to or toward its original state.
B) An optical fiber comprising a core made of PMMA
containing 5 to 30 % by weight of a plasticizer and a cladding made of a fluororesin.
Since thls type of PMMA optical fiber is flexible due to the presence of the plasticizer in the PMMA, it is not necessary to stretch the optical fiber during fabrication.
Therefore, it shrinks only to a small extent. However, the cladding of this type of optical fiber should be made thicker than that of an optical fiber oE type A, since diffusion and migration of the plasticizer should be prevented by the cladding. For example, the thickness of the cladding is usually 100 to 500 ~m. Since light is transmitted -through the core portion, the thicker cladding makes the core cross section smaller, if the total cross sectional area of the waveguide is to be the same, so that -the efficiency of light transmission becomes lower. In other words, for a constant cross section of the waveguide, it is preferable to make the core larger and the wall of the cladding thinner.
C) An optical fiber comprising a core of poly-(isobutyl methacrylate) and a cladding made of a fluororesin.
This optical fiber has substantially the same attenuation of its light transmission and small shrinking rate as the PM~A
optical fiber. However, this optical fiber is brittle and fragile, since poly(isobutyl methacrylate) is rigid and less flexible. Elongation at break is only about 5 %. Thus, this fiber lacks the important advantage of the plas-tic optical fiber, namely resistant to bending and tension. The reason for this may be that isobutyl methacrylate has a branched butyl group.
It has been proposed to make an optical waveguide from a copolymer of isobutyl methacrylate/n-butyl methacrylate in a ratio of 4:1 to 2:3 (cf Japanese Patent Publication No.
162849/1983), or PMMA or PMMA plasticized with adipate (cf.
Japanese Patent Application No. 162847/1983). However, these optical waveguides are not completely satisfactory. For example, PMMA or the isobutyl methacrylate/n-butyl methacrylate copolymer is brittle and does not have enough flexibili-ty. If the waveguide is stretched to impart flexibility to it, it shrinks when heated. PMMA plasticized with adipate has inferior light transmission characteristics, since the plasticizer deteriorates the transparency oE the PMMA and scatters light.
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In addition, it is very difficult to obtain highly pure adipate by purification.
Several methods have been proposed for the production of an optical waveguide containing an image fiber. Among them, the most advantageous are a method proposed in Japanese Patent Application No. 162847-1983 which comprises co-extruding a core material and a cladding material while simultaneously supplying a metal wire to the co-extrusion die to form an optical waveguide having the metal wire therein, and then withdrawing the wire from the waveguide to form a bore, and a method proposed in Japanese Patent Application No. 25866/1984 which comprises co-extruding a core material and a cladding material while simultaneously supplying a hollow fiber made of a polymer or quartz to a co-extrusion die to form an optical waveguide with a bore.
However, the above proposed methods are not suitable for producing an optical sensor having a small outer diameter.
This is because the optical image fiber or bundle should be inserted into a thin bore made in the optical waveguide during which the waveguide tends to be damaged by the inserted image fiber or bundle. In addition, it is difficult by these methods to produce an optical sensor with flexibility and bending strength, since the sensor contains the unstretchable metal wire or hollow fiber.
One object of the present lnvention is to provide an optical waveguide having good characteristics such as light transmission proper-ty and fiexibility, for use as an element of an optical sensor.
Another object of the present invention is to provide a novel method for producing such an optical waveguide.
According to one aspect of the present invention, there is provided an optical waveguide for illumination comprising a core made of a transparent polymer having a glass transition temperature no higher than 50C and a cladding made of a polymer having a lower refractive index than that of the core.
The transparent polymer of the core preferably has a glass -transition temperature of 0 to 40C. The transparent polymer may be a homo~ or co-polymer of alkyl methacrylate. The -alkyl group of the methacrylate is preferably a straight C3-C8, especially C3-C6 alkyl group, for example, n-propyl, n-butyl, n-pentyl and n-hexyl. The copolymer may comprise at least two different alkyl methacrylates, or at least one alkyl methacrylate and at least one other copolymerizable monomer (e.g. alkyl acrylate such as methyl acrylate and ethyl acrylate). In the copolymer, the content of alkyl methacrylate is preferably no smaller than 85 % by mole.
The transparent polymer can be prepared by polymerizing the above monomer(s) in the presence of a conventional polymerization initia-tor used for initiating polymerization of methacrylate. Specific examples of the initiator are azo compounds such as 2,2'-azobisisobutzronitrile and azo-t-butane, and peroxide compounds such as butylperoxide. A chain transfer agent such as n-butylmercaptan and t-butylmercaptan may be used.
As the cladding material, any one of conventionally used polymers can be used, so far as it has a lower refractive index than that of the core polymer. Specific examples of the cladding material are fluororesins (e.g. polyvinylidene fluoride, vinylidene fluoride/tetrafluoroethylene copolymer, homo- or co-polymer of fluorine-containing alkyl methacrylate and a blend thereof), silicone resins, ethylene/vinyl acetate copolymer and the like.
An optical waveguide according to the invention may be produced by any method. For example, -the waveguide is preferably produced by a method proposed in Japanese Patent Application No. 162847-lg83 which comprises co-extruding a core material and a cladding material while simultaneously supplying a metal wire to a co-extrusion die to form an optical waveguide having the metal wire therein, and then withdrawing the wire from the waveguide to form a bore, or a method proposed in Japanese Patent Application No. 25866/1984 which comprises co-extruding a core material and a cladding material while simultaneously supplying a hollow fiber made of a polymer or quartz to a co-extrusion die to form an optical waveguide with a bore.
An optical waveguide containing an imaye fiber is produced by the method described in Japanese Patent Application No.
25866/1984 modified by replacing the hollow fiber with an image fiber.
Therefore, according to another aspect of the present invention, there is provided a method for producing an optical 5 waveguide comprising a core and a cladding and containing an image fiber therein, which method comprises co-extruding a core material and a cladding material while simultaneously supplying an image fiber to a co-extrusion die.
The image fiber is usually made of quartz, multi-10 component glass or a polymer, and preferably has a number ofpicture elements of at least 6,000.
A method for producing such an optical wavegui.de will now be described by way of example with reference to the accompanying drawings.
Fig. 2 schematically shows one embodiment of apparatus for producing an optical waveguide according to the method of the present invention. The core material and the cladding material are respectively supplied from a core material extruder 22 and a cladding material extruder 23, and are co-extruded by a co-20 extrusion head 24. Simultaneously, an image fiber 11 is supplied from an image fiber supplier 21 to the head 24. The extruded waveguide 10, containing the image fiber 11 in the core, is passed through a cooling zone 25 and wound by a winder 26.
The waveguide produced has a cross section as shown for example in Fig. 3, in which the image fiber 11 is surrounded by the optical image guide for illumination consisting of the core 12 and the claddings 13.
Although, in the above description, there is only one 30 image fiber, two or more image fibers can be contained in a waveguide of the invention. Further, a hollow member can be contained in the waveguide, together with the image fiber.
The present invention will be illustrated by the following examples.
Examples 1 and 2 n-Butyl methacrylate (in Example 1) or a mixture of n-butyl methacrylate and methyl methacrylate in a molar ratio of 90:10 (in Example 2) was polymerized in the presence of -- 7 ~
In addition, it is usable as a fiber scope for medical use.
Optical waveguides may be made of glass or plastic. A
plastic optical waveguide is preferably used for illumination, since the material itself is highly elastic and flexible.
An optical sensor transmits light and/or images, and is composed of an optical waveguide as well as an optical image fiber and, optionally, a tube member and/or a continuous bore which transmit a fluid.
To enable the background to the invention to be explained with the aid of diagrams, the figures of the drawings will first be listed.
Fig. 1 is a cross section of one embodiment of an optical waveguide for illumination, Fig. 2 schematically shows one embodiment of apparatus for producing an optical waveguide containing an image fiber, and Fig. 3 is a cross section of one embodiment of an optical waveguide containing an image fiber.
Fig. 1 shows a cross section of one example of an optical waveguide for illumination to be used as a medical fiber scope.
The waveguide 1 comprises a core 2 and outer and inner claddings 3 and 3'. Bores 4 surrounded by the inner claddings 3' are used for transporting a fluid or inserting an optical image fiber therein. The sizes of the core and cladding vary with the end use of the waveguide. Generally, the diameter of the core is from 0.25 to 1.00 mm, and the wall thickness of the cladding is from lO to 20 ~m (0.01 to 0.02 mm).
The conventional plastic optical fiber predominantly comprises a core made of poly(methyl methacrylate) (hereinafter referred to as "PMMA"), although it may comprise a core made of other transparent plastics such as polystyrene. However, the number of highly transparent plastics is not large. A
commercially available plastic optical fiber comprises a core made of PMMA or polystyrene. Between them, the former is more important, since it has better optical transmission charac-teristics than the latter.
The polymethacrylate type of optical fiber includes the following three types:
A) An optical fiber comprising a core made of PMMA and a cladding made of a fluororesin.
This type of PMMA optical fiber has good light transmission characteristics and low attenuation due to absorption, and is widely commercially available. However, it has the drawback that it shrinks substantially at a temperature higher than 30 100C. For example, at 120C, it shrinks to a length of about 50 % of its original length in several seconds. This is because the PMMA optical fiber is stretched during fabrication to impart flexibility to the fiber, since the unstretched PMMA
optical fiber has poor flexibility. When heated, the stretched PMMA optical fiber recovers to or toward its original state.
B) An optical fiber comprising a core made of PMMA
containing 5 to 30 % by weight of a plasticizer and a cladding made of a fluororesin.
Since thls type of PMMA optical fiber is flexible due to the presence of the plasticizer in the PMMA, it is not necessary to stretch the optical fiber during fabrication.
Therefore, it shrinks only to a small extent. However, the cladding of this type of optical fiber should be made thicker than that of an optical fiber oE type A, since diffusion and migration of the plasticizer should be prevented by the cladding. For example, the thickness of the cladding is usually 100 to 500 ~m. Since light is transmitted -through the core portion, the thicker cladding makes the core cross section smaller, if the total cross sectional area of the waveguide is to be the same, so that -the efficiency of light transmission becomes lower. In other words, for a constant cross section of the waveguide, it is preferable to make the core larger and the wall of the cladding thinner.
C) An optical fiber comprising a core of poly-(isobutyl methacrylate) and a cladding made of a fluororesin.
This optical fiber has substantially the same attenuation of its light transmission and small shrinking rate as the PM~A
optical fiber. However, this optical fiber is brittle and fragile, since poly(isobutyl methacrylate) is rigid and less flexible. Elongation at break is only about 5 %. Thus, this fiber lacks the important advantage of the plas-tic optical fiber, namely resistant to bending and tension. The reason for this may be that isobutyl methacrylate has a branched butyl group.
It has been proposed to make an optical waveguide from a copolymer of isobutyl methacrylate/n-butyl methacrylate in a ratio of 4:1 to 2:3 (cf Japanese Patent Publication No.
162849/1983), or PMMA or PMMA plasticized with adipate (cf.
Japanese Patent Application No. 162847/1983). However, these optical waveguides are not completely satisfactory. For example, PMMA or the isobutyl methacrylate/n-butyl methacrylate copolymer is brittle and does not have enough flexibili-ty. If the waveguide is stretched to impart flexibility to it, it shrinks when heated. PMMA plasticized with adipate has inferior light transmission characteristics, since the plasticizer deteriorates the transparency oE the PMMA and scatters light.
3q ~f~
In addition, it is very difficult to obtain highly pure adipate by purification.
Several methods have been proposed for the production of an optical waveguide containing an image fiber. Among them, the most advantageous are a method proposed in Japanese Patent Application No. 162847-1983 which comprises co-extruding a core material and a cladding material while simultaneously supplying a metal wire to the co-extrusion die to form an optical waveguide having the metal wire therein, and then withdrawing the wire from the waveguide to form a bore, and a method proposed in Japanese Patent Application No. 25866/1984 which comprises co-extruding a core material and a cladding material while simultaneously supplying a hollow fiber made of a polymer or quartz to a co-extrusion die to form an optical waveguide with a bore.
However, the above proposed methods are not suitable for producing an optical sensor having a small outer diameter.
This is because the optical image fiber or bundle should be inserted into a thin bore made in the optical waveguide during which the waveguide tends to be damaged by the inserted image fiber or bundle. In addition, it is difficult by these methods to produce an optical sensor with flexibility and bending strength, since the sensor contains the unstretchable metal wire or hollow fiber.
One object of the present lnvention is to provide an optical waveguide having good characteristics such as light transmission proper-ty and fiexibility, for use as an element of an optical sensor.
Another object of the present invention is to provide a novel method for producing such an optical waveguide.
According to one aspect of the present invention, there is provided an optical waveguide for illumination comprising a core made of a transparent polymer having a glass transition temperature no higher than 50C and a cladding made of a polymer having a lower refractive index than that of the core.
The transparent polymer of the core preferably has a glass -transition temperature of 0 to 40C. The transparent polymer may be a homo~ or co-polymer of alkyl methacrylate. The -alkyl group of the methacrylate is preferably a straight C3-C8, especially C3-C6 alkyl group, for example, n-propyl, n-butyl, n-pentyl and n-hexyl. The copolymer may comprise at least two different alkyl methacrylates, or at least one alkyl methacrylate and at least one other copolymerizable monomer (e.g. alkyl acrylate such as methyl acrylate and ethyl acrylate). In the copolymer, the content of alkyl methacrylate is preferably no smaller than 85 % by mole.
The transparent polymer can be prepared by polymerizing the above monomer(s) in the presence of a conventional polymerization initia-tor used for initiating polymerization of methacrylate. Specific examples of the initiator are azo compounds such as 2,2'-azobisisobutzronitrile and azo-t-butane, and peroxide compounds such as butylperoxide. A chain transfer agent such as n-butylmercaptan and t-butylmercaptan may be used.
As the cladding material, any one of conventionally used polymers can be used, so far as it has a lower refractive index than that of the core polymer. Specific examples of the cladding material are fluororesins (e.g. polyvinylidene fluoride, vinylidene fluoride/tetrafluoroethylene copolymer, homo- or co-polymer of fluorine-containing alkyl methacrylate and a blend thereof), silicone resins, ethylene/vinyl acetate copolymer and the like.
An optical waveguide according to the invention may be produced by any method. For example, -the waveguide is preferably produced by a method proposed in Japanese Patent Application No. 162847-lg83 which comprises co-extruding a core material and a cladding material while simultaneously supplying a metal wire to a co-extrusion die to form an optical waveguide having the metal wire therein, and then withdrawing the wire from the waveguide to form a bore, or a method proposed in Japanese Patent Application No. 25866/1984 which comprises co-extruding a core material and a cladding material while simultaneously supplying a hollow fiber made of a polymer or quartz to a co-extrusion die to form an optical waveguide with a bore.
An optical waveguide containing an imaye fiber is produced by the method described in Japanese Patent Application No.
25866/1984 modified by replacing the hollow fiber with an image fiber.
Therefore, according to another aspect of the present invention, there is provided a method for producing an optical 5 waveguide comprising a core and a cladding and containing an image fiber therein, which method comprises co-extruding a core material and a cladding material while simultaneously supplying an image fiber to a co-extrusion die.
The image fiber is usually made of quartz, multi-10 component glass or a polymer, and preferably has a number ofpicture elements of at least 6,000.
A method for producing such an optical wavegui.de will now be described by way of example with reference to the accompanying drawings.
Fig. 2 schematically shows one embodiment of apparatus for producing an optical waveguide according to the method of the present invention. The core material and the cladding material are respectively supplied from a core material extruder 22 and a cladding material extruder 23, and are co-extruded by a co-20 extrusion head 24. Simultaneously, an image fiber 11 is supplied from an image fiber supplier 21 to the head 24. The extruded waveguide 10, containing the image fiber 11 in the core, is passed through a cooling zone 25 and wound by a winder 26.
The waveguide produced has a cross section as shown for example in Fig. 3, in which the image fiber 11 is surrounded by the optical image guide for illumination consisting of the core 12 and the claddings 13.
Although, in the above description, there is only one 30 image fiber, two or more image fibers can be contained in a waveguide of the invention. Further, a hollow member can be contained in the waveguide, together with the image fiber.
The present invention will be illustrated by the following examples.
Examples 1 and 2 n-Butyl methacrylate (in Example 1) or a mixture of n-butyl methacrylate and methyl methacrylate in a molar ratio of 90:10 (in Example 2) was polymerized in the presence of -- 7 ~
2,2'-azobisisobutyronitrile (0.01 % by mole) (a polymerization initiator) and n-butylmercaptan (0.3 % by mole) (a chain transfer agent) at ~0C for 14 hours, at 100C for 4 hours and then at 130C for ~ hours. The glass transition temperatures of the produced polymer and copolymer were respectively 20C
and 29C.
The polymer was drawn to form a fiber having an outer diameter of 1.0 mm and examined for physical properties (coefficient of thermal shrinkage, longitudinal elastic modulus, strength, elongation at break, allowable twisting and thermal decomposition temperature). The results are shown in the Table.
"Thermal shrinkage" is measured by keeping 100 mm of the fiber at 120C for 60 minutes.
"Longitudinal elastic modulus" and "elongation at break"
are measured by means of an Instron tester.
"Strength" is tensile stress when the fiber starts to elongate during measuring modulus by the Instron tester.
"Allowable twisting" is the number of turns per unit length (1 m) when the fiber starts to break by twisting.
The polymer as the core material was extruded at 130C
together with a cladding material (copolymer of tetrafluoro-propyl methacrylate and octafluoropentyl methacrylate in a molar ratio of 30:70) on three annealed copper wires having various diameters in an unstretched state. Then, the copper wires were removed from the core to form an optical waveguide having three bore in the core as shown ln Fig. 1.
The outer diameter of the waveguide was 2.2 mm, the bore diameter of the large bore was 0.5 mm and the bore diame-ter of each of two small bores was 0.02 mm. The attenuation of light transmission of the waveguide was measured as follows:
He-Ne laser light having a wavelength of 633 nm was transmitted through the waveguide of 5 m in length. The attenuation of light transmission L is calculated according to the following equation:
L = - log -1 Io .. . . . .
., wherein I is the strength of incident light, Io is the strength of outgoing light and 1 is the length of the waveguide.
Comparative Example 1 In the same manner as in Examples 1 and 2 but using as a core material PMMA having a glass transition temperature of 105C, a waveguide was produced and examined for the same properties as in Examples 1 and 2.
g Table _ Example Comp.
11 2 Example 1 _ l Coefficient of 4 4 49 thermal shrinkage (~) _ Longitudinal 1 17.7 56.~ 350 elastic modulus (kg/mm2) ¦
Tensile strength (~g/mm2) ¦ 0.35 0.83 ¦ 12.0 _ _ Elongation at break (~) ¦280 ¦ 210 80 _ Allowable twisting (turns/m) ¦ 9.3 2.7 14.1 Thermal decomposition 265 230 300 temperature (C) Attenuation (dB/km) ¦400 ¦ 400 ¦ 400 Example 3 By means of the apparatus as shown in Fig. 2, n-butylmethacrylate polymer having a glass transition temperature of 20C as the core material and a copolymer of tetra-fluoropropyl methacrylate/octafluoropentyl methacrylate in a molar ratio of 30:70 as the cladding material was co-extruded while supplying a quartz made image fiber having 6,000 picture elements to produce a waveguide containing the image fiber in the core, a cross section of which is shown in Fig. 3. The outer diameter of the waveguide was 0.75 mm, and the wall thickness of each of the claddings was 20 ~m. Elongation at break, 280 %. Allowable twisting, ~.3 turns/m. Attenuation of light transmission, 400 dB/km. (These were measured by the same manners as in Examples 1 and 2).
and 29C.
The polymer was drawn to form a fiber having an outer diameter of 1.0 mm and examined for physical properties (coefficient of thermal shrinkage, longitudinal elastic modulus, strength, elongation at break, allowable twisting and thermal decomposition temperature). The results are shown in the Table.
"Thermal shrinkage" is measured by keeping 100 mm of the fiber at 120C for 60 minutes.
"Longitudinal elastic modulus" and "elongation at break"
are measured by means of an Instron tester.
"Strength" is tensile stress when the fiber starts to elongate during measuring modulus by the Instron tester.
"Allowable twisting" is the number of turns per unit length (1 m) when the fiber starts to break by twisting.
The polymer as the core material was extruded at 130C
together with a cladding material (copolymer of tetrafluoro-propyl methacrylate and octafluoropentyl methacrylate in a molar ratio of 30:70) on three annealed copper wires having various diameters in an unstretched state. Then, the copper wires were removed from the core to form an optical waveguide having three bore in the core as shown ln Fig. 1.
The outer diameter of the waveguide was 2.2 mm, the bore diameter of the large bore was 0.5 mm and the bore diame-ter of each of two small bores was 0.02 mm. The attenuation of light transmission of the waveguide was measured as follows:
He-Ne laser light having a wavelength of 633 nm was transmitted through the waveguide of 5 m in length. The attenuation of light transmission L is calculated according to the following equation:
L = - log -1 Io .. . . . .
., wherein I is the strength of incident light, Io is the strength of outgoing light and 1 is the length of the waveguide.
Comparative Example 1 In the same manner as in Examples 1 and 2 but using as a core material PMMA having a glass transition temperature of 105C, a waveguide was produced and examined for the same properties as in Examples 1 and 2.
g Table _ Example Comp.
11 2 Example 1 _ l Coefficient of 4 4 49 thermal shrinkage (~) _ Longitudinal 1 17.7 56.~ 350 elastic modulus (kg/mm2) ¦
Tensile strength (~g/mm2) ¦ 0.35 0.83 ¦ 12.0 _ _ Elongation at break (~) ¦280 ¦ 210 80 _ Allowable twisting (turns/m) ¦ 9.3 2.7 14.1 Thermal decomposition 265 230 300 temperature (C) Attenuation (dB/km) ¦400 ¦ 400 ¦ 400 Example 3 By means of the apparatus as shown in Fig. 2, n-butylmethacrylate polymer having a glass transition temperature of 20C as the core material and a copolymer of tetra-fluoropropyl methacrylate/octafluoropentyl methacrylate in a molar ratio of 30:70 as the cladding material was co-extruded while supplying a quartz made image fiber having 6,000 picture elements to produce a waveguide containing the image fiber in the core, a cross section of which is shown in Fig. 3. The outer diameter of the waveguide was 0.75 mm, and the wall thickness of each of the claddings was 20 ~m. Elongation at break, 280 %. Allowable twisting, ~.3 turns/m. Attenuation of light transmission, 400 dB/km. (These were measured by the same manners as in Examples 1 and 2).
Claims (9)
1. An optical waveguide for illumination comprising a core made of a transparent polymer having a glass transition temperature no higher than 50°C and a cladding made of a polymer having a lower refractive index than that of the core and surrounding the core.
2. An optical waveguide according to claim 1, wherein the transparent polymer of the core has a glass transition temperature of 0 to 40°C.
3. An optical waveguide according to claim 1, wherein the transparent polymer is a homo- or co-polymer of alkyl methacrylate.
4. An optical waveguide according to claim 3, wherein the alkyl methacrylate is at least one selected from the group consisting of n-propyl methacrylate, n-butyl meth-acrylate, n-pentyl methacrylate and n-hexyl methacrylate.
5. A method for producing an optical waveguide comprising a core and a cladding and containing an image fiber therein, which method comprises co-extruding a core material and a cladding material while simultaneously supplying an image fiber to a co-extrusion die.
6. A method according to claim 5, wherein the cladding material is a transparent polymer having a glass transition temperature no higher than 50°C and the cladding material has a lower refractive index than that of the core material.
7. A method according to claim 6, wherein the transparent polymer of the core has a glass transition temperature of 0 to 40°C.
8. A method according to claim 5, wherein the transparent polymer is a homo- or co-polymer of alkyl methacrylate.
9. A method according to claim 8, wherein the alkyl methacrylate is at least one selected from the group consisting of n-propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate and n-hexyl methacrylate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000499250A CA1290602C (en) | 1986-01-09 | 1986-01-09 | Optical waveguide for illumination and production of the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000499250A CA1290602C (en) | 1986-01-09 | 1986-01-09 | Optical waveguide for illumination and production of the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1290602C true CA1290602C (en) | 1991-10-15 |
Family
ID=4132256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000499250A Expired - Fee Related CA1290602C (en) | 1986-01-09 | 1986-01-09 | Optical waveguide for illumination and production of the same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1290602C (en) |
-
1986
- 1986-01-09 CA CA000499250A patent/CA1290602C/en not_active Expired - Fee Related
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