摘要:
In a double-clad optical fiber comprising a core having an index of refraction n.sub.1, an inner cladding surrounding the core and having an index of refraction n.sub.2, and a first outer cladding surrounding the inner cladding and having an index of refraction n.sub.3 (wherein n.sub.1 >n.sub.2 >n.sub.3), the softness of the first outer cladding often renders it difficult to perform polishing or other mechanical operations on the end of the fiber. To reduce such difficulties it is advantageous to remove the first outer cladding from a limited end portion of the fiber, replacing it with a second outer cladding having an index of refraction n.sub.4 (wherein n.sub.2 >n.sub.4) and a hardness which is greater than that of the first outer cladding.
摘要:
A fiber optic laser pumped via its cladding has a liquid component in the cladding and an index of refraction sufficient to promote total internal reflection of light carried by the cladding for pumping the laser. In one embodiment, the liquid component is provided by immersing the fiber clad with a curable polymer and a protective coating in a fluorinated organic compound.
摘要:
Photosensitizing dyes are often used in conjunction with a photoacid generator in holographic recording media. Conventional photosensitizing dyes typically are limited by having an appreciable absorption of light when used in a sufficient concentration, such that the intensity of light decreases significantly with penetration into a recording medium. The present invention discloses a number of new 5-alkynyl substituted napthacene photosensitizing dyes that have low extinction coefficients coupled with good sensitizing properties, such that the problems associated with the photosensitizing dyes absorbing light are significantly reduced.
摘要:
A process for generation of acid uses a medium comprising a first acid-generating component capable of generating a first acid, and a secondary acid generator, this secondary acid generator being capable of thermal decomposition to form a secondary acid, the thermal decomposition of the secondary acid generator being catalyzed by the first acid. At least part of the medium is exposed to so as to cause formation of the first acid from the first acid-generating component; and the medium is then heated to cause, in the exposed part of the medium, acid-catalyzed thermal decomposition of the secondary acid generator and formation of the secondary acid. The secondary acid generator has a first site bearing a first leaving group and a second site bearing a second leaving group, the first leaving group being capable of protonation by the first acid, with expulsion of the first leaving group to form a cation which electrophilically adds to an unsaturated reagent bearing a proton at the site of addition and a proton-containing nucleophilic grouping at an adjacent site, following which said proton on the reagent is lost and the second leaving group is displaced by said nucleophilic grouping, the second leaving group, in combination with a proton, forming the secondary acid. Preferred variants of the process are of the types described in U.S. Pat. Nos. 5,286,612; 5,334,489; 5,395,736; 5,441,850 and 5,453,345.
摘要:
In a process for cladding an optical fiber, a photoinitiator monomer having both a photoinitiating group and an ethylenically unsaturated group is reacted with a fluorosubstituted monomer having an ethylenically unsaturated group, thereby preparing a copolymer having pendant photoinitiating groups. This copolymer is then mixed with a fluorosubstituted diacrylate, thereby forming a photopolymerizable composition, which is coated on to the optical fiber and exposed to ultraviolet light, thereby curing the photopolymerizable composition to produce a cladding on the optical fiber. Preferred claddings can have refractive indices below 1.35.
摘要:
The present invention discloses a new class of triarylsulfonium salt photoacid generators (PAGs), which are thermally stable and can be activated by long wavelength UV or visible light. The sulfonium PAGs of the present invention are additionally soluble in monomers that can be polymerized by cationic polymerization chemistry, and mixtures of said sulfonium PAGs and monomers can be stored for long periods of time without undergoing polymerization. Furthermore, typical holographic recording media comprising one of these sulfonium PAGs, polymerizable monomer(s), a sensitizing dye, and a binder can be stored for long periods of time without exhibiting significant loss of recording sensitivity. Preferred sulfonium PAGs of the present invention are sulfonium PAGs substituted with one or more fluoro or fluoroalkyl groups.
摘要:
A binary image comprising a plurality of first areas, at which a porous or particulate image-forming substance is adhered to a substrate, and a plurality of second areas, at which the substrate is free from the image-forming substance, is protected by laminating thereto a laminating sheet comprising a durable layer and a support layer with the durable layer facing the image, so that the durable layer adheres to both the first and second areas of the image. The support layer is then displaced away from the image such that the durable layer remains attached to the image. The durable layer is substantially transparent and comprises a polymeric organic material having incorporated therein a siloxane, the siloxane being incorporated into the polymeric material in such a manner that it is not removed therefrom by hexane, isopropanol or water.
摘要:
A laminar thermal imaging medium is prepared from a first element comprising a first sheet transparent to image-forming radiation and having at least a surface zone or layer of polymeric material heat-activatable upon subjection of the thermal imaging medium to brief and intense radiation, the first element carrying a layer of porous or particulate image-forming substance having cohesivity in excess of its adhesivity for the polymeric heat-activatable layer, and, on the opposed side of the layer of porous or particulate image-forming substance from the surface zone or layer, a first layer of adhesive, and a second element comprising a second sheet carrying a second layer of adhesive. The second layer of adhesive comprises a polymeric hardenable adhesive comprising a macromolecular organic binder having acidic groups, and a photopolymerizable monomer. The first and second elements are laminated together with the first and second layers of adhesive in contact with one another, so forming a unitary laminar medium in which the hardenable adhesive remains in its unhardened condition and serves to reduce the tendency for the unitary laminar medium to delaminate on application of stresses to the medium. Only a short lag time, typically about 10-90 seconds, is required between lamination and curing of the hardenable adhesive in order to provide a strong bond between the two elements following curing.
摘要:
In a process for cladding an optical fiber, a photoinitiator monomer having both a photoinitiating group and an ethylenically unsaturated group is reacted with a fluorosubstituted monomer having an ethylenically unsaturated group, thereby preparing a copolymer having pendant photoinitiating groups. This copolymer is then mixed with a fluorosubstituted diacrylate, thereby forming a photopolymerizable composition, which is coated on to the optical fiber and exposed to ultraviolet light, thereby curing the photopolymerizable composition to produce a cladding on the optical fiber. Preferred claddings can have refractive indices below 1.35.
摘要:
A binary image comprising a plurality of first areas, at which a porous or particulate image-forming substance is adhered to a substrate, and a plurality of second areas, at which the substrate is free from the image-forming substance, is protected by laminating thereto a laminating sheet comprising a durable layer and a support layer with the durable layer facing the image, so that the durable layer adheres to both the first and second areas of the image. The support layer is then displaced away from the image such that the durable layer remains attached to the image. The durable layer is substantially transparent and comprises a polymeric organic material having incorporated therein a siloxane, the siloxane being incorporated into the polymeric material in such a manner that it is not removed therefrom by hexane, isopropanol or water.