Abstract: A branched type light transmission system including a plurality of light transmission tubes each comprising a flexible cylindrical cladding and a transparent core filled in the cladding and which has a higher index of refraction than the cladding. The core is made of an elastically deformable solid substance, and the plurality of light transmission tubes are bundled together at the light-incident ends thereof with a binding member and thus applied with an external pressure to deform each light transmission tube in order to minimize the clearance between the light transmission tubes.

Abstract: In an optical waveguide tube comprising a tubular cladding filled with a solid core having a higher refractive index than the cladding, a light transmissive window member is disposed in close contact with at least the end face of the core on a light incident side for protecting the core end face from thermal influence and contamination. Means disposed around the cladding and the window member for securing the window member to the cladding may be a tape wrapped around them or a heat shrinkable sleeve or a ferrule. Alternatively, a ferrule surrounding the outer periphery of the cladding at each end is fastened for securing the cladding to the core at each end for preventing the core from projecting out of the cladding. The ferrule may have a collar disposed in abutment with the core end face.

Abstract: The invention relates to an optical waveguide tube comprising a tubular cladding filled with a solid core having a higher refractive index than the cladding. In one form, a resin material having a Tg of up to 50.degree. C. and a modulus of elasticity of up to 10.sup.9 dyne/cm.sup.2 is used as the core. In another form, a copolymer of acrylic acid, methacrylic acid or a lower alcohol ester thereof with a higher alkyl (meth)acrylate is used as the core, preferably in combination with a phosphate, aromatic carboxylate, aliphatic carboxylic acid, aliphatic carboxylate or glycol. In a third form, such an optical waveguide tube is prepared by filling a hollow tubular transparent cladding having opposite open ends with a liquid monomeric charge and causing the monomeric charge to polymerize while pressurizing the exposed surfaces of the monomeric charge inwardly from the opposite open ends along an axial direction of the cladding, thereby forming a core within the cladding.