Abstract: Provided is a covering tool and a covering method capable of suppressing damage to an impervious layer while reducing the strength of a diameter-expanding holding member. A covering tool includes a cold shrink tube, a diameter-expanding holding member that holds the cold shrink tube in a state in which a diameter of the cold shrink tube is expanded, an impervious layer provided outside the cold shrink tube, and a cushion layer provided outside the cold shrink tube and bonded to the impervious layer.

Abstract: A covering processing tool performs a covering process of a cable connection portion and is provided with a first tubular unit extending in an axial direction, a second tubular unit disposed so as to surround the first tubular unit on an outer peripheral side, and a third tubular unit disposed so as to surround the first tubular unit on the outer peripheral side. The second tubular unit is installed on the first tubular unit so when extracting a first diameter expansion holding member of the first tubular unit, by supporting the second tubular unit from an outer peripheral side, relative movement in an axial direction and a circumferential direction of the first tubular unit relative to the second tubular unit is suppressed.

Abstract: Problem: To provide a covering processing tool and a covering processing method that can improve an operation efficiency of covering a cable connection portion. Solution: A covering processing tool is a covering processing tool that performs a covering process of a cable connection portion and is provided with a first tubular unit extending in an axial direction, a second to bular unit disposed so as to surround the first tubular unit on an outer peripheral side, and a third tubular unit disposed so as to surround the first tubular unit on the outer peripheral side. The second tubular unit is installed on the first tubular unit so when extracting a first diameter expansion holding member of the first tubular unit, by supporting the second tubular unit from an outer peripher al side, relative movement in an axial direction and a circumferential direction of the first tubular unit relative to the second tubular unit is suppressed.

Abstract: To provide a Fresnel lens wherein changes in focal length due to temperature dependence of the refractive index can be compensated. By introducing a fractal structure into prisms in a peripheral region in which the prism angle is large and therefore the aspect ratio h/p of the prisms is large, the aspect ratio is reduced from h/p to h?/p and the slope of the envelope 20 to the underside of the slopping face is reduced, and thereby a shape in which a change in focal length due to temperature dependence of refractive index can be compensated for by a change in the shape of lenses due to expansion/contraction, is obtained.

Abstract: When using an acrylic resin with a refractive index of 1.494, for example, the structure of the Fresnel lens is such that in a segment where a deviation angle of 19.5° or less is required, refraction-only prisms which do not cause any reflections are used, while in a segment where a deviation angle of 31.0° or larger is required, single-step total reflection prisms in which light is totally internally reflected once and then refracted are used and, in a segment where a deviation angle not smaller than 19.5° but not larger than 31.0° is required, two-step total reflection prisms in which light is totally internally reflected twice and then refracted are used.

Abstract: When using an acrylic resin with a refractive index of 1.494, for example, the structure of the Fresnel lens is such that in a segment where a deviation angle of 19.5° or less is required, refraction-only prisms which do not cause any reflections are used, while in a segment where a deviation angle of 31.0° or larger is required, single-step total reflection prisms in which light is totally internally reflected once and then refracted are used and, in a segment where a deviation angle not smaller than 19.5° but not larger than 31.0° is required, two-step total reflection prisms in which light is totally internally reflected twice and then refracted are used.

Abstract: [Problems] To provide a body section with sufficient rigidity without impairment of the sliding facilitating ability of a sliding section of a slidingly detachable core member included in a cold shrink tube unit. [Solving Means] A slidingly detachable core member 12 includes a body section 22 that forms a hollow cylinder, and a sliding section 24 that is integrated with one axial end of the body section 22 and is so flexible as to be turned over to lie on the outer circumferential surface of the body section 22. The body section 22 consists of a plurality of plate-like portions 26 that are assembled to form the hollow cylinder. The sliding section 24 consists of a plurality of porous structural parts 28 that are formed adjacently to the plate-like portions 26 respectively. The core member 12 is incorporated in a seal region of an elastic tube member included in a cold contractile unit with the sliding section thereof turned over to lie on the outer circumferential surface of the body section 22.

Abstract: A removable core for a pre-stretched elastomeric tube includes a serpentine rather than helical arrangement for break lines around the core which permits the core to be withdrawn in one continuous pulling operation rather than the intermittent, rotating operation required in the past.