A light-guide device includes a light guiding element (13) with a number of faces, including two parallel faces (26), for guiding light by internal reflection. A transparent optical element (19) has an interface surface for attachment to a coupling surface (14) of the light guiding element, and is configured such that light propagating within the transparent optical element passes through the interface surface and the coupling surface (14) so as to propagate within the light guiding element (13). A non-transparent coating (15) is applied to at least part of one or more faces of the light guiding element (13), defining an edge (17) adjacent to, or overlapping, the coupling surface (14) of the light guiding element (13). A quantity of transparent adhesive is deployed between the coupling surface and the interface surface so as to form an optically transmissive interface. An overspill region 31 of the adhesive extends to, and overlaps, the edge (17).

Provided is a display module including a display element, and a light-guiding optical device that guides image light emitted from the display element to form an exit pupil, in which the light-guiding optical device is an off-axis optical system. The off-axis optical system includes a first optical surface, a second optical surface, a first light-shielding portion, the first light-shielding portion being formed at the first optical surface, and a second light-shielding portion, the second light-shielding portion being formed at the second optical surface, in which the first light-shielding portion exposes, through a first aperture, a part of the first optical surface, and the second light-shielding portion exposes, through a second aperture, a part of the second optical surface, the first aperture and the second aperture having mutually different shapes.

Embodiments of the disclosure relate to a method of controlling tension on a buffer tube produced on a buffer tube processing line. In the method, the buffer tube is directed through a compression caterpillar. A speed of and a gap between drive belts of the compression caterpillar are set to achieve a desired tension on the buffer tube. Tension on the buffer tube is measured as the buffer tube passes between the drive belts. It is determined whether the measured tension on the buffer tube is within an acceptable range, and the gap between the drive belts is decreased in increments while the buffer tube passes between the drive belts until the tension is within the acceptable range.

An object of the present invention is to provide a production method for producing an optical fiber ribbon that has an identification mark for identification, in which optical transmission loss is unlikely to be caused. A production method for producing an optical fiber cable for achieving the above objective includes: curing a photocurable resin by irradiating the photocurable resin with light, the photocurable resin being disposed to couple together a plurality of single-core coated optical fibers arranged in parallel; and forming a plurality of identification marks on the photocurable resin cured, the forming being performed by applying ink by an ink-jet method, in which the forming the plurality of identification marks is performed in a state in which a temperature of the photocurable resin is lower than or equal to 37.3 C.

A plastic reflective waveguide is manufactured using a soft transfer stamp formed in a first mold using a liquid injection molding process to provide the stamp with parallel wall surfaces having a zero degree draft angle. The soft transfer stamp is placed as an insert in a second mold utilized in a multi-stage thermoplastic injection molding process. A first thermoplastic injection molding stage molds a base part of the plastic reflective waveguide having parallel wall surfaces with a zero degree draft angle. The soft transfer stamp is removed from the second mold and a partially-reflective coating is applied to the base part. A second thermoplastic injection molding stage is utilized to create a secondary part of the plastic reflective waveguide. The raw plastic reflective waveguide is ejected from the second mold and subjected to additional manufacturing processes to realize a finished part meeting design requirements for size and form factor.

A light-guide device includes a light guiding element (13) with a number of faces, including two parallel faces (26), for guiding light by internal reflection. A transparent optical element (19) has an interface surface for attachment to a coupling surface (14) of the light guiding element, and is configured such that light propagating within the transparent optical element passes through the interface surface and the coupling surface (14) so as to propagate within the light guiding element (13). A non-transparent coating (15) is applied to at least part of one or more faces of the light guiding element (13), defining an edge (17) adjacent to, or overlapping, the coupling surface (14) of the light guiding element (13). A quantity of transparent adhesive is deployed between the coupling surface and the interface surface so as to form an optically transmissive interface. An overspill region 31 of the adhesive extends to, and overlaps, the edge (17).