An optical sight, which includes a light source and a lens system wherein the lens system is an image of the light source, serving as an aiming point to the pointer's eye. The lens system has a reflecting surface for reflection in the direction of the pointer's eye of radiation from the light source. Means are provided for making a periodic change of the luminance of the image of the light source with a frequency with the perceptibility range of the eye.

An image display apparatus which enables observation of a clear image at a wide field angle with substantially no reduction in the brightness of the observation image, and which is extremely small in size and light in weight and hence unlikely to cause the observer to be fatigued. The image display apparatus includes an image display device (6) for displaying an image, and an ocular optical system (7) for projecting the image displayed by the image display device (6) and for leading the projecte...

In an optical head for optical beacon, a prism 5 is arranged immediately after light emitting elements 1 of an optical head 10 in light radiating directions of the light emitting elements 1, so that the paths along which light rays travel immediately after the radiation can be curved by the prism 5. As a result of this configuration, if the index of refraction of a material of which the prism 5 is made and the angle of a slope of the prism 5 are set to proper values, the light rays can be inject...

An optical element of this invention converts incident light having a predetermined shape and a predetermined intensity distribution into output light having a desired shape and a uniform intensity distribution. Furthermore, in an optical device of this invention, which has this optical element as a first optical element, a light source radiates a light beam having the predetermined beam shape and the predetermined intensity distribution, the first optical element shapes the beam shape of the in...

An optical bench comprising parallel, horizontal primary and secondary ways and a plate-like carrier seated on and slidable longitudinally along two of the ways. A secondary way is circular in cross section and is provided thereon with a longitudinally slidable collar having an external circumferential groove with side walls perpendicular to the ways. The carrier has a notch providing oppositely facing edges respectively receivable in diametrically opposed portions of the groove and engageable w...

An optical phase modulator comprises a semiconductive body having first, second and thrid layers, the second layer being contiguous with and intermediate to the first and third layers and being of a material having a bandgap and free carrier concentration lower than that of both of the first and third layers. Optical radiation to be modulated is transmitted through the second layer across which is applied an electric field to effect the modulation. In a preferred embodiment the body and the fiel...

Optical viewports are disclosed which comprise an optically clear, relatively brittle, layer, such as glass, and an optically clear, flexible, tough polymeric film weakly bonded to the back of the brittle layer. A sharp impact force on the surface of the brittle layer results in fragmentation of that layer and partial delamination of the polymeric film from the surface of the brittle layer. The delamination results in improved dissipation of the impact energy, and the tough polymeric film retain...

The specification discloses optical systems for forming aberrated images of objects, and for forming true images of the objects from the aberrated images, using light filters in the path of image-forming light. Filters are shown located in a Fourier transform plane, and in the principal plane of an image-forming lens system.

An optical system for projecting a uniform field of light to expose a light-sensitive surface through a transparency in proximity to, or in contact with, the light-sensitive surface comprises a light source, a condenser consisting of two plano-convex quartz lenses, and a field lens consisting of a single plano-convex quartz lens, all disposed serially along an optical axis. The condenser and the field lens are disposed so as to image a light image plane beyond the field lens onto a curved surfac...

An optical cable comprises an elongate central core consisting of at least one non-optical reinforcing member, a plurality of optical bundles arranged together in at least one stranded layer about the core and, surrounding the stranded body so formed, an outer protective sheath. Each optical bundle comprises a group of optical fibres or a group of fibres including at least one optical fibre and at least one non-optical reinforcing fibre or other reinforcing elongate element. The or each non-opti...