An optical marker for use in determining the position of a target point which is in alignment with a given or required point, which generally comprises a projector assembly supported by a substantially threelegged support by means of a gimbaled mechanism for movement in all directions. The projector assembly emits a pair of light beams from both ends thereof which are in alignment with respect to each other: one light beam being adapted to be centered with the given or required point and the oth...

An optical cable comprises a central elongate non-optical reinforcing member; a plurality of optical fibres and/or groups of optical fibres for use together as a single light guide, which optical fibres and/or groups of optical fibres are secured side by side on or within a substantially flat flexible support member which is lapped helically about the reinforcing member in at least one layer; and an outer protective sheath. The position of each optical fibre or group of optical fibres with respe...

Optical correlator for comparing a test sample with a standard object in which a diffractive image of the sample is projected on a holographic filter by a beam of coherent light. The light beam being diffracted by the filter is subsequently conveyed through an apertured diaphragm into a light-measuring apparatus generating an electrical signal proportionate to the intensity of the received light. An auxiliary filter is positioned either forwardly or rearwardly of the holographic filter, and is e...

A coupler to be disposed between two sections of optical signal transmission line for extracting a fraction of the energy transmitted thereby and for coupling to the transmission line substantially all of an input optical signal. An optical signal from one section of transmission line partially reflects from a first optical interface, the reflected portion of the signal being extracted from the transmission line and the refracted portion being coupled by a tapered transparent rod to the remainin...

An optical element and a method of forming such an optical element are disclosed. The optical element comprises a base of optically transparent material, a layer or several layers of material having selected physical and optical properties, and a coating integrally formed to the substrate and having substantially the same optical properties as the substrate so that the said layer or layers is or are effectively embedded therein. The layer or layers may be discontinuous e.g. formed as stripes, or...

The substances proustite Ag.sub.3 AsS.sub.3 and pyrargyrite Ag.sub.3 SbS.sub.3 and solid solutions of the two are useful non-linear materials and have applications in non-linear devices. They occur in nature but in a small and optically imperfect form. However, they may be prepared having a good optical quality and a large size by synthetic growth from the melt such as by Stockbarger growth, provided that steps are taken to alleviate the problem of cellular growth. The materials grown in such a ...

A wide web is mounted on a pair of moving rollers with the web made of a transparent material being at least the width of the music sheet and having at least two vertical lines drawn the width of the web so as to pass these lines in front of the sheet of music in a timed relationship according to the speed at which the notes are to be played.

An optical cable comprises at least one optical bundle, at least one separate elongate non-optical reinforcing member, and, surrounding the bundle or bundles and the reinforcing member or members, an outer protective sheath. The or each optical bundle of the cable includes a plurality of elongate optical elements each consisting of at least one optical fibre, the optical elements being at least partially embedded in and mutually separated by encapsulating material throughout the length of the bu...

Compounds of the formula ##SPC1## Wherein R.sub.1 and R.sub.2 denote hydrogen, halogen, nitrile, alkoxy, alkyl, aryl, cycloalkyl, aralkyl, carboxyl or carboxylic acid ester groups are suitable for the optical brightening of synthetic organic high molecular materials.

A flux scanner which is comprised of a rotating polygon for scanning a beam of radiated flux transverse a photoreceptive medium. In the beam path between the flux source and the polygon, an astigmatic-beam expander lens is employed to focus the flux distributions to a spot at an image plane. The astigmatic lens is configured so as to produce a very narrow beam of flux to control the size of the spot in a direction orthogonal to the transverse direction, without any loss of efficiency. Between th...