Abstract: A touch-sensitive key particularly for use in a fibre-optic system has a radiation propagating unit (3) with a touching surface (5). Radiation input and output devices, such as optical fibres (1, 2), are arranged respectively to direct radiation at the touching surface (5) through the unit (3) and to receive such radiation scattered from the touching surface (5) through the unit (3). The unit (3) incorporates a radiation collecting arrangement to reduce radiation losses between the input and output devices. In one embodiment this arrangement is achieved by using a unit (3) in the form of an optical-fibre light guide. In a further embodiment the unit (9) has a suitably curved touching surface (10) which has a focusing action. In other embodiments focusing mirrors (19, 22) are used. In order to discriminate between internal radiation and external radiation entering the unit, air gaps (4, 14, 21, 26) may be provided e.g. between the output device and the unit, and also radiation-absorbing material (15, 28, 27).

Abstract: An image monochromator is arranged to receive light at an input thereof simultaneously from an entire object field to be viewed and to produce and transmit a viewable image of the entire object field simultaneously through an output thereof at a selected wavelength band. The monochromator has inner and outer optical systems, the inner system comprising an input slit which is projected on an output slit through imaging means such as lenses or mirrors, via dispersive means such as a diffraction grating or prism operable to transmit light at a tunable narrow wavelength band.

Abstract: A touch-sensitive key has a radiation-propagating prism or plate between a radiation source and a radiation detector. Radiation is scattered from a top surface of the prism or plate so as to reach and activate the detector through a side surface when the top surface is touched. External radiation is free to enter the prism or plate and to leave through the side surface but this radiation is not capable of actuating the detector. In one embodiment the detector is spaced from the side surface so that it cannot be reached by external radiation. In an alternative embodiment, external radiation is subject to multiple reflections within the prism or plate and at each reflection part of the radiation is transmitted through the pertaining surface to be absorbed in a substrate layer.

Abstract: An objective, for example for a television camera, has a pinhole aperture (3) and an electronic image intensifier (5) arranged behind the aperture. The pinhole aperture gives extreme depth of field and the image intensifier has adequate gain to compensate for the low yield of the aperture. The aperture may be defined in an opaque layer deposited on a glass plate. The image intensifier may comprise a multichannel plate.

Abstract: The present invention briefly refers to a window squeegee for use in washing windows and similar plane surfaces. It comprises a handle (1) having an attachment portion (3) for a scraper blade (4), the scraper blade being detachable secured to the attachment portion (3). The scraper blade (4) is constituted by a rubber blade (6) which is clamped between the legs of a metal strip (5) having substantially U-shaped cross-section. The attachment portion (3) is suitably comprising two protruding shoulders (9) adapted to contact one of the legs of the scraper blade strip (5) and at least one tongue (10) adapted to contact the other leg of the scraper blade strip (5). The tongue or tongues are provided with a ridge (11) protruding towards the scraper blade (4) and receiving in a notch (8) in the other leg of the scraper blade strip (5).

Abstract: In an optoelectronic circuit element for effecting a manually controlled output signal comprising at least one radiation-emitting element, a radiation-propagating unit and at least one radiation-sensitive element, the radiation-propagating unit being a solid body which is transparent to the radiation in question and which has an interface which is exposed to radiation from the radiation-propagating unit, an identifiable change in the state of the radiation-sensitive element is effected by changes in the conditions for total internal reflection of the radiation at the interface arising from contact of an actuating body, say a finger, with said interface.

Abstract: An opto-electronic detector has a radiation-emitting element and a radiation receiving element which are linked optically and also by an electronic circuit so that the radiation-emitting element is caused to produce radiation pulses due to feedback between the radiation-emitting and receiving elements.The construction of the electronic circuit is such that sharp pulses are produced having an amplitude and frequency dependent on the optical feedback factor, and such that the pulses are spaced by intervals in which the radiation-emitting element is entirely extinguished.The electronic circuit comprises a current amplifier (T2) which feeds the radiation-emitting element (D1). This amplifier is controlled by the radiation-receiving element (T1) and by a filter (R1C1) which incorporates a storage element such as a capacitor.