Glass machining

NDUSTRY Glass machining Machining of glass on a lathe has been shown to be possible by heating the glass, which permits a continuous chip to be removed as with many metals. By selection of conditions it is possible to obtain a transparent glass surface of optical quality. This method is of interest for the manufacture of aspherical lenses, which cannot be produced by conventional grinding and polishing methods.

Philips, P.O. Box 523, 5600 AM Eindhoven, The Netherlands. E n e r g y saving l i g h t i n g Energy savings of around 250 000 kWh or 30% are expected during the first year of operation of the Austrian Arlberg Tunnel, thanks to a new computer-regulated lighting system. Designed by Zumtobel Aktiengesellschaft, Dornbirn,.the system employs 10 000 fluorescent tubes set end to end in a single continuous strip, giving better visual conditions than the spaced roof lighting previously used and substantially lowering the hazards associated with tunnel driving conditions.

Workpiece and tool tip shown during machining of glass

The Arlberg lighting system is adjusted automatically to suit the prevailing traffic conditions. Thus, in normal traffic, an energy demand of 150 kWh at 30% luminous flux is required, rising to 280 kWh only in cases of an emergency when full intensity is called for. Overall photometric efficiency is further enhanced by use of a parabolic reflector luminaire system which is particularly advantageous when tunnel fogging, caused by diesel fumes, becomes intense.

Du Pont (UK) Ltd., 18 Breams Buildings, Fetter Lane, London, EC4A 1FtT

SI RA reports The annual report 1979 of SIRA shows for the financial year ended

Energy requirement of the turnnel was reduced from 14 W to 10 W per metre

OPTICS AND LASER TECHNOLOGY . FEBRUARY 1980

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