HOLOPHANE LTD., LONDON, S.W.1.

A new development in street lighting technique employing horizontally-burning Mercury Discharge Lamps, in conjunction with a highly efficient optical system providing semi-cut-off light distribution characteristics.

The high intrinsic brightness of the light source is shielded by the reflector assembly in the lantern hood, thus avoiding glare conditions, while the combined reflector refractor assembly affords a controlled two-way non-axial distribution, promoting adequate road surface and background brightness when installed in accordance with Group "A" requirements.

These lanterns employ two-piece refractors so designed that the functional prismatic surfaces are internally sealed, presenting smooth exterior surfaces, thus facilitating cleaning and maintaining optimum efficiency over longer periods. Available in types suitable for Groups "A" and "B roads, and all installation requirements.

Designed to produce suitable vertical and lateral light control in conjunction with Sodium Discharge Lamps. Two piece refractor panels with internally sealed prisms and smooth exterior surfaces, re-direct the light flux into a well-controlled two-way non-axial distribution, while the low brightness of the refractor lantern ensures excellent visibility.

Simplicity and efficiency, together with low initial and operating costs, are the primary features underlying the design of this refractor lantern series. Available for lamp ranges suited to both Groups "A" and "B" installations, together with alternative refractor designs for symmetrical and two-way non-axial distributions.

This lantern embodies one of the most advanced and efficient types of bowl refractors, designed for use with vertically-burning Mercury Discharge Lamps. The light control is obtained by the use of patented reflector diffuser prisms carried on the inside of the glass, which are so designed as to give a wide spread of light at relatively low angles and a more restricted spread at high angles of emission, thus varying the width of the beams to match the angular width of the roadway at different angles of elevation.

Two sizes are available, to suit Groups "A" and "B" installations, while the refractor bowl can be supplied in alternative types to provide symmetrical, two-way axial, or two-way non-axial distributions. The lantern is also available for side entry mounting.