Prismatic element for maximising directional efficiency of light source - has moulded or ground refracting and reflecting element in front of light source for re-directing stray and secondary light flux

摘要

The prismatic element (1) of glass or other transparent material is positioned in front of the light source of a lighting unit (not shown) in order to re-direct light rays which deviate by more than 45 deg. from the main flux direction into a path contained by an angle of less than 45 deg.. The element (1) is formed by grinding or moulding the frustum of a cone to generate the facets (8) at an angle (beta) to the optical axis, a central conical depression (3) of angle (alpha) and a facetted cone (5) of angle (gamma). Stray light and secondary reflections are re-aligned by refraction and total internal reflection to maximise the resultant flux distribution and minimise glare. USE/ADVANTAGE - Concentrates usable lightflux for improved distribution and efficiency of illumination of surfaces. Has corrective influence on effectiveness of reflectors or glare-reduction screens which improves functional and aesthetic performance.