New process provides more comfortable lighting
Lisbeth Sellereite
Photo: Jan D. Martens
Modern fluorescent light tubes are smaller and use less energy than their predecessors. However, the light they give off is more intense. This places new demands on the reflectors guiding the light. A new technique for making reflector material should provide more effective and comfortable lighting.
Reflectors for florescent tubes: Glamox Reflectormatte (center) has light scattering properties between specular (left) and matte (right) surfaces. The lower pictures show how the different materials reflect a laser beam.
"As the intensity of fluorescent lighting increases, so does the importance of choosing the reflector material," says Jan Morten Søraker, project engineer at Glamox, the company using an innovative technique to produce reflector material.
Glamox calls the result "Reflectormatte". It has a fine-grained surface that spreads the light without harsh reflections. The finish of the surface is between that of specular (glossy) and matte. It should effectively illuminate offices and public buildings and still provide comfortable lighting.
"Most people find that the transition between light and shadow strains their eyes," says senior scientist Rudie Spooren at SINTEF Materials Technology.
Eliminating the transition isn't the solution since light and shadow affect the perception of shape and depth. No reflector material satisfies all illumination needs.
"In a gas station a specular reflector is preferable since it concentrates the light so that reflections on the windows don't make it difficult to see out," says Søraker. On the other hand, matte reflectors are often chosen for offshore applications since they spread the light more and make it easier to see the lamp from a distance.
A new process
Through a cooperative effort funded by the Research Council of Norway, the new reflector material was developed by the lighting manufacturer Glamox, Hydro Aluminum, who provided the raw materials, and SINTEF Materials Technology.
"Using manufacturing equipment which Glamox already had, and taking advantage of the unique properties of the raw material from Hydro, we devised a new and more economical method for producing a reflectormatte surface," reports Spooren.
The Glamox Reflectormatte is made of rolled aluminum that is first shaped into the finished reflector. A patent-pending electrochemical process creates the fine-grained surfaces.
"The material in the reflectors meets international standards for light fittings. Meanwhile, the surface is durable and easy to keep clean," Søraker reports. "Since specular and matt finishes have different areas of application, we still produce them as well."
Eight years ago over 90 % of all reflectors being sold in Europe were specular. Last year this proportion was down to 60 % because matte and reflectormatte products are being used more. One reason for this is the increased awareness of the importance of proper lighting in the work place.
Contact at SINTEF: Rudie Spooren
Tel.: +47 73 59 82 21.
E-mail: Rudie.Spooren@matec.sintef.no