Shedding Some Light on LED Diffusers and Lenses

Advances in LED technology have been rapid in recent years. With ever increasing pressure on businesses to reduce energy consumption, LEDs have become more prominent in the lighting market due to their very low running cost.

The light output of LEDs has improved considerably in recent years, and this factor, in conjunction with a significant reduction in component costs is making new LED lighting projects extremely viable.

LEDs however do have one significant drawback in that they produce a very direct pinpoint light output. This creates ‘spotting’ where the LED is visible as a bright spot or as a string of bright spots in strip lights. Traditionally, with fluorescent tubes, lighting diffusers have been produced with opal or frosted effects to disguise the tubes. Opals are purely pigmentation added to clear base polymer to mask the light source. Frosted light diffusers are manufactured by using a blend of two different polymers which have different refractive indices thus giving diffusion of the light source.

Unfortunately opal materials are unsuitable for new LED technology, because they do not successfully mask bright spots produced and they reduce the light output to such an extent that they make the investment in LED technology less attractive financially. Initially frosted polymers were acceptable to the lighting industry as their ability to mask the LED was good however this was at the expense of light output, which in time has become more critical.

Naturally, polymer manufacturers have continuously tried to develop a product that will offer good light diffusion of the LED, eliminate spotting and provide maximum light output. The ‘holy grail’ for the lighting industry remains the maximum diffusion of the light source with no loss of light output and whilst  polymer producers and extruders like ourselves have yet to achieve this goal, we have made major progress.  The latest materials used for producing light diffusers now generate approximately 85 percent light transmission for a given thickness of 1.5mm.

Where spotting is not considered an issue and the pure functionality of the LED is uppermost then we are being challenged to produce bespoke LED lenses that control the distribution of the beam from the LEDs in a very specific manner. This is usually achieved using a series of linear lenses inclined at differing angles to project the light in a very defined pattern.

Alternatively, where a more focused light beam is required, a design incorporating a domed or shaped lens that magnifies or redirects the beam of the LED can be produced. Given the limitations of the extrusion process however, these designs are very challenging insofar as varying thicknesses of material create cooling issues and considerable difficulties in maintaining a straight product.

In the last 10 years, Condale Plastics has undertaken a number of successful projects for clients manufacturing bespoke light diffusers and lenses to a high standard that provide the desired light transmission and dispersion. The knowledge we have gained working with architects and lighting manufacturers means we can offer precise technical input at the design stage of new lighting products, including recommendations on the best material for the required usage.