Thermoplastic LED lenses in greenhouse lighting can degrade over time, resulting in discolouring and failure of the optics. That's what researchers of Dow concluded from a study that evaluated the aging performance of commercially available lens clusters in LED lighting.
© Dow Chemicals
Blue light photothermal aging
The study examined blue-light photothermal aging of both silicone and thermoplastic optics made of polycarbonate (PC), polymethyl methacrylate (PMMA) and high-temperature-resistant PMMA (HT-PMMA). Dow itself produces silicone optics.
Dow's study subjected lens clusters to photothermal stress similar to the operating conditions of optics in luminaires for high-power LED lighting. "The principal finding is that most of the tested thermoplastic lens clusters discolour over time and ultimately fail catastrophically", the researchers share. "Gradual degradation by discolouration is known to reduce light output, but the study shows that catastrophic failure may be difficult to predict and requires long test times."
© Dow Chemicals
Thermoplastic optics
Dow's white paper about the subject is titled "Blue Light Photothermal Aging of Thermoplastic and Silicone Lens Clusters," authored by Martijn Beukema and Kevin Van Tiggelen, Senior Technical Service & Development Scientist for Lighting at Dow. They say the research arrives at a time when the global lighting industry is growing rapidly, fueled by increased adoption of energy-efficient LED modules.
"The longevity and light output efficiency of these LED modules is critical, but thermoplastic optics may present limitations in terms of performance and reliability depending on their specific configurations", the team says. Dow itself produces moldable optical silicones under their SILASTIC™ brand.
"Our study was conducted to bridge the knowledge gap on blue light photothermal aging of lens clusters commonly used by luminaire makers for applications such as street and sports lighting," said Martijn Beukema, Technical Service & Development Scientist and Application Technology Leader for Lighting at Dow. He also confirms that this white paper is applicable to horticultural applications.
"Luminaire manufacturers are encouraged to take this data into account when choosing optical materials during the design process, and to recognize silicone optics as a reliable alternative that can enhance product longevity and minimise the risk of major failures."
For more information:
https://engage.dow.com/lmcontactus
