Okay now I understand. Yeah those lenses will definitely concentrate the footprint but it would require you to mount it higher because of it but then again it depends on what diode you are concentrating. Not positive on how much extra heat they create but most of the the heat is transferring from the diode to the heatsink in the back.
So also there is a UL code for commercial agricultural lights that puts a minimum standard on the horticultural light industry and I believe one of those standards is having a cover over the diode with some kind of lens or cover. Perhaps that is why they were using it. Maybe they were playing towards that side of the industry.
The transition to indoor agriculture presents new challenges to those called upon to inspect, approve and sign off on specialized grow facilities. Learn about the new safety standards emerging for equipment used in these facilities.
www.ul.com
I suspect this is also why you see many DIY kits that are just about made.