Intermediate LED Cases of Lens Deterioration in Popular Lights

Users who are viewing this thread

luxdium

Well-known member
Location
Fremont, CA
Country flag
Since January 2021, we’ve been conducting a study on lens melt of popular light optics, with emphasis on those made by AquaIllumination/Ecotech. With a dataset of over 145 cases across product lines, we've collected enough data to come to a conclusion of the true cause of the issue.

We elaborate on our findings below.

*Note: These findings apply to other lights as well, especially those that use plastic optics, so this is not a one brand vs another kind of a thing and under no circumstances is this a thread meant to undermine any party. This was an investigation sparked by genuine curiosity, and since we had more access to these lights than others, these were carefully examined. There is nothing unsafe about them in any form. This was just an investigation on the materials over a harsh environment, like a marine environment. *

Over the social media platforms and forums, there are numerous theories and sometimes myths of the true cause of the melt. Here, we will address each commonly discussed one, using AI lights as an example which were studied with careful detail.


Spectrum and Material Degradation
The first one that comes is whether these lights emit true UVA. While the "UV" and Violet LEDs peak between 404-416nm and have a trailing edge that crosses some UVA, the emitters in question typically aren’t radiating all of their energy in UVA.

146316165_1296227164075049_2203505019126131964_n.jpeg



Since most manufacturers typically do not specify the material they use to make their lenses, it is difficult to understand the limits of the materials. Through light absorption spectroscopy it was determined that the optics of these lights are made of a form of acrylic, likely PMMA, or Poly(methyl methacrylate), a common material of choice by many optics manufacturers.

271046161_1515032275527869_3272275970967392560_n.jpeg


This material typically has a visible light transmission of 91-92%, which is in line with the marketed claims for the optics. Through experimentation, it was found that the lenses can filter up to 94% of UV-A between 350nm and 400nm with the remaining 6% between 395 and 400nm passing with minimal inefficiency.

234209537_156113896631416_5311282095160904332_n.png



Additionally, as a long-term test of the extended effects of UVA on the material in the lens, we modified a Prime Freshwater puck with a 395nm UVA diode. Since 2018, this light has been running for 9 hours a day at full brightness over a high tech freshwater planted tank with no apparent signs of melting.

Prime FW UVA.jpg


UVA LED.png


Given these findings, the spectrum alone is likely not the primary cause of melt.

Setting Channels above 100% and LED Failure
A common misconception about LED failure is setting the settings too high. There are some lights like AI's which allow users to set intensities beyond 100%. Despite being known as "Hyperdrive," this feature does not raise the power of the LEDs, or overdrive them beyond their specifications, but more or less dynamically dims the other channels so that at near full brightness, the sum of the power draw at peak settings does not exceed the ratings for the fixture. Thus, setting the UV and Violet channels above 100% will not shorten the life of the LEDs by themselves. However, the brighter the light is set, the more heat the LEDs will produce. More heat, if not efficiently removed from the boards will degrade the life of the LEDs, and in rare cases may cause color shifts (eg. sky blue shifting towards green), or even cause them to develop fissures and catastrophically fail (blackout).

93418498_1509677202544117_1239312791785963520_n (2).png


The underlying causes for settings-related LED failure fall into two categories: manufacturing errors (eg. soldering defects) and lack of heatsink cleaning, with more weightage on the cause of failure stemming from the assembly.

Setting Channels above 100% and Lens Melt
A theory that is widely distributed is setting certain channels above or close to 100% directly causes melting lenses. Typically these are the UV and VI channels. While the UV and VI LEDs do produce the most heat of all the LEDs on most boards and sometimes sit at the center, which is the hottest point of the fixture, the lens material typically still has a melting temperature of around 160ºC, or 320ºF. At no point do the surface temperatures of the LEDs reach 160ºC.

Given the high melting point of the plastic and the fact that other colors such as Royal Blue LEDs which run cooler also have their optics distort, temperature cannot solely be the cause of the melt. Furthermore, users who run their UV and Violet channels at relatively lower settings of around 45% also report cases of lens melt.

Lens degredation.JPG

In this picture, we see a 440nm Orphek LED develop a distorted lens. Note that blue LEDs between 440-460nm are typically very efficient.

Dust in the Heatsink and Lens Melt
Dust buildup does cause marked inefficiencies in the thermal management system of a light. However, isolating the issue of trapped dust from the lack of maintenance of a light fixture that results in optical deformation is quite difficult. While a plausible cause, it takes more heat to cause the optics to melt than the inefficiencies from dust-driven thermal inefficiencies. Typically, if the light is functioning properly, it will go into thermal shutdown mode before this happens. However, sometimes the failsafe does not work as intended and the solder mask in the lights can discolor before the unit turns off due to overheating.

Saltwater spray and Lens Melt
Given the ester groups which naturally make the material susceptible to chemical exposure, PMMA, the material used in the lenses, is mixed with proprietary ratios of stabilizing co-monomers which improve the resistance of the thermoplastic to UV and chemical exposure. However, in the event of contact with saltwater, or volatiles, the heat from the LED module is enough to trigger the breakdown of the chemical structure of the lens material. What is observed as melt is actually the disassociation of the lens material to its primitive forms (methyl methacrylate monomers). This typically begins when a droplet of saltwater lands on the lens or dries up near it. With the impurities in the saltwater remaining on the optical surface, light is absorbed and the salts along with other trace elements begin to act like receptors, and may initiate color instability in the optics, thus starting a chain reaction which in the presence of oxygen, may damage the structure of the plastic. The depolymerized acrylics are damaging to the LEDs themselves as they can volatize and get embedded in the silicone primary optics of the LED lenses, thereby reducing light output. Of the 145 observed cases of lens melt with the AquaIllumination and Ecotech models studied, 127 cases showed signs of saltwater spray by the fixture or the optics. Given that 88% of melted lenses began with salt exposure, or showed signs of ingress, there is sufficient reason to believe that the root cause of lens melt involves saltwater spray in some form.

Lens depolymerization.jpg

In this picture, it is apparent that that the secondary optics depolymerized. Note the presence of the green salts. Blue-green salts are typically rich in elements such as copper, which can oxidize in the presence of moisture and saltwater volatiles. While methyl methacrylate monomers are clear, there are impurities and contaminants from the volatiles that can cause them to discolor.

Cree LED VOC.png

Lastly, in this picture from Cree-LED, it is also apparent that such organic compounds can volatize and diffuse inside the primary optics of LEDs. (normal LED on the left and compromised LED on the right) This has a side-effect of reducing the luminous intensity of the diode as foreign material occludes the emissive area of the chip. According to Cree-LED, these organics can dissipate if the LED is allowed ample time to off-gas. Given the possibility of these occurrences, Cree-LED recommends not hermetically sealing luminaires. Which is one reason most light fixtures are not entirely waterproof. A warm saltwater environment that off-gasses VOCs, definitely poses a unique engineering challenge for light manufacturers.

Key Takeaways
Irrespective of the manufacturer, as long as the lenses are made of PMMA and LEDs are placed in close proximity to them, lens degradation will affect the lights. For the most part, the best form of prevention is to avoid exposing the lights to saltwater spray, and cleaning the lenses as soon as saltwater is observed around them. Cleaning should only be done with an RODI-moistened, lint-free microfiber cloth, while the fixture is off and has cooled. The microfiber cloth used for cleaning eyeglasses is acceptable for this. Just ensure there are no oils saturated in the microfiber. In the event that more thorough cleaning is desired, the lens should be removed from the fixture and cleaned with a dilute detergent-water solution and rinsed with RODI before being left to completely dry.

The use of a lid that reduces the occurrence of saltwater mist or splashes to the lens may significantly improve lens life. A mounting height that puts the lights away from the water surface is also recommended. Typically, a distance of 8 inches or more should be adequate. In the event that the lights are installed in a canopy, additional air circulation fans that vent outside the hood must be installed to ensure the units are not subject to elevated humidity and Volatile Organic Compounds (VOCs).

Conclusion
While we would have appreciated if manufacturers were more open to sharing more information about lens failure and perhaps publishing support materials that explain best practices, it is understandable that conducting studies and trials over a large sample group in the wild may be challenging, especially when there are so many variables involved. That said, we hope with our findings, they can make improvements where needed.

In the meantime, these findings should also help us keep our lights running longer with minimal worry of their lenses melting.
 
Last edited:

saf1

Well-known member
Country flag
Awesome info… it always bothered me people say leds will last billion years yet don’t seem to. I guess due to our harsh marine environments and the constant feeling that people NEED to upgrade to the latest version.

People, some, say they last longer or a very long time. Most manufactures will place a "life expectancy" in the form of hours. Hobbyist even get upset with that but that is what the manufacture notes and advises.
 

saf1

Well-known member
Country flag
Since January 2021, we’ve been conducting a study on lens melt of popular light optics, with emphasis on those made by AquaIllumination/Ecotech. With a dataset of over 145 cases across product lines, we've collected enough data to come to a conclusion of the true cause of the issue.

We elaborate on our findings below.

*Note: These findings apply to other lights as well, especially those that use plastic optics, so this is not a one brand vs another kind of a thing and under no circumstances is this a thread meant to undermine any party. This was an investigation sparked by pure curiosity, and since we had more access to these lights than others, these were carefully examined. There is nothing unsafe about them in any form. This was just an investigation with materials over a harsh environment, like a marine environment. *

Over the social media platforms and forums, there are numerous theories and sometimes myths of the true cause of the melt. Here, we will address each commonly discussed one, using AI lights as an example which were studied with careful detail.


Spectrum and Material Degradation
The first one that comes is whether these lights emit true UVA. While the "UV" and Violet LEDs peak between 404-416nm and have a trailing edge that crosses some UVA, the emitters in question typically aren’t radiating all of their energy in UVA.

View attachment 53659


Since most manufacturers typically do not specify the material they use to make their lenses, it is difficult to understand the limits of the materials. Through light absorption spectroscopy it was determined that the optics of these lights are made of a form of acrylic, likely PMMA, or Poly(methyl methacrylate), a common material of choice by many optics manufacturers.

View attachment 53658

This material typically has a visible light transmission of 91-92%, which is in line with the marketed claims for the optics. Through experimentation, it was found that the lenses can filter up to 94% of UV-A between 350nm and 400nm with the remaining 6% between 395 and 400nm passing with minimal inefficiency.

View attachment 53660


Additionally, as a long-term test of the extended effects of UVA on the material in the lens, we modified a Prime Freshwater puck with a 395nm UVA diode. Since 2018, this light has been running for 9 hours a day at full brightness over a high tech freshwater planted tank with no apparent signs of melting.

View attachment 53662

View attachment 53663

Given these findings, the spectrum alone is likely not the primary cause of melt.

Setting Channels above 100% and LED Failure
A common misconception about LED failure is setting the settings too high. There are some lights like AI's which allow users to set intensities beyond 100%. Despite being known as "Hyperdrive," this feature does not raise the power of the LEDs, or overdrive them beyond their specifications, but more or less dynamically dims the other channels so that at near full brightness, the sum of the power draw at peak settings does not exceed the ratings for the fixture. Thus, setting the UV and Violet channels above 100% will not shorten the life of the LEDs by themselves. However, the brighter the light is set, the more heat the LEDs will produce. More heat, if not efficiently removed from the boards will degrade the life of the LEDs, and in rare cases may cause color shifts (eg. sky blue shifting towards green), or even cause them to develop fissures and catastrophically fail (blackout).

View attachment 53665


The underlying causes for settings-related LED failure fall into two categories: manufacturing errors (eg. soldering defects) and lack of heatsink cleaning, with more weightage on the cause of failure stemming from the assembly.

Setting Channels above 100% and Lens Melt
A theory that is widely distributed is setting certain channels above or close to 100% directly causes melting lenses. Typically these are the UV and VI channels. While the UV and VI LEDs do produce the most heat of all the LEDs on most boards and sometimes sit at the center, which is the hottest point of the fixture, the lens material typically still has a melting temperature of around 160ºC, or 320ºF. At no point do the surface temperatures of the LEDs reach 160ºC.

Given the high melting point of the plastic and the fact that other colors such as Royal Blue LEDs which run cooler also have their optics distort, temperature cannot solely be the cause of the melt. Furthermore, users who run their UV and Violet channels at relatively lower settings of around 45% also report cases of lens melt.

View attachment 53677
In this picture, we see a 440nm Orphek LED develop a distorted lens. Note that blue LEDs between 440-460nm are typically very efficient.

Dust in the Heatsink and Lens Melt
Dust buildup does cause marked inefficiencies in the thermal management system of a light. However, isolating the issue of trapped dust from the lack of maintenance of a light fixture that results in optical deformation is quite difficult. While a plausible cause, it takes more heat to cause the optics to melt than the inefficiencies from dust-driven thermal inefficiencies. Typically, if the light is functioning properly, it will go into thermal shutdown mode before this happens. However, sometimes the failsafe does not work as intended and the solder mask in the lights can discolor before the unit turns off due to overheating.

Saltwater spray and Lens Melt
Given the ester groups which naturally make the material susceptible to chemical exposure, PMMA, the material used in the lenses, is mixed with proprietary ratios of stabilizing co-monomers which improve the resistance of the thermoplastic to UV and chemical exposure. However, in the event of contact with saltwater, or volatiles, the heat from the LED module is enough to trigger the breakdown of the chemical structure of the lens material. What is observed as melt is actually the disassociation of the lens material to its primitive forms (methyl methacrylate monomers). This typically begins when a droplet of saltwater lands on the lens or dries up near it. With the impurities in the saltwater remaining on the optical surface, light is absorbed and the salts along with other trace elements begin to act like receptors, and may initiate color instability in the optics, thus starting a chain reaction which in the presence of oxygen, may damage the structure of the plastic. The depolymerized acrylics are damaging to the LEDs themselves as they can volatize and get embedded in the silicone primary optics of the LED lenses, thereby reducing light output. Of the 145 observed cases of lens melt with AquaIllumination and Ecotech models, 127 cases show signs of saltwater spray by the fixture or the optics. Given that 88% of melted lenses began with salt exposure, or showed signs of ingress, there is sufficient reason to believe that the root cause of lens melt involves saltwater spray in some form.

View attachment 53666
In this picture, it is apparent that that the secondary optics depolymerized. Note the presence of the green salts. Blue-green salts are typically rich in elements such as copper, which can oxidize in the presence of moist, saltwater volatiles. While methyl methacrylate monomers are clear, there are impurities and contaminants that can cause them discolor.

View attachment 53675
Lastly, in this picture from Cree-LED, it is apparent that VOCs can volatize and get embedded inside the primary optics of LEDs.



Key Takeaways
Irrespective of the manufacturer, as long as the lenses are made of PMMA and LEDs are placed in close proximity to them, lens degradation will affect the lights. For the most part, the best form of prevention is to avoid exposing the lights to saltwater spray, and cleaning the lenses as soon as saltwater is observed around them. Cleaning should only be done with an RODI-moistened, lint-free microfiber cloth, while the fixture is off and has cooled. The microfiber cloth used for cleaning eyeglasses is acceptable for this. Just ensure there are no oils saturated in the microfiber. In the event that more thorough cleaning is desired, the lens should be removed from the fixture and cleaned with a dilute detergent-water solution and rinsed with RODI before being left to completely dry.

The use of a lid that reduces the occurrence of saltwater mist or splashes to the lens may significantly improve lens life. A mounting height that puts the lights away from the water surface is also recommended. Typically, a distance of 8 inches or more should be adequate. In the event that the lights are installed in a canopy, additional air circulation fans that vent outside the hood must be installed to ensure the units are not subject to elevated humidity and Volatile Organic Compounds (VOCs).

Conclusion
While we would have appreciated if manufacturers were more open to sharing more information about lens failure and perhaps publishing support materials that explain best practices, it is understandable that conducting studies and trials over a large sample group in the wild may be challenging, especially when there are so many variables involved. That said, we hope with our findings, they can make improvements where needed.

In the meantime, these findings should also help us keep our lights running longer with minimal worry of their lenses melting.

Your sample size was 145?
 
Top