long term led par levels discussion

[reeferfoxx]

Sorry for bumping this thread and not sure if t was talked about, but the degradation of 360nm - 450nm led chips is somewhat substantial. I suppose I neglected to even think about it. Most if not all LED chips are made with a plastic primary lens that does cause yellowing. In fact here is 8 months worth of a 390nm Epistar chip.

Decided to replace the two 390nm(UV) chips with 450nm(blue). They were due for a change out but didn't want to risk bleaching. Here are some macro shots.
6-8 months of use...

 

[oreo54]

Some just cut the lens off...

 

[reeferfoxx]

Some just cut the lens off...

;Woot I've been googling this idea all day without resolve! I'm revamping my layout and I want the 390's but dont want to switch them out. Is it safe to do so?;Wideyed

 

[reeferfoxx]

Just removed some lenses on a couple "tester" chips. It does seem to be ok to remove the lense. In these pics you'll notice one lense is cloudy and the other is without the lense.

 

[sghera64]

I understand what you are attempting but caution you on what is really obtainable.
Worrying about PAR decreases in 10 years is a bit much..
Anyways how the pros are wrestling w/ it.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwieyf-4lLrYAhUU6mMKHUf6C6AQFggxMAE&url=http://www.cree.com/led-components/media/documents/XLamp_lumen_maintenance.pdf&usg=AOvVaw1M0oDOoyrPOOzrDklnju8n
http://www.lighting.philips.com/mai...e-life-of-leds-measured-as-lumen-depreciation
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwieyf-4lLrYAhUU6mMKHUf6C6AQFgg9MAM&url=http://cool.conservation-us.org/byorg/us-doe/lifetime_white_leds_aug16_r1.pdf&usg=AOvVaw0SdTd3Ud7ZJGIrEdCsaOUv

There is one more "gotcha" here.. A tube or bulb may be rated at 20000 hours WHEN the bulb survives that long.. Many fail long before reaching their lumen maintenance point.
LESS likely w/ LED's...

And there is the future..


248F for us in the US...........

Yikes! Pretty soon we’ll be cooking food with IR LEDs in our led-o-vens.

 

[oreo54]

Just removed some lenses on a couple "tester" chips. It does seem to be ok to remove the lense. In these pics you'll notice one lense is cloudy and the other is without the lense.

...snip...

funny about that.. I did at one time go through a thread where this was done and tested.. Also couldn't find it again..or any others..

anyways.. x-section:

 

[reeferfoxx]

I did at one time go through a thread where this was done and tested

And it seemed ok?

 

[oreo54]

Yes.. only question was exposing the chip to the elements..w/ secodary lenses this is (partially) eliminated..
violets and UV chips tend to be short lived anyways so it is more of a stop gap measure..
Royal blues are more "robust"..in general
https://www.nano-reef.com/forums/topic/353014-is-this-led-diode-burnt/
https://www.nano-reef.com/forums/to...leds-browning-out-new-silicone-lenses-better/

Update: Since the Violet LEDS seemed nearly useless, I decided to play with them. In short, I sanded the the encapsulant/dome down to see how far the browning went. Well, it's NOT on the surface but definitely within the composition of the encapsulant itself (about half-way), which indicates to me there were contaminates during manufacturing. Or is porous? Probably not.
This said - both LEDS are working OK now. I don't know how much the beam angle has been affected by grinding the dome flat but given I use them as accent lighting just above the water's surface, they seem to be doing the job for now.
Thus, if any of you have browned out encapsulant, pull out the dremel, grind down the dome until the brown is gone, and then polish. I'm guessing that if also using a lense, grinding down has very little effect final beam angle.