Just getting into tinkering with flashlights and know just enough to be dangerous. There was a chunk of silicone on top of the dome shaped lens when I received it. I used my nail to try and scrape it off and the whole lenz came off exposing the LED. I want to put it back and the question is can I use ordinary clear silicone to set it back or is there a special kind? This is a P60 style Cree R2 LED drop in 225 lumen. Also this thing is brighter with the lens off. Kinda like it.
LED lens seperated
- Thread starter maitland
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Before this gets out of hand we need to correct some things. I am assuming you are talking about the Cree XR-E LED. Knocking the dome off does not make it brighter but about 30% dimmer. In a reflectored light the spot of the beam may appear brighter due to the tighter collimation because the LED die is not being magnified by the dome. Some people have used common clear silicone and had it work OK but do not expect it to be as good as new. Also I have seen absolutely no evidence to show that with the dome off the phosphor degrades. So if you like it better that way then stick with it.
csshih
Flashlight Enthusiast
The "dome", or optics, is very efficient at transmitting light. Without it, there will actually be some output lost.
I am still wondering what kind of silicone I should use to put it back on with. It really sounds like a cheese ball way to apply the lens but this is how they did it. The lens is literally around 3/16" wide and dome shaped with a flat bottom. The silicone actually encapsulated the led so it must be heat resistant. Getting back to the brightness loss and gain with or without the lens, what I have noticed is that there is for sure more ambient light when the lens is off. When the lens is on, it is a lot smoother more direct beam but again not brighter.
nikon
Flashlight Enthusiast
They use silicone to hold the dome in place for two reasons...it's clear and it's stable up to several hundred degrees. You can try using any clear silicone to put the dome back on but there's no guarantee it will hold. Also, you'll always have a spot under the dome that looks like it exploded.
It is impossible for it to be brighter without the dome. Your eyes are being tricked. The dome is key to light extraction. I and others have tested this by intentionally removing domes and using light meters to measure the change in light output.
Like I said if you like the new beam than there is no need to do anything. If you really want to do things right you can take a sample of the optical gel and send it to a lab to find out the exact refractive index. From memory that will cost you about $1000. Then you can buy a roughly $100 bottle of optical gel to match. Or you could just use normal Home Depot clear silicone or even better replace the LED with a new one.
Niteowl
Enlightened
FWIW, I used super-glue to re-attach a dome on a XR-E recently. Seems to work fine but I haven't left it turned on for more than a few minutes at a time.
:thumbsdow
Niteowl
Enlightened
"For What It's Worth"
It is not a recommendation to do it. I mentioned it because I tried it and the results have been fine so far, not having expected it to work at all. It's holding and the beam looks "Good As New".
I have another emitter to replace the one I "fixed", but seeing as how the beam is as nice as before, I'm not in any hurry. It's a Q3-5C and I really like it.
Some time in the near future, I'll pop in a fresh cell and leave it on high until it either runs down or fails. I'll try to remember to report back.
"For What It's Worth"
It is not a recommendation to do it. I mentioned it because I tried it and the results have been fine so far, not having expected it to work at all. It's holding and the beam looks "Good As New".
I have another emitter to replace the one I "fixed", but seeing as how the beam is as nice as before, I'm not in any hurry. It's a Q3-5C and I really like it.
Some time in the near future, I'll pop in a fresh cell and leave it on high until it either runs down or fails. I'll try to remember to report back.
I would worry about off-gassing contaminating the lens or reflector. Also I think heat cycling will break the glue bond since it is so ridged.
