What is under the Cree lens

snipinglight

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Sep 2, 2006
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Today I look at the Cree under the microscope and found that under the acrylic lens is some kind of silicon gel. Can anyone confirm this and what is the purpose of the silicon gel?
 

SemiMan

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It is Silicon gel. It is used to encapsulate the die and the bonding wires for protection and to provide an optical interface to the LED. This is pretty much standard on all high powered LEDs.

Semiman
 

snipinglight

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Between the metal ring and clear acrylic lens u can use a piece of paper to pick some of the gel out, but only a bit of it if you try it under the microscope
 

Tritium

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Its "SUPER" glass. Fused quartz can be heated to red hot and plunged into water without cracking or shattering. (Not relevant to flashlights but interesting)

Thurmond
 

Russell52

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Has anyone noticed a rippled effect on any of there crees? I have one that gives me a funny beam,and it looks as if the dome is not smooth..

Russ
 

Tritium

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Russell52 said:
Has anyone noticed a rippled effect on any of there crees? I have one that gives me a funny beam,and it looks as if the dome is not smooth..

Russ

Yes I have. I had one emitter that had a "fracture" in the silicon gel. This caused a terrible beam as it was acting like a beamsplitter and sending light in all kinds of directions. Firm downward pressure after applying a "tiny" amount of heat from a heat gun "healed" the fracture. Great beam now.

Thurmond
 

IsaacHayes

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I've seen several glass domes on crees that varry in smoothness. Some have rings or ridges on them I guess from how they are molded? The led has silicone gel underneath so the lens can "float" with varying temperature.
 
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