Dedoming IR LEDs

Flashlights, IR illuminators. Projects, reviews and queries. DIY 'stickies' here too.
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yabba
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Joined: 18 Nov 2015, 10:01
Location: Samoa

Dedoming IR LEDs

Post by yabba » 23 Jan 2018, 06:37

Hi Guys,
Got a question that I have not found much info on. Has anyone tried dedoming IR LEDs such as the 4715AS? If so what was the effect? Is it similar to dedoming a white LED. I have a AS in a T67. I was wondering why I have not heard more of people dedoming them.
Thanks
Yabba

superslack
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Location: Virginia

Re: Dedoming IR LEDs

Post by superslack » 25 Jan 2018, 00:51

I don't think there is a large flashlight mod crowd here. The IR illuminator is probably considered more of a tool/necessity compared to the NV itself.

Also, the newest IR LEDs have enough throw in a zoomable flashlight to illuminate targets extremely far out there.

Potentially, you could dedome an IR LED and then get the same throw at a lower amperage/power. This may reduce visible IR signature. Try it and let us know what you find.

yabba
Posts: 35
Joined: 18 Nov 2015, 10:01
Location: Samoa

Re: Dedoming IR LEDs

Post by yabba » 25 Jan 2018, 04:44

superslack wrote:I don't think there is a large flashlight mod crowd here. The IR illuminator is probably considered more of a tool/necessity compared to the NV itself.

Also, the newest IR LEDs have enough throw in a zoomable flashlight to illuminate targets extremely far out there.

Potentially, you could dedome an IR LED and then get the same throw at a lower amperage/power. This may reduce visible IR signature. Try it and let us know what you find.
Thanks, I am a bit hesitant to experiment on my only AS pill until I know how it works for IR as the next replacement is some distance away.
I ask this because from what I read de-doming gives a longer throw due to the Apparent "smaller emitter" as well as reducing the wave length due to the lack of TIR "from dome" re-entering the die. Then by adding a "wavien collar" it can further increase the throw due to the recycling of wasted spill light that is redirected back to the die to further excite the emitter.

superslack
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Joined: 08 Feb 2016, 23:58
Location: Virginia

Re: Dedoming IR LEDs

Post by superslack » 25 Jan 2018, 15:00

Is the throw with an sfh4715as not sufficient? What is your goal with more throw?

Check out sedstar's old posts on lens combos for it lights. It might be interesting to you.

yabba
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Joined: 18 Nov 2015, 10:01
Location: Samoa

Re: Dedoming IR LEDs

Post by yabba » 26 Jan 2018, 03:35

superslack wrote:Is the throw with an sfh4715as not sufficient? What is your goal with more throw?

Check out sedstar's old posts on lens combos for it lights. It might be interesting to you.
I'm interested in getting the furthest possible throw with what I have. I have a long range spotter with a number of large Broadcast lens ie. Fujion 1/2" 128mm f1.4, 1/2" 214mm f2.0. but the ir circle is larger then my picture on my screen so by reducing the LED beam angle to match my view I should be able to considerably increase the viewing distance. I will try to have a look at those old posts that you mentioned.

lightmesser
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Location: Eastern Europe

Re: Dedoming IR LEDs

Post by lightmesser » 27 Jan 2018, 10:33

You'd better get yourself a Rubby :)

I know a guy who did de-doming of 4715as and he got only smaller die projection. For example T50 goes to T67 die size but performance are not going much up I'm afraid. Well maybe slightly gain judging with eye method...

But lets say this way... You have T20 which have fairly large die projection which perfectly covers scope field of view on 3,5-4x mag and you find it is to large for lets say 6-7x magnification... So if you de dome it in T20 it die projection will get smaller and will perfectly cover scope fov on 6-7x mag. So T20 die size will go to T50 die size.

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cliveward
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Re: Dedoming IR LEDs

Post by cliveward » 27 Jan 2018, 12:59

Something we have experimented with ages ago.

You get a tighter beam as lightmesser says, but also loose a lot of power.

Roughly speaking a smaller beam but with the same power density as before it was de-domed so not worth pursuing.


Cheers





Clive

yabba
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Joined: 18 Nov 2015, 10:01
Location: Samoa

Re: Dedoming IR LEDs

Post by yabba » 27 Jan 2018, 19:01

Thanks Guys,
So looks like the simply de-doming is not the best idea :cry: . Though has anyone made use of a "wavien collar"?, it appears to increase the throw by the recycling of wasted spill light that is redirected back to the die to further excite the emitter in a de-domed system.

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