LEDs & Other Stuff - (Reference Guide)


Probably more like 60m diameter for the XHP-70.2 with dome. If you want a smaller hotspot and more throw you should shave (dedome) the XHP-70.2.

Can you tell us the focal length of your lens (assuming that it is in fact an aspheric)?

my lens’s focal length is about 4.5cm .
at 7meter distance spot diameter is 70cm so by using triangle rules at 1000meter distance spot diameter is about 100 meter.

I calculate 124m diameter in 1000m distance using my method (ignoring the corners of the LED).

De-doming the LED and driving it with a high current (FET driver) will get you your 1.5km of throw. The hotspot will be 50% smaller.

i think 124 meter spot at 1KM isn’t that bad for XHP70.2 are you agree?
i’m using my DIY fet driver now and it’s max current can go around 20A.
i have another question.how de-doming can affect on spot diameter?

Here is a comparison I did using the xhp-70. The dome and die size is the same for 70.2, so I would expect the same difference in diameter. (The 70.2 has less donut hole shape)

(Size comparison only)

Read this.

i have an idea.can i use a 80 degree reflector in combination with my lens to collect whole light?is that a good idea?

No, that won't work (using parabolic reflectors). An elliptical reflector could work, but nobody really does that. A dual-lens system definitely works if you do it correctly.

Interesting how “dome off” makes the flag stand at attention.


De-domed is a bit brighter & cooler with less spill and there’s a doughnut hole. I think I prefer domed, taking trade-off of brightness for warmer, smoother beam and greater spill.

Don’t look at brightness, color or spill. The picture was taken on different days with different camera settings. The picture is just to show the hot spot diameter difference. Both have a donut hole pattern, but shaved dome makes it more pronounced.

Ah, OK. Thanks for clarifying. A more prominent doughnut hole would drive me a little batty. I’m so used to nice solid hot spots.

Awesome stuff here.

Another time came back to this CRX’s masterpiece. Whoooa, maaaaan, you should call yourself “torchopedia”. Another time I’m stunned how comprehensive is the first post. Just awesome.
(sorry, I just had to share my thoughts)

He’s the man if you want the best glowy stuff made without getting a second mortgage to pay for it :+1:

Just dropped by. I'm here to say that the Osram CULPM1.TG pictures in the opening post seem incorrect, looks like the die area isn't properly set as it looks exactly like the CSLPM1.TG, only rotated. Being a 4040 emitter it should look 25% smaller both in width and height (versus the 3030).

Cheers ^:)

Good catch :+1:

I have to admire you. Very useful posts.

Awesome CRX, you are amazing. Really thank you for your great effort.

From Andy LEDSign Malaysia

Wow…. I just can’t find any word to say how gorgeous it is !!!
Any way, thanks a lot for doing this…

Anyone know what this is? I don’t think it matches any in the OP.