LEDing a diode

Hi all,
I'm new to this hobby. During this last month I've been building my first blue laser using the 9mm diode sold by DTR. Tonight I read something about "LEDing a diode" and I got scared about the possibility I LEDed my poor diode. I'm running it with a single 3.7V 18650 cell (it's fairly underpowered) but the beam is hardly visible during daylight and it's definitely not as bright as I expected. I know 9mm are stronger than 5.6mm common ones, but even if I'm quite good at soldering I'm afraid I did a mess...
Here is one pic in strong light conditions:



Sorry for the awful image quality, it was taken with my mobile phone (tough it has a very good camera)
I think it's no more than 50-60mW :yabbem: the beam is pretty visible, but not so bright here are some pics (tonight here in Milan the Moon is very bright):
With flash-LED:




No flash:



At home, no light:



I'm very sorry for the poor quality, but my 500D camera is out for repairs

Many thanks to DTR who helped me a lot during these months and to all the people who are going to answer this topic

You got to link directly to the image, not the the page with the image. The beam isn't supposed to be visible during the daylight, you need over 4W for that to happen (my 4.4W was visible in daylight)

It's impossible to tell the condition of your diode from pictures, as different cameras and different settings capture the beams differently.

The beam and dot looks good. Can you show the raw output of the diode without the lens ? It can tell us if your diode has LEDed but I don't think it is.

(the direct link to the image doesn't work , I'm trying to make it work, I had to link the page, sorry for that).
The laser has no burning abilities, it isn't warm at all.

edit: ok, just wait a few seconds blord

no burning? LED or you need to adjust current. what driver are you using?

Here is the RAW inpunt pic:

I'm running the diode with the X-Drive 1.8A driver. As I told in my first message I'm running the diode with a single 2500mAh 3.7V 18650 cell, so it's definitely underpowered.

you can really only tell if we see the raw diode output without the lens but based on the pics it looks fine to me. These diodes are supposed to run on 2 3.7v batteries so you're getting less than half the possible output.

EDIT- Based on the raw output pic it looks like you definitely have something obscuring the diode lens/window but it doesn't appear to have LED'd.

So first thing to do is clean off the obstruction.

Also you said it yourself that you're only running it on one 3.7 cell when you know you're supposed to use 2. So i don't get why you're surprised about low output. :thinking:

@sopark4000: the raw output pic is linked in the prevoius message , just give a look to it. Maybe it's a bit dusty in the module :/, but I can't say, I'm definitely not an expert.

@sopark4000: I know that a post like this "Oh no, I'm running with a single 18650 3.7V cell my diode instead of two and it seems to be underpowered..." sounds crazy, but thinking to the diode efficiency curve and whatsoever I would be able to hypotesize the output of the laser that should be, at 3.7V, more or less 200-300mW. Am I wrong?

I'll soon test it with two 16340 cells that unfortunately can't be easily found in the shops here in Italy. I've still to wait a week or two

I'm also waiting for the shipment of an order I made to DTR a couple of days ago. I hope not to do the same errors I did in this project (for example not heatsinking the driver since I'm too lazy ). It would be great if anyone can tell me if I've damaged my diode or not.

otto9407 said:

@sopark4000: the raw output pic is linked in the prevoius message , just give a look to it. Maybe it's a bit dusty in the module :/, but I can't say, I'm definitely not an expert.

@sopark4000: I know that a post like this "Oh no, I'm running with a single 18650 3.7V cell my diode instead of two and it seems to be underpowered..." sounds crazy, but thinking to the diode efficiency curve and whatsoever I would be able to hypotesize the output of the laser that should be, at 3.7V, more or less 200-300mW. Am I wrong?

Click to expand...

Anywhere from 200-400 sounds about right for a single cell. When you can I would say try running it on 2 cells and see if the output increases to "normal" levels.

But everything else aside based on your raw output pic it doesn't look like you LED'd it or anything but definitely try and see if there is something on the lens or window.

A lot of times when something (a little dirt, lint etc) is on the lens it gets sort of baked on from all the heat and can be difficult to get off but because you've been running it at such a low power it might not be to difficult to get off. Use a magnifying glass and take a look at the lens and window. If there is something there try using a Q-tip and some isopropyl alcohol to clean it off. Be careful with the q-tips though because many of them use a little bit of glue to hold the cotton on and you don't want to dissolve that with the alcohol and have the glue end up on your lenses.

you're gonna be amazed when you put two cells to it.

Your issue is running it on one cell. That's not even close to enough power. You will get normal output when you put in two batteries. Its going to blow your mind on two cells believe me.

Thank you for your answers. Now I've just to wait for the cells (it's taking so long!). I'll post some pics soon (I hope ).

Where are your other cells coming from?

I've bought 4 16340 cells from China. 2 x 880mA protected by Trustfire and 2 x 1000mA by Eneloop (Panasonic, so very good quality cells). I'm going also to build another pointer soon

You will probably end up not even using the Trustfires since you have the other cells. They could be backups I guess. Eneloop(Sanyo/Panasonic) cells are pretty good so you should have no issues hitting your lasers maximum potential. The only other cell that may out perform in raw current driving would be a couple AW IMR cells but you likely won't need them with those Eneloop cells around.