Faulty Laser Diode? Or did I fry it...

[pupper42]

Hey everyone,
Sorry if there was already a post about this, I did use the search function but didn't find much stuff.
Anyways I bought two SLD3134VL 20mw 405nm diodes from eBay and they arrived in plastic packaging (not even in antiESD bags).
So I tried out one of the diodes by using a constant current driver built from an LM317. The diode needs 32mA (max rating) so I used a 40 ohm resistor between the adjust and output pin (I put one 47 ohm and one 270 ohm resistor in parallel). I powered the driver using 11V and connected the diode (LD anode to +, common to -) but it wasn't very bright. Next I tried the other diode and it was super bright for a split second and then it fried.
So I'm not sure if I'm giving too much current to the diodes (maybe the tolerance of the resistors is too large?) or if the diodes are somehow faulty or got damaged (maybe ESD damage?).
Does anyone know what I did wrong? Or if the diodes are actually faulty does anyone know any reliable sources to get decent powered 405nm diodes?
Thanks everyone

 

[Lifetime17]

Hi,
I have this build with a 405nm/5.6mm diode its a Sharp 1.1W 405nm diode. in the host it puts out over 1800mW's with a G2 lens.
I have no idea what went wrong with you diodes and yes it could have been faulty ESD practices.
What diode is the 405 ant referent numbers for it?
Rich

 

[Philipnzw]

Those Sony 405nm are kinda wack imo. I had a 150mW version a while ago. I decided to over drive it slightly, I'm guessing 200mA. It died after 3 days. I think it's just the nature of these 405nm diodes. I heard that they are very delicate to current spikes and seem to die often. My friend has a similar experience with those Sony 405s, they died randomly even when powered at normal settings.

 

[Cyparagon]

I don't suppose you connected the diode to the output pin, Mr. Pupper? 11V generated by what? A picture of your setup may help a great deal.

 

[Encap]

405nm is difficult to see and even if running perfectly 20mW 405nm is not going to be very bright so...
20mW of 532nm green is about 8X brighter than 20mW 450nm blue which is 10X btighter than 20mW 405nm.

 

[pupper42]

405nm is difficult to see and even if running perfectly 20mW 405nm is not going to be very bright so...
20mW of 532nm green is about 8X brighter than 20mW 450nm blue which is 10X btighter than 20mW 405nm.

I see, but I'm fairly certain it's wayy too dim. It can barely illuminate my hand 10cm away

I don't suppose you connected the diode to the output pin, Mr. Pupper? 11V generated by what? A picture of your setup may help a great deal.

So I'm using this circuit powered by a Lipo battery. I connected Iout to the LD anode, and ground to the common pin of the diode. Instead of the 10 ohm resistor I'm using 40 ohms.
View attachment 69493View attachment 69494

Here's some photos:
View attachment 69492View attachment 69495
I don't think the diode's lasing since it doesn't look like its got those speckles.
I can use this driver to power these red modules I have that have a similar current to these 405nm ones.
Thanks for you help

 

[Cyparagon]

It would appear I somehow I guessed the problem correctly. Your positive lead is soldered to the OUT pin. It should be soldered the the ADJ pin. I would think this bypasses the regulator entirely, minus some intrinsic voltage drop. I don't see how this (exact) setup could power any red, as it would likely kill most laser diodes.

 

[pupper42]

It would appear I somehow I guessed the problem correctly. Your positive lead is soldered to the OUT pin. It should be soldered the the ADJ pin. I would think this bypasses the regulator entirely, minus some intrinsic voltage drop. I don't see how this (exact) setup could power any red, as it would likely kill most laser diodes.

Oh my I feel so stupid lol
Thanks so much for the help
Just wondering do you think I should increase the resistance a bit more in case the tolerance is outside the acceptable limits
EDIT: Nevermind, just checked it with a mulitimeter, seems to be within the limits

Thanks everyone for your replies! You all really helped

 

[Snecho]

Thanks everyone for your replies! You all really helped

Glad you got it worked out!

I'm curious about why you have and are using a Zippy Li-Po pack. Are you into R/C?

 

[Buffo]

using a Zippy Li-Po pack. Are you into R/C?

Hmmm - 3S lipo with XT60 connector... I'm guessing a 250 series quad-copter?

Adam

 

[Snecho]

Hmmm - 3S lipo with XT60 connector... I'm guessing a 250 series quad-copter?

Adam

Hmmm, could be. I've mostly seen XT60 connectors on surface vehicles such as buggies and trucks, but I guess they have been getting more and more popular.

I guess you're into R/C too?

As you can see, I'm more used to blue EC3 and little red JST connectors lol

 

[pupper42]

Glad you got it worked out!

I'm curious about why you have and are using a Zippy Li-Po pack. Are you into R/C?

Well I tried making an RC plane but I think I broke the ESC... so I'm just reusing the battery for lasers lol
Though when I have time I might try again...

 

[Buffo]

I've been into RC off and on ever since the late 1970's. Started with planes (glow fuel) when I was very young and never got very good. Sold everything when I got into High School.

Jumped into 1/10th scale off-road cars in the mid 1980's (Ni-Cd) and had a ton of fun. Started racing with a crappy Tamiya Grasshopper and eventually graduated to an RC-10. (This was back in the AM radio days, mind you. Airtronics XL2P for the win!)

Then I moved, the local hobby shop in my new location closed, and I had no one to race with anymore. So I got out of the hobby for a good 20 years.

Picked up a cheap fixed-pitch heli on a whim about 9 years ago and it was enough to suck me back in. Purchased several fixed-pitch birds as I learned how to fly all over again. Eventually moved up to collective pitch but I soon got bored (probably because I never was very good at flying CP.) Currently have 3 collective pitch birds that I never fly anymore (150, 250, and 450).

I do have quite a collection of quad-copters though, including at least a half-dozen FPV racing quads. Four of them are in the 250-285 class, but the fastest one is a 150 class Diatone GT that absolutely screams with a 4S. Unfortunately I currently have everything packed up in the storage unit. (Haven't gone out to fly since before COVID hit.)

Every year at SELEM for the last 3 or 4 years we've raced quads in the field next to the parking lot, and it was always great fun. Really going to miss that this year.

For the older folks (like me) who enjoyed RC cars back in the day, I can offer this advice: Modern technology has *vastly* improved this hobby! LiPo batteries are amazing, the new radios are fantastic, and parts are cheaper than ever. But that's not the best part... The best part is adding FPV to a car! Yeah, FPV flying is cool, but not everyone wants to learn how to fly. But putting a tiny camera on a 1/10th scale car so you can zoom around in the backyard is waaaay more fun than it should be. Given that you can get an all-up camera and transmitter for around $40 and a set of FPV goggles for $60, there's no reason you shouldn't at least give it a try.

Adam

 

[hakzaw1]

405nm is difficult to see and even if running perfectly 20mW 405nm is not going to be very bright so...
20mW of 532nm green is about 8X brighter than 20mW 450nm blue which is 10X btighter than 20mW 405nm.

this ^^^ is what I also think--20mW of 405 is not very powerful looking --even 1W of 405 looks somewhat harmless but as said very dangerous. safety first - always buy your eye protection BEFORE buying/making the laser.

hak

 

[Buffo]

20mW of 405 is not very powerful looking

Good point Len. Although based on the discussion above it seems likely that pupper42 may have fried his diode. If it was lasing he should have seen *something*...

One easy way to tell if a 405 nm laser diode is, in fact, lasing is to aim the spot onto a sheet of notebook paper. Nearly all commercial paper contains optical brighteners that make the paper appear whiter. Optical brighteners are dyes (and in some cases, pigments as well) that absorb UV light and fluoresce in the blue spectrum. By adding extra blue to the light reflected from the paper it appears to be a brighter white to our eyes. This stuff is added to all kinds of products, including paper, textiles, and even laundry detergent! (One of the companies at the chemical manufacturing site where I work used to make a whole bunch of these types of products, and I've actually worked with the concentrated product quite a few times.)

Anyway, 405 nm light is very hard to see with the human eye, as you pointed out. *But*, 405 nm is close enough to UV that it will excite the optical brightener dyes that are added to notebook paper. When this happens, the dim, fuzzy, almost invisible violet dot will immediately change to a bright sky-blue color, and in some cases the spot may even look white. If you see this effect, you know the laser diode is actually lasing. The giveaway is that tiny but bright blue spot on the page, which is caused by the fluorescence of the optical brightener. It means you've got a collimated beam of 405 nm light hitting the page.

even 1W of 405 looks somewhat harmless but as said very dangerous

Another good point. 405 nm is inherently more dangerous than other wavelengths, even at lower powers, but 1 watt of 405 is downright scary!

Obviously shorter wavelength light = higher energy per photon, and it also means a smaller diffraction limit so your focus spot is smaller. But once you get to 440 nm or shorter you have enough energy to actually start chemically-bleaching the photo-receptors in your eye, which is damned dangerous. As for the focus spot issue, you can easily etch/burn/char leather with just 50 mw of 405 if you focus it to a diffraction-limited spot. You won't get the same effect with 50 mw of 660 nm red though.

So yeah, always be safe, but be especially cautious when working with 405.

Adam

 

[pupper42]

Thanks for the safety advice as well, I'll keep it in mind
I've got the Eagle Pair safety goggles as well