my 2 16x BDR-209 builds a 1 single mode 638

[Johnnyboy]

Hi guys I have built 2 "405nm" lasers with pretty cool looking hosts the silver one uses a driver that set to 700mA and the black one has the same stuf) The host with all black with a logo has the single mode 638nm diode and a driver set to 400mA I have 2 638's but I added this one randomly for fun.

But I noticed with the two Blu-rays even when both are set on the same current, one appears noticeably brighter than the other, I don't really know why that is but I know these diodes are not really 405nm. If I had to guess the silver one has a 415nm diode slightly more or less - Which would be the brighter one. The other one has probably a 410nm wavelength more or less idk but it's not as visible. I have read somewhere on the forums that these diodes can reach 415nm+ and some just don't. This could be why one appears more visible than the other. I wonder what the max wavelength these diodes can really reach? A 420 or 425nm blu-ray would be pretty cool to have but I doubt the BDR's can reach that.
I have them both set at 700mA time well tell how long they will last there. If they last then I will plan on building another with a higher current. Anyways I figure I would share some of my builts.

I even tried new batteries for both but it's the same as before. I got them diodes both from Techhood.

 

[paul1598419]

Re: my 2 16x BDR-209 builds a 1 one single mode 638

The BDR-209 diodes, like all laser diodes don't give the same optical power just because the diodes are set to the same current. Every diode is unique in this way, and optical power is also determined by the type of lens you use. Your beam shot doesn't look collimated. That is the reason for the lens.Until you measure the power of each laser, you can't know what power they are putting out. Setting the current for 700 mA is quite high and may cause these to die prematurely. I wouldn't try to set them even higher.

 

[Benm]

Re: my 2 16x BDR-209 builds a 1 one single mode 638

If you have everything equal (module, lenses, drivers etc) there can be a significant difference in how bright the beam appears to your eyes based on wavelength. So yes, 415 would appear much brighter than 405 at the exact same power level.

You can measure the power with an LPM if you want, which should give roughly the same reading to both, despite one looking much brighter than the other.

I'm not entirely sure what the tolerance range on these 405 nm diodes actually is, but i doubt it would be much beyond 515 nm or so. After all they need to read and write blu ray discs that require a fairly narrow window of wavelengths to work at all.

The question remains what happens if they produce a batch that for some reason as a wavelength too long to be suitable for reading discs: would they just be discarded, or be sold on ebay or something as they would be very good for the laser hobby market despite being unusable for the intended purpose?

Wavelength will also increase a bit with temperature, but running them really hot just to get longer wavelength seems to shorten diode life by quite a bit.

 

[paul1598419]

Re: my 2 16x BDR-209 builds a 1 one single mode 638

I would be amazed to find any of these that could be pushed past 440nm. Probably can't even get near there. DTR recommends maximum current be set at 600 mA, but many have failed at this level. It would be better to set it to 500 mA which should give an output between 775 mW and 850 mW with an aspheric lens. To know for sure, you would have to measure the power.

 

[Johnnyboy]

Re: my 2 16x BDR-209 builds a 1 one single mode 638

This post is was a month ago but looks like the window in the 'brighter' diode is all screwed up now anyway, The diode still works but I think something might have got on the window and got burned up from the laser then damaging the diode can window part. I tried cleaning it and no luck it's probably permanently damaged. The dot of the laser now looks really badly messy. I guess its time to get another one to replace it. There might be a way to fix that but I think I would be better off getting another one anyway. At first I thought it was the focusing lens so I put a new one on there and it looked the same way all messed up. That really sucks because It's been a while and the laser was still 'kicking and it didn't die yet from the 700mA current but then something else like the diode glass part got all fcked up on it anyway. Talk about bad luck. I seen other posts people had the same problem with diode cans. That's a really shitty thing to happen to a good laser diode.

 

[Benm]

Considering the low cost of the diodes replacing it would be best, though you could attempt to remove the window (de-can the diode). It's not always succesful or easy, but you can try if you were to trash it otherwise.

 

[paul1598419]

That 3.8mm diode might be very difficult to remove the can from and still have a working diode. The TO5s are much easier to de-can.

 

[Miya]

BDR-209 is 420nm ~ 425nm? it is Higher wavelength than S06J. I killed many BDR-209 build. Also recently, it has been selling two legs
I wonder if I will succeed if I make BDR-209. :cryyy: