200mW PHR blu ray

[IgorT]

So, i had this host ready for a 6x, but shipping took a little longer, than expected, and i was without a personal blu ray... So i put in a PHR and set it to 160mA.

It was doing 154mW for a while, but then the power started dropping. At first i wasn't sure if it is degrading or if it's just the temperature, as it was very cold when i built it, and the last few days were getting hotter and hotter.

I was leaving it on for at least 90 minutes every day, and sometimes up to two and half hours, to see what happens at this current. After i got the 6x diode, i started leaving the PHR on even longer, because i wanted it to either die, and make room for the 6x, or proove, that it can make it. But it just didn't want to die, while the power slowly got lower and lower, untill it ended up at 147mW, after about 20 hours of total run time.


Eventually, i got tired of waiting, so i changed the current to 180mA. I also put a 405nm AR coated glass lens in, before turning it on.

Well, it didn't make it for long. But i did manage to take a few pictures, before it died.
It peaked above 200mW, and dropped to 198mW, as it warmed up.

Too bad my name isn't Dave... : On the other hand, i was never this happy about a diode dying before.. ;D

 

[nikokapo]

hahha cool!!


too bad you didnt get sky at night pictures of it

 

[IgorT]

Well, yeah, but in about an hour, this will be a 200mW laser again. Only that this time, it won't die..


But now that i killed it, i can't help but wonder, how much longer this diode could have made it, if i left it at 160mA...
I need to hook one up permanently, just to test this. I have one with normal efficiency, and a broken leg - a perfect candidate..

 

[daguin]

Well, yeah, but in about an hour, this will be a 200mW laser again. Only that this time, it won't die..


But now that i killed it, i can't help but wonder, how much longer this diode could have made it, if i left it at 160mA...
I need to hook one up permanently, just to test this. I have one with normal efficiency, and a broken leg - a perfect candidate..

And stop leaving them on for 90 minutes!

<sheesh> I thought I was cruel . . . .

Peace,
dave

 

[IgorT]

I kinda regret not setting it to this level from the start tho. Then it would still work, if i wasn't leaving it on this much. And the power would have been higher, had i not waited for it to degrade first..

I had one, that did even more power, than this one, at the same current. But it died before i got the lenses..

 

[IgorT]

And stop leaving them on for 90 minutes!

<sheesh>  I thought I was cruel . . . .

Haha, well, i want to see how long they can take these currents.. How much would you say you use yours per day?

Otherwise, i don't leave it on for 90 minutes at once.. 90 minutes is just the average total per day. 30 minutes (without a break) of this is playing at night, 30 (no break) is testing or measuring temperature (stays below body temp). And 30 more is when i just pick it up and use it for a minute or two every now and then.

All together, it amounts to 90. But i have left it on for 60 minutes at once, a couple of times, to measure the temperature.. After 30 minutes it was 33°C, and after 60, it was 36°C or so.. That was at 24°C ambient..



Since they are not overheating, i do not believe a duty cycle would prolong their life in hours of use.. In days, yes, because it would limit the total time of use per day.. But i'm still wondering what will happen after those reach 20 hours... Unless 10°C make a huge difference of course.. Who knows..

 

[IgorT]

Otherwise, how else can we figure out the max safe power for these?

I will hook up the broken leg diode to 143mA permanently now, to see if it can make it, and for how long..
I'll let it cool off every day, and measure it's power.. I REALLY hope i notice no degradation at this current.

Then, if something happens, i will make a constant temperature setup, with a peltier, and a special buck peltier driver with a temperature sensor, and try again, to see if a few degrees of temperature really matter this much...

 

[jamie.91]

OMG thats great this is what the laser community realy needs

 

[daguin]

Otherwise, how else can we figure out the max safe power for these?

I will hook up the broken leg diode to 143mA permanently now, to see if it can make it, and for how long..
I'll let it cool off every day, and measure it's power.. I REALLY hope i notice no degradation at this current.

Then, if something happens, i will make a constant temperature setup, with a peltier, and a special peltier driver, and try again, to see if a few degrees of temperature really matter this much.

I run mine about 15-20 minutes a day. I believe that this is a much more realistic "usage" test. I really do appreciate your "long-term" tests. However, if you truly believe that the temperature and length of burn are not a factor, why not just leave it on until it dies? Why limit it to 30-90 minute burns? That way you will kow exactly how long it will burn. I believe that you are also bringing into the equation, length of enduring the heat produced while removing the stress of turning it on and off. That is nice for testing the limits of the diode, but not easily translatable into everyday use of a hand held laser.

My records show that my 190mW unit has just over 7 hours of burn time on it now. It has taken a month to get to that level. Plus, more than 3/4 of that was in the first two weeks of "hell" that I put it through. With your testing it would take less than 5 days to reach that usage level. However, even in the "hell week" it rarely gets longer than a 2 minute burn. Unless it's going into a spirograph or a scanner, it will rarely be on for that long anyway.

We are pushing these well past their rated outputs. I think that they should be tested as close to "real life" as possible. I don't really care how long it would work in a DVD burner at these output levels. Even then, how many DVD's does the average person burn a day. I want to know how it will work as a laser pointer.

Peace,
dave

 

[IgorT]

Well, if this really is the 60mW Sanyo diode, then we are really torturing them!

I mean, with reds, we usually pushed them to their pulsed ratings, which are about 2x the CW rating. Here, we think we are gentle to it, if we "only" push it to 120mW.. And the rated powers are without optics! So when you're getting 100mW after a plastic lens, you're already pushing it to twice it's rated CW power..

If it is the Sanyo diode of course.. And if it is, then it was doing over three times it's rated power in the above picture..


I really want to figure out what power they can do reliably, without fear of failure.

According to the datasheet, the Sanyo diode can live for 8000 hours at 25°C and 5200 hours at 50°C.. That's if it's doing 60mW... Who knows what happens at twice that power or more....



EDIT: I forgot to emphasise, that the temperature/lifetime example is about constant power, not constant current. At a higher temperature, the same power requires quite a bit more current. Which is why the difference in expected lifetime between 25°and 50° is so big..

At constant current, the difference between these two temperatures should not be as dramatic. But we do not yet have a baseline for high powers..

 

[IgorT]

However, if you truly believe that the temperature and length of burn are not a factor, why not just leave it on until it dies?  Why limit it to 30-90 minute burns?  That way you will kow exactly how long it will burn.

Well, yeah. That's why said i'll hook one up permanently to 143mA. I wanted to do it before, but i ran out of diodes.. I have one, that got stuck in the module, and broke a leg.. It has a good average efficiency, so what better use for it, than this..

Temperature does matter of course. But normally, they are meant to work at up to 70°C.. Of course, that is when not pushed..
No one knows how temperature matters at the currents we are using yet.. That's why i would also like to make another unit at the same power but at a constant temperature, to see if there is a difference..

But as i said in a previous post, i really don't know how it matters, or what matters. I'm just thinking out loud, trying to figure it out...

We are pushing these well past their rated outputs.  I think that they should be tested as close to "real life" as possible.  I don't really care how long it would work in a DVD burner at these output levels.  Even then, how many DVD's does the average person burn a day.  I want to know how it will work as a laser pointer.

I agree, Dave. But i do not have a "laser accelerated aging machine" other than myself..  ;D

And i can not spend all day turning it on and off, with pauses in between, to let it cool off. So i do a little of everything. I pick it up every now and then and power it for two minutes. And then i leave it on for 30 minutes, when playing outside at night - in this case i often forget about time untill after.

The temperature measurements also did their part in aging it, but they were mostly meant to test the functionality of the heatsink.

But i do torture my personal lasers on purpose. I want to see what happens. If they die, i want them to die in my hands...



Otherwise, 7 hours is a lot for 190mW! Is it still keeping the same power as at the start?

 

[IgorT]

I guess i'll have to reduce my personal laser use per day..   :-[

 

[daguin]

Otherwise, 7 hours is a lot for 190mW! Is it still keeping the same power as at the start?

Damnable floppy fingers

The laser is being powered at 190m[highlight]A[/highlight]. It is putting out 180m[highlight]W[/highlight] (the 7 hours one w/ Merideth glass) The power output is the same. I have had to recharge the battery once in that time. It made me very sad when it went dark the first time. Then I remembered it was a flexdrive and recharged the battery

My 200mA one is putting out 185mW (w/ Merideth glass). It has only been in testing about a week now.

I proof read . . .honest I do :-[

Peace,
dave

 

[IgorT]

Hehe.. Well, 180mW is still a lot, even after a Meredith. That would mean 160mW after a plastic lens.

The diode i killed in the picture above did 154mW before the current change, according to my meter (or 165mW, according to Scopeguy's meter. BTW, this is why i'm asking, if you compared your meters - so that i could compare my finding to yours)..

And with this diode, the degradation was noticable in under 7 hours, which again makes me wonder, what voodo you are using..


But if the little difference in temperature is such a big factor, the constant temperature setup would show this..
Besides, i really want to find an excuse, to put that special Peltier driver together..  :

 

[daguin]

Besides, i really want to find an excuse, to put that special Peltier driver together.. :

I wholeheartedly agree that putting the Peltier together is a good idea. I would love to see what happens when we take heat out of the equation.

Speaking of heat. Tallaxo is making me a big heat sink. I think that I'm going to wait for it before I fire the 300mA laser back up. I would like to take heat out of its equation as well.

Peace,
dave


P.S. It's not voodoo. It's JuJu

Peace,
dave

 

[IgorT]

I think that Jayrob's heatsinks are more than enough, to eliminate heat problems with normal use. These diodes don't heat up much.

But if you want to leave one on for hours, then a big heatsink would definitelly be beneficial..


Oh wait, for the 300mA! I was thinking in normal terms... Whatever that is... : Yeah, you might want to mount that one to as large a block of aluminum, as possible.... ;D

Where will you mount it?



I really want to make that thing, i just don't know when i will find time to draw the peltier driver board, with all the other projects.. :-/ The buck regulator has so many legs, it looks like a mutant caterpillar! It's a very complicated circuit.